I've used OCaml a bit and found various issues with it:
* Terrible Windows support. With OCaml 5 it's upgraded to "pretty bad".
* The syntax is hard to parse for humans. Often it turns into a word soup, without any helpful punctuation to tell you what things are. It's like reading a book with no paragraphs, capitalisation or punctuation.
* The syntax isn't recoverable. Sometimes you can add a single character and the error message is essentially "syntax error in these 1000 lines".
* Ocamlfmt is pretty bad. It thinks it is writing prose. It will even put complex `match`es on one line if they fit. Really hurts readability.
* The documentation is super terse. Very few examples.
* OPAM. In theory... I feel like it should be great. But in practice I find it to be incomprehensible, full of surprising behaviours, and also surprisingly buggy. I still can't believe the bug where it can't find `curl` if you're in more than 32 Unix groups.
* Optional type annotation for function signatures throws away a significant benefit of static typing - documentation/understanding and nice error messages.
* Tiny ecosystem. Rust gets flak for its small standard library, but OCaml doesn't even have a built in function to copy files.
* Like all FP languages it has a weird obsession with singly linked lists, which are actually a pretty awful data structure.
It's not all bad though, and I'd definitely take it over C and Python. Definitely wouldn't pick it over Rust though, unless I was really worried about compile times.
I would suggest that people interested in using OCaml on Windows (or indeed, OCaml at all) try F# instead. It is still an ML-family language. Incidentally, by targeting the CLR, F# is considerably more deployable (both to users and to developers) than OCaml is. Plus, any old NuGet library written in C# or VB.NET can be used almost trivially in F#. This also solves the problem OP listed about a tiny ecosystem, because the C#/.NET ecosystem is massive.
I couldn't agree more with the parent commenter about OCaml documentation. Functional programmers appear to love terseness to an almost extreme degree. Things like `first` are abbreviated to `fst`, which is just odd. Especially now that good IntelliSense means there is no real functional (heh) difference between typing `.fi` and pressing Tab, and typing `.fs` and pressing Tab.
The F# documentation is comparatively very spiffy and detailed, with plenty of examples[1][2][3].
To decide on a language for a math research project, I implemented a toy problem in many languages: What is the distribution of cycle counts for signed permutations on n letters? Use all cores in parallel.
C++ 100 19.57s
Rust 96 20.40s
F# 95 20.52s
Nim 75 26.04s
Julia 64 30.40s
Ocaml 48 41.07s
Haskell 41 47.64s
Chez 39 49.53s
Swift 33 58.46s
Lean 7 278.88s
Tarjan, n = 10
Nyx - Apple M4 Max - 12 performance and 4 efficiency cores
n! * 2^n = 3,715,891,200 signed permutations
score = gops normalized so best language averages 100
time = running time in seconds
This had me briefly smitten with F#, till I realized the extent that rusty .NET bed springs were poking through. Same as the JVM and Clojure, or Erlang and Elixir. The F# JIT compiler is nevertheless pretty amazing.
I nearly settled on OCaml. After AI warning me that proper work-stealing parallelism is a massive, sophisticated project to code properly, the 40 lines of OCaml code I wrote that beat available libraries is my favorite code file in years.
Nevertheless, once one understands lazy evaluation in Haskell, it's hard to use any other language. The log slowdown for conventional use of a functional data structure becomes a linear speedup once one exploits persistence.
F# is a nice language, but it depends on .NET, so a direct comparison to OCaml is not possible. The .NET runtime dependency often makes things unnecessarily complex and fragile. There must be a reason why Golang (no VM runtime) is successful despite entering the market very late after Java and C# had already established clear dominance.
Easier deployment helped, but nowadays it’s common to put a single Go executable in a container anyway. .net core doesn’t have much if any disadvantage there.
Go was made by Google flawed, but with clarity of purpose and consistently usable libraries.
.NET spent years forked into framework and core and unclear open source future.
Java struggled to scale down and Oracle caused similar distrust as Microsoft.
While I agree with most points, .NET or JRE introduce additional complexity that may not be welcome in every setting. I've worked for several companies where upgrading to a newer version of .NET was always a major pain point, especially for applications that weren't very actively developed. There is limited security support for each major .NET version, so at some point, you and your customers need to upgrade. Such problems are non-existent if you don't have a separate VM runtime dependency.
> I've worked for several companies where upgrading to a newer version of .NET was always a major pain point,
This was so difficult for the teams I work with that the person who became the team specialist in MSBuild, dotnet, and C# basically punched his ticket and received a couple of promotions. The work is so miserable and challenging that basically no one else Will take it.
I've struggled to understand why .net upgrades are so painful and laborious despite the maturity of the languages and ecosystems. I had assumed that, as with Powershell, C# and .net behind the scenes are undergoing enormous changes as Microsoft attempts to improve or add support for historically neglected platforms and hardware, and so I had assumed also that these were temporary problems, just badly managed growing pains on a path to major improvement, but I gather from your comment that the problem has a long history and is systemic. Awful.
MSBuild has been a huge source of the suffering I've experienced while working on these projects. The documentation is, in my experience, a nightmare: exhaustingly verbose, full of jargon, and uncanny in its ability to talk around an issue, concept, or functionality without clarifying anything conceptually or practically. I find this throughout Microsoft docs.
Upgrading a modern .NET (Core) version often means changing just versions in the project file. Upgrading from the old .NET Framework is bit more challenging, but we have also successfully upgraded a couple of Framework projects to modern .NET without too many issues.
I don't think so. Upgrading to a newer major version of the C++ runtime essentially involves recompiling, unless you're dealing with an application that's 15 years or older. You can even instruct the compiler to use an older C++ standard if your code won't compile with the newer one. There is also an option to compile the runtime statically, though it is obviously not recommended.
F# is indeed an ML-family language, but at this point it doesn't have all that much in common with OCaml specifically: it doesn't have the latter's structurally typed object model with inferred row-polymorphic types, nor its extremely powerful module system, not even many convenience features like open variants.
F# has plenty of features that OCaml doesn't have like proper cross-platform support, proper deployment, active patterns, units of measure, computation expressions, type providers, interfaces on unions and records, etc. F# is probably faster as well and definitely has a larger ecosystem through .NET.
F# is worse because the type inferencing isn't as good. You need to type annotate in more places. It's a drag, because it feels like a missed opportunity to let the machine do work for you.
Additionally, one of the most pleasant and unique features of OCaml, strong named arguments, doesn't exist in F# (except in methods or whatever). Most programming languages don't have this (or it's hamfisted like in more dynamic languages) so it doesn't seem like a loss, unless you are very cozy with them in OCaml.
(I'm bitter about this one because named arguments give safety and convenience. But when you combine them with currying it's like 4 or 5 design patterns that are elegantly provided for you. You just do it implicitly, without ever having to study a book about using them.)
Finally, F# brings back the NULL problem that OCaml worked so hard to eradicate.
Nearly the same as with positional argument: Partially applying a function to a named argument creates a closure with this argument filled in, and you can apply the argument in whichever order you want:
let f a ~x ~y b = a + x + y + b
let g = f ~y:1 (* g is closure with the argument named ~y filled in *)
let h = g 2 (* another closure with the first positional argument filled in *)
let int_15 = h 8 ~x:4 (* = g 2 8 ~y:4 = f ~y:1 2 8 ~x:4 *)
The more complex interaction is rather with type inference and currying, or the interaction between currying and optional arguments.
> * OPAM. In theory... I feel like it should be great. But in practice I find it to be incomprehensible, full of surprising behaviours, and also surprisingly buggy. I still can't believe the bug where it can't find `curl` if you're in more than 32 Unix groups.
A lot of these are learning curve issues, but once you scale them you still permanently suffer with a very deficient, fragmented ecosystem. Until you have built up your own curated set of dependencies for your business stack, anyway.
> * Ocamlfmt is pretty bad. It thinks it is writing prose. It will even put complex `match`es on one line if they fit. Really hurts readability.
I suggest configuring ocamlformat to use the janestreet profile for better defaults.
> * Optional type annotation for function signatures throws away a significant benefit of static typing - documentation/understanding and nice error messages.
People should be providing .mli files, but don't. That said, an IDE with type hints helps this enormously. The VS Code plugin for OCaml is the best experience for noobs, hands down.
> * Like all FP languages it has a weird obsession with singly linked lists, which are actually a pretty awful data structure
This made me chuckle. I've had that thought before, shouldn't the default be a vector on modern devices? Of course other collection types are available.
The reason why functional languages like linked lists so much is because they are very easy to make immutable without a lot of pain all around. If you implement an immutable vector in a straightforward way, though, you basically need to do a lot of copying for any operation that needs to construct one (the rigmarole with immutable strings, and existence of hacks such as StringBuilder, is a good illustration of the problem).
But you can have a data structure that is more like vector under the hood while still supporting efficient copy-with-modifications. Clojure vectors, for example.
That makes sense. But LinkedIn lists are horrible for cache efficient things no? I think there was an article on HN from a Golang perspective padding structs or something such that they are efficient wrt to cache hits.
LinkedIn lists will tell you they contain one new element, but you have to click on a link and scroll through their suggested new elements to see what it is
I'd say that functional programming is probably one of the only domains where linked lists actually make sense. Vectors certainty have their use in more places though.
A good compiler will make the lists disappear in many cases. No runtime overhead. I actually love single linked lists as a way to break down sequences of problem steps.
I believe it's possible in theory - Koka has a whole "functional but in-place" set of compiler optimisations that essentially translate functional algorithms into imperative ones. But I think that's also possible in Koka in part because of its ownership rules that track where objects are created and freed, so might also not be feasible for OCaml.
I mean, the set of valid deforestation transformations you could do to an OCaml program is not literally the empty set, but OCaml functions can do I/O, update refs, and throw exceptions, as well as failing to terminate, so you would have to be sure that none of the code you were running in the wrong order did any of those things. I don't think the garbage collection issues you mention are a problem, though maybe I don't understand them?
Part of what Koka's functional-but-in-place system relies on is the Perceus program analysis, which, as I understand it, is kind of like a limited Rust-like lifetime analysis which can determine statically the lifetime of different objects and whether they can be reused or discarded or whatever. That way, if you're, say, mapping over a linked list, rather than construct a whole new list for the new entries, the Koka compiler simply mutates the old list with the new values. You write a pure, functional algorithm, and Koka converts it to the imperative equivalent.
That said, I think this is somewhat unrelated to the idea of making linked lists disappear - Koka is still using linked lists, but optimising their allocation and deallocation, whereas Haskell can convert a linked list to an array and do a different set of optimisations there.
Why would a specific way of structuring data in memory be relevant to breaking down sequences of problem steps?
If what you mean is the ability to think in terms of "first" and "rest", that's just an interface that doesn't have to be backed by a linked list implementation.
Not GP but bump allocation (OCaml's GC uses a bump allocator into the young heap) mitigates this somewhat, list nodes tend to be allocated near each other. It is worse than the guaranteed contiguous access patterns of a vector, but it's not completely scattered either.
+10 for bad windows support, i think this is a key and weirdly underestimated reason
just to give an idea how bad, until recently, you could not just go to ocaml.org and download ocaml for windows, you had to either download one for mingw or wsl
so for many it was just not installable, i.e. for many we didnt have ocaml for windows, until very very recently
The Windows support is bad because OCaml is a PL designed by people who are deep in Linux life. Windows is not something that keeps them up at night. (Which isn't to say they didn't try, just, you know, not as much as it takes)
One of the things people often neglect to mention in their love letters to the language (except for Anil Madhavapeddy) is that it actually feels UNIXy. It feels like home.
If that's what you use as your yardstick of what's Unixy, then I guess you don't consider "find" to be Unixy, in spite of being one of the early Programmer's Workbench tools.
Short options were a compromise to deal with the limits of the input hardware at the time. Double dashes were a workaround for the post-dash option car crash traditional Unix tooling allows because teletypes were so slow. There is nothing particularly Unixy about any of these options other than the leading hyphen convention.
Caml was developed in 01985, Linux was first released in 01991, and Caml was extended into OCaml in 01996. I don't think the developers were using Linux at the time; SunOS 4 would be my best guess. I didn't work on it, but I was in the sort of internetty environment that OCaml came from, and I was using Solaris at work and got my first Linux box at home. As another commenter mentioned, the command line follows Unix conventions rather than the Linux conventions from GNU.
It's just sort of anachronistic. Caml was no more designed by people deep in Linux life than James Clerk Maxwell was into aviation or Christopher Columbus liked to visit the Massachusetts Bay Colony. They probably would have been, but the timelines didn't allow it.
Sure. The larger point was about Windows. You would or would not agree that people doing PL research on SunOS workstations (or whatever UNIX) would also not give a shit about Windows?
Windows didn't exist in 01985. I mean, Microsoft did release a product by that name at the end of the year, but it wasn't an operating system.
I remember that in 01998 or 01999 I asked Andrew Tanenbaum, a different European CS professor, what he thought about Linux. His impression was still that it was some kind of hobbyist project for people who (paraphrasing here and reading between the lines) couldn't afford a real computer. So I suspect that, even when Caml became OCaml, its developers saw Linux as belonging to the same crowd as Microsoft Windows, rather than to the systems they were used to.
But even that Windows/Unix OS dichotomy didn't exist when the programming language was designed. They might have been thinking about Unix vs. VMS, or Unix vs. GCOS, or Unix vs. Oberon, or BSD vs. System V, but definitely not Linux vs. Windows.
I don't think you would be flagged. Rust definitely has flaws:
* Compile time is only ok. On par with C++.
* Async has a surprisingly number of footguns and ergonomic issues.
* There's no good solution to self-borrowing or partial borrows.
* While using macros is fine, writing them is pretty awful. Fortunately you rarely need to do that. Relatedly it is missing introspection support.
* Sometimes the types and lifetimes get very complex.
But overall I still much prefer it to OCaml. The syntax is much nicer, it's easier to read, the ecosystem and tooling are much better, the documentation is much better, and it actively hates linked lists!
* Crates.io is an unmoderated wasteland of infinite transitive dependency chaos
But my "favourite":
* It's 2025 and allocator-api (or its competitors) is still in nightly only and no sign of stabilizing
I work almost exclusively in Rust, and I like the language but in many respects a) Rust is the language that tokio ate, and b) it has been deluged with people coming from the NodeJS/NPM ecosystem doing Web Scale Development(tm) and its terrible practices around dependency management.
> Crates.io is an unmoderated wasteland of infinite transitive dependency chaos
Well, I'm not sure I agree with that. If by "unmoderated" you mean anyone can upload a crate without going through bureaucratic approvals processes then that seems like a good thing to me!
But you did remind me of one other majorly annoying thing about the crate system: the global namespace. It doesn't have the same security issues as Python's global package namespace, but it is really really annoying because you pretty much have to break large projects down into multiple crates for compile time reasons, and then good luck publishing those on crates.io. Plus you end up with a load of crate names like `myproject-foo`, `myproject-bar`, which is very verbose.
Oh and yeah, the Tokio situation is a bit sad.
Also the proliferation of some types of crates like error handling. This should really be in the standard library by now (or at least fairly soon). Any large project ends up with like 5 different error handling libraries just because dependencies made different choices about which to use. It's not a major issue but it is silly.
Overall though, still my favourite language by far.
I think the error type stuff should be less prominent, and really shouldn't be front-and-center in the standard library, or any library. Error handling is undoubtedly important, but its expression in the API is a different matter. I don't have fully formed opinions, but I do feel that the common recommendations are bad.
On the topic of allocators, I noticed some PRs to add allocator support to more types recently...great, now we just need to stabil—oh, wait. Although I care more about not stabilizing a bad API than eternal unstability, if it comes down to that.
The problem for me is that instead of focusing on the problem at hand and the business logic, I have to focus on the Rust memory model and the borrow checker. And seems very verbose.
Thing is, if I sketch something in pseudocode, I should be able to translate it to any mainstream programming languages. With Rust I can't just do that, I have to bend the problem to fit the way the language works.
That third issue is very annoying. C++ in visual studio often has that and I'll help someone who has like 2,000 weird errors and my response is usually "looks like a missing semicolon to me" and they're like "????" Why wouldn't it be able to just say that.
> The documentation is super terse. Very few examples.
I agree. OCaml is a complex language with very beginner-unfriendly documentation. In fact, I would even say it's unfriendly to engineers (as developers). The OCaml community prefers to see this language as an academic affair and doesn't see the need to attract the masses. E.g. Rust is an example of the opposite. It's a complex language, but it's pushing hard to become mainstream.
This was my problem as well, the object oriented related syntax is just too much. ML of which caml is a version of, has really tight syntax. The “o” in ocaml ruins it imo.
No offense but the only time I have encountered objects in Ocaml was while using LablGTK a long time ago and the object syntax was pretty clean and not far from the module one. They are also structurally typed which is very handy.
Considering it only impacts a fairly small subset of the language, could you explain how it supposedly ruins everything?
It's interesting reading many of the associated comments, because there is a genuinely active effort to address many of the pain points of the language:
* Windows support has improved to the point where you can just download opam, and it will configure and set up a working compiler and language tools for you[^1]. The compiler team treat Windows as an first tier target. opam repository maintainers ensure new libraries and library versions added to the opam repository are compiled and tested for Windows compatibility, and authors are encouraged to fix it before making a release if its reasonably straightforward
* debugger support with gdb (and lldb) is slowly being improved thanks to efforts at Tarides
* opam is relatively stable (I've never found it "buggy and surprising"), but
there are aspects (like switches that behave more like python venvs) which don't provide the most modern behaviour. dune package management (which is still in the works) will simplify this considerably, but opam continues to see active development and improvement from release to release.
* the platform team (again) are working on improving documentation with worked recipes and examples for popular uses cases (outside of the usual compiler and code generation cases) with the OCaml Cookbook: https://ocaml.org/cookbook
There are other things I find frustrating or that I work around, or are more misperceptions:
* there isn't a builtin way to copy files because the standard library is deliberately very small (like Rust), but there is a significant ecosystem of packages (this is different to other languages which cram a lot into their standard library). The result is a lot of friction for newcomers who have to install something to get what they need done, but that's valued by more experienced developers who don't want the whole kitchen sink in their binary and all its supply chain issues.[^2]
* the type inference can be a bit of a love/hate thing. Many people find it frustrating because of the way it works, and start annotating everything to short-circuit it. I've personally found it requires a bit of work to understand what it is doing, and when to rely on it, and when not to (essentially not trying to make it do things it simply will never be able to do).[^3]
* most people use singly-linked lists because they work reasonably well for their use cases and don't get in their way. There are other data structures, they work well and have better performance (for where it is needed). The language is pragmatic enough to offer mutable and immutable versions.
* ocamlformat is designed to work without defaults (but some of them I find annoying and reconfigure)
Please don't take this as an apology for its shortcomings - any language used in the wild has its frustrations, and more "niche" languages like OCaml have more than a few. But for me it's amazing how much the language has been modernised (effects-based runtime, multicore, etc) without breaking compatibility or adding reams of complexity to the language. Many of these things have taken a long time, but the result is usually much cleaner and better thought out than if they were rushed.
[^1] This in itself is not enough, and still "too slow". It will improve with efforts like relocatable OCaml (enabling binary distribution instead of compiling from source everywhere) and disentangling the build system from Unixisms that require Cygwin.
[^2] I particularly appreciate that the opam repository is actively tested (all new package releases are tested in a CI for dependency compatibility and working tests), curated (if its too small to be library, it will probably be rejected) and pruned (unmaintained packages are now being archived)
[^3] OCaml sets expectations around its type inference ("no annotations!") very high, but the reality is that it relies on a very tightly designed and internally coherent set of language constructs in order to achieve a high level of type inference / low level of annotation, but these are very different to how type inference works in other languages. For example, I try and avoid using the same field name in a module because of the "flat namespace" of field names used to infer record types, but this isn't always possible (e.g. generated code), so I find myself compensating by moving things into separate modules (which are relatively cheap and don't pollute the scope as much).
> It just genuinely felt like the Go language designers didn’t want to engage with any of the ideas coming from functional programming.
You'd be right.
"The key point here is our programmers are Googlers, they’re not researchers. They’re typically, fairly young, fresh out of school, probably learned Java, maybe learned C or C++, probably learned Python. They’re not capable of understanding a brilliant language but we want to use them to build good software. So, the language that we give them has to be easy for them to understand and easy to adopt. – Rob Pike 1"
"It must be familiar, roughly C-like. Programmers working at Google are early in their careers and are most familiar with procedural languages, particularly from the C family. The need to get programmers productive quickly in a new language means that the language cannot be too radical. – Rob Pike 2"
Talking as someone who wrote OCaml at work for a while, the benefits of functional programming and the type guarantees that it's ilk provides cannot be understated; you only start to reach them, however, once most developers have shifted their way of thinking rather extremely, which is a time cost that that designers of Go did not want new Googlers to pay.
Well, sure, but this is a problem nearly as old as Go itself. I thought they were referring to larger more recent things, like how generics work, or something to that effect.
Functional programming is a different way of thinking about solving problems. People say it's about thinking about "what you're trying to compute" versus "how you're computing it," but quite frankly that never made sense to me. I prefer to think about it in terms of thinking about relationships (FP) versus thinking about steps over time (procedural).
This, at least for me, brings the act of writing a specific piece of code more inline with how I think about the system as a whole. I spend less energy worrying about the current state of the world and more about composing small, predictable operations on relationships.
As for what you can read, I find it's just best to get going with something like OCaml or F# and write something that can take advantage of that paradigm in a relatively straightforward way, like a compiler or something else with a lot of graph operations. You'll learn pretty quickly what the language wants you to do.
To this day, whenever I see Machine Learning abbreviated, my heart skips a beat, then I become crestfallen as I realize I'm not about to read something about Meta Language.
You believe I'd purposefully misread an abbreviation in a comment about misreading abbreviations, and also coincidentally tried to make fun of two other nationalities (maybe even three, depending on political views), all at the same time?
I mean pohl's joke above whooshed kjmh so it's all fine. The important thing for threads like this one is for us to name drop all of the weird programming languages that we have used, publicly avow the greatness of ones that we have not, and make a New Year's resolution that we will never follow, to actually pick up those great languages and write something in them...
I'd rather have that issue than seeing "AI" plastered all over the place. I'm of the opinion AI should be reserved for artificial general intelligence. These things aren't intelligent yet. They're just em-bloat-ified traditional machine learning techniques. Not that they're useless. I just hate the terminology.
If people start using the term AI, we better be living in I, Robot. Not whatever the hell this is.
We lost this fight at least by 1994 when Sun acquired “Thinking Machines,” which to its credit was bankrupting itself by making highly parallel supercomputers, at least. Now of course there is a new AI company of the same name. If the wrestling world echoes the computing world, one can only wonder what in 5-10 years will be the equivalent of Undertaker throwing Mankind off of Hell In A Cell to plummet 16 feet down through an announcer’s table...
I think Richard Feldman [0] proposed some of the most reasonable theories as to why functional programming isn't the norm. Your language needs to be the platform-exclusive language for a widely used platform, have a killer application for a highly desired application domain, or be backed by a monster war-chest of marketing money to sway opinions.
Since Feldman's talk, Python has grown much faster in popularity in the sense of wide use in the market place... but mostly because it's the scripting language of choice for PyTorch and AI-adjacent libraries/tooling/frameworks which is... a killer application.
I like OCaml. I started evaluating functional programming in it by taking the INRIA course online. I spent the last four and half years working in Haskell. I've built some side projects in Zig. I was a CL stan for many years. I asked this question a lot. We often say, "use the best tool for the job." Often that means, "use the tool that's available."
I think languages like OCaml, Rust, Haskell etc can be "popular," but in the sense that people like to talk about them and want to learn them and be able to use them (at least, as trends come and go). It's different from "popular" as in, "widely adopted."
> mostly because it's the scripting language of choice for PyTorch and AI-adjacent libraries/tooling/frameworks
I would politely disagree. Torch started in Lua, and switched to Python because of its already soaring popularity. Whatever drove Python's growth predates modern AI frameworks
Python was already big for scientists back in 2010. I remember working on Python tooling at the time, and DS/ML was one of our single largest user groups. It was already popular enough to have an IDE specifically for scientific Python use: https://en.wikipedia.org/wiki/Spyder_(software).
As far as I could tell, it had to do with two things. First, Python is notoriously dynamic and extensible, making it possible to implement "sloppy" syntax like advanced slicing or dataframes. But also, those guys had lots of pre-existing C and Fortran code, and Python had one of the easiest extensibility APIs to wrap it as high-level packages. And with IPython, you had a nice REPL with graphing to use all that from, and then of course notebooks happened.
Yeah, I can see that. At the time of the talk Feldman claims Python is a slow-and-steady language. It definitely did get a lot of support from the scientific/engineering community for a long time. I spent a good part of my career with Python from about 2006-2016.
It had boosts from Django... but it never had Rails' level of popularity. You kinda have to be first-to-market and that good to get the "killer app" effect.
It's also been integrated as the scripting language for several popular software pacakges (Blender comes to mind).
Machine learning and now... "AI"; seems to be a market cornered by Python quite a bit.
I had already learned Basic, C++, Java, and C#. I wanted to add a dynamic scripting language that was cross-platform under my belt.
A lot of my peers were in the same boat.
Python seemed at the time, to be the only general purpose scripting language that was easy to use on multiple platforms.
I had heard bad things about Perl being write only, and Ruby being tough to deploy, I also found it hard to read. (Which is a shame they are wonderful languages, though Ruby is dog slow, Python is slow too, but Ruby is worse somehow).
IIRC Google and some other large companies were pushing it as one of their official languages.
Right as Python was rocketing in popularity, Go came out, and I also heard a lot of good things about Clojure (they seemed neck and neck in popularity from my incorrect perspective at the time, lol).
Do you mean the comic was responsible, or the comic explains why Python is popular? It is definitely the ecosystem. As you said its general purpose. It is used for numerical computing and visualisation, web apps, GUIs, sysadmin. Even a reasonably popular DVCS is written in Python.
I look at how people write TypeScript these days, and think about how the world might have been different if, 10-15 years ago, these functional languages had been a bit closer to the imperative world. OCaml allows mutation and side effects and could even feel a bit imperative if it weren't for the "let ... in" syntax.
Let's face it, syntax matters. We saw that with Elixir becoming much more popular than Erlang ever did. We saw it with TypeScript being able to introduce a fairly complex type system into JavaScript, and becoming successful among web devs by adapting to established ecosystem and offering a gradual approach, rather than forcing an entirely new, incompatible paradigm on it. The TypeScript story seems a little improbable in hindsight, but it was able to get there by offering an incremental path and making a lot of compromises (such as config options to allow less strict enforcement) along the way.
Personally, I think a new syntax for OCaml might actually be successful if done right. Sure, there have been multiple attempts (the "revised" syntax, Reason, etc.), but none of them are really willing to modernize in ways that would attract your average programmer. The toolchain also needs work to appeal to non-OCaml programmers.
Could you explain how Reason syntax isn't "really willing to modernize in ways that would attract your average programmer"? I'm trying to understand what do you even mean.
I've seen JS using lambdas instead of classic functions like that in the wild. And that Reason can be made more JS-idiomatic without changes to the syntax:
No macros, limited support for higher order functions. Its big drawback is the small ecosystem.
I like TCL, but its not really comparable to lisp. Its definitely a great scripting language and is a lot more flexible than it gets credit for.
It got a lot of things right. Event driven concurrency (and its got a good threading model) which is often given as a reason to use JS to right servers. Sandboxing untrusted code. Easy GUIs with Tk. Easy cross platform deployment. Unfortunately it never got traction.
Categorically not true. Tcl got a LOT of traction. Expect was everywhere. Tk kicked ass and took names. AOLserver, anyone? VLSI CAD stuff still uses it today.
It just got pushed out of the way over time. IMO, mostly because VB6 took its niche of easy GUI.
> It is an old language, and there are a few features that could probably be left out like the OOP-related features, and some libraries in the ecosystem over-complicate things like in Haskell.
If one can stand a language that is just a little bit older, there is always Standard ML. It is like OCaml, but perfect!
I love standard ml (I'm currently writing a compiler for it), but it's far from perfect. There are weird special cases in the language definition like the ad-hoc overloading between int and real, or the annoying value restriction. Records also feel half-baked, with no support for updating fields or for partially-specified records where the full set of fields is not known
While it's not yet standard nearly all Standard ML implementations support what has become known as "Successor ML" [0]. A large subset of Successor ML is common to SML/NJ, MLton, Poly/ML, MLKit and other implementations.
That includes record update syntax, binary literals, and more expressive patterns among other deficiencies in Standard ML.
For me the two big remaining issues are:
1) There's only limited Unicode support in both the core language and the standard library. This is a big issue for many real-world programs including these days the compilers for which SML is otherwise a wonderful language.
2) The module system is a "shadow language" [0] which mirrors parts of SML but which has less expressiveness where modules cannot be treated as first-class values in the program. Also if you define infix operators in a module their fixity isn't exported along with the function type. (Little annoyance that gets me every time I am inclined to write Haskell-style code with lots of operators. Though maybe that's just another hint from the universe that I shouldn't write code like that.) Of course, the fix to that would be a fundamentally different language; not a revised SML.
I far preferred Standard ML when I learned both back in the day, but it was OCaml that won the headspace it seemed.
Ironically probably because it had the "O"bjects in it, "which was the style of the time"... something that has since dropped off the trendiness charts.
I love SML, and came to OCaml a bit begrudgingly initially just for a larger ecosystem. But, I think the object system gets a unjustly bad wrap. The OCaml object system is dope. It is rarely needed and not the best feature for most use cases, but when you want structurally-typed records, or need open recursion (or need to represent JS objects for the amazing `Js_of_ocaml`), they are a perfect fit.
I've dabbled in F# (and aside from the rough setup with little coherent information at the time) had a pretty good time. Actor-based concurrency was easy to grok. The one gotcha was whenever those mutable Arrays entered the picture.
I'd like to hear some practical reasons for preferring OCaml over F#. [Hoping I don't get a lot about MS & .NET which are valid concerns but not what I'm curious about.] I want to know more about day to day usage pros/cons.
It's a matter of trends: F# is losing compatibility with the overall CLR ecosystem due to the churn in C# features with poor F# interop, but F# has already mingled its design with the CLR's, too much to live on its own as a native language. Plus its compiler is slow and the tooling is getting increasingly unstable.
Meanwhile, OCaml got rid of its global lock, got a really fast-compiling native toolchain with stable and improving editor tooling, and has a cleaner language design with some really powerful features unavailable to F#, like modules/functors, GADTs, effects or preprocessors. It somehow got immutable arrays before F#!
F# still has an edge on some domains due to having unboxed types, SIMD, better Windows support and the CLR's overall performance. But the first two are already in the OxCaml fork and will hopefully get upstreamed in the following years, and the third is improving already, now that the opam package manager supports Windows.
> has an edge on some domains due to having unboxed types
If a language makes "unboxed types" a feature, a specific distinction, and has to sell "removing global lock" as something that is a massive breakthrough and not table stakes from 1.0, it can't possibly be compared to F# in favourable light.
I vouched for your dead comment because I get where you're coming from. But OCaml 1.0 was in 1996 in an academic setting. I care about the language I can use now, not the one I didn't use.
Let's not dismiss that their solution to remove the global lock has been both simpler than Python's (better funded?) ongoing work and backwards compatible; and the multicore support came with both a memory model with strong guarantees around data races, and effect handlers which generalize lightweight threads.
I agree that lack of unboxed types is a fatal flaw for several domains (Worse, domains I care about! I usually consider Rust/Go/.NET for those.) But when the comparison with OCaml is favourable to F#, the gap isn't much wider than just unboxed types. F# has an identity crisis between the ML parts and the CLR parts, its C# interop is decaying as the ecosystem evolves, and newer .NET APIs aren't even compatible with F# idioms (here's a .NET 6+ example [1]).
Ref structs are hard to solve because they require, in some ways, a lot more work than the way C# solved the lifetimes as the lifetimes in F# may need to become much closer to what they are in Rust. Some constructs may not be able to consume them still (can’t move ref struct into an object with effective lifetime ‘static) and there really is no easy solution short of language editions and breaking standard library changes. A limited improvement is possible, but we’re still in the realm where the lifetimes may become a part of type identity or somehow generalized over, which is hard.
OCaml predates multicore CPUs. Having a global lock was basically free at the time it was invented. It's totally crazy to dislike a language because the authors made a decision that was obviously correct at the time.
F# uses the CLR term "value types" instead, or sometimes "struct" types as in the C# keyword.
These are usually defined with the [<Struct>] attribute over a regular type definition, or using the struct keyword before tuple/anonymous record types. Also, the original 'T option type now has a value-type successor 'T voption.
We’ve used f# professionally for the computations-intensive parts of our product for a couple of years. Here’s what comes to mind:
1. Interop with C# is great, but interop for C# clients using an F# library is terrible. C# wants more explicit types, which can be quite hard for the F# authors to write, and downright impossible for C# programmers to figure out. You end up maintaining a C#-shell for your F# program, and sooner or later you find yourself doing “just a tiny feature” in the C# shell to avoid the hassle. Now you have a weird hybrid code base.
2. Dotnet ecosystem is comprehensive, you’ve got state-of-the web app frameworks, ORMs, what have you. But is all OOP, state abounds, referential equality is the norm. If you want to write Ocaml/F#, you don’t want to think like that. (And once you’ve used discriminated unions, C# error-handling seems like it belongs in the 1980’ies.)
3. The Microsoft toolchain is cool and smooth when it works, very hard to wrangle when it doesn’t. Seemingly simple things, like copying static files to output folders, require semi-archaic invocations in XML file. It’s about mindset: if development is clicking things in a GUI for you, Visual Studio is great (until it stubbornly refuses to do something) ; if you want more Unix/CLI approach, it can be done, and vscode, will sort of help you, but it’s awkward.
4. Compile-times used to be great, but are deteriorating for us. (This is both F# and C#.)
5. Perf was never a problem.
6. Light syntax (indentation defines block structure) is very nice until it isn’t; then you spend 45 minutes how to indent record updates. (Incidentally, “nice-until-it-isn’t” is a good headline for the whole dotnet ecosystem.
7. Testing is quite doable with dotnet frameworks, but awkward. Moreover. you’ll want something like quickcheck and maybe fuzzing; they exist, but again, awkward.
We’ve been looking at ocaml recently, and I don’t buy the framework/ecosystem argument. On the contrary, all the important stuff is there, and seems sometimes easier to use. Having written some experimental code in Ocaml, I think language ergonomics are better. It sort of makes sense: the Ocaml guys have had 35 years or so to make the language /nice/. I think they succeeded, at least writing feels, somehow, much more natural and much less inhibited than writing F#.
I did get some sense of that where F# sort of (actually is) 2nd class to C# which is slowly gaining some F# features, but F# itself isn't well promoted/supported.
As for missing language features, they can also be a double-edged sword. I slid down that slippery slope in an earlier venture with Scala. (IIRC mostly implicits and compile times).
There are libraries that simulate a lot of these things (e.g. https://github.com/G-Research/TypeEquality for GADTs). You're absolutely right that it's not as first class as in OCaml, but the tools are there if you want them.
I've written type-equality witnesses in F#, they can kinda recover type equalities (with cast methods) but not refute them, so you still need to raise exceptions for those cases.
OCaml is a much more powerful language. Take a look at functors, for example, or modules as first-class values, or GADTs, or its object system that can do type inference from use:
# let foo x = x#frob;;
val foo : < frob : 'a; .. > -> 'a = <fun>
F# is often called "OCaml for .NET", but it is a misrepresentation. It is an ML-family language for .NET, but aside from that ML core they don't have much in common.
Whether those features are more valuable to you than the ability to tap into .NET libraries depends largely on what you're doing.
OCaml has been one of those "almost there" languages since at least 2002. Most of the worthwhile ideas in OCaml will be absorbed into more popular languages by the time existing friction is sorted out. :/
> Our hope is that these extensions can over time be contributed to upstream OCaml.
Yeah, its more just extensions to support their use cases at scale. Think of it more as bleeding edge ocmal, once they work out kinks/concerns they'll get merged back into the language OR if it remains ultra specific it'll stay in oxcaml.
Python gets forked in other investment banks as well. I wouldn’t say that is evidence of any deficiencies, rather they just want to deal with their own idiosyncrasies.
The main user has been writing extensions to the compiler that they test before pushing for integration like they have done for the past twenty years or so. They publish these versions since last year.
Hardly a failure and certainly not something mandatory to keep things from failing over. Your initial comment is extremely disingenuous.
A different perspective is that JS has made practical application of PLT part of their secret sauce, and deepening into their PLT roots is thickening the sauce.
This is the wrong interpretation of the oxcaml project. If you look at the features and work on it, it's primarily performance or parallelism safety features.
The latter going much further than most mainstream languages.
Yeah, but when these things happen I ask myself, is Jane Street successful because of ocaml, or did they just happen to pick ocaml and then make it work?
There might be some power in attracting all the people who happen to love ocaml, if there are enough of competent people to staff your company, but that's more a case of cornering a small niche than picking on technical merits
They've spoken about this before and might not have picked OCaml if they had to make the decision again today. I think at the time it made the most sense.They can also make it work in any language as they claim to only recruit the best and brightest in the world (this may be the truth). My opinion is they could have chosen many languages and had similar results while balancing different trade-offs.
Regarding attracting talent, they've said they don't care about existing knowledge of OCaml as the language part is something they train staff on anyway. Their interviews are brutal from what I recall. I could be an OCaml expert and have no chance of making it through an interview without equal talent in high performance fintech and relevant mathematics.
> I could be an OCaml expert and have no chance of making it through an interview without equal talent in high performance fintech and relevant mathematics.
Unless their hiring process has changed in the past few years, if you're a dev they're not hiring you for your financial skills, just general problem solving and software development ability. It is (was?) the usual Google-style algorithms/data structures rigamarole, but somewhat more challenging.
Do those devs actively use OCaml? I thought most of the folks writing OCaml were writing the actual trade algorithms as opposed to infrastructure folks. My post was made off what I recall their lead technologist saying.
Absolutely. Everyone uses OCaml at Jane Street; pretty much everything at Jane Street is OCaml. If an OCaml version of something doesn't exist, there's a decent enough chance that they'll write it themselves rather than resort to a non-OCaml solution.
Like I said, my information might be a hair out of date, but it's first-hand.
Gotcha. Mine is just some old blog posts and a long talk from the guy that got OCaml started. Nothing like your actual first person experience. Thanks for adding!
Unless you're building another JS, it'd be nice if there were other companies so heavily invested in it. There's a lot out there beyond compiler prototypes and high speed financial trades, but there's not enough talk of people using ocaml for those things.
Ocaml was (historically, at least) used by Facebook for basically all of their linter/compiler/type checker work. The hack checker was in Ocaml, as was the JS thing (flow, maybe?).
So that does seem to be a good use-case for the language.
That was why I mentioned compilers along with HFT. Rust was originally an ocaml based compiler too.
I don't build HFTs and my compilers are just for fun. None of my day jobs have ever been a situation where the smaller ecosystem and community of ocaml was offset by anything ocaml did better than the selected options like .net, Java, go, rails, C or anything else I've touched. Heck, I've written more zig for an employer than ocaml, and that was for a toy DSL engine that we never ended up using.
Because plenty of people have been shipping great projects in Ocaml since it was released so it doesn’t seem to be much of an issue to many.
I doubt Ocaml will be surpassed soon. They just added an effect system to the multicore rewrite so all things being considered, they seem to be pulling even more ahead.
Beginners face the following problems: there's multiple standard libraries, many documents are barely more than type signatures, and data structures aren't printable by default. Experts also face the problem of a very tiny library ecosystem, and tooling that's often a decade behind more mainstream languages (proper gdb support when?). OCaml added multicore support recently, but now there is the whole Eio/Lwt/Async thing.
I used to be a language nerd long ago. Many a fine hour spent on LtU. But ultimately, the ecosystem's size dwarfs the importance of the language itself. I'm sympathetic, since I'm a Common Lisp man, but I don't kid myself either: Common Lisp isn't (e.g.) Rust. I like hacking with a relic of the past, and that's okay too.
TBH I think it's rather a post-hoc rationalization of why the language is not popular.
> there's multiple standard libraries
Scala has a far more fragmented ecosystem with Cats, Scalaz, Zio and Akka. C++ and Java have a bunch of stdlib extensions like boost, Guava, Apache Commons etc.
> many documents are barely more than type signatures
Can be said of most of Java, Kotlin, Scala, Erlang etc etc. Just compiled javadocs, sometimes with a couple of unhelpful lines.
> data structures aren't printable by default
Neither they are in C++
I think the real reason it's not popular is that there are languages which solve more or less the same problems of system programming but look far more familiar to an avg. programmer who was raised on C++ and Java.
I wanted to use OCaml since 2002, since it was a GC'd language with good performance, achieving a lot with relatively few lines of code. Being a language nerd, I was (am?) positively inclined to the language. Yet there was always something that made it notably less pleasant to solve my current problem in than in than some other language.
If it had trouble getting traction with me, that's bad news.
Meanwhile the mainstream has progressed a lot since 2000. GC is the standard, closures are normal, pattern matching and destructuring are increasingly so. While HM-style type inference is not mainstream, local type inference is (and I'm no longer convinced that global type inference is the way). Algebraic data types aren't unusual anymore.
A few years back I just threw in the towel and went with Rust; this happened after I volunteered to improve OCaml's gdb support (including DWARF hell), which went nowhere. I wish Rust compiled faster, and a GC'd language is usually more productive for my problems, but in every other regard it stole what should have been OCaml's thunder. And when popular successor languages eventually appear, they'll do it even better.
Pony's garbage collection and runtime can
yield performance faster than C/C++/Rust because
the compiler eliminates data races at
compile time, and thus no locks are needed.
It features implementations of Dmitri Vyukov
(www.1024cores.net) algorithms for
work stealing and Multi-producer single
consumer queues that use only a single atomic
instruction to read. The designer,
Sylvan Clebsch, is an ex-game-developer and
ex-high-frequency-trading-infrastructure
engineering lead; he knew what he was
doing when he designed the language
for high performance on multicore systems.
On the other hand, you do have to re-wire
your thinking to think in terms of Actors
and their state, and this is kind of hard
to wrap one's head around if you are used
to Go's CSP or the popular async/await
approaches -- it is a somewhat
different paradigm.
You probably know it, but Common Lisp May be a bit dated but it’s extremely modern in terms of features since you can add almost any feature to the language in libraries! I use it exactly because it’s old and battle tested and I don’t need to wait years for a language designer to give me a feature , I can just add it myself, though these days it has everything done already!
There is only one standard library and it shipped with the compiler.
> data structures aren't printable by default
So? That’s the case with most languages. Ocaml has a deriver to make types printable and a REPL which automatically prints for testing.
> tooling that's often a decade behind more mainstream languages
Opam is a fully featured package manager, dune works fine, bucks2 supports Ocaml.
> proper gdb support when?
Ocaml has had a rewindable debugger since approximately forever.
> OCaml added multicore support recently, but now there is the whole Eio/Lwt/Async thing.
Lwt was the default and everyone agrees eio is the future now that effects are there. Async is a Janestreet thing with pretty much no impact on the language outside of Janestreet.
Honestly, I maintained my initial point. Ocaml alleged frictions were always widely overstated.
When I was writing Ocaml professionally 15 years ago, there was no dune and no opam and it was already fairly easy to use the language.
Rocq is an excellent example of something OCaml was designed for. FFTW3 is another great example. Unison too.
Generally, you want stuff where you have to build a fairly large core from scratch. Most programs out there doesn't really fit that too well nowadays. We tend to glue things more than write from nothing.
Rocq, Pfff and Flow, Vpnkit in Docker for Mac and Windows, the web version of Facebook Messenger at a point, Tezos, Unison, the Xen cloud platform, the Mirage unikernel.
> Why isn't it more popular if it's so good? Because popularity and merit are not the same thing.
Yes! To add to that, the question itself is wrong. We should be asking, how is OCaml able to be so good without being popular? People get the whole thing backward.
The popular languages are typically popular first, then get good later as a result of that popularity. They have to work, they have to be good, they're too big to fail.
This is what happened with Java. It was marketed like crazy at first and only later got refined in terms of tooling and the JVM itself. The R programming language was a mess for data wrangling, but once it was popular, people built things like the tidyverse or the data.table library. The Python ecosystem was disaster with all different testing packages, build tools, and ways to create and manage virtual environments, until the relatively recent arrival of uv, more than three decades after the creation of Python itself. And then there's javascript that's had more money, blood, sweat, and tears poured into it to be improved in one way or another because that's what practically anything running in a browser is using.
Music being "good" is subjective. A programming language, however, can objectively be better if it allows a subset of programmers to better solve certain problems.
The reason for why OCaml is not more popular, thus, is that this subset is small. The reason for this may be either (a) habit or (b) it's not that much better than other languages. I'm gravitating to (b). OCaml guys seem to be quite dogmatic for the wrong reasons.
I posit (c) it’s from France and written mostly by French people and American naturally gravitates towards languages which generate hype in English and preferably from the USA.
Also it didn’t employ a marketing team to work on outreached and write fancy comments here and some people who have used it for 10 minutes are apparently offended by the Pascal-like syntax and can’t stop discussing it on every Ocaml discussion making every actual users tired.
Elixir is the closest thing to OCaml that has a chance at semi-mainstream usage IMO.
It has basically all of the stuff about functional programming that makes it easier to reason about your code & get work done - immutability, pattern matching, actors, etc. But without monads or a complicated type system that would give it a higher barrier to entry. And of course it's built on top of the Erlang BEAM runtime, which has a great track record as a foundation for backend systems. It doesn't have static typing, although the type system is a lot stronger than most other dynamic languages like JS or Python, and the language devs are currently adding gradual type checking into the compiler.
I think that a better question is why F# isn't a more popular language, since it's much closer to OCaml, than Elixir and you can use the whole Dotnet ecosystem in F#, which is one of the weakest points of OCaml (no libraries).
The answer is (most likely) Microsoft, I kid you not. I've worked with F# professionally for many years is its incredible how they are literally sitting atop a gold mine that is the output of Microsoft research and do basically nothing with it. Even though it's sold as an ecosystem, .NET revolves around C# and its related tooling.
"Type Providers" are an example of such negligence btw, it's something from the early 2010's that never got popular even though some of its ideas (Typed SQL that can generate compile-time errors) are getting traction now in other ecosystems (like Rust's SQLx).
My team used SQL Providers in a actual production system, combined with Fable (to leverage F# on the front end) and people always commented how our demos had literally 0 bugs, maybe it was too productive for our own good.
I think it’s odd that elixir doesn’t get more love. It ticks a lot of boxes that folks here get excited about, has a great ecosystem and tooling, BEAM is great, and it’s much more syntactically familiar than erlang to my eye. I know of a couple companies aside from the perennial goto examples that built sizable saas products backed by it.
I always wanted to learn Elixir but never had a project where it could show it strengths. Good old PHP works perfectly fine.
Also corporations like their devs to be easily replaceable which is easier with more mainstream languages, so it is always hard for "newer" languages to gain traction. That said I am totally rooting for Elixir.
I think it’s great for boring stuff — the Phoenix web framework is really straightforward. Learning a whole new language paradigm and environment for a professional project you need to be productive in ASAP is definitely the worst kind of ‘not boring’ though.
I know of a Haskell shop and everybody said they’d have a hell of a time finding people… but all them nerds were (and are) tripping over themselves to work there because they love Haskell… though some I’ve talked to ended up not liking Haskell in production after working there. There seems to be a similar dynamic, if a bit less extreme, in Elixir shops.
The BEAM VM executing bytecode is slower than a compiled binary. Sure, it is great when compared to Python and other interpreted languages. Not so much when you need fast processing and raw CPU performance. It also loses out to the JVM in performance, but wins in memory consumption.
It is slower, but a big cause of the slowness is a lot of copying (immutable data structures and separate heaps for every process). Nowadays the BEAM has a JIT.
If you use type guards correctly the performance can be surprisingly good. Not C/C++/Rust/Go/Java good, but not too far off either. This is definitely a corner-case though.
But how many things involve fulfilling basic requests over a network pulling information from a database? Most things just don’t need that kind of performance.
Sure for basic, dead CRUD, the choice of middleware language rarely makes any difference.
But even bog-standard business processes eventually find the need for data-processing, crypto and parsing - the use-cases where people code Elixir NIF's. That is why for example you have projects like html5ever_elixir for parsing HTML/XML. Another use case is crypto - you have NIF's for several crypto libraries. Data processing - there are NIF's for Rust polars.
From a technical perspective, this is the overwhelming majority of what makes the Net happen. BEAM is great for that and many other things, like extremely reliable communication streams.
Use the right tool for the job. Rust sucks for high-level systems automation but that doesn’t make it any less useful than bash. It’s all about about use cases and Elixir fits many common use cases nicely, while providing some nice-to-haves that people often ask for in other common web dev environments.
Elixir is good at managing complexity. I love flattening hierarchy and dealing with edge cases right in function definitions using pattern matching. Every other language without it just feels crippled after getting used to the feature.
You don't get it from language tooling because you are compiling to a bytecode that runs in a virtual machine (BEAM).
The current tool to wrap your bytecode with a VM so that it becomes standalone is Burrito[1], but there's some language support[2] (I think only for the arch that your CPU is currently running? contra Golang) and an older project called Distillery[3].
I really wish people would quit pushing "functional". People equate that with "My programming is now always a recursive logic puzzle."
Talk about "immutable by default". Talk about "strong typing". Talk about "encapsulating side effects". Talk about "race free programming".
Those are the things that programmers currently care about. A lot of current Rust programmers are people who came there almost exclusively for "strong typing".
Having loops is not the defining feature that separates functional from imperative. Where did this idea come from? I'm suddenly seeing it in a lot of places.
It is not the defining feature but loss of the loop is one of the most obvious differences for people who look at a functional language Rust has immutability, pattern matching, etc, but it remains an imperative language with "some functional features". Or this is my subjective analysis.
So is Haskell not functional? Or an imperative language with some functional features?
-- ghci> example
-- Triangular number 1 is 0
-- Triangular number 2 is 1
-- Triangular number 3 is 3
-- Triangular number 4 is 6
-- Triangular number 5 is 10
example = runEff $ \io -> evalState 0 $ \st -> do
for_ [1..5] $ \i -> do
n <- get st
let msg = "Triangular number " <> show i <> " is " <> show n
effIO io (putStrLn msg)
st += i
where
st += n = modify st (+ n)
(This is not a trick question. Simon Peyton Jones described Haskell as "the world's finest imperative language" [1], and I agree. This code is written using https://hackage.haskell.org/package/bluefin)
[1] Tackling the Awkward Squad:
monadic input/output, concurrency, exceptions, and
foreign-language calls in Haskell
But, again, loops aren't automatically imperative per se. Consider loop / recur in Clojure for an example. For someone coming from JavaScript, it's not really much different from writing a while loop where every branch has to terminate with an explicit break or continue.
You can be functional "in spirit" more than purely functional. OCaml and Standard ML falls into this category. Ocaml has loops for instance. You might just not see many loops if code is written by OCaml developers, because there's frankly no need to use them in a lot of places. You often want to lift the abstraction level of iteration to an arbitrary data structure such that you get freedom of implementation. See Applicative and Monad.
BEAM performance model trades throughput for isolation, which hurts CPU-bound tasks, and ironically, whenever you need speed, you end up using NIFs that break BEAM safety guarantees, and reintroduce the exact fragility Elixir was supposed to avoid.
In 2025, Elixir is a beautiful system for a niche that infrastructure has already abstracted away.
> In 2025, Elixir is a beautiful system for a niche that infrastructure has already abstracted away.
Do you mean Kubernetes?
My mental model of Erlang and Elixir is programming languages where the qualities of k8s are pushed into the language itself. On the one hand this restricts you to those two languages (or other ports to BEAM), on the other hand it allows you to get the kinds of fall over, scaling, and robustness of k8s at a much more responsive and granular level.
> whenever you need speed, you end up using NIFs that break BEAM safety guarantees, and reintroduce the exact fragility Elixir was supposed to avoid.
That's like complaining that unsafe{} breaks Rust's safety guarantees. It's true in some sense, but the breakage is in a smaller and more easily tested place.
It's not isolation which hampers throughput. That's a red herring. In fact, isolation increases throughput, because it reduces synchronization. A group of isolated tasks are embarrassingly parallel by definition.
The throughput loss stems from a design which require excessive communication. But such a design will always be slow, no matter your execution model. Modern CPUs simply don't cope well if cores need to send data between them. Neither does a GPU.
The grand design of BEAM is that you are copying data rather than passing it by reference. A copy operation severs a data dependency by design. Once the copy is handed somewhere, that part can operate in isolation. And modern computers are far better at copying data around than what people think. The exception are big-blocks-of-data(tm), but binaries are read-only in BEAM and thus not copied.
Sure, if you set up a problem which requires a ton of communication, then this model suffers. But so does your GPU if you do the same thing.
As Joe Armstrong said: our webserver is a thousand small webservers, each serving one request.
Virtually none of them have to communicate with each other.
It's compiled to Erlang, not BEAM bytecode, as the latter is not a stable, backward-compatible API to target, and you lose all of the optimization work put into the Erlang compiler. It's also compiled to JavaScript, so it can run on both the front-end and back-end.
What you wrote is roughly equivalent to this in C:
{
const int x = 1;
{
const int x = 2;
}
}
which is to say, there are two different `x` in there, both immutable, one shadowing the other. You can observe this if you capture the one that is shadowed in a closure:
iex(1)> x = 1
1
iex(2)> f = fn () -> x end
#Function<43.113135111/0 in :erl_eval.expr/6>
iex(3)> x = 2
2
iex(4)> f.()
1
> OCaml is weird in that it’s a garbage collected language for systems, similar to Go.
I don't understand why this isn't more popular. For most areas, I'd gladly take a garbage collector over manual memory management or explicit borrow checking. I think the GC in D was one of it's best features, but it's downfall nonetheless as everyone got spooked by those two letters.
I like the ML languages, and as many others I spent a lot of time with F#.
I would love to spend more time but even though Microsoft gives it plenty of support (nowhere near as much as C#), the community is just too small (and seems to have gotten smaller).
Anecdotally we are using F# more than ever before, and it works for us for a large sized organisation. Fast code, it is keeping up with the .NET features that matter for that (e.g. spans), and tbh has still been getting better over the years. In fact I find some of the new features like Span, SIMD/intrinsics somewhat synergise with existing F# features (e.g. inline). C# IMO still hasn't quite caught up but is getting there. Comparing to Go/Java/etc I can usually get faster code out of the .NET runtime as well especially in our domain which requires large scale computation. If I was to move to something else for our domain it would be C++ or Rust. F# piggy backing of the .NET platform in general, has a decent ecosystem and easy onboarding cross platform and gets a lot "for free" (e.g. CLI, GC improvements).
Community is an interesting thing, and for some people I guess it is important. For me language is just a tool having coded for quite some time and seen communities come and go; don't care about being known or showing an example per se. If the tool on the balance allows me to write faster code, with less errors quicker and can be given to generic teams (e.g. ex Python, JS devs) with some in house training its a win. For me personally I just keep building large scale interesting systems with F#; its a tool and once you get a hang of its quirks (it does have some small ones) quite a good one that hits that sweet spot IMO.
My feeling however is with AI/LLM's communities and syntax in general is in decline and less important especially for niche languages. Language matters less than the platform, ecosystem, etc. Its easier to learn a language then ever before for example, and get help from it. Any zero cost abstraction can be emulated with more code generation as well as much as I would hate reviewing it. More important is can you read the review the code easily, and does the platform offer you the things you need to deliver software to your requirements or not and can people pick it up.
Interesting take. I agree with you mostly but regarding "community" I am more thinking of the side effects there in terms of _other_ people developing interesting libraries etc.
I don't know if AI can change that but when using python, there is a feeling that there is an awesome quality library for just about anything.
I get that, which is why I said it is important for some people depending on the domain and I meant in general language communities. Python is different at least to me given AI and being the first target for not just software improvements but hardware usage (e.g. GPU accelerated specialised libs) and training materials/examples. It is the AI community not the Python community per se; the AI community just targets Python. JS is also a little different given browsers are so ubiquitous and their own target with JS being the main language that works there.
Otherwise in most mainstream platforms there is enough libraries for most things already; which includes .NET. It's rare not to find a well maintained lib for the majority of use cases in general whether it is .NET, Java, Go, etc which is why w.r.t long term risk a used platform is more important than the syntax of a language and its abstractions. Web frameworks, SDK's, DB drivers, etc etc are all there and generally well tested so you won't be stuck if you adopt F#. I evaluate on more objective metrics like performance, platform improvements, compatibility with other software/hardware, etc etc. It isn't that risky to adopt F# IMO (similar risk to .NET in general) - to me its just another syntax/tool in my toolbelt with some extra features than usual if I'm developing things typical in that .NET/Java/Go abstraction level.
Yes, in every ML/OCaml tutorial, sooner or later the words object, class, and type inference appear and that’s when a once–minimalist language turns into an academic Frankenstein.
I don't think objects and classes are used much by OCaml programmers (not by me anyway). Type inference is a rather fundamental feature, and fairly easy to understand.
It's not a minimalist language, you know what the "O" in Ocaml stands for right? It's a multi-paradigm language that explicitly accommodates more styles of programming than Caml, it's why it exists.
I kind of wish (like the OP mentioned) there was a ML (ocaml) like language that compiled to Go source. You would get the best of both worlds and access to a huge ecosystem.
I've never used it so can't speak from any experience, and unfortunately it doesn't seem particularly active (and doesn't mention a current status anywhere), and doesn't have a license, so shrug. When it's been posted here (https://news.ycombinator.com/item?id=40211891), people seemed pretty excited about it.
Borgo looks like some guys phd thesis. It looks like it was a fun experiment.
I feel a new simple ocaml like language that just compiled to Go would be really popular, really fast. And it would not even need to build a ecosystem, as Go already have all the things you need.
I find it interesting that 80% of the Ocaml discussions here are similar to what I encounter during the change management phase on every complex project I work on: "But it’s different from what I’m used and must therefore be bad. Look, the syntax, it doesn’t look like usual. Scary."
15% are people trying to sell their own language of choice sometimes with the argument that "it’s less scary, look".
I would be shocked if a mere 5% is actual engagement with the topic at hand sometimes while pointing flaws which are very real.
From there, I gather two things, the main one being: maybe Meta was right actually. People are that limited and the syntax should have been changed just to be done with the topic.
OCaml’s REPL is lovely, but I found myself having some friction with initial startup. The build/package system was pretty convoluted, and I ended up choosing JS’s Core stdlib for my needs (a simple compiler). With the new multicore release it’d be cool to see OCaml in some more practical projects!
Many learning materials will push you that way, but the vast majority of FOSS packages don't use it.
There's nothing inherently wrong with using Jane Street's stdlibs if you miss the goodies they provide, but be aware the API suffers breaking changes from time to time and they support less targets than regular OCaml. I personally stopped using them, and use a few libraries from dbunzli and c-cube instead to fill the gaps.
OCaml is fantastic, but I avoided it and went with Rust for many projects because it had no multicore story and no green threads for a very long time. But it has that now, and I wish I could go back and start everything over in OCaml.
I've also felt very similar, and adopted Rust for those reasons. Even though I'd still love to have a garbage collected, AOT compiled ML-variant, using OCaml still feels like a step backwards now. OCaml's module system and generics feel clumsy and unintuitive now that I've used Rust's Trait system.
From an outsider's perspective, it feels like Ocaml has more active development of features, between the new effects system they added in 5 and all the work Janestreet is doing to let Ocaml developers have more control over performance.
F# is not stagnant thankfully, it gets updates with each new version of dotnet (though I haven't checked what is coming with dotnet 10), but I don't recall anything on the level of the above Ocaml changes in years.
Oh yeah I love f#, I need to find more excuses to use it. I just wish it felt like MS was willing to invest more into it. But at least they have not abandoned it and continue to put some resources into its ongoing growth.
As a Rust newbie and seasoned Go dev, I'm pretty interested to knownwhere would people experienced in both OCaml and Haskell, would put it in the spectrum.
Languages have features/constructs. It's better to look at what those are. And far more importantly: how they interact.
Take something like subtyping for instance. What makes this hard to implement is that it interacts with everything else in your language: polymorphism, GADTs, ...
Or take something like Garbage Collection. It's presence/absence has a large say in everything done in said language. Rust is uniquely not GC'ed, but Go, OCaml and Haskell all are. That by itself creates some interesting behavior. If we hand something to a process and get something back, we don't care if the thing we handed got changed or not if we have a GC. But in Rust, we do. We can avoid allocations and keep references if the process didn't change the thing after all. This permeates all of the language.
My team still has 8 year old Haskell systems in production. We pivoted away from the language a few years ago, which I discuss here a bit: https://news.ycombinator.com/item?id=37746386
I personally love ML languages and would be happy to keep developing in them, but the ecosystem support can be a bit of a hassle if you aren't willing to invest in writing and maintaining libraries yourself.
OCaml has some high profile use at Jane Street which is a major fintech firm. Haskell is more research oriented. Both are cool, but wouldn't be my choice for most uses.
OCaml did become popular, but via Rust, which took the best parts of OCaml and made the language more imperative feeling. That's what OCaml was missing!
True, but writing imperative code in OCaml feels quite right. Maybe it's just me, but it always feels significantly clunkier than the functional equivalent. I've had things I've been implementing and though "this works be easier to express imperatively", and almost invariably I've gone and rewritten the code to be functional because of how ungainly the imperative implementation ended up being. It feels a bit too much like somebody embedded a subset of Rexx or Pascal awkwardly into an otherwise perfectly reasonable functional language
Rust is very different from Ocaml. Rust is a low level language with a borrow checkers, traits, no first class module system, no GADT, no effects.
The similarities are fairly superficial actually. It’s just that Rust is less behind the PL forefront that people are used to and has old features which look impressive when you discover them like variants.
There is little overlap between what you would sanely use Rust for and what you would use Ocaml for. It’s just that weirdly people use Rust for things it’s not really suited for.
As someone who has worked professionally in both, programming in rust does not feel much like programming in OCaml. Working with traits in an imperative manual memory managed language is really different than working with proper modules in a mixed paradigm language with an awesome GC.
Expression-based, immutable by default, pattern matching, static typing, and result / option types are the mix of features that make Rust what it is at its core, and each of those you'll find in OCaml. There's a couple others but that's the heart of it.
I'm not saying that Rust feels like Ocaml as some are interpreting, I said Rust is more imperative feeling, they're not the same. The reason Rust has had success bringing these features to the mainstream where Ocaml has not, I believe, is because Rust does not describe itself as a functional language, where as Ocaml does, right up front. Therefore, despite Rust having a reputation for being difficult, new learners are less intimidated by it than something calling itself "functional". I see it all the time. By the time they learn Rust, they are ready to take on a language like Ocaml, because they've already learned some of the best parts of that language via Rust.
Note my comment about their similarities is not at the level of borrow checkers and garbage collectors.
I loved Ocaml but now I love TypeScript more. It's got about the same amount of type safety, the ergonomics are better to me, and the packaging and ecosystem tooling are leaps and bounds above anything else.
Both languages have robust and expressive type systems. My experience is that TypeScript's is also more flexible. In Ocaml everything is cool as long as you stick with the functional programming style. But every "interesting" program also has imperative, non-functional-programming parts, and TypeScript has really good automatic "type narrowing" features that make that part much safer in my experience. In Ocaml however, type narrowing isn't automatic at all.
TypeScript certainly has a more complicated and flexible type systems in many respects, but it is not the same w/r/t safety. It is quite common to run across `any`s all over the place in TypeScript code, and there is no such thing in OCaml. TypeScript's systems is explicitly unsound (i.e., not fully type safe) by design: https://www.typescriptlang.org/docs/handbook/type-compatibil...
Ocaml has exactly the same kinds of escape hatches, like Obj.magic or unsafe accessors. The way I see it. it's a matter of community practice more than language capabilities. Typescript in practice has has the safety net of being interpreted rather than compiled, so I guess people tend to abuse its type flexibility more.
But if you write without the escape hatches in both languages, in my experience the safety is exactly the same and the cost of that safety is lower in TypeScript.
A very common example I've encountered is values in a const array which you want to iterate on and have guarantees about. TypeScript has a great idiom for this:
```
const arr = ['a', 'b'] as const;
type arrType = typeof arr[number];
for (const x of arr) {
if (x === 'a') {
...
} else {
// Type checker knows x === 'b'
}
}
```
First off, the escape hatches in TypeScript are way too accessible compared to OCaml: `JSON.parse(...) as MyInterface` is everywhere and completely broken.
And second, you're dismissing the fact that TypeScript is unsound, even worse it is so by design. Easy examples: uninitialized variables holding undefined when their type says they can't [1]; array covariance [2]; and function parameter bivariance, which is part of the TypeScript playground's own example on soundness issues [3] but at least this one can be configured away.
C# and Java made the same mistake of array covariance, but they have the decency of checking for it at runtime.
As for your example, I agree that TypeScript unions and singleton types are powerful, but I can't see what are you speficially missing here that pattern matching and maybe an additional variant type doesn't get you in OCaml. You get exhaustiveness checking and can narrow the value down to the payload of the variant.
Thanks, these are good examples of holes in typescript that I wasn't aware of. I guess I haven't pushed it enough yet to run into them. I agree Ocaml wouldn't fail.
> I can't see what are you speficially missing here that pattern matching and maybe an additional variant type doesn't get you in OCaml. You get exhaustiveness checking and can narrow the value down to the payload of the variant.
A couple things, being constrained to pattern matching in places where imperative programming would be more natural, having to declare lots of special purpose types explicitly vs being able to rely on ad hoc duck typing.
I absolutely love the idea and methods behind OCaml, but the syntax.....
I also love Haskell and already feel that its syntax is not easy to grok on larger projects, but OCaml basically went "hold my beer" and went to town on that.
> why isn’t OCaml more popular
I've used OCaml a bit and found various issues with it:
* Terrible Windows support. With OCaml 5 it's upgraded to "pretty bad".
* The syntax is hard to parse for humans. Often it turns into a word soup, without any helpful punctuation to tell you what things are. It's like reading a book with no paragraphs, capitalisation or punctuation.
* The syntax isn't recoverable. Sometimes you can add a single character and the error message is essentially "syntax error in these 1000 lines".
* Ocamlfmt is pretty bad. It thinks it is writing prose. It will even put complex `match`es on one line if they fit. Really hurts readability.
* The documentation is super terse. Very few examples.
* OPAM. In theory... I feel like it should be great. But in practice I find it to be incomprehensible, full of surprising behaviours, and also surprisingly buggy. I still can't believe the bug where it can't find `curl` if you're in more than 32 Unix groups.
* Optional type annotation for function signatures throws away a significant benefit of static typing - documentation/understanding and nice error messages.
* Tiny ecosystem. Rust gets flak for its small standard library, but OCaml doesn't even have a built in function to copy files.
* Like all FP languages it has a weird obsession with singly linked lists, which are actually a pretty awful data structure.
It's not all bad though, and I'd definitely take it over C and Python. Definitely wouldn't pick it over Rust though, unless I was really worried about compile times.
I would suggest that people interested in using OCaml on Windows (or indeed, OCaml at all) try F# instead. It is still an ML-family language. Incidentally, by targeting the CLR, F# is considerably more deployable (both to users and to developers) than OCaml is. Plus, any old NuGet library written in C# or VB.NET can be used almost trivially in F#. This also solves the problem OP listed about a tiny ecosystem, because the C#/.NET ecosystem is massive.
I couldn't agree more with the parent commenter about OCaml documentation. Functional programmers appear to love terseness to an almost extreme degree. Things like `first` are abbreviated to `fst`, which is just odd. Especially now that good IntelliSense means there is no real functional (heh) difference between typing `.fi` and pressing Tab, and typing `.fs` and pressing Tab.
The F# documentation is comparatively very spiffy and detailed, with plenty of examples[1][2][3].
[1]: https://learn.microsoft.com/en-gb/dotnet/fsharp/language-ref...
[2]: https://fsharp.github.io/fsharp-core-docs/
[3]: https://fsprojects.github.io/fsharp-cheatsheet/fsharp-cheats...
To decide on a language for a math research project, I implemented a toy problem in many languages: What is the distribution of cycle counts for signed permutations on n letters? Use all cores in parallel.
This had me briefly smitten with F#, till I realized the extent that rusty .NET bed springs were poking through. Same as the JVM and Clojure, or Erlang and Elixir. The F# JIT compiler is nevertheless pretty amazing.I nearly settled on OCaml. After AI warning me that proper work-stealing parallelism is a massive, sophisticated project to code properly, the 40 lines of OCaml code I wrote that beat available libraries is my favorite code file in years.
Nevertheless, once one understands lazy evaluation in Haskell, it's hard to use any other language. The log slowdown for conventional use of a functional data structure becomes a linear speedup once one exploits persistence.
F# is a nice language, but it depends on .NET, so a direct comparison to OCaml is not possible. The .NET runtime dependency often makes things unnecessarily complex and fragile. There must be a reason why Golang (no VM runtime) is successful despite entering the market very late after Java and C# had already established clear dominance.
Easier deployment helped, but nowadays it’s common to put a single Go executable in a container anyway. .net core doesn’t have much if any disadvantage there.
Go was made by Google flawed, but with clarity of purpose and consistently usable libraries.
.NET spent years forked into framework and core and unclear open source future.
Java struggled to scale down and Oracle caused similar distrust as Microsoft.
While I agree with most points, .NET or JRE introduce additional complexity that may not be welcome in every setting. I've worked for several companies where upgrading to a newer version of .NET was always a major pain point, especially for applications that weren't very actively developed. There is limited security support for each major .NET version, so at some point, you and your customers need to upgrade. Such problems are non-existent if you don't have a separate VM runtime dependency.
> I've worked for several companies where upgrading to a newer version of .NET was always a major pain point,
This was so difficult for the teams I work with that the person who became the team specialist in MSBuild, dotnet, and C# basically punched his ticket and received a couple of promotions. The work is so miserable and challenging that basically no one else Will take it.
I've struggled to understand why .net upgrades are so painful and laborious despite the maturity of the languages and ecosystems. I had assumed that, as with Powershell, C# and .net behind the scenes are undergoing enormous changes as Microsoft attempts to improve or add support for historically neglected platforms and hardware, and so I had assumed also that these were temporary problems, just badly managed growing pains on a path to major improvement, but I gather from your comment that the problem has a long history and is systemic. Awful.
MSBuild has been a huge source of the suffering I've experienced while working on these projects. The documentation is, in my experience, a nightmare: exhaustingly verbose, full of jargon, and uncanny in its ability to talk around an issue, concept, or functionality without clarifying anything conceptually or practically. I find this throughout Microsoft docs.
Upgrading a modern .NET (Core) version often means changing just versions in the project file. Upgrading from the old .NET Framework is bit more challenging, but we have also successfully upgraded a couple of Framework projects to modern .NET without too many issues.
I don’t think that has anything to do with VMs, the same happens with C++ runtime libraries.
The difference is Go really focused on continuity and compatibility, while .NET didn’t.
> ...the same happens with C++ runtime libraries
I don't think so. Upgrading to a newer major version of the C++ runtime essentially involves recompiling, unless you're dealing with an application that's 15 years or older. You can even instruct the compiler to use an older C++ standard if your code won't compile with the newer one. There is also an option to compile the runtime statically, though it is obviously not recommended.
.NET is a different story [1]
[1]: https://learn.microsoft.com/en-us/dotnet/core/compatibility/...
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I would really like to read more about this!
F# would be awesome but for the dogs*t .Net backend that made the tiniest error insoluble
What about D? Can you post any of the 10 source codes?
Interesting, would be a good blog post to read.
No Fortran?
F# is indeed an ML-family language, but at this point it doesn't have all that much in common with OCaml specifically: it doesn't have the latter's structurally typed object model with inferred row-polymorphic types, nor its extremely powerful module system, not even many convenience features like open variants.
F# has plenty of features that OCaml doesn't have like proper cross-platform support, proper deployment, active patterns, units of measure, computation expressions, type providers, interfaces on unions and records, etc. F# is probably faster as well and definitely has a larger ecosystem through .NET.
F# pretty much assumes you already know C#. I found that it made it hard to get up to speed on it. I really do enjoy the the syntax though.
I find F# nowhere near as good as OCaml and think this comparison is ugly, but if I was forced to use a .NET platform I would almost certainly use F#
> nowhere near as good as OCaml
I'd really like to hear more about this. From what I've used of F# and OCaml, both languages are around 95% the same.
I'll give you my top 3.
F# is worse because the type inferencing isn't as good. You need to type annotate in more places. It's a drag, because it feels like a missed opportunity to let the machine do work for you.
Additionally, one of the most pleasant and unique features of OCaml, strong named arguments, doesn't exist in F# (except in methods or whatever). Most programming languages don't have this (or it's hamfisted like in more dynamic languages) so it doesn't seem like a loss, unless you are very cozy with them in OCaml.
(I'm bitter about this one because named arguments give safety and convenience. But when you combine them with currying it's like 4 or 5 design patterns that are elegantly provided for you. You just do it implicitly, without ever having to study a book about using them.)
Finally, F# brings back the NULL problem that OCaml worked so hard to eradicate.
And you cannot have default arguments for function parameters in F#. They are only allowed with methods.
interesting. how named arguments work with currying?
Nearly the same as with positional argument: Partially applying a function to a named argument creates a closure with this argument filled in, and you can apply the argument in whichever order you want:
The more complex interaction is rather with type inference and currying, or the interaction between currying and optional arguments.If you are interested, I think I adress this here https://xvw.lol/en/articles/why-ocaml.html#ocaml-and-f
Thanks, this is a very nice article.
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> * OPAM. In theory... I feel like it should be great. But in practice I find it to be incomprehensible, full of surprising behaviours, and also surprisingly buggy. I still can't believe the bug where it can't find `curl` if you're in more than 32 Unix groups.
I couldn’t believe this was an actual bug in opam, and I found it: https://github.com/ocaml/opam/issues/5373
I don’t think that’s an opam bug, it’s an issue with musl, and they just happened to build their binaries with it.
A lot of these are learning curve issues, but once you scale them you still permanently suffer with a very deficient, fragmented ecosystem. Until you have built up your own curated set of dependencies for your business stack, anyway.
> * Ocamlfmt is pretty bad. It thinks it is writing prose. It will even put complex `match`es on one line if they fit. Really hurts readability.
I suggest configuring ocamlformat to use the janestreet profile for better defaults.
> * Optional type annotation for function signatures throws away a significant benefit of static typing - documentation/understanding and nice error messages.
People should be providing .mli files, but don't. That said, an IDE with type hints helps this enormously. The VS Code plugin for OCaml is the best experience for noobs, hands down.
> OPAM
yes
With all the issues, how does janestreet love it so?
> * Like all FP languages it has a weird obsession with singly linked lists, which are actually a pretty awful data structure
This made me chuckle. I've had that thought before, shouldn't the default be a vector on modern devices? Of course other collection types are available.
The reason why functional languages like linked lists so much is because they are very easy to make immutable without a lot of pain all around. If you implement an immutable vector in a straightforward way, though, you basically need to do a lot of copying for any operation that needs to construct one (the rigmarole with immutable strings, and existence of hacks such as StringBuilder, is a good illustration of the problem).
But you can have a data structure that is more like vector under the hood while still supporting efficient copy-with-modifications. Clojure vectors, for example.
That makes sense. But LinkedIn lists are horrible for cache efficient things no? I think there was an article on HN from a Golang perspective padding structs or something such that they are efficient wrt to cache hits.
> But LinkedIn lists are horrible for cache efficient things no?
LinkedIn Lists you say? (Sorry. (But not that sorry.))
Edit meta sidenote: in this modern meme world, it's virtually impossible to know if a typo is a typo or just a meme you haven't heard of yet.
LinkedIn lists will tell you they contain one new element, but you have to click on a link and scroll through their suggested new elements to see what it is
Do they also always end with an element that tells you what the LinkedIn list taught it about B2B sales?
lol my phone autocorrected ugh.
But you know what I mean. Some grace would be nice.
I know. It was just too hard to pass up. :)
Well you got me. I audibly groaned and slapped my forehead.
They are, but you don't tend to keep them around in memory long enough. Start consuming the front before you produce the back.
Which is a pity, you can fit entire small arrays in a cache line to end up with no pointer chasing at all.
I'd say that functional programming is probably one of the only domains where linked lists actually make sense. Vectors certainty have their use in more places though.
A good compiler will make the lists disappear in many cases. No runtime overhead. I actually love single linked lists as a way to break down sequences of problem steps.
In Haskell, yes, because laziness permits deforestation. ML, including OCaml, is eager and consequently cannot do this.
I believe it's possible in theory - Koka has a whole "functional but in-place" set of compiler optimisations that essentially translate functional algorithms into imperative ones. But I think that's also possible in Koka in part because of its ownership rules that track where objects are created and freed, so might also not be feasible for OCaml.
I mean, the set of valid deforestation transformations you could do to an OCaml program is not literally the empty set, but OCaml functions can do I/O, update refs, and throw exceptions, as well as failing to terminate, so you would have to be sure that none of the code you were running in the wrong order did any of those things. I don't think the garbage collection issues you mention are a problem, though maybe I don't understand them?
Part of what Koka's functional-but-in-place system relies on is the Perceus program analysis, which, as I understand it, is kind of like a limited Rust-like lifetime analysis which can determine statically the lifetime of different objects and whether they can be reused or discarded or whatever. That way, if you're, say, mapping over a linked list, rather than construct a whole new list for the new entries, the Koka compiler simply mutates the old list with the new values. You write a pure, functional algorithm, and Koka converts it to the imperative equivalent.
That said, I think this is somewhat unrelated to the idea of making linked lists disappear - Koka is still using linked lists, but optimising their allocation and deallocation, whereas Haskell can convert a linked list to an array and do a different set of optimisations there.
See: https://koka-lang.github.io/koka/doc/book.html#sec-fbip
Why would a specific way of structuring data in memory be relevant to breaking down sequences of problem steps?
If what you mean is the ability to think in terms of "first" and "rest", that's just an interface that doesn't have to be backed by a linked list implementation.
I’m curious what you mean. Surely there’s the overhead of unpredictable memory access?
Not GP but bump allocation (OCaml's GC uses a bump allocator into the young heap) mitigates this somewhat, list nodes tend to be allocated near each other. It is worse than the guaranteed contiguous access patterns of a vector, but it's not completely scattered either.
Ah yes, our old friend - the sufficiently smart compiler.
+10 for bad windows support, i think this is a key and weirdly underestimated reason
just to give an idea how bad, until recently, you could not just go to ocaml.org and download ocaml for windows, you had to either download one for mingw or wsl
so for many it was just not installable, i.e. for many we didnt have ocaml for windows, until very very recently
> just to give an idea how bad, until recently, you could not just go to ocaml.org and download ocaml for windows
On the other hand, you could get ocaml for Windows from Microsoft ever since 2005.
F# is not "OCaml for Windows". Not even close.
The Windows support is bad because OCaml is a PL designed by people who are deep in Linux life. Windows is not something that keeps them up at night. (Which isn't to say they didn't try, just, you know, not as much as it takes)
One of the things people often neglect to mention in their love letters to the language (except for Anil Madhavapeddy) is that it actually feels UNIXy. It feels like home.
> designed by people who are deep in Linux life.
> it actually feels UNIXy. It feels like home.
They use single dashes for long options.
This is not home.
https://linux.die.net/man/1/ocaml
Unix doesn't use double dashes for options; that's a GNU thing, and, as everyone knows, GNU's Not Unix.
Normally the Unix/GNU opposition is irrelevant at this point, but you managed to pick one of the few significant points of difference.
If that's what you use as your yardstick of what's Unixy, then I guess you don't consider "find" to be Unixy, in spite of being one of the early Programmer's Workbench tools.
Short options were a compromise to deal with the limits of the input hardware at the time. Double dashes were a workaround for the post-dash option car crash traditional Unix tooling allows because teletypes were so slow. There is nothing particularly Unixy about any of these options other than the leading hyphen convention.
OCaml using single hyphens is not un-Unixy.
Caml was developed in 01985, Linux was first released in 01991, and Caml was extended into OCaml in 01996. I don't think the developers were using Linux at the time; SunOS 4 would be my best guess. I didn't work on it, but I was in the sort of internetty environment that OCaml came from, and I was using Solaris at work and got my first Linux box at home. As another commenter mentioned, the command line follows Unix conventions rather than the Linux conventions from GNU.
Forgive me for implying the Linux lifestyle and UNIX lifestyle were anything close to the same thing.
I will turn in my Plan 9 install media and my copy of The Design and Implementation of the 4.3BSD Operating System at the nearest DEC service center.
It's just sort of anachronistic. Caml was no more designed by people deep in Linux life than James Clerk Maxwell was into aviation or Christopher Columbus liked to visit the Massachusetts Bay Colony. They probably would have been, but the timelines didn't allow it.
Sure. The larger point was about Windows. You would or would not agree that people doing PL research on SunOS workstations (or whatever UNIX) would also not give a shit about Windows?
Windows didn't exist in 01985. I mean, Microsoft did release a product by that name at the end of the year, but it wasn't an operating system.
I remember that in 01998 or 01999 I asked Andrew Tanenbaum, a different European CS professor, what he thought about Linux. His impression was still that it was some kind of hobbyist project for people who (paraphrasing here and reading between the lines) couldn't afford a real computer. So I suspect that, even when Caml became OCaml, its developers saw Linux as belonging to the same crowd as Microsoft Windows, rather than to the systems they were used to.
But even that Windows/Unix OS dichotomy didn't exist when the programming language was designed. They might have been thinking about Unix vs. VMS, or Unix vs. GCOS, or Unix vs. Oberon, or BSD vs. System V, but definitely not Linux vs. Windows.
Opam on Windows is a masterpiece of engineering
can you elaborate, or maybe share a blog post about it
Have to find time for this. The TLDR is that it just works.
I wish I could make a list like this about rust in this place and not be flagged.
I don't think you would be flagged. Rust definitely has flaws:
* Compile time is only ok. On par with C++.
* Async has a surprisingly number of footguns and ergonomic issues.
* There's no good solution to self-borrowing or partial borrows.
* While using macros is fine, writing them is pretty awful. Fortunately you rarely need to do that. Relatedly it is missing introspection support.
* Sometimes the types and lifetimes get very complex.
But overall I still much prefer it to OCaml. The syntax is much nicer, it's easier to read, the ecosystem and tooling are much better, the documentation is much better, and it actively hates linked lists!
You missed one:
* Crates.io is an unmoderated wasteland of infinite transitive dependency chaos
But my "favourite":
* It's 2025 and allocator-api (or its competitors) is still in nightly only and no sign of stabilizing
I work almost exclusively in Rust, and I like the language but in many respects a) Rust is the language that tokio ate, and b) it has been deluged with people coming from the NodeJS/NPM ecosystem doing Web Scale Development(tm) and its terrible practices around dependency management.
> Crates.io is an unmoderated wasteland of infinite transitive dependency chaos
Well, I'm not sure I agree with that. If by "unmoderated" you mean anyone can upload a crate without going through bureaucratic approvals processes then that seems like a good thing to me!
But you did remind me of one other majorly annoying thing about the crate system: the global namespace. It doesn't have the same security issues as Python's global package namespace, but it is really really annoying because you pretty much have to break large projects down into multiple crates for compile time reasons, and then good luck publishing those on crates.io. Plus you end up with a load of crate names like `myproject-foo`, `myproject-bar`, which is very verbose.
Oh and yeah, the Tokio situation is a bit sad.
Also the proliferation of some types of crates like error handling. This should really be in the standard library by now (or at least fairly soon). Any large project ends up with like 5 different error handling libraries just because dependencies made different choices about which to use. It's not a major issue but it is silly.
Overall though, still my favourite language by far.
I think the error type stuff should be less prominent, and really shouldn't be front-and-center in the standard library, or any library. Error handling is undoubtedly important, but its expression in the API is a different matter. I don't have fully formed opinions, but I do feel that the common recommendations are bad.
On the topic of allocators, I noticed some PRs to add allocator support to more types recently...great, now we just need to stabil—oh, wait. Although I care more about not stabilizing a bad API than eternal unstability, if it comes down to that.
The problem for me is that instead of focusing on the problem at hand and the business logic, I have to focus on the Rust memory model and the borrow checker. And seems very verbose.
Thing is, if I sketch something in pseudocode, I should be able to translate it to any mainstream programming languages. With Rust I can't just do that, I have to bend the problem to fit the way the language works.
That third issue is very annoying. C++ in visual studio often has that and I'll help someone who has like 2,000 weird errors and my response is usually "looks like a missing semicolon to me" and they're like "????" Why wouldn't it be able to just say that.
> The documentation is super terse. Very few examples.
I agree. OCaml is a complex language with very beginner-unfriendly documentation. In fact, I would even say it's unfriendly to engineers (as developers). The OCaml community prefers to see this language as an academic affair and doesn't see the need to attract the masses. E.g. Rust is an example of the opposite. It's a complex language, but it's pushing hard to become mainstream.
I just don't get these comments about syntax...
Just taking the first example I can find of some auto-formatted OCaml code
https://github.com/janestreet/core/blob/master/command/src/c...
It doesn't look more a soup of words than any other language. Not sure what's hard to parse for humans.
> The syntax is hard to parse for humans
This was my problem as well, the object oriented related syntax is just too much. ML of which caml is a version of, has really tight syntax. The “o” in ocaml ruins it imo.
No offense but the only time I have encountered objects in Ocaml was while using LablGTK a long time ago and the object syntax was pretty clean and not far from the module one. They are also structurally typed which is very handy.
Considering it only impacts a fairly small subset of the language, could you explain how it supposedly ruins everything?
I kinda feel that singly linked lists isn't a data structure in FP as much as a (dynamic) control flow structure. It's okay in that application.
> The syntax is hard to parse for humans.
Funny how tastes differ. I'm glad it has a syntax that eschews all the noise that the blub languages add.
It's interesting reading many of the associated comments, because there is a genuinely active effort to address many of the pain points of the language:
* Windows support has improved to the point where you can just download opam, and it will configure and set up a working compiler and language tools for you[^1]. The compiler team treat Windows as an first tier target. opam repository maintainers ensure new libraries and library versions added to the opam repository are compiled and tested for Windows compatibility, and authors are encouraged to fix it before making a release if its reasonably straightforward
* debugger support with gdb (and lldb) is slowly being improved thanks to efforts at Tarides
* opam is relatively stable (I've never found it "buggy and surprising"), but there are aspects (like switches that behave more like python venvs) which don't provide the most modern behaviour. dune package management (which is still in the works) will simplify this considerably, but opam continues to see active development and improvement from release to release.
* the platform team (again) are working on improving documentation with worked recipes and examples for popular uses cases (outside of the usual compiler and code generation cases) with the OCaml Cookbook: https://ocaml.org/cookbook
There are other things I find frustrating or that I work around, or are more misperceptions:
* there isn't a builtin way to copy files because the standard library is deliberately very small (like Rust), but there is a significant ecosystem of packages (this is different to other languages which cram a lot into their standard library). The result is a lot of friction for newcomers who have to install something to get what they need done, but that's valued by more experienced developers who don't want the whole kitchen sink in their binary and all its supply chain issues.[^2]
* the type inference can be a bit of a love/hate thing. Many people find it frustrating because of the way it works, and start annotating everything to short-circuit it. I've personally found it requires a bit of work to understand what it is doing, and when to rely on it, and when not to (essentially not trying to make it do things it simply will never be able to do).[^3]
* most people use singly-linked lists because they work reasonably well for their use cases and don't get in their way. There are other data structures, they work well and have better performance (for where it is needed). The language is pragmatic enough to offer mutable and immutable versions.
* ocamlformat is designed to work without defaults (but some of them I find annoying and reconfigure)
Please don't take this as an apology for its shortcomings - any language used in the wild has its frustrations, and more "niche" languages like OCaml have more than a few. But for me it's amazing how much the language has been modernised (effects-based runtime, multicore, etc) without breaking compatibility or adding reams of complexity to the language. Many of these things have taken a long time, but the result is usually much cleaner and better thought out than if they were rushed.
[^1] This in itself is not enough, and still "too slow". It will improve with efforts like relocatable OCaml (enabling binary distribution instead of compiling from source everywhere) and disentangling the build system from Unixisms that require Cygwin.
[^2] I particularly appreciate that the opam repository is actively tested (all new package releases are tested in a CI for dependency compatibility and working tests), curated (if its too small to be library, it will probably be rejected) and pruned (unmaintained packages are now being archived)
[^3] OCaml sets expectations around its type inference ("no annotations!") very high, but the reality is that it relies on a very tightly designed and internally coherent set of language constructs in order to achieve a high level of type inference / low level of annotation, but these are very different to how type inference works in other languages. For example, I try and avoid using the same field name in a module because of the "flat namespace" of field names used to infer record types, but this isn't always possible (e.g. generated code), so I find myself compensating by moving things into separate modules (which are relatively cheap and don't pollute the scope as much).
> It just genuinely felt like the Go language designers didn’t want to engage with any of the ideas coming from functional programming.
You'd be right.
"The key point here is our programmers are Googlers, they’re not researchers. They’re typically, fairly young, fresh out of school, probably learned Java, maybe learned C or C++, probably learned Python. They’re not capable of understanding a brilliant language but we want to use them to build good software. So, the language that we give them has to be easy for them to understand and easy to adopt. – Rob Pike 1"
"It must be familiar, roughly C-like. Programmers working at Google are early in their careers and are most familiar with procedural languages, particularly from the C family. The need to get programmers productive quickly in a new language means that the language cannot be too radical. – Rob Pike 2"
Talking as someone who wrote OCaml at work for a while, the benefits of functional programming and the type guarantees that it's ilk provides cannot be understated; you only start to reach them, however, once most developers have shifted their way of thinking rather extremely, which is a time cost that that designers of Go did not want new Googlers to pay.
You would be surprised how many Googlers think the Go team is making bad decision after bad decision.
Not just Googlers. There is a certain pragmatism and then there is being stubborn.
How so? I’m not that familiar with Go anymore.
Search any Go codebase for err != nil, for starters.
Well, sure, but this is a problem nearly as old as Go itself. I thought they were referring to larger more recent things, like how generics work, or something to that effect.
> is a problem nearly as old as Go itself
It's as old as C. C and Go are the only two significant languages which end up constantly checking for errors like this.
I am exactly the type of novice programmer described in the quotes.
>have shifted their way of thinking rather extremely
What could I read to shift my way of thinking?
The signals & threads episode about OCaml strongly piqued my interest, and not because I have any JS delusions (they would never, lol).
Functional programming is a different way of thinking about solving problems. People say it's about thinking about "what you're trying to compute" versus "how you're computing it," but quite frankly that never made sense to me. I prefer to think about it in terms of thinking about relationships (FP) versus thinking about steps over time (procedural).
This, at least for me, brings the act of writing a specific piece of code more inline with how I think about the system as a whole. I spend less energy worrying about the current state of the world and more about composing small, predictable operations on relationships.
As for what you can read, I find it's just best to get going with something like OCaml or F# and write something that can take advantage of that paradigm in a relatively straightforward way, like a compiler or something else with a lot of graph operations. You'll learn pretty quickly what the language wants you to do.
To this day, whenever I see Machine Learning abbreviated, my heart skips a beat, then I become crestfallen as I realize I'm not about to read something about Meta Language.
ML refers to Meta Language and LLM refers to Languages and Logic Montreal [0], a PL theory group. [0] https://llm.uqam.ca
> PL theory group
I know there are great many Polish people in the world, but why it matters so much in this case? They could have been any nationality, even French!
I believe many people use PL to mean programming language. I'm wondering if your joke just wooshed me.
You believe I'd purposefully misread an abbreviation in a comment about misreading abbreviations, and also coincidentally tried to make fun of two other nationalities (maybe even three, depending on political views), all at the same time?
I would never.
I mean pohl's joke above whooshed kjmh so it's all fine. The important thing for threads like this one is for us to name drop all of the weird programming languages that we have used, publicly avow the greatness of ones that we have not, and make a New Year's resolution that we will never follow, to actually pick up those great languages and write something in them...
> make a New Year's resolution that we will never follow, to actually pick up those great languages and write something in them...
Why must you call me out in this way? How did I wrong you, that I deserve this?
I'd rather have that issue than seeing "AI" plastered all over the place. I'm of the opinion AI should be reserved for artificial general intelligence. These things aren't intelligent yet. They're just em-bloat-ified traditional machine learning techniques. Not that they're useless. I just hate the terminology.
If people start using the term AI, we better be living in I, Robot. Not whatever the hell this is.
Tangential rant. Sorry.
We lost this fight at least by 1994 when Sun acquired “Thinking Machines,” which to its credit was bankrupting itself by making highly parallel supercomputers, at least. Now of course there is a new AI company of the same name. If the wrestling world echoes the computing world, one can only wonder what in 5-10 years will be the equivalent of Undertaker throwing Mankind off of Hell In A Cell to plummet 16 feet down through an announcer’s table...
I believe that current publicly available Ais are more intelligent than a non trivial fraction of adults.
I also think AK would fit better.
AK-42
ML blew my mind back in the late 1980s when I got to use it on a 80286 machine for the first time!
Thanks for posting about ML! I made a post similar to yours a couple of years ago and got downvoted, lol.
Why isn't it more popular?
I think Richard Feldman [0] proposed some of the most reasonable theories as to why functional programming isn't the norm. Your language needs to be the platform-exclusive language for a widely used platform, have a killer application for a highly desired application domain, or be backed by a monster war-chest of marketing money to sway opinions.
Since Feldman's talk, Python has grown much faster in popularity in the sense of wide use in the market place... but mostly because it's the scripting language of choice for PyTorch and AI-adjacent libraries/tooling/frameworks which is... a killer application.
I like OCaml. I started evaluating functional programming in it by taking the INRIA course online. I spent the last four and half years working in Haskell. I've built some side projects in Zig. I was a CL stan for many years. I asked this question a lot. We often say, "use the best tool for the job." Often that means, "use the tool that's available."
I think languages like OCaml, Rust, Haskell etc can be "popular," but in the sense that people like to talk about them and want to learn them and be able to use them (at least, as trends come and go). It's different from "popular" as in, "widely adopted."
[0] https://www.youtube.com/watch?v=QyJZzq0v7Z4
> mostly because it's the scripting language of choice for PyTorch and AI-adjacent libraries/tooling/frameworks
I would politely disagree. Torch started in Lua, and switched to Python because of its already soaring popularity. Whatever drove Python's growth predates modern AI frameworks
Python was already big for scientists back in 2010. I remember working on Python tooling at the time, and DS/ML was one of our single largest user groups. It was already popular enough to have an IDE specifically for scientific Python use: https://en.wikipedia.org/wiki/Spyder_(software).
As far as I could tell, it had to do with two things. First, Python is notoriously dynamic and extensible, making it possible to implement "sloppy" syntax like advanced slicing or dataframes. But also, those guys had lots of pre-existing C and Fortran code, and Python had one of the easiest extensibility APIs to wrap it as high-level packages. And with IPython, you had a nice REPL with graphing to use all that from, and then of course notebooks happened.
Yeah, I can see that. At the time of the talk Feldman claims Python is a slow-and-steady language. It definitely did get a lot of support from the scientific/engineering community for a long time. I spent a good part of my career with Python from about 2006-2016.
It had boosts from Django... but it never had Rails' level of popularity. You kinda have to be first-to-market and that good to get the "killer app" effect.
It's also been integrated as the scripting language for several popular software pacakges (Blender comes to mind).
Machine learning and now... "AI"; seems to be a market cornered by Python quite a bit.
Google blessed Python at a time when Java didn’t even have lambdas.
A MAJOR portion of popularity was because of this xkcd comic.
https://xkcd.com/353/
It hit the front page of Slashdot, Digg, Reddit, made the rounds on Hacker news, etc... (https://news.ycombinator.com/item?id=86246)
Django was also very popular at the time.
I had already learned Basic, C++, Java, and C#. I wanted to add a dynamic scripting language that was cross-platform under my belt.
A lot of my peers were in the same boat.
Python seemed at the time, to be the only general purpose scripting language that was easy to use on multiple platforms.
I had heard bad things about Perl being write only, and Ruby being tough to deploy, I also found it hard to read. (Which is a shame they are wonderful languages, though Ruby is dog slow, Python is slow too, but Ruby is worse somehow).
IIRC Google and some other large companies were pushing it as one of their official languages.
Right as Python was rocketing in popularity, Go came out, and I also heard a lot of good things about Clojure (they seemed neck and neck in popularity from my incorrect perspective at the time, lol).
I think Python became popular before Go came out.
Do you mean the comic was responsible, or the comic explains why Python is popular? It is definitely the ecosystem. As you said its general purpose. It is used for numerical computing and visualisation, web apps, GUIs, sysadmin. Even a reasonably popular DVCS is written in Python.
I wrote: “Right as Python was rocketing in popularity, Go came out.”
I wasn’t talking chronology of first release, just describing the overlap in hype cycles back then.
The comic was released in 2007, and started heading to the moon. Go came out around 2009, and almost instantly got traction.
I do not mean to disagree with just, just wanted to clarify some wording and add to the "general purpose aspect of Python.
I look at how people write TypeScript these days, and think about how the world might have been different if, 10-15 years ago, these functional languages had been a bit closer to the imperative world. OCaml allows mutation and side effects and could even feel a bit imperative if it weren't for the "let ... in" syntax.
Let's face it, syntax matters. We saw that with Elixir becoming much more popular than Erlang ever did. We saw it with TypeScript being able to introduce a fairly complex type system into JavaScript, and becoming successful among web devs by adapting to established ecosystem and offering a gradual approach, rather than forcing an entirely new, incompatible paradigm on it. The TypeScript story seems a little improbable in hindsight, but it was able to get there by offering an incremental path and making a lot of compromises (such as config options to allow less strict enforcement) along the way.
Personally, I think a new syntax for OCaml might actually be successful if done right. Sure, there have been multiple attempts (the "revised" syntax, Reason, etc.), but none of them are really willing to modernize in ways that would attract your average programmer. The toolchain also needs work to appeal to non-OCaml programmers.
Could you explain how Reason syntax isn't "really willing to modernize in ways that would attract your average programmer"? I'm trying to understand what do you even mean.
Reason still looks like an ML-style language rather than something from the C family of things (where JavaScript ultimately comes from).
For example, in Reason, a function is:
A more JS-like syntax might be: Or at least:But the Reason example you shared is almost valid TypeScript already!
https://www.typescriptlang.org/play/?#code/DYUwLgBAHgXBAUBDO...
I've seen JS using lambdas instead of classic functions like that in the wild. And that Reason can be made more JS-idiomatic without changes to the syntax:
[flagged]
TCL it's almost Lisp with strings instead of atom lists. I prefer it a little over Perl.
No macros, limited support for higher order functions. Its big drawback is the small ecosystem.
I like TCL, but its not really comparable to lisp. Its definitely a great scripting language and is a lot more flexible than it gets credit for.
It got a lot of things right. Event driven concurrency (and its got a good threading model) which is often given as a reason to use JS to right servers. Sandboxing untrusted code. Easy GUIs with Tk. Easy cross platform deployment. Unfortunately it never got traction.
> Unfortunately it never got traction.
Categorically not true. Tcl got a LOT of traction. Expect was everywhere. Tk kicked ass and took names. AOLserver, anyone? VLSI CAD stuff still uses it today.
It just got pushed out of the way over time. IMO, mostly because VB6 took its niche of easy GUI.
> It is an old language, and there are a few features that could probably be left out like the OOP-related features, and some libraries in the ecosystem over-complicate things like in Haskell.
If one can stand a language that is just a little bit older, there is always Standard ML. It is like OCaml, but perfect!
I love standard ml (I'm currently writing a compiler for it), but it's far from perfect. There are weird special cases in the language definition like the ad-hoc overloading between int and real, or the annoying value restriction. Records also feel half-baked, with no support for updating fields or for partially-specified records where the full set of fields is not known
> with no support for updating fields
While it's not yet standard nearly all Standard ML implementations support what has become known as "Successor ML" [0]. A large subset of Successor ML is common to SML/NJ, MLton, Poly/ML, MLKit and other implementations.
That includes record update syntax, binary literals, and more expressive patterns among other deficiencies in Standard ML.
For me the two big remaining issues are:
1) There's only limited Unicode support in both the core language and the standard library. This is a big issue for many real-world programs including these days the compilers for which SML is otherwise a wonderful language.
2) The module system is a "shadow language" [0] which mirrors parts of SML but which has less expressiveness where modules cannot be treated as first-class values in the program. Also if you define infix operators in a module their fixity isn't exported along with the function type. (Little annoyance that gets me every time I am inclined to write Haskell-style code with lots of operators. Though maybe that's just another hint from the universe that I shouldn't write code like that.) Of course, the fix to that would be a fundamentally different language; not a revised SML.
[0] http://mlton.org/SuccessorML
[1] https://gbracha.blogspot.com/2014/09/a-domain-of-shadows.htm...
As I was saying, Successor ML is like OCaml, but perfect!
I've written a fair amount of SML (though years ago) and I can't remember the value restriction ever being an issue.
I certainly agree that SML isn't really a production language, though.
I far preferred Standard ML when I learned both back in the day, but it was OCaml that won the headspace it seemed.
Ironically probably because it had the "O"bjects in it, "which was the style of the time"... something that has since dropped off the trendiness charts.
I love SML, and came to OCaml a bit begrudgingly initially just for a larger ecosystem. But, I think the object system gets a unjustly bad wrap. The OCaml object system is dope. It is rarely needed and not the best feature for most use cases, but when you want structurally-typed records, or need open recursion (or need to represent JS objects for the amazing `Js_of_ocaml`), they are a perfect fit.
I've dabbled in F# (and aside from the rough setup with little coherent information at the time) had a pretty good time. Actor-based concurrency was easy to grok. The one gotcha was whenever those mutable Arrays entered the picture.
I'd like to hear some practical reasons for preferring OCaml over F#. [Hoping I don't get a lot about MS & .NET which are valid concerns but not what I'm curious about.] I want to know more about day to day usage pros/cons.
It's a matter of trends: F# is losing compatibility with the overall CLR ecosystem due to the churn in C# features with poor F# interop, but F# has already mingled its design with the CLR's, too much to live on its own as a native language. Plus its compiler is slow and the tooling is getting increasingly unstable.
Meanwhile, OCaml got rid of its global lock, got a really fast-compiling native toolchain with stable and improving editor tooling, and has a cleaner language design with some really powerful features unavailable to F#, like modules/functors, GADTs, effects or preprocessors. It somehow got immutable arrays before F#!
F# still has an edge on some domains due to having unboxed types, SIMD, better Windows support and the CLR's overall performance. But the first two are already in the OxCaml fork and will hopefully get upstreamed in the following years, and the third is improving already, now that the opam package manager supports Windows.
> has an edge on some domains due to having unboxed types
If a language makes "unboxed types" a feature, a specific distinction, and has to sell "removing global lock" as something that is a massive breakthrough and not table stakes from 1.0, it can't possibly be compared to F# in favourable light.
I vouched for your dead comment because I get where you're coming from. But OCaml 1.0 was in 1996 in an academic setting. I care about the language I can use now, not the one I didn't use.
Let's not dismiss that their solution to remove the global lock has been both simpler than Python's (better funded?) ongoing work and backwards compatible; and the multicore support came with both a memory model with strong guarantees around data races, and effect handlers which generalize lightweight threads.
I agree that lack of unboxed types is a fatal flaw for several domains (Worse, domains I care about! I usually consider Rust/Go/.NET for those.) But when the comparison with OCaml is favourable to F#, the gap isn't much wider than just unboxed types. F# has an identity crisis between the ML parts and the CLR parts, its C# interop is decaying as the ecosystem evolves, and newer .NET APIs aren't even compatible with F# idioms (here's a .NET 6+ example [1]).
[1]: https://sharplab.io/#v2:DYLgZgzgNAJiDUAfA9gBwKYDsAEBlAnhAC7o...
Ref structs are hard to solve because they require, in some ways, a lot more work than the way C# solved the lifetimes as the lifetimes in F# may need to become much closer to what they are in Rust. Some constructs may not be able to consume them still (can’t move ref struct into an object with effective lifetime ‘static) and there really is no easy solution short of language editions and breaking standard library changes. A limited improvement is possible, but we’re still in the realm where the lifetimes may become a part of type identity or somehow generalized over, which is hard.
OCaml predates multicore CPUs. Having a global lock was basically free at the time it was invented. It's totally crazy to dislike a language because the authors made a decision that was obviously correct at the time.
Where can I read more on F# unboxed types? My searches are only turning up examples of unboxed primitives.
Where's the equivalent to https://hackage-content.haskell.org/package/vector-0.13.2.0/... ?
F# uses the CLR term "value types" instead, or sometimes "struct" types as in the C# keyword.
These are usually defined with the [<Struct>] attribute over a regular type definition, or using the struct keyword before tuple/anonymous record types. Also, the original 'T option type now has a value-type successor 'T voption.
In .NET the unboxed types are value types and boxed types are reference types. And you can box and unbox them.
We’ve used f# professionally for the computations-intensive parts of our product for a couple of years. Here’s what comes to mind:
1. Interop with C# is great, but interop for C# clients using an F# library is terrible. C# wants more explicit types, which can be quite hard for the F# authors to write, and downright impossible for C# programmers to figure out. You end up maintaining a C#-shell for your F# program, and sooner or later you find yourself doing “just a tiny feature” in the C# shell to avoid the hassle. Now you have a weird hybrid code base.
2. Dotnet ecosystem is comprehensive, you’ve got state-of-the web app frameworks, ORMs, what have you. But is all OOP, state abounds, referential equality is the norm. If you want to write Ocaml/F#, you don’t want to think like that. (And once you’ve used discriminated unions, C# error-handling seems like it belongs in the 1980’ies.)
3. The Microsoft toolchain is cool and smooth when it works, very hard to wrangle when it doesn’t. Seemingly simple things, like copying static files to output folders, require semi-archaic invocations in XML file. It’s about mindset: if development is clicking things in a GUI for you, Visual Studio is great (until it stubbornly refuses to do something) ; if you want more Unix/CLI approach, it can be done, and vscode, will sort of help you, but it’s awkward.
4. Compile-times used to be great, but are deteriorating for us. (This is both F# and C#.)
5. Perf was never a problem.
6. Light syntax (indentation defines block structure) is very nice until it isn’t; then you spend 45 minutes how to indent record updates. (Incidentally, “nice-until-it-isn’t” is a good headline for the whole dotnet ecosystem.
7. Testing is quite doable with dotnet frameworks, but awkward. Moreover. you’ll want something like quickcheck and maybe fuzzing; they exist, but again, awkward.
We’ve been looking at ocaml recently, and I don’t buy the framework/ecosystem argument. On the contrary, all the important stuff is there, and seems sometimes easier to use. Having written some experimental code in Ocaml, I think language ergonomics are better. It sort of makes sense: the Ocaml guys have had 35 years or so to make the language /nice/. I think they succeeded, at least writing feels, somehow, much more natural and much less inhibited than writing F#.
> I'd like to hear some practical reasons for preferring OCaml over F#
Bigger native ecosystem. C#/.net integration is a double edged sword: a lot of libraries, but the libraries are not written in canonical F#.
A lot of language features F# misses, like effect handlers, modules, GADTs etc.
I did get some sense of that where F# sort of (actually is) 2nd class to C# which is slowly gaining some F# features, but F# itself isn't well promoted/supported.
As for missing language features, they can also be a double-edged sword. I slid down that slippery slope in an earlier venture with Scala. (IIRC mostly implicits and compile times).
There are libraries that simulate a lot of these things (e.g. https://github.com/G-Research/TypeEquality for GADTs). You're absolutely right that it's not as first class as in OCaml, but the tools are there if you want them.
I've written type-equality witnesses in F#, they can kinda recover type equalities (with cast methods) but not refute them, so you still need to raise exceptions for those cases.
OCaml is a much more powerful language. Take a look at functors, for example, or modules as first-class values, or GADTs, or its object system that can do type inference from use:
F# is often called "OCaml for .NET", but it is a misrepresentation. It is an ML-family language for .NET, but aside from that ML core they don't have much in common.Whether those features are more valuable to you than the ability to tap into .NET libraries depends largely on what you're doing.
OCaml has been one of those "almost there" languages since at least 2002. Most of the worthwhile ideas in OCaml will be absorbed into more popular languages by the time existing friction is sorted out. :/
Perhaps OCaml is the Velvet Underground of languages. Only a few thousand people learned OCaml but every one made a programming language[1]
[1]: https://quoteinvestigator.com/2016/03/01/velvet/
Xavier Leroy as Lou Reed... :-) Don't forget the amazing theorem provers too, like Imandra ( https://www.imandra.ai/core ), HOL-Light ( https://hol-light.github.io/ ) and Rocq ( https://rocq-prover.org/ ), ... !
That would be Elm :)
I've been saying for ages! Gleam, Roc, Derw, Gren, Cara, Zokka, and the error messages in Rust.
https://news.ycombinator.com/item?id=45646520#45752905
Roc says hi!
Almost there, but in the meantime supporting a casual squillion dollars of trades at JS
Yes and they had to basically build their own version of the compiler to keep everything from falling over (https://oxcaml.org/).
> Our hope is that these extensions can over time be contributed to upstream OCaml.
Yeah, its more just extensions to support their use cases at scale. Think of it more as bleeding edge ocmal, once they work out kinks/concerns they'll get merged back into the language OR if it remains ultra specific it'll stay in oxcaml.
Not a complete own version lol
Yes but the context of the thread is OCaml being "almost there". Having to build this stuff in-house is pretty good evidence.
I don’t know about that.
Python gets forked in other investment banks as well. I wouldn’t say that is evidence of any deficiencies, rather they just want to deal with their own idiosyncrasies.
See https://calpaterson.com/bank-python.html
Evidence of what?
The main user has been writing extensions to the compiler that they test before pushing for integration like they have done for the past twenty years or so. They publish these versions since last year.
Hardly a failure and certainly not something mandatory to keep things from failing over. Your initial comment is extremely disingenuous.
A different perspective is that JS has made practical application of PLT part of their secret sauce, and deepening into their PLT roots is thickening the sauce.
This is the wrong interpretation of the oxcaml project. If you look at the features and work on it, it's primarily performance or parallelism safety features.
The latter going much further than most mainstream languages.
Yeah, but when these things happen I ask myself, is Jane Street successful because of ocaml, or did they just happen to pick ocaml and then make it work?
There might be some power in attracting all the people who happen to love ocaml, if there are enough of competent people to staff your company, but that's more a case of cornering a small niche than picking on technical merits
They've spoken about this before and might not have picked OCaml if they had to make the decision again today. I think at the time it made the most sense.They can also make it work in any language as they claim to only recruit the best and brightest in the world (this may be the truth). My opinion is they could have chosen many languages and had similar results while balancing different trade-offs.
Regarding attracting talent, they've said they don't care about existing knowledge of OCaml as the language part is something they train staff on anyway. Their interviews are brutal from what I recall. I could be an OCaml expert and have no chance of making it through an interview without equal talent in high performance fintech and relevant mathematics.
> I could be an OCaml expert and have no chance of making it through an interview without equal talent in high performance fintech and relevant mathematics.
Unless their hiring process has changed in the past few years, if you're a dev they're not hiring you for your financial skills, just general problem solving and software development ability. It is (was?) the usual Google-style algorithms/data structures rigamarole, but somewhat more challenging.
Do those devs actively use OCaml? I thought most of the folks writing OCaml were writing the actual trade algorithms as opposed to infrastructure folks. My post was made off what I recall their lead technologist saying.
Absolutely. Everyone uses OCaml at Jane Street; pretty much everything at Jane Street is OCaml. If an OCaml version of something doesn't exist, there's a decent enough chance that they'll write it themselves rather than resort to a non-OCaml solution.
Like I said, my information might be a hair out of date, but it's first-hand.
Gotcha. Mine is just some old blog posts and a long talk from the guy that got OCaml started. Nothing like your actual first person experience. Thanks for adding!
Yes, everybody in JaneStreet is expected to be able to use Ocaml, Neovim, and R/Julia/etc.
Everybody in the company is expected to be able to sling numbers in text on a computer super efficiently.
They also build custom emacs tooling
Clearly Jane Street wouldn't be where it is, a top proprietary trading firm in US, without static type checking.
Unless you're building another JS, it'd be nice if there were other companies so heavily invested in it. There's a lot out there beyond compiler prototypes and high speed financial trades, but there's not enough talk of people using ocaml for those things.
Ocaml was (historically, at least) used by Facebook for basically all of their linter/compiler/type checker work. The hack checker was in Ocaml, as was the JS thing (flow, maybe?).
So that does seem to be a good use-case for the language.
That was why I mentioned compilers along with HFT. Rust was originally an ocaml based compiler too.
I don't build HFTs and my compilers are just for fun. None of my day jobs have ever been a situation where the smaller ecosystem and community of ocaml was offset by anything ocaml did better than the selected options like .net, Java, go, rails, C or anything else I've touched. Heck, I've written more zig for an employer than ocaml, and that was for a toy DSL engine that we never ended up using.
What is this alleged friction?
Because plenty of people have been shipping great projects in Ocaml since it was released so it doesn’t seem to be much of an issue to many.
I doubt Ocaml will be surpassed soon. They just added an effect system to the multicore rewrite so all things being considered, they seem to be pulling even more ahead.
Alleged? Come now.
Beginners face the following problems: there's multiple standard libraries, many documents are barely more than type signatures, and data structures aren't printable by default. Experts also face the problem of a very tiny library ecosystem, and tooling that's often a decade behind more mainstream languages (proper gdb support when?). OCaml added multicore support recently, but now there is the whole Eio/Lwt/Async thing.
I used to be a language nerd long ago. Many a fine hour spent on LtU. But ultimately, the ecosystem's size dwarfs the importance of the language itself. I'm sympathetic, since I'm a Common Lisp man, but I don't kid myself either: Common Lisp isn't (e.g.) Rust. I like hacking with a relic of the past, and that's okay too.
TBH I think it's rather a post-hoc rationalization of why the language is not popular.
> there's multiple standard libraries
Scala has a far more fragmented ecosystem with Cats, Scalaz, Zio and Akka. C++ and Java have a bunch of stdlib extensions like boost, Guava, Apache Commons etc.
> many documents are barely more than type signatures
Can be said of most of Java, Kotlin, Scala, Erlang etc etc. Just compiled javadocs, sometimes with a couple of unhelpful lines.
> data structures aren't printable by default
Neither they are in C++
I think the real reason it's not popular is that there are languages which solve more or less the same problems of system programming but look far more familiar to an avg. programmer who was raised on C++ and Java.
Maybe it's post-hoc?
I wanted to use OCaml since 2002, since it was a GC'd language with good performance, achieving a lot with relatively few lines of code. Being a language nerd, I was (am?) positively inclined to the language. Yet there was always something that made it notably less pleasant to solve my current problem in than in than some other language.
If it had trouble getting traction with me, that's bad news.
Meanwhile the mainstream has progressed a lot since 2000. GC is the standard, closures are normal, pattern matching and destructuring are increasingly so. While HM-style type inference is not mainstream, local type inference is (and I'm no longer convinced that global type inference is the way). Algebraic data types aren't unusual anymore.
A few years back I just threw in the towel and went with Rust; this happened after I volunteered to improve OCaml's gdb support (including DWARF hell), which went nowhere. I wish Rust compiled faster, and a GC'd language is usually more productive for my problems, but in every other regard it stole what should have been OCaml's thunder. And when popular successor languages eventually appear, they'll do it even better.
Off-topic: What language would you say is the closest thing to "Rust with a GC"?
(Rust has refcounting, but it's slow, and needing to handle cycles manually limits its usefulness.)
The closest thing to "Rust with a GC" in my mind is Ponylang or just Pony:
https://www.ponylang.io/ https://github.com/ponylang/ponyc
The Pony community is here:
https://ponylang.zulipchat.com/
Pony's garbage collection and runtime can yield performance faster than C/C++/Rust because the compiler eliminates data races at compile time, and thus no locks are needed.
It features implementations of Dmitri Vyukov (www.1024cores.net) algorithms for work stealing and Multi-producer single consumer queues that use only a single atomic instruction to read. The designer, Sylvan Clebsch, is an ex-game-developer and ex-high-frequency-trading-infrastructure engineering lead; he knew what he was doing when he designed the language for high performance on multicore systems.
On the other hand, you do have to re-wire your thinking to think in terms of Actors and their state, and this is kind of hard to wrap one's head around if you are used to Go's CSP or the popular async/await approaches -- it is a somewhat different paradigm.
GC was standard already in 2000: Perl, Python, Ruby, Java and JS all had GC from day 1.
Crappy GC for most of them, but... fair point.
You probably know it, but Common Lisp May be a bit dated but it’s extremely modern in terms of features since you can add almost any feature to the language in libraries! I use it exactly because it’s old and battle tested and I don’t need to wait years for a language designer to give me a feature , I can just add it myself, though these days it has everything done already!
> there's multiple standard libraries
There is only one standard library and it shipped with the compiler.
> data structures aren't printable by default
So? That’s the case with most languages. Ocaml has a deriver to make types printable and a REPL which automatically prints for testing.
> tooling that's often a decade behind more mainstream languages
Opam is a fully featured package manager, dune works fine, bucks2 supports Ocaml.
> proper gdb support when?
Ocaml has had a rewindable debugger since approximately forever.
> OCaml added multicore support recently, but now there is the whole Eio/Lwt/Async thing.
Lwt was the default and everyone agrees eio is the future now that effects are there. Async is a Janestreet thing with pretty much no impact on the language outside of Janestreet.
Honestly, I maintained my initial point. Ocaml alleged frictions were always widely overstated.
When I was writing Ocaml professionally 15 years ago, there was no dune and no opam and it was already fairly easy to use the language.
> Because plenty of people have been shipping great projects in Ocaml
What applications are written in OCaml? All I can think of (which says more about me than it does about OCaml) is the original Rust compiler.
Even Haskell has Pandoc and Xmonad.
Rocq is an excellent example of something OCaml was designed for. FFTW3 is another great example. Unison too.
Generally, you want stuff where you have to build a fairly large core from scratch. Most programs out there doesn't really fit that too well nowadays. We tend to glue things more than write from nothing.
Rocq, Pfff and Flow, Vpnkit in Docker for Mac and Windows, the web version of Facebook Messenger at a point, Tezos, Unison, the Xen cloud platform, the Mirage unikernel.
For me the issue is ecosystem. The foundations are great but I need more useful and well supported packages.
For example, there is no OAuth2 client library for OCaml [1]
[1] https://ocaml.org/docs/is-ocaml-web-yet
Why isn't it more popular if it's so good? Because popularity and merit are not the same thing. People confuse them all the time though.
Check out the most popular music today. Like the top ten songs currently. Do you think those are really the best songs out there?
Popularity is mostly driven by either trends or momentum.
> Why isn't it more popular if it's so good? Because popularity and merit are not the same thing.
Yes! To add to that, the question itself is wrong. We should be asking, how is OCaml able to be so good without being popular? People get the whole thing backward.
The popular languages are typically popular first, then get good later as a result of that popularity. They have to work, they have to be good, they're too big to fail.
This is what happened with Java. It was marketed like crazy at first and only later got refined in terms of tooling and the JVM itself. The R programming language was a mess for data wrangling, but once it was popular, people built things like the tidyverse or the data.table library. The Python ecosystem was disaster with all different testing packages, build tools, and ways to create and manage virtual environments, until the relatively recent arrival of uv, more than three decades after the creation of Python itself. And then there's javascript that's had more money, blood, sweat, and tears poured into it to be improved in one way or another because that's what practically anything running in a browser is using.
I think popularity and regarded favorably are probably inversely correlated.
Many of the most popular languages are also the most hated. Many of the more niche languages are viewed the most favorably.
It is easy to dislike something yo are familiar with, and easy to be overoptimistic about something you don't know as well.
"the grass is always greener ... "
Music being "good" is subjective. A programming language, however, can objectively be better if it allows a subset of programmers to better solve certain problems.
The reason for why OCaml is not more popular, thus, is that this subset is small. The reason for this may be either (a) habit or (b) it's not that much better than other languages. I'm gravitating to (b). OCaml guys seem to be quite dogmatic for the wrong reasons.
I posit (c) it’s from France and written mostly by French people and American naturally gravitates towards languages which generate hype in English and preferably from the USA.
Also it didn’t employ a marketing team to work on outreached and write fancy comments here and some people who have used it for 10 minutes are apparently offended by the Pascal-like syntax and can’t stop discussing it on every Ocaml discussion making every actual users tired.
The popularity of a language usually translates into better support, tooling and learning materials.
Elixir is the closest thing to OCaml that has a chance at semi-mainstream usage IMO.
It has basically all of the stuff about functional programming that makes it easier to reason about your code & get work done - immutability, pattern matching, actors, etc. But without monads or a complicated type system that would give it a higher barrier to entry. And of course it's built on top of the Erlang BEAM runtime, which has a great track record as a foundation for backend systems. It doesn't have static typing, although the type system is a lot stronger than most other dynamic languages like JS or Python, and the language devs are currently adding gradual type checking into the compiler.
I think that a better question is why F# isn't a more popular language, since it's much closer to OCaml, than Elixir and you can use the whole Dotnet ecosystem in F#, which is one of the weakest points of OCaml (no libraries).
The answer is (most likely) Microsoft, I kid you not. I've worked with F# professionally for many years is its incredible how they are literally sitting atop a gold mine that is the output of Microsoft research and do basically nothing with it. Even though it's sold as an ecosystem, .NET revolves around C# and its related tooling.
"Type Providers" are an example of such negligence btw, it's something from the early 2010's that never got popular even though some of its ideas (Typed SQL that can generate compile-time errors) are getting traction now in other ecosystems (like Rust's SQLx).
My team used SQL Providers in a actual production system, combined with Fable (to leverage F# on the front end) and people always commented how our demos had literally 0 bugs, maybe it was too productive for our own good.
I think it’s odd that elixir doesn’t get more love. It ticks a lot of boxes that folks here get excited about, has a great ecosystem and tooling, BEAM is great, and it’s much more syntactically familiar than erlang to my eye. I know of a couple companies aside from the perennial goto examples that built sizable saas products backed by it.
The backend work I do is just super boring.
I always wanted to learn Elixir but never had a project where it could show it strengths. Good old PHP works perfectly fine.
Also corporations like their devs to be easily replaceable which is easier with more mainstream languages, so it is always hard for "newer" languages to gain traction. That said I am totally rooting for Elixir.
I think it’s great for boring stuff — the Phoenix web framework is really straightforward. Learning a whole new language paradigm and environment for a professional project you need to be productive in ASAP is definitely the worst kind of ‘not boring’ though.
I know of a Haskell shop and everybody said they’d have a hell of a time finding people… but all them nerds were (and are) tripping over themselves to work there because they love Haskell… though some I’ve talked to ended up not liking Haskell in production after working there. There seems to be a similar dynamic, if a bit less extreme, in Elixir shops.
The BEAM VM executing bytecode is slower than a compiled binary. Sure, it is great when compared to Python and other interpreted languages. Not so much when you need fast processing and raw CPU performance. It also loses out to the JVM in performance, but wins in memory consumption.
It is slower, but a big cause of the slowness is a lot of copying (immutable data structures and separate heaps for every process). Nowadays the BEAM has a JIT.
If you use type guards correctly the performance can be surprisingly good. Not C/C++/Rust/Go/Java good, but not too far off either. This is definitely a corner-case though.
But how many things involve fulfilling basic requests over a network pulling information from a database? Most things just don’t need that kind of performance.
Sure for basic, dead CRUD, the choice of middleware language rarely makes any difference.
But even bog-standard business processes eventually find the need for data-processing, crypto and parsing - the use-cases where people code Elixir NIF's. That is why for example you have projects like html5ever_elixir for parsing HTML/XML. Another use case is crypto - you have NIF's for several crypto libraries. Data processing - there are NIF's for Rust polars.
> Sure for basic, dead CRUD
From a technical perspective, this is the overwhelming majority of what makes the Net happen. BEAM is great for that and many other things, like extremely reliable communication streams.
Use the right tool for the job. Rust sucks for high-level systems automation but that doesn’t make it any less useful than bash. It’s all about about use cases and Elixir fits many common use cases nicely, while providing some nice-to-haves that people often ask for in other common web dev environments.
Elixir is good at managing complexity. I love flattening hierarchy and dealing with edge cases right in function definitions using pattern matching. Every other language without it just feels crippled after getting used to the feature.
What does deployment look like? Can you get a static binary easily like with Go?
You don't get it from language tooling because you are compiling to a bytecode that runs in a virtual machine (BEAM).
The current tool to wrap your bytecode with a VM so that it becomes standalone is Burrito[1], but there's some language support[2] (I think only for the arch that your CPU is currently running? contra Golang) and an older project called Distillery[3].
1: https://github.com/burrito-elixir/burrito
2: https://hexdocs.pm/mix/Mix.Tasks.Release.html
3: https://hexdocs.pm/distillery/home.html
If it's functional (recursion vs imperative loops) most people/organizations will not use it. At this point that is just the reality.
I really wish people would quit pushing "functional". People equate that with "My programming is now always a recursive logic puzzle."
Talk about "immutable by default". Talk about "strong typing". Talk about "encapsulating side effects". Talk about "race free programming".
Those are the things that programmers currently care about. A lot of current Rust programmers are people who came there almost exclusively for "strong typing".
Having loops is not the defining feature that separates functional from imperative. Where did this idea come from? I'm suddenly seeing it in a lot of places.
It is not the defining feature but loss of the loop is one of the most obvious differences for people who look at a functional language Rust has immutability, pattern matching, etc, but it remains an imperative language with "some functional features". Or this is my subjective analysis.
So is Haskell not functional? Or an imperative language with some functional features?
(This is not a trick question. Simon Peyton Jones described Haskell as "the world's finest imperative language" [1], and I agree. This code is written using https://hackage.haskell.org/package/bluefin)[1] Tackling the Awkward Squad: monadic input/output, concurrency, exceptions, and foreign-language calls in Haskell
But, again, loops aren't automatically imperative per se. Consider loop / recur in Clojure for an example. For someone coming from JavaScript, it's not really much different from writing a while loop where every branch has to terminate with an explicit break or continue.
You can be functional "in spirit" more than purely functional. OCaml and Standard ML falls into this category. Ocaml has loops for instance. You might just not see many loops if code is written by OCaml developers, because there's frankly no need to use them in a lot of places. You often want to lift the abstraction level of iteration to an arbitrary data structure such that you get freedom of implementation. See Applicative and Monad.
its a simplification of immutability and its consequences
Writing OCaml and writing Elixir code is much different for me. OCaml requires more braincells, while Elixir is more flexible.
BEAM performance model trades throughput for isolation, which hurts CPU-bound tasks, and ironically, whenever you need speed, you end up using NIFs that break BEAM safety guarantees, and reintroduce the exact fragility Elixir was supposed to avoid.
In 2025, Elixir is a beautiful system for a niche that infrastructure has already abstracted away.
> In 2025, Elixir is a beautiful system for a niche that infrastructure has already abstracted away.
Do you mean Kubernetes?
My mental model of Erlang and Elixir is programming languages where the qualities of k8s are pushed into the language itself. On the one hand this restricts you to those two languages (or other ports to BEAM), on the other hand it allows you to get the kinds of fall over, scaling, and robustness of k8s at a much more responsive and granular level.
> whenever you need speed, you end up using NIFs that break BEAM safety guarantees, and reintroduce the exact fragility Elixir was supposed to avoid.
That's like complaining that unsafe{} breaks Rust's safety guarantees. It's true in some sense, but the breakage is in a smaller and more easily tested place.
It's not isolation which hampers throughput. That's a red herring. In fact, isolation increases throughput, because it reduces synchronization. A group of isolated tasks are embarrassingly parallel by definition.
The throughput loss stems from a design which require excessive communication. But such a design will always be slow, no matter your execution model. Modern CPUs simply don't cope well if cores need to send data between them. Neither does a GPU.
But the isolation is what necessitates (or at least encourages) a design that requires more communication, isn't it?
Not a priori.
The grand design of BEAM is that you are copying data rather than passing it by reference. A copy operation severs a data dependency by design. Once the copy is handed somewhere, that part can operate in isolation. And modern computers are far better at copying data around than what people think. The exception are big-blocks-of-data(tm), but binaries are read-only in BEAM and thus not copied.
Sure, if you set up a problem which requires a ton of communication, then this model suffers. But so does your GPU if you do the same thing.
As Joe Armstrong said: our webserver is a thousand small webservers, each serving one request.
Virtually none of them have to communicate with each other.
I do not think that monads/type system are issue, but yes BEAM runtime is killer feature.
Gleam also. But i cant justify a non compiled language in many things i do.
gleam is compiled... to erlang bytecode
It's compiled to Erlang, not BEAM bytecode, as the latter is not a stable, backward-compatible API to target, and you lose all of the optimization work put into the Erlang compiler. It's also compiled to JavaScript, so it can run on both the front-end and back-end.
I want a static binary. Not some IR i run on some VM.
immutability?
What's immutable about elixir? It's one of the things which I MISS from Erlang -- immutability.This is like saying Haskell doesn't have immutability because it has the state monad, or that rust doesn't because you can shadow with let.
Data is immutable and thats much more important than whether local variables can be modified imo.
Shadowing is not mutability. The former isn't affected by control flow nor does it affect closures.
What you wrote is roughly equivalent to this in C:
which is to say, there are two different `x` in there, both immutable, one shadowing the other. You can observe this if you capture the one that is shadowed in a closure:> OCaml is weird in that it’s a garbage collected language for systems, similar to Go.
I don't understand why this isn't more popular. For most areas, I'd gladly take a garbage collector over manual memory management or explicit borrow checking. I think the GC in D was one of it's best features, but it's downfall nonetheless as everyone got spooked by those two letters.
There's some other stuff, but I personally believe if the tooling was closer to Rust/Go than C, it would be a lot, lot more popular.
Nobody wants to effectively learn a lisp to configure a build system.
Dune is quite good these days. The lisp part is really just sexps (not a full languge). But i kind of get your point.
I like the ML languages, and as many others I spent a lot of time with F#.
I would love to spend more time but even though Microsoft gives it plenty of support (nowhere near as much as C#), the community is just too small (and seems to have gotten smaller).
Looking at https://www.tiobe.com/tiobe-index/ numbers fall off pretty quickly from the top 5-7.
Guessing this is the same for OCaml, even if the language as such is nice.
Anecdotally we are using F# more than ever before, and it works for us for a large sized organisation. Fast code, it is keeping up with the .NET features that matter for that (e.g. spans), and tbh has still been getting better over the years. In fact I find some of the new features like Span, SIMD/intrinsics somewhat synergise with existing F# features (e.g. inline). C# IMO still hasn't quite caught up but is getting there. Comparing to Go/Java/etc I can usually get faster code out of the .NET runtime as well especially in our domain which requires large scale computation. If I was to move to something else for our domain it would be C++ or Rust. F# piggy backing of the .NET platform in general, has a decent ecosystem and easy onboarding cross platform and gets a lot "for free" (e.g. CLI, GC improvements).
Community is an interesting thing, and for some people I guess it is important. For me language is just a tool having coded for quite some time and seen communities come and go; don't care about being known or showing an example per se. If the tool on the balance allows me to write faster code, with less errors quicker and can be given to generic teams (e.g. ex Python, JS devs) with some in house training its a win. For me personally I just keep building large scale interesting systems with F#; its a tool and once you get a hang of its quirks (it does have some small ones) quite a good one that hits that sweet spot IMO.
My feeling however is with AI/LLM's communities and syntax in general is in decline and less important especially for niche languages. Language matters less than the platform, ecosystem, etc. Its easier to learn a language then ever before for example, and get help from it. Any zero cost abstraction can be emulated with more code generation as well as much as I would hate reviewing it. More important is can you read the review the code easily, and does the platform offer you the things you need to deliver software to your requirements or not and can people pick it up.
Interesting take. I agree with you mostly but regarding "community" I am more thinking of the side effects there in terms of _other_ people developing interesting libraries etc.
I don't know if AI can change that but when using python, there is a feeling that there is an awesome quality library for just about anything.
I get that, which is why I said it is important for some people depending on the domain and I meant in general language communities. Python is different at least to me given AI and being the first target for not just software improvements but hardware usage (e.g. GPU accelerated specialised libs) and training materials/examples. It is the AI community not the Python community per se; the AI community just targets Python. JS is also a little different given browsers are so ubiquitous and their own target with JS being the main language that works there.
Otherwise in most mainstream platforms there is enough libraries for most things already; which includes .NET. It's rare not to find a well maintained lib for the majority of use cases in general whether it is .NET, Java, Go, etc which is why w.r.t long term risk a used platform is more important than the syntax of a language and its abstractions. Web frameworks, SDK's, DB drivers, etc etc are all there and generally well tested so you won't be stuck if you adopt F#. I evaluate on more objective metrics like performance, platform improvements, compatibility with other software/hardware, etc etc. It isn't that risky to adopt F# IMO (similar risk to .NET in general) - to me its just another syntax/tool in my toolbelt with some extra features than usual if I'm developing things typical in that .NET/Java/Go abstraction level.
One of the best P2P clients ever created is written in OCaml: https://github.com/ygrek/mldonkey
I'm still surprised it can do so many things so well, so fast.
fun fact: the secret sauce that makes fftw fast is a code generator written in ocaml: https://github.com/FFTW/fftw3/tree/master/genfft
Yes, in every ML/OCaml tutorial, sooner or later the words object, class, and type inference appear and that’s when a once–minimalist language turns into an academic Frankenstein.
I don't think objects and classes are used much by OCaml programmers (not by me anyway). Type inference is a rather fundamental feature, and fairly easy to understand.
It's not a minimalist language, you know what the "O" in Ocaml stands for right? It's a multi-paradigm language that explicitly accommodates more styles of programming than Caml, it's why it exists.
Why does type inference contribute to that issue?
I kind of wish (like the OP mentioned) there was a ML (ocaml) like language that compiled to Go source. You would get the best of both worlds and access to a huge ecosystem.
There's Borgo: https://github.com/borgo-lang/borgo
I've never used it so can't speak from any experience, and unfortunately it doesn't seem particularly active (and doesn't mention a current status anywhere), and doesn't have a license, so shrug. When it's been posted here (https://news.ycombinator.com/item?id=40211891), people seemed pretty excited about it.
Borgo looks like some guys phd thesis. It looks like it was a fun experiment.
I feel a new simple ocaml like language that just compiled to Go would be really popular, really fast. And it would not even need to build a ecosystem, as Go already have all the things you need.
Something like what Gleam is for Erlang.
Well I need both float and double, so cannot even start using it.
> why isn’t OCaml more popular?
Hashtbl.add table key value
Precedence, nominal inheritance, HKTs, incoherent typeclasses make Scala much less aesthetically pleasant but much more productive.
I find it interesting that 80% of the Ocaml discussions here are similar to what I encounter during the change management phase on every complex project I work on: "But it’s different from what I’m used and must therefore be bad. Look, the syntax, it doesn’t look like usual. Scary."
15% are people trying to sell their own language of choice sometimes with the argument that "it’s less scary, look".
I would be shocked if a mere 5% is actual engagement with the topic at hand sometimes while pointing flaws which are very real.
From there, I gather two things, the main one being: maybe Meta was right actually. People are that limited and the syntax should have been changed just to be done with the topic.
OCaml’s REPL is lovely, but I found myself having some friction with initial startup. The build/package system was pretty convoluted, and I ended up choosing JS’s Core stdlib for my needs (a simple compiler). With the new multicore release it’d be cool to see OCaml in some more practical projects!
As an OCaml-curious, is this the community recommendation, to choose the Jane Street stdlib if you’re just getting started?
It's probably the path of least resistance if following the Real World OCaml book (https://dev.realworldocaml.org/), which is quite excellent.
Many learning materials will push you that way, but the vast majority of FOSS packages don't use it.
There's nothing inherently wrong with using Jane Street's stdlibs if you miss the goodies they provide, but be aware the API suffers breaking changes from time to time and they support less targets than regular OCaml. I personally stopped using them, and use a few libraries from dbunzli and c-cube instead to fill the gaps.
OCaml is fantastic, but I avoided it and went with Rust for many projects because it had no multicore story and no green threads for a very long time. But it has that now, and I wish I could go back and start everything over in OCaml.
I've also felt very similar, and adopted Rust for those reasons. Even though I'd still love to have a garbage collected, AOT compiled ML-variant, using OCaml still feels like a step backwards now. OCaml's module system and generics feel clumsy and unintuitive now that I've used Rust's Trait system.
For something a bit more modern but still related to OCaml, one can try F#.
F# is a practical choice but the language features are quite far behind OCaml now.
{Ecosystem, Functors} - choose 1
From an outsider's perspective, it feels like Ocaml has more active development of features, between the new effects system they added in 5 and all the work Janestreet is doing to let Ocaml developers have more control over performance.
F# is not stagnant thankfully, it gets updates with each new version of dotnet (though I haven't checked what is coming with dotnet 10), but I don't recall anything on the level of the above Ocaml changes in years.
Applicative Computation Expressions are a big deal (added in F# 5). Recent changes have been smaller in scope.
Unfortunately lots of the more advanced stuff seems to be blocked on C# team making a decision. They want a smooth interop story.
But F# remains a solid choice for general purpose programming. It's fast, stable and .NET is mainstream.
Oh yeah I love f#, I need to find more excuses to use it. I just wish it felt like MS was willing to invest more into it. But at least they have not abandoned it and continue to put some resources into its ongoing growth.
F# also has a real slow compiler. Last time hello world took a few secs on brand new mac.
What about a strict subset of C#. The use case for F# seems to be shrinking because MS is putting all its energy in language.
This isn't true, because more is not always better.
C# has lots of anti-features that F# does not have.
> Fast compile times
> Fewer abstractions, and an easy to understand runtime
> Strong static guarantees
> Functional programming constructs. Especially pattern matching and sum types.
> Good performance
> Good documentation
I feel this is also Elm!
Elm is pure-functional, unlike OCaml, which has easy escape hatches (refs) when you need mutability.
I feel as a frontend language Elm has somewhat less need for mutability. At least I haven't missed it.
As a Rust newbie and seasoned Go dev, I'm pretty interested to knownwhere would people experienced in both OCaml and Haskell, would put it in the spectrum.
I don't think it's a spectrum.
Languages have features/constructs. It's better to look at what those are. And far more importantly: how they interact.
Take something like subtyping for instance. What makes this hard to implement is that it interacts with everything else in your language: polymorphism, GADTs, ...
Or take something like Garbage Collection. It's presence/absence has a large say in everything done in said language. Rust is uniquely not GC'ed, but Go, OCaml and Haskell all are. That by itself creates some interesting behavior. If we hand something to a process and get something back, we don't care if the thing we handed got changed or not if we have a GC. But in Rust, we do. We can avoid allocations and keep references if the process didn't change the thing after all. This permeates all of the language.
My team still has 8 year old Haskell systems in production. We pivoted away from the language a few years ago, which I discuss here a bit: https://news.ycombinator.com/item?id=37746386
I personally love ML languages and would be happy to keep developing in them, but the ecosystem support can be a bit of a hassle if you aren't willing to invest in writing and maintaining libraries yourself.
What spectrum? Language practicality? Popularity?
OCaml has some high profile use at Jane Street which is a major fintech firm. Haskell is more research oriented. Both are cool, but wouldn't be my choice for most uses.
What does "it" refer to? Ocaml?
The problem I see for the adoption is that the landscape is very fragmented.
ML is a family of languages and we have StandardML with different implementations, OCaml with official path and JS path, F# and whatnot.
This is the problem for Lisp, too as there are many Lisps.
Little known fact: OCaml was at one point called "Zinc" ("Zinc is not Caml").
Perhaps the language would be more lucky with the original name. Zinc is used to galvanize steel and prevent Rust formation[1].
[1] https://en.wikipedia.org/wiki/Galvanization
Lots of complaints about the OCaml syntax here.. is ReasonML dead?
is very alive, released with OCaml 5.4 support and improving bit by bit
>why isn’t OCaml more popular?
OCaml did become popular, but via Rust, which took the best parts of OCaml and made the language more imperative feeling. That's what OCaml was missing!
Ocaml can be as imperative as you need it to be. Or as functional.
It has no dogmatic inclination towards functional. It has a very pragmatic approach to mutation.
True, but writing imperative code in OCaml feels quite right. Maybe it's just me, but it always feels significantly clunkier than the functional equivalent. I've had things I've been implementing and though "this works be easier to express imperatively", and almost invariably I've gone and rewritten the code to be functional because of how ungainly the imperative implementation ended up being. It feels a bit too much like somebody embedded a subset of Rexx or Pascal awkwardly into an otherwise perfectly reasonable functional language
Rust is very different from Ocaml. Rust is a low level language with a borrow checkers, traits, no first class module system, no GADT, no effects.
The similarities are fairly superficial actually. It’s just that Rust is less behind the PL forefront that people are used to and has old features which look impressive when you discover them like variants.
There is little overlap between what you would sanely use Rust for and what you would use Ocaml for. It’s just that weirdly people use Rust for things it’s not really suited for.
As someone who has worked professionally in both, programming in rust does not feel much like programming in OCaml. Working with traits in an imperative manual memory managed language is really different than working with proper modules in a mixed paradigm language with an awesome GC.
Aside from ADTs, what else did Rust take from OCaml?
Expression-based, immutable by default, pattern matching, static typing, and result / option types are the mix of features that make Rust what it is at its core, and each of those you'll find in OCaml. There's a couple others but that's the heart of it.
I'm not saying that Rust feels like Ocaml as some are interpreting, I said Rust is more imperative feeling, they're not the same. The reason Rust has had success bringing these features to the mainstream where Ocaml has not, I believe, is because Rust does not describe itself as a functional language, where as Ocaml does, right up front. Therefore, despite Rust having a reputation for being difficult, new learners are less intimidated by it than something calling itself "functional". I see it all the time. By the time they learn Rust, they are ready to take on a language like Ocaml, because they've already learned some of the best parts of that language via Rust.
Note my comment about their similarities is not at the level of borrow checkers and garbage collectors.
Offtopic HTML issue to the author: there is a trailing </head> tag at the end of your generated HTML after the </body> (instead of </html>).
I don't see it...the end of the document is:
I updated it just now :).
Fixed it, thanks for pointing it out :)
"but the more I use it the more I feel like this old language had it all figured out,"
sounds superficially similar to Common Lisp
I loved Ocaml but now I love TypeScript more. It's got about the same amount of type safety, the ergonomics are better to me, and the packaging and ecosystem tooling are leaps and bounds above anything else.
You would not really build the same software tho.
> It's got about the same amount of type safety
What?
Both languages have robust and expressive type systems. My experience is that TypeScript's is also more flexible. In Ocaml everything is cool as long as you stick with the functional programming style. But every "interesting" program also has imperative, non-functional-programming parts, and TypeScript has really good automatic "type narrowing" features that make that part much safer in my experience. In Ocaml however, type narrowing isn't automatic at all.
TypeScript certainly has a more complicated and flexible type systems in many respects, but it is not the same w/r/t safety. It is quite common to run across `any`s all over the place in TypeScript code, and there is no such thing in OCaml. TypeScript's systems is explicitly unsound (i.e., not fully type safe) by design: https://www.typescriptlang.org/docs/handbook/type-compatibil...
Ocaml has exactly the same kinds of escape hatches, like Obj.magic or unsafe accessors. The way I see it. it's a matter of community practice more than language capabilities. Typescript in practice has has the safety net of being interpreted rather than compiled, so I guess people tend to abuse its type flexibility more.
But if you write without the escape hatches in both languages, in my experience the safety is exactly the same and the cost of that safety is lower in TypeScript.
A very common example I've encountered is values in a const array which you want to iterate on and have guarantees about. TypeScript has a great idiom for this:
``` const arr = ['a', 'b'] as const; type arrType = typeof arr[number];
for (const x of arr) { if (x === 'a') { ... } else { // Type checker knows x === 'b' } } ```
I haven't experienced the same with Ocaml
First off, the escape hatches in TypeScript are way too accessible compared to OCaml: `JSON.parse(...) as MyInterface` is everywhere and completely broken.
And second, you're dismissing the fact that TypeScript is unsound, even worse it is so by design. Easy examples: uninitialized variables holding undefined when their type says they can't [1]; array covariance [2]; and function parameter bivariance, which is part of the TypeScript playground's own example on soundness issues [3] but at least this one can be configured away.
C# and Java made the same mistake of array covariance, but they have the decency of checking for it at runtime.
[1]: https://www.typescriptlang.org/play/?#code/DYUwLgBAHgXBB2BXA... [2]: https://www.typescriptlang.org/play/?#code/MYewdgzgLgBAllApg... [3]: https://www.typescriptlang.org/play/?strictFunctionTypes=fal...
As for your example, I agree that TypeScript unions and singleton types are powerful, but I can't see what are you speficially missing here that pattern matching and maybe an additional variant type doesn't get you in OCaml. You get exhaustiveness checking and can narrow the value down to the payload of the variant.
Thanks, these are good examples of holes in typescript that I wasn't aware of. I guess I haven't pushed it enough yet to run into them. I agree Ocaml wouldn't fail.
> I can't see what are you speficially missing here that pattern matching and maybe an additional variant type doesn't get you in OCaml. You get exhaustiveness checking and can narrow the value down to the payload of the variant.
A couple things, being constrained to pattern matching in places where imperative programming would be more natural, having to declare lots of special purpose types explicitly vs being able to rely on ad hoc duck typing.
Came here to say I love Ocaml too
darklang team loved ocaml too. in the end they ended up using f#.
I absolutely love the idea and methods behind OCaml, but the syntax..... I also love Haskell and already feel that its syntax is not easy to grok on larger projects, but OCaml basically went "hold my beer" and went to town on that.