It’s wild how easy it is to build robust systems with Effect.
I’m working on a little social media web app and it has been so incredibly simple to build the API and a background worker process with Effect. I get logging, telemetry, error handling, concurrency, API doc generation, and more for free!
I think this library gets somewhat maligned for being complex, which I don’t think is fair for how much it offers given how much more complex a an equivalent solution would be without Effect.
With v4, I also don’t feel like I am even having to wrestle with TypeScript’s type system at all. I define some basic interfaces for my services and schemas for my data models and everything is just inferred through usage for the most part. It honestly starts to feel like I’m writing JavaScript for the most part.
This library gets lots of comparisons to functional programming languages/libraries, which is fair, but I think someone working in .NET/C# would be feel right at home.
I was (still am) a huge fan of fp-ts [1], which, in effect, was rolled into the Effect-TS ecosystem. And I'm still bummed TS+ [2] didn't work out, because I've never managed to love Effect-TS the way I loved fp-ts.
Maybe it's the lack of tacit function calling, the conventions, AI/modern-marketing push, or simply the daunting scope and scale (even more so with v4).
Still, despite my gripes, if you're willing to spend the time and effort, it's the safest and most elegant way to write TypeScript. Plus, it's now dependency-free, and the increasingly good LSP/editor support removes a lot of the friction that used to come with completions and diagnostics.
Sometimes I use the wayback machine to visit marketing pages before the advent of AI, so I can get a better understanding of what they actually do instead of just a bunch of AI jargon.
As a Python person, that 2nd one looks like a bug. Expecting an exception there. Although also Python doesn't have an `undefined`; `None` would have to suffice.
The types allow you to very narrowly define functions so that you can, for example, require that a NonEmptyArray be passed. This helps to fulfill that requirement without casts.
part of it is because js is a throwing language, and since there are no "checked" exceptions they need to basically rebuild the universe in their paradigm.
but they seem to want to rebuild everything, eg
> The Console service exposes common console methods such as logging, warnings, errors, groups, counters, tables, and timers. Because console access goes through a service, programs can use custom console implementations in tests or other environments. This module also includes scoped helpers that close console groups or timers automatically.
Petty aside: Several JS people I know who were previously quite down on using a dependency injection framework are now seeing the benefits after adopting Effect. The most egregious example being a colleague who considered the adaption of DI tooling to be a language-level defect. It’s now one of his primary selling points for Effect.
fiber/effects for UI and event bus, eg. OpenCode's opentui and harness are built on this library, been using the 4-beta whilst hacking on some OpenCode plugins
Is there a way to implement Effect without it becoming a leaky abstraction that takes over your whole app? Presumably you'd have to create an entire abstraction layer with strict boundaries, such as nestjs does with RxJS Observables, but even that has problems with leaking Observables when you need to hook into the framework's lifecycle.
Absolutely you can. Every Effect program has to be run via some call to a ‘runX()’ function that accepts your Effect program. And the call-site where you run it is the boundary of your Effect program so you can make your app as much or as little Effect as you want.
It is hard to understand why one would want to introduce this into their codebase given how functional javascript is right away. It lives in the spectrum of rxjs - super powerful, but is it necessary? Can all of those concepts be distilled down into what you would use on the day to day (just a few), with less concept density, and just as much functional goodness?
Effect is to TypeScript what TypeScript is to Effect. It just pays off. But most of the learning curve or the unfamiliarity with syntax and even concepts goes away with AI. In fact, the same reasons why it makes it good for teams makes it good for AI. When a team member or an agent use the Effect patterns, I know I there is a lot less they could have messed up.
One issue with Effect is that it's hard to intro because it does many things. But it does them well, and it does all of them because only a coherent system can deliver the promise of allowing you to write production-ready TypeScript.
I'll list some things:
- Effects: how you describe programs. For some people it helps to think of them as promises on steroids. In addition to tracking the return type, they track the types of errors it could fail with, as well as its dependencies (see context/layers).
- Fibers: primitives for concurrency—but most of the time you don't have to think about them because the `Effect` methods handle most common scenarios
- Context/Layers: type-safe dependency injection. Have your cake and eat it too. You define context interfaces, use them within effects, and TypeScript forces you provide implementations of those interfaces via layers. Layers can provide more than one context, and can also depend on other layers. Very powerful.
- Schema: think Zod, but with the concept of codecs (to be fair Zod has this too), which means you define how things encode (e.g. what API takes and responds with) and decode (e.g. what my app works with). I love `Model`, which derives schemas for the API side and repo (db) side, so I can define a domain model declaratively with things like "account number should be replaced with * except the last 4 digits in the API; it should be Redacted (wrapped, can't leak to logs etc) within the app logic, and should be encrypted in the database".
- Standard library: lots of things that should standard in JS/TS and aren't, or exist but are not coherent or play well together.
When I don't use Effect, I have to choose between doing things well or shipping (and suffering the consequences). And I don't mean just strings, dates, decimals. I mean also queues, cache, etc.
- SQL primitives to work with transactions, migrations, queries. There are interfaces on top of this for popular ORMs.
- HTTP server; and ways to define your API with types and schemas, then implement it.
I can't wait for Rust to someday have something even part way as clear at composing systems.
Eventually I really hope we see programming languages that lean back in to what Erlang started more. This is a leap, but imo having inbuilt great patterns for system design would look a whole lot like Effect! Systems practically assemble themselves. There's great powerful meaningful abstractions under foot.
The only other meaningful effort I can call out is Clojure, which made a handful of good primitives. That community only really used atoms and defs, less refs (software transactional memory) and agents, is what I've been told.
It’s wild how easy it is to build robust systems with Effect.
I’m working on a little social media web app and it has been so incredibly simple to build the API and a background worker process with Effect. I get logging, telemetry, error handling, concurrency, API doc generation, and more for free!
I think this library gets somewhat maligned for being complex, which I don’t think is fair for how much it offers given how much more complex a an equivalent solution would be without Effect.
With v4, I also don’t feel like I am even having to wrestle with TypeScript’s type system at all. I define some basic interfaces for my services and schemas for my data models and everything is just inferred through usage for the most part. It honestly starts to feel like I’m writing JavaScript for the most part.
This library gets lots of comparisons to functional programming languages/libraries, which is fair, but I think someone working in .NET/C# would be feel right at home.
I was (still am) a huge fan of fp-ts [1], which, in effect, was rolled into the Effect-TS ecosystem. And I'm still bummed TS+ [2] didn't work out, because I've never managed to love Effect-TS the way I loved fp-ts.
Maybe it's the lack of tacit function calling, the conventions, AI/modern-marketing push, or simply the daunting scope and scale (even more so with v4).
Still, despite my gripes, if you're willing to spend the time and effort, it's the safest and most elegant way to write TypeScript. Plus, it's now dependency-free, and the increasingly good LSP/editor support removes a lot of the friction that used to come with completions and diagnostics.
[1] https://github.com/gcanti/fp-ts [2] https://effect.website/blog/ts-plus-postmortem
Three clicks, no info what effect 4.0 is, except that it's AI-ready, safe, good, and re-built from the ground up. No idea what it actually is.
I had the same thought, until I realized the posted link is for their 4.0 release rather than their homepage.
Their main page makes the product pretty clear.
https://effect.website
Still can’t tell if it’s a language, library or framework
Have you tried reading the big bold text at the top of the page?
> Reliable TypeScript for the AI era
It is a library.
You forgot the /s
Not only that but the play tab is broken. The default example does not compile in their own playground. And I'm still not sure what this thing is.
Sometimes I use the wayback machine to visit marketing pages before the advent of AI, so I can get a better understanding of what they actually do instead of just a bunch of AI jargon.
it's for people who want to write ocaml or rust, but in typescript for some reason
It does seem like they're boiling the ocean, for... whatever reason programmers do these things.
Rebuild JS's core data structures: https://effect.website/docs/v4/api/effect/Array
Then rebuild the entire JS ecosystem on top of their custom data structures.
And then the main heading on their home page is "Reliable TypeScript for the AI era"? Really? I'll pass.
It literally says:
> Works with JavaScript arrays
Yes but why? Why should I import a giant dependency to do this:
instead of using what's built in to the language?You wouldn't. Effect isn't an array library.
did you read the docs? it says
"Use when you need to guarantee a non-empty result after adding a required trailing value."
...whatever that means lol
NonEmpty is a type that allows you to distinguish between:
As a Python person, that 2nd one looks like a bug. Expecting an exception there. Although also Python doesn't have an `undefined`; `None` would have to suffice.
The types allow you to very narrowly define functions so that you can, for example, require that a NonEmptyArray be passed. This helps to fulfill that requirement without casts.
part of it is because js is a throwing language, and since there are no "checked" exceptions they need to basically rebuild the universe in their paradigm.
but they seem to want to rebuild everything, eg
> The Console service exposes common console methods such as logging, warnings, errors, groups, counters, tables, and timers. Because console access goes through a service, programs can use custom console implementations in tests or other environments. This module also includes scoped helpers that close console groups or timers automatically.
yeah idk mate
Console is the very core of what I expect an effect system to need to reimplement.
Console is IO and IO is the effect.
This is super useful though. It allows you to swap out implementations for things like logging and monitoring. Not sure what the confusion is here.
Petty aside: Several JS people I know who were previously quite down on using a dependency injection framework are now seeing the benefits after adopting Effect. The most egregious example being a colleague who considered the adaption of DI tooling to be a language-level defect. It’s now one of his primary selling points for Effect.
fiber/effects for UI and event bus, eg. OpenCode's opentui and harness are built on this library, been using the 4-beta whilst hacking on some OpenCode plugins
It's made with Npm, which makes me wonder if it's really safe ...
But I only read the news when it comes to npm, so maybe my fear is not justified.
What do you mean by "made with npm"?
Is there a way to implement Effect without it becoming a leaky abstraction that takes over your whole app? Presumably you'd have to create an entire abstraction layer with strict boundaries, such as nestjs does with RxJS Observables, but even that has problems with leaking Observables when you need to hook into the framework's lifecycle.
Absolutely you can. Every Effect program has to be run via some call to a ‘runX()’ function that accepts your Effect program. And the call-site where you run it is the boundary of your Effect program so you can make your app as much or as little Effect as you want.
It is hard to understand why one would want to introduce this into their codebase given how functional javascript is right away. It lives in the spectrum of rxjs - super powerful, but is it necessary? Can all of those concepts be distilled down into what you would use on the day to day (just a few), with less concept density, and just as much functional goodness?
Try it out! Translate a few of the privatives and then see what happens when you try composing a few different ones.
Is this like a spring boot for typescript or something like that? Looks kind of interesting
It's like Scala and Spring Boot had a baby and the baby was in typescript. Super solid project great engineers.
Effect is to TypeScript what TypeScript is to Effect. It just pays off. But most of the learning curve or the unfamiliarity with syntax and even concepts goes away with AI. In fact, the same reasons why it makes it good for teams makes it good for AI. When a team member or an agent use the Effect patterns, I know I there is a lot less they could have messed up.
One issue with Effect is that it's hard to intro because it does many things. But it does them well, and it does all of them because only a coherent system can deliver the promise of allowing you to write production-ready TypeScript.
I'll list some things:
- Effects: how you describe programs. For some people it helps to think of them as promises on steroids. In addition to tracking the return type, they track the types of errors it could fail with, as well as its dependencies (see context/layers).
- Fibers: primitives for concurrency—but most of the time you don't have to think about them because the `Effect` methods handle most common scenarios
- Context/Layers: type-safe dependency injection. Have your cake and eat it too. You define context interfaces, use them within effects, and TypeScript forces you provide implementations of those interfaces via layers. Layers can provide more than one context, and can also depend on other layers. Very powerful.
- Schema: think Zod, but with the concept of codecs (to be fair Zod has this too), which means you define how things encode (e.g. what API takes and responds with) and decode (e.g. what my app works with). I love `Model`, which derives schemas for the API side and repo (db) side, so I can define a domain model declaratively with things like "account number should be replaced with * except the last 4 digits in the API; it should be Redacted (wrapped, can't leak to logs etc) within the app logic, and should be encrypted in the database".
- Standard library: lots of things that should standard in JS/TS and aren't, or exist but are not coherent or play well together. When I don't use Effect, I have to choose between doing things well or shipping (and suffering the consequences). And I don't mean just strings, dates, decimals. I mean also queues, cache, etc.
- SQL primitives to work with transactions, migrations, queries. There are interfaces on top of this for popular ORMs.
- HTTP server; and ways to define your API with types and schemas, then implement it.
- Telemetry, logging by default
...and I could go on. I am not looking back.
I can't wait for Rust to someday have something even part way as clear at composing systems.
Eventually I really hope we see programming languages that lean back in to what Erlang started more. This is a leap, but imo having inbuilt great patterns for system design would look a whole lot like Effect! Systems practically assemble themselves. There's great powerful meaningful abstractions under foot.
The only other meaningful effort I can call out is Clojure, which made a handful of good primitives. That community only really used atoms and defs, less refs (software transactional memory) and agents, is what I've been told.