Mattia Crovero

I’ve been working on an @EffectTS_ package to make it easier to use Effect in the @nextjs App Router world by providing "effectful" wrappers and middlewares. 🚀 Try it out and give early feedback at: github.com/mcrovero/effec…

@berenddeboer Llms are really getting good at Effect, glad you’re enjoying it, any feedback is more than welcome!

Image giving github.com/mcrovero/effec… to your frontend developer, and asking them to implemen it! Claude just jumps straight in, with utter confidence. Loving it @mcrovero

Effect + Next.js: Managed Runtimes, Middleware, DX Improvements By Mattia Crovero @mcrovero | Effect Milan 2025 youtube.com/watch?v=GX5enI…

Thanks again to the @EffectTS_ team for the amazing meetup in Milan yesterday, it was great meeting everyone! looking forward to the next event

Kicking off our first Effect Meetup in Milan 🇮🇹

eslint is not a fan of the Effect.map name choice

@TimZolleis @EffectTS_ yes! it's flexible enough for many use cases. at the end of the day it’s just an effect runner that forwards the args and enriches the errors but it's nice because you can use Effect.fn in framework-exposed handlers and get error tracing + automatic spans for free

@mcrovero @EffectTS_ this looks really good, brb gonna steal for rrv7

I’m looking for the smallest helper to start using @EffectTS_ in a Next.js project.. here’s what I came up with so far

github.com/mcrovero/effec… Here's the full code

@MattiaManzati @EffectTS_ 🤯 this is insane, good job! I tried the vscode extension to see effect spans but I feel like vscode is really limiting ui, is there a web version exposed when starting the dev server? With other features like this one it can be really useful to have them in a web gui

Any real world application has a complex tree of dependencies. @EffectTS_ Layers keep them manageable… and with this, they become even nicer! Learn how 👇

@ditorodev @EffectTS_ @nextjs @MichaelArnaldi @kitlangton for now it's a server only library. so for typed client/server communication you’d still need to encode/decode manually. but it would be really nice especially for server actions, maybe even integrated with something like effect-atom from @tim_smart

@mcrovero @EffectTS_ @nextjs cc @MichaelArnaldi @kitlangton just curious if it all being effectful makes it possible to have fully typed client/server comms but in a totally different manner to trpc

I’ve been working on an @EffectTS_ package to make it easier to use Effect in the @nextjs App Router world by providing "effectful" wrappers and middlewares. 🚀 Try it out and give early feedback at: github.com/mcrovero/effec…

@ditorodev @MichaelArnaldi @EffectTS_ route handlers are coming next! But you can also check out @ethanniser’s examples to achieve it the vanilla way effectbyexample.com/nextjs-api-han…

@MichaelArnaldi @EffectTS_ @mcrovero Appreciate it! Also realizing I’m not pilled enough lol This just scream to me “yeah just harder nextjs” I think tho it makes a lot of sense just too “dirty”. Makes sense because it aligns a lot with the curve of complexity explained in the effect website

Feeling intelligent today got my first service and endpoint done in @EffectTS_ I also realized no fucking sense to do nextjs api with effect unless you do RPC or am I still dumb?

@ethanniser @EffectTS_ @nextjs but the idea is to provide a tracer with the current nextjs request span as parent span

@mcrovero @EffectTS_ @nextjs How did you set this up and could we add it to effectbyexample.com/nextjs-api-han…

So good.. free end-to-end tracing thanks to @EffectTS_ and @nextjs automatic spans

@ethanniser @EffectTS_ @nextjs the screenshot comes from github.com/mcrovero/effec… but it is using my library, i'm working on a vanilla example.

@frederic_ooo @EffectTS_ @nextjs Just don’t leave the unattended for too long 😂

@mcrovero @EffectTS_ @nextjs i thought if grafana touched nextjs it would just segfault

@matodev @EffectTS_ @nextjs yes but the stacktrace is enriched by the library to include effect's one. you can still improve it by giving names to generator functions

@mcrovero @EffectTS_ @nextjs does this cause the page component to become an anonymous function causing error logs to be harder to debug?

Actually enjoying working with @EffectTS_ and @nextjs. Check out the example repo below 👇

@AndersonAndrue Unfortunately Effect.fn cannot infer the type from the build handler, you'd need to specify the type every time like `Effect.fn(function* ({ searchParams }: EffectNextParams) {`, right now you can use middlewares to add spans

@mcrovero instead of `.build(({ searchParams }) => Effect.gen` just do `.build(Effect.fn(function*({ searchParams}) {`

we must not be advertising Effect.fn() enough, I keep seeing examples like these from people trying Effect

@elie2222 Yes, that’s true, but how do you know what errors you’ll get and where? You’d need to add something like neverthrow, but then with zod, p-retry, etc., it turns into library sprawl that you could instead standardize with a single package

@mcrovero Plenty of ways to show errors in nextjs. There’s an error.ts file for example. Error boundary another option in react.

Will Effect ever go mainstream? This looks painful

@sa_khan12 @dillon_mulroy @EffectTS_ @nextjs theme: vercel ray.so

@mcrovero @dillon_mulroy @EffectTS_ @nextjs What theme is this? Or is this a code ss bg?