fp-ts and effect-ts

[shinzui]

Hi,

I am confused about the announcement of fp-ts joining the effect-ts ecosystem. Can someone please clarify the implication of the announcement on fp-ts, io-ts, and monocle-ts?

[gcanti]

All new developments will happen under the effect org, roughly speaking there are the following correspondencies:

• fp-ts = effect/data + effect/io
• io-ts = effect/schema
• monocle-ts = fp-ts/optic (not yet accepted into the effect org)

When possible, some of the features designed and implemented in the effect/* packages will be backported to fp-ts in order to

• make easier switching to effect
• make fp-ts better for users who don't want or can't switch to effect

[p3tr2005]

thanks, dude. now i don't have to switch into effect cause i like the fp-ts so much.

[shinzui]

@gcanti Thank you for answering. I'm one of the users who don't want to switch to effect, so it's reassuring that fp-ts will not be only in maintenance mode.

[nandin-borjigin]

There is one more package @effect/typeclass which has the typeclasses using v3 HKT.

[albertodiazdorado]

@gcanti If we are using fp-ts, should we migrate our projects to effect-ts? Is there any timeline (or deadline) for the migration?

[gcanti]

"should"? not at all, it's only worth migrating to effect-ts if the benefits it offers outweigh the costs of migration

[albertodiazdorado]

Oh perfect, that's great!

I had (mis)understood that fp-ts was on the way to being discontinued (as in "We backport bugfxix in Node20 to Node16, but eventually Node16 will no longer be supported" ). Thanks for the clarification :)

[noncom]

I totally don't understand this. Could someone please actually explain?

Looking at both fp-ts and Effect all I see is that these libraries have quite different functionalities with just some minor intersection:

• Effect
  • All about application-level composition,
  • Task composition and scheduling, including IO, etc
  • Catching errors in FP-like way. This concludes the whole FP part. It's like 5% of what fp-ts has.
  • Schema verification
  • Other practical things, Effect is simply bigger, having a lot of stuff for writing actual application architecture. It's going to be all over the place.
• fp-ts
  • A ton of FP-related type-theoretic concepts like HKT, Lattices, Group, Category, Comonad, etc
  • Some provisional task management, just to kind of apply some FP to it, but apparently just not so advanced as in Effect
  • Focuses on math-y things, without any attempt to influence how you architecture your app.

The fact that they both have the Either type, some means to wrap errors and tasks, doesn't make them two versions of the same library. And it is impossible to comprehend how Effect is a better version of fp-ts.

What am I missing? How do we arrive at the conclusion that Effect is fp-ts v3?