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by hocuspocus 1948 days ago
Nowadays many libraries in and around the Typelevel ecosystem work well together.

There seems to be a real demand for the Zio ecosystem and I wish it all the success it deserves, but its opinionated approach doesn't necessarily solve a problem that people have.
1 comments
eweise 1948 days ago
Sure it does. The problem is how to create a stable set of cross cutting technologies that enable you to concentrate on building the thing you want.
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hocuspocus 1948 days ago
I have no problems building the things I want using libraries based on Cats Effect.
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eweise 1948 days ago
Great. No sure how standardizing on Cats Effect is different than standardizing on ZIO. That's basically my point. ZIO provides a bunch of libraries that work well together.
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type_enthusiast 1947 days ago
I think there's room for both things, and we don't really have to (passive-agressively) squabble about which is better.

cats-effect is a meta-abstraction _and_ a concrete implementation of that abstraction. All of its functionality is abstract over the effect type, which for a lot of library use cases is good! (for example, this enables using ZIO with c-e ecosystem libraries; if c-e took the same tactic as ZIO then this wouldn't be possible)

When you get down to the application level, though – essentially the effect type is going to be fixed. I doesn't _have_ to be, but it takes superhuman levels of discipline not to make it that way. And ZIO is built for that – if the effect type is fixed to ZIO, it grants a lot of ergonomic benefits. So, ZIO ecosystem components are built with that in mind, and give a lot of ergonomics and higher-level semantics that aren't possible with c-e (or abstract effect types).

If cats-effect split the meta-abstraction and the implementation into two libraries, I think this debate would be moot. But, having the implementation together with the meta-abstraction makes cats-effect more likely to leak the latter into the former (I think it's gotten a lot better about this lately, though).

Anyway, just saying – both libraries are great, and they're different, and nobody should be made to feel bad about using either one of them.

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hocuspocus 1947 days ago
The core difference is that Cats Effect is a fairly extensible effect type, with a full type class hierarchy. It's easy for compatible libraries to use and provide only what they need.

JDG argues against the "tagless final" pattern and brings some valid points, but in practice they aren't a problem if you don't overdo it. So in my case, I don't see the appeal in switching to a less mature ecosystem, at least based on this premise alone.

Before using Cats Effect/http4s/fs2/... I worked a few years using the Akka ecosystem (Play and then Akka http, streams, clustering, event-sourcing, ...) and while the underlying technology is solid, I was not a big fan of the experience overall. To me, the Typelevel ecosystem has mostly figured out what Scala should look like today.

If people find an answer in Zio, that's great, it doesn't have to be zero-sum.

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