eioio VS effects-examples

the actual project (Readme has some code samples): https://github.com/ocaml-multicore/eio

For 5.0+ you might want to look at https://github.com/ocaml-multicore/eio for how effects can make async much more pleasant

Great post! I would love to see this extended to OCaml 5 (with eio) and Haskell

Second, effects enable a new style of concurrency libraries like eio that forgoes the need to wrap every asynchronous computation in a monad.

> This is realllly unidiomatic in real world Haskell.

Whether idiomatic or not does not matter. It proves my point:

IO won't save you, and even very mundane effects are not part of the game…

Idris is the "better Haskell" sure, but the effect tracking is still part of the uncanny valley (still IO monad based).

Koka is a toy, and Frank mostly "only a paper" (even there is some code out there).

The "Frank concept" is to some degree implemented in the Unison language, though:

https://www.unison-lang.org/learn/fundamentals/abilities/

Having a notion of co-effects (or however you please to call them) is imho actually much more important than talking about effects (as effects are in fact neither values nor types—something that all the IO kludges get wrong).

I think the first practicable approach in the mainstream about this topic will be what gets researched and developed for Scala. The main take away is that you need to look at things form the co-effects side first and foremost!

In case anybody is interested in what happens in Scala land in this regard:

https://www.slideshare.net/slideshow/embed_code/key/aLE9M37d...

https://docs.scala-lang.org/scala3/reference/experimental/cc...

But also the development in OCaml seems interesting:

https://github.com/ocaml-multicore/eio#design-note-capabilit...

Look mom, "effects", but without the monad headache!

To enable access to all these features, an exciting new library called Eio is being developed. It uses a new paradigm of direct-style concurrent I/O programming, without the need for monads or async/await, thus avoiding the function colour problem.

Isn't a language described very similar to the (future) OCaml with effects (https://github.com/ocaml-multicore/effects-examples) added?

Sure. They probably don't mention coeffects so often because their effect system subsumes both effects (actions to be performed) and coeffects (information from the context), and it can do way more than what you're proposing. Here are some examples you may take a look. The dynamic state example in there could be adapted to act as coeffects (contexts) as you suggest. For coeffects in particular, this is a great resource. You may also be interested in Koka's documentation, as it was designed to be a language with effects and coeffects since the beginning (OCaml did only retrofit them recently).

Good question!

https://github.com/ocaml-multicore/effects-examples has links to tutorials and examples for how effects can be used.

There's also some slides from KC's talk on effect handlers https://kcsrk.info/slides/handlers_edinburgh.pdf and materials from the CUFP 17 tutorial: https://github.com/ocamllabs/ocaml-effects-tutorial

https://gopiandcode.uk/logs/log-bye-bye-monads-algebraic-eff... this is also a great introduction

Here's a post outlining the part that people are excited about. Here's the examples list if you'd like more concrete examples.

To be honest, though, despite it being cool that OCaml finally has a concrete multicore release date, I'm more interested in the effect handlers. After reading these slides and this article on the topic I realised OCaml getting support for algebraic effects is way more interesting than the parallelism support.

I think it's not discussed enough how things like language features shape how library APIs are formed. People usually seem to only consider the question "how would I use this feature?" and not "how would the standard library look like with this feature?", which is surprising given how much builtin libraries affect the pleasantness of a language.

One of the things I'm excited to see is the cap-std project for Rust [0] given what Pony [1] has demonstrated is possible with capabilities. I'm also hoping that languages like Koka [2] and OCaml [3] will demonstrate interesting use cases for algebraic effects.

[0] https://github.com/bytecodealliance/cap-std

[1] https://www.ponylang.io/discover

[2] https://koka-lang.github.io

[3] https://github.com/ocaml-multicore/effects-examples

Just randomly stumbled upon this example, which is exactly what you were asking about. It is a strongly-typed fork() that uses first-class effects.