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Comment by jon_smark | Hacker News Reader

Are the plans for typed algebraic effects solidifying, or are they still nebulous? Concretely, are you willing to take a guess as to when we are expected to see OCaml 6? ;-)

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Rather than a full effect system, we're very likely to have lexically scoped "checked" effects with the help of modal types. I briefly talked about it at the end of my ICFP keynote: https://icfp22.sigplan.org/details/icfp-2022-papers/48/Retro...

There are other cool stuff that is being worked on, which I am very excited about: https://discuss.ocaml.org/t/jane-street-compiler-development.... Hopefully, we will see many of these make it into OCaml 6.

Thanks for the reply. I hope that the array and list comprehensions land soon in upstream; it's a useful and hopefully not-too-controversial feature.

I'm more ambivalent regarding the local allocations and the unboxed types. I totally understand why they'd be useful when you are trying to squeeze every last drop of performance, but they do require a not-so-trivial complexification of the language.

The local types are less invasive than the full support for typed effects. In particular, they are opt-in and associated complexity is pay-as-you-go. In my initial experiments, they seemed pretty nice to program with.

The type system for algebraic effects is still in the research and design phase at this point.

Right now, I am not even taking a guess of what will be the defining new major features of OCaml 6 (effect system + modular implicits maybe? Maybe not?).

Thanks for the reply. I'm hoping that modular macros land soon. I'm very ambivalent about the PPX mechanism, and I hope that modular macros reduces the need of PPX.

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