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Rust uses Hindley-Milner type inference. OCaml uses Hindley-Milner. Swift apparently uses a variant of the system with more features. None of these make use of

Rust uses Hindley-Milner type inference. OCaml uses Hindley-Milner. Swift apparently uses a variant of the system with more features. None of these make use of monads or anything rooted in category theory. https://en.wikipedia.org/wiki/Hindley%E2%80%93Milner_type_system https://en.wikipedia.org/wiki/Hindley%E2%80%93Milner_type_sy... HM is a type system that also gives you an algorithm to infer types without having to do the "List<Integer> foo = new ArrayList<Integer>()" dance from languages without type inference. That's it. It has nothing to do with category theory.

steveklabnik 9y ago
(Rust doesn't use Hindley-Milner, though the plan is to try to move closer to it in the future)
- mrkgnao 9y ago
  Oh, thanks for the correction. It would appear that my knowledge is out of date: did Rust use something closer to H-M in the past? (Going off of https://github.com/rust-lang/rust/pull/15955 https://github.com/rust-lang/rust/pull/15955 here.)
  - steveklabnik 9y ago
    For more, see here: https://www.reddit.com/r/rust/comments/6fs5q9/language_servers_and_ides/dikywtc/ https://www.reddit.com/r/rust/comments/6fs5q9/language_serve... see aturon's reply about that PR/blog post. Rust has done almost everything in the past; I wouldn't be surprised if somewhere back in there it was actually HM. :)
jolux 9y ago
Arguably optionals are monadic.
- mrkgnao 9y ago
  Optionals are also "applicative", but Haskellers used them for a long time before applicative functors became popular. A concept can support a certain way of thinking about it without everyone needing to think that way :)
  - jolux 9y ago
    you don't need to think that way, no, but i was pretty sure that rust optionals were modeled after the maybe monad. perhaps not.
    - jolux 9y ago
      oh ok i misread your original, you were only referring to type inference. i thought you were saying none of the languages mentioned had monads.

steveklabnik 9y ago

(Rust doesn't use Hindley-Milner, though the plan is to try to move closer to it in the future)

mrkgnao 9y ago
Oh, thanks for the correction. It would appear that my knowledge is out of date: did Rust use something closer to H-M in the past? (Going off of https://github.com/rust-lang/rust/pull/15955 https://github.com/rust-lang/rust/pull/15955 here.)
- steveklabnik 9y ago
  For more, see here: https://www.reddit.com/r/rust/comments/6fs5q9/language_servers_and_ides/dikywtc/ https://www.reddit.com/r/rust/comments/6fs5q9/language_serve... see aturon's reply about that PR/blog post. Rust has done almost everything in the past; I wouldn't be surprised if somewhere back in there it was actually HM. :)

jolux 9y ago

Arguably optionals are monadic.

mrkgnao 9y ago
Optionals are also "applicative", but Haskellers used them for a long time before applicative functors became popular. A concept can support a certain way of thinking about it without everyone needing to think that way :)
- jolux 9y ago
  you don't need to think that way, no, but i was pretty sure that rust optionals were modeled after the maybe monad. perhaps not.
  - jolux 9y ago
    oh ok i misread your original, you were only referring to type inference. i thought you were saying none of the languages mentioned had monads.