2 ms·

I'm not that familiar with Rust at the moment, could you expand?

benreesman 5y ago
GP is referring to a Rust language feature called “traits” that is a quirky subset of a Haskell language feature called “type classes”. Type classes are based on firmer theoretical footing (I think the original paper is called “Making Ad-Hoc Polymorphism Less Ad-Hoc”) and therefore run into fewer weird corner cases. That’s not to say that Rust traits are “bad”, they’re useful and arguably cleaner than the C++ version of the idea (“concepts”), but a Haskell hacker writing Rust is liable to grumble now and again at the weird edge cases.
ReleaseCandidat 5y ago
To use traits like you would type classes in Haskell, for example to define functors or monads in a general way, you need higher kinded types. Which can kind[oh, what a pun] of be implemented in Rust. So yes! You can use higher kinded types in rust. Whether you should I will leave up to you. But it certainly doesn't seem like a very attractive option for most projects considering the syntactic noise of the implementation, a typechecker that gets often confused and requires help, as well as error messages that don't make much sense. Especially the last is a shame since extremely helpful error messages is what rust is known for, and I wholeheartedly agree (under normal circumstances). https://hugopeters.me/posts/14/ https://hugopeters.me/posts/14/ Yes, But Why, Really? Because sometimes one just gets homesick for Haskell and wants to implement the Functor hierarchy. You'll find this in the higher-cat crate. It's not really very suited for writing good Rust code, but it makes Haskell programmers feel happy and it has a lot of funny words. https://docs.rs/higher/latest/higher/ https://docs.rs/higher/latest/higher/ A proposal for an addition to Rust, to get generic monads and (Haskell-like) do-notation for them: https://varkor.github.io/blog/2019/03/28/idiomatic-monads-in-rust.html https://varkor.github.io/blog/2019/03/28/idiomatic-monads-in...

GP is referring to a Rust language feature called “traits” that is a quirky subset of a Haskell language feature called “type classes”. Type classes are based on firmer theoretical footing (I think the original paper is called “Making Ad-Hoc Polymorphism Less Ad-Hoc”) and therefore run into fewer weird corner cases. That’s not to say that Rust traits are “bad”, they’re useful and arguably cleaner than the C++ version of the idea (“concepts”), but a Haskell hacker writing Rust is liable to grumble now and again at the weird edge cases.

ReleaseCandidat 5y ago

To use traits like you would type classes in Haskell, for example to define functors or monads in a general way, you need higher kinded types. Which can kind[oh, what a pun] of be implemented in Rust. So yes! You can use higher kinded types in rust. Whether you should I will leave up to you. But it certainly doesn't seem like a very attractive option for most projects considering the syntactic noise of the implementation, a typechecker that gets often confused and requires help, as well as error messages that don't make much sense. Especially the last is a shame since extremely helpful error messages is what rust is known for, and I wholeheartedly agree (under normal circumstances). https://hugopeters.me/posts/14/ https://hugopeters.me/posts/14/ Yes, But Why, Really? Because sometimes one just gets homesick for Haskell and wants to implement the Functor hierarchy. You'll find this in the higher-cat crate. It's not really very suited for writing good Rust code, but it makes Haskell programmers feel happy and it has a lot of funny words. https://docs.rs/higher/latest/higher/ https://docs.rs/higher/latest/higher/ A proposal for an addition to Rust, to get generic monads and (Haskell-like) do-notation for them: https://varkor.github.io/blog/2019/03/28/idiomatic-monads-in-rust.html https://varkor.github.io/blog/2019/03/28/idiomatic-monads-in...