If we were to create a Rust version of this page for Haskell, what cool programming techniques would you add to it?

  • tuna@discuss.tchncs.de
    0·
    4 months ago

    Something i didnt know for a long time (even though its mentioned in the book pretty sure) is that enum discriminants work like functions

    #[derive(Debug, PartialEq, Eq)]
enum Foo {
    Bar(i32),
}

let x: Vec<_> = [1, 2, 3]
    .into_iter()
    .map(Foo::Bar)
    .collect();
assert_eq!(
    x,
    vec![Foo::Bar(1), Foo::Bar(2), Foo::Bar(3)]
);

    Not too crazy but its something that blew my mind when i first saw it

    • Ephera@lemmy.ml
      0·
      4 months ago

      This works with anything that one might call “named tuples”.

      So, you can also define a struct like so and it’ll work:

      struct Baz(i32);

      On the other hand, if you define an enum variant with the normal struct syntax, it does not work:

      enum Foo {
    ...
    Qux { something: i32 } //cannot omit braces
}
      • barsoap@lemm.ee
        0·
        4 months ago

        Enum constructors are functions, this typechecks:

        fn foo<T>() {
    let f: fn(T) -> Option<T> = Some;
}

        I was a bit apprehensive because rust has like a gazillion different function types but here it seems to work like just any other language with a HM type system.