But foo(x : int) is a string! It literally reads "foo applied to x". In the function definition, it appears to be used as a left-hand-side pattern which is "matched". The definition is written as if to say, whenever the term foo(x) is encountered, use this definition here. At least, that was my expectation.
> Haskell doesn't use that notation either
OCaml does and Haskell once had a proposal to add it. Haskell type signatures are normally written separately, but it does support annotating patterns with the right extensions.
fn foo(x: int) -> ReturnType {
body
}
Function {
name: foo
signature: (x: int) -> ReturnType
body: body
}
A "better" way to write this (in that it breaks down the syntax into the order it is best understood) might be
static foo: (Int -> ReturnType) = {
let x = arg0;
body
}
It's mixing up assigning a global variable, specifying that variables type, and destructuring an argument list into individual arguments, in one line. I've played at making my own language, and this is one part that I've never been satisfied with.
Personally I'd probably at least go with a `foo = <anonymous function>` syntax to split out the assigning part. But that's spending "strangeness budget" because that's not how C/Python/Java do it, and I can understand the decision to not spend that budget here...
Can you say so decisively for a language with first-class functions?
foo :: (Int, Int) -> Int
foo (x, y) = ...
Haskell doesn't use that notation either, it uses -> both for the parameter list and for the return type, and separates argument names (arguably, these are poor choices, since currying is not an efficient CPU-native operation and not intuitive so distinguishing between multiple arguments and returning closures is useful, and argument names are useful for documentation).