Implicit arguments

[robrix]

This is the definition of List.pure added in #154:

let pure = Declaration("List.pure",
    type: .Type => { A in A --> List.ref[A] },
    value: () => { A, a in cons[A, a, `nil`[A]] })

Syntax notwithstanding, this is much like in a “real” language. However, since there are no implicit arguments, we always have to apply the type parameters explicitly in the values of functions. This is (apparently) unnecessary! We should be able to reduce that down to:

let pure = Declaration("List.pure",
    type: () => { A in A --> List.ref[A] },
    value: () => { a in cons[a, `nil`] })

Apparently, implicit arguments will allow this. I just have no idea how they work.

[robrix]

Turns out I was conflating implicit arguments and type erasure. Filed #160 about erasure.

[robrix]

This was not closed by #161.

[robrix]

Looks like it requires unification.