CODEWITHSUNDEEP
swiftswift2
Alfred Zien
Alfred Zien

Reputation: 1044

Specify type of polymorphic function to pass it as argument

I have function curry that takes a function (A, B) -> C as an argument, and returns A -> B -> C. It works fine on function g(a: Int, b: Int) -> Int. Also, I have function f, that is polymorphic, so its type is ambigous. Here is the code:

func g(a: Int, b: Int) -> Int { return a + b }

func f(a: Int, b: Int) -> Int { return a + b }
func f(a: Float, b: Float) -> Float { return a + b }

func curry<A, B, C>(f: (A, B) -> C) -> A -> B -> C {
  return { a in { b in f(a, b) } }
}

let curriedG = curry(g) //curriedG type Int -> Int -> Int

let curriedF = curry(f) //Error, Ambigous use of 'f(_:b:)'

It is obvious, that I can't do curry(f), but, is there any way, so I could specify, that I want to use specific f() implementation?

Why I need this. Because of initialisers. I want to curry specific initialiser, lets say struct A has two initialisers: init(t: T, y: Y) and init(u: U, h: H), I want to curry one of them.

Thanks!

Upvotes: 1

Views: 117

Answers (1)

Martin R
Martin R

Reputation: 539945

Since f is overloaded, you have to specify which f you want:

let curriedF = curry(f as (Float, Float) -> Float)

or, alternatively, what the result should be:

let curriedF = curry(f) as Float -> Float -> Float

Upvotes: 1

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