Haskell.swift

const.swift

func const<A, B>(a: A) -> B -> A {
  return { _ in a }
}

curry.swift

func curry<A, B>(_ function: (A) -> B) -> (A) -> B {
    return { (`a`: A) -> B in function(`a`) }
}

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

func curry<A, B, C, D>(_ function: (A, B, C) -> D) -> (A) -> (B) -> (C) -> D {
    return { (`a`: A) -> (B) -> (C) -> D in { (`b`: B) -> (C) -> D in { (`c`: C) -> D in function(`a`, `b`, `c`) } } }
}

id.swift

func id<A>(a: A) -> A {
  return a
}