Function compsition in swift (based on https://twitter.com/jckarter/status/473642680782573569)

compose.swift

operator infix • { associativity right }
@infix func •<A,B,C> (f : B->C, g : A->B) -> (A->C) {
    return  { (x : A) in f(g(x)) }
}

func inc(a : Int) -> Int { return a+1 }
func show(a : Int) -> String { return String(a) }

let f = show • inc • inc

6.1.1

infix operator • { associativity right }
func •<A,B,C> (f : B->C, g : A->B) -> (A->C) {
    return  { (x : A) in f(g(x)) }
}