Simple implementation of a partial function in Swift

Partial.swift

func partial<T, S, A>(f: ((T, S) -> A), t : T) -> (S -> A) {
    return { (s:S) in
        return f(t, s)
    }
}

// Bind the first argument
let addTwenty = partial(+, 20)

// Call the new function
addTwenty(10)