curry() in Swift

curry.swift

// Credit: https://twitter.com/eridius/status/474990322506670080

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

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

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


curry(+)(100)(2)                                                    // 102

let addFour = curry(+)(4)
addFour(10)                                                         // 14


import Foundation

func display(format: NSString, a: NSNumber, b: NSNumber) -> NSString {
    let sum: NSNumber = a.integerValue + b.integerValue
    return NSString(format: format, a, b, sum)
}

let displayFormula = curry(display)("%@ + %@ = %@")
let displayEnglish = curry(display)("The sum of %@ and %@ is %@")

displayFormula(200)(50)                                              // "200 + 50 = 250"
displayEnglish(200)(50)                                              // "The sum of 200 and 50 is 250"

Credit goes to Kevin Ballard: https://twitter.com/eridius/status/474990322506670080