curryingFun.playground

/// Adds two numbers. Not curried.
func f(x: Int, y: Int) -> Int {
    return x + y
}

/// h(x) takes an integer and generates a function g(y), which
/// returns the sum of x (now fixed) and y.
func h(x: Int) -> ((Int) -> Int) {
    func g(y: Int) -> Int {
        return x + y
    }
    return g
}


/// A swiftier version of h(x)
func swiftyH(x: Int) -> (Int) -> Int {
    return { y in x + y }
}

/// The swiftiest version of all
func swiftiestAdd(x: Int)(y: Int) -> Int {
    return x + y
}

// It's true. It's all true!
f(3, 5) == h(3)(5)
h(3)(5) == swiftyH(3)(5)
swiftyH(3)(5) == swiftiestAdd(3)(y: 5)


/// An example of how instance methods are
/// curried functions
class Toilet {
    func flush(nTimes: Int) -> String {
        return "flushing \(nTimes) times!"
    }
}

let t = Toilet()
t.flush(5)
let flush = Toilet.flush(t)