Memoized Fibonnaci series

fibMemoized

// this version of memoize is from the WWDC 2014 Advanced Swift session
// https://developer.apple.com/videos/wwdc/2014/?id=404

func memoize<T: Hashable, U>(body: (T -> U, T) -> U ) -> (T) -> U {
    var memo = [T: U]()
    var result: (T -> U)!
    result = {
        value in
        if let cached = memo[value] { return cached }
    
        let toCache = body(result, value)
        memo[value] = toCache
        return toCache
    }
    return result
}

var fib = memoize {
    (fib: Int -> Int, val: Int) -> Int in
    return val == 1 || val == 0 ? 1 : fib(val - 1) + fib(val - 2)
}

let fib5 = fib(7)
// 21