mattdenner

I’ve been writing a load of Swift code recently for work and this has lead me into the world of typed functional programming. The app needs to build certain objects from a comma separated string, and this lead me to applicative functors, which lead me to brain ache but enlightenment. So here’s my thoughts on how I got to understand these a little better.

All of the code is in Swift, so less clean than Haskell. I’m also only a about 6 weeks into Swift development so I probably haven’t got all of the idioms right. I’ve avoided the optional shorthand wherever possible here, preferring Optional<Type> over Type? because I believe the latter is hiding something that helps understand this code in the context of other generic classes.

It’s also long! I think it’s probably the longest blog post I’ve ever written but I found it interesting and useful, for myself, to write. If you’re one of those people who skip to the end of a book to find out whodunit then I’ve included

natecook1000

// (c) 2015 Nate Cook, licensed under the MIT license
//
// Fisher-Yates shuffle as protocol extensions

extension CollectionType {
    /// Return a copy of `self` with its elements shuffled
    func shuffle() -> [Generator.Element] {
        var list = Array(self)
        list.shuffleInPlace()
        return list