NachoSoto

//
//  Signal+Extensions.swift
//  Khan Academy
//
//  Created by Nacho Soto on 10/1/15.
//  Copyright © 2015 Khan Academy. All rights reserved.
//

import ReactiveCocoa

JadenGeller

// In languages like Python and Haskell, we can write list comprehension syntax like
// super simply to generate complex lists. Below, for example, we find all numbers that are
// the product of two sides of a triangle.
//   [a * b | a <- [1..10], b <- [1..10], c <- [1..10], a * a + b * b == c * c]

// Why is this called nondeterministic computation? Because we essentially try ALL possible combinations
// of these values (a,b) and--you can imagine--run them all simultanously and get the result that matches the predicate.
// Now, obviously, this doesn't all happen at the same time, but that's the idea behind the nondeterminism.

// Let's examine how we can get a similiar result in Swift! We'll start super simple and work

chriseidhof

// This accompanies http://chris.eidhof.nl/posts/repmin-in-swift.html

import UIKit

// Unfortunately, we need Box

public class Box<T> {
    public let unbox: T
    public init(_ value: T) { self.unbox = value }
}

kongtomorrow

func myAnd(lhs : Bool, rhs : @auto_closure () -> Bool) -> Bool {
    if lhs {
        return rhs()
    } else {
        return false
    }
}

func logAndBool(val : Bool) -> Bool {
    println("evaluating and returning \(val)!")