Turning Swift into Ruby

array_extension.swift

import Foundation

extension Array {
  func each(task: (Element) -> ()) {
    for element in self {
      task(element)
    }
  }
  
  func eachWithIndex(start: Int? = nil, task: (Int, Element) -> ()) {
    let add = start ?? 0
    
    for (index, element) in enumerate() {
      task(index + add, element)
    }
  }
  
  func zip<U>(other: [U]) -> [(Element, U)] {
    var result: [(Element, U)] = []
    
    for (index, element) in enumerate() {
      if index >= other.count {
        break
      }
      result.append((element, other[index]))
    }
    
    return result
  }
}

let test = ["a", "b", "c"]
test.eachWithIndex(1) { print("\($0): \($1)") }
// 1: a
// 2: b
// 3: c
test.zip([1, 2]).each { print($0) }
// ("a", 1)
// ("b", 2)

compare.swift

import Foundation

enum Compare: Int {
  case Right = -1, Equal, Left
}

infix operator <=> {}

func <=> <T: Comparable>(left: T, right: T) -> Compare {
  if left == right {
    return .Equal
  } else if left > right {
    return .Left
  } else {
    return .Right
  }
}

1 <=> 1             // .Equal
2.4 <=> 2.9         // .Right
"b" <=> "a"         // .Left
(0 <=> 1).rawValue  // -1

switch 0 <=> 1 {
case .Equal, .Left: print("That's odd")
default: print("All good")
}
// prints "All good"

int_extension.swift

import Foundation

extension Int {
  var hours: Int {
    return self * 3600
  }
  
  var ago: NSDate {
    return NSDate().dateByAddingTimeInterval(-NSTimeInterval(self))
  }
  
  var fromNow: NSDate {
    return NSDate().dateByAddingTimeInterval(NSTimeInterval(self))
  }
  
  func times(task: (Int) -> ()) {
    for i in 0..<self { task(i) }
  }
}

print(NSDate())        // 2016-01-08 09:19:20 +0000
print(3.hours.ago)     // 2016-01-08 06:19:20 +0000
print(2.hours.fromNow) // 2016-01-08 11:19:55 +0000

2.times { print($0) }  // prints 0 and 1