An implementation of Zip2 for different length Sequences, that fills the missing entries with nil.
Updated for Swift 4, based on a solution in this StackOverflow thread: https://stackoverflow.com/questions/25153477/in-swift-i-would-like-to-join-two-sequences-in-to-a-sequence-of-tuples
let first: [String] = ["a", "b", "c", "d"]
let second: [Int] = [1, 2]
let actual = Array(Zip2WithNilPadding(first, second))
# [(Optional("a"), Optional(1)), (Optional("b"), Optional(2)), (Optional("c"), Optional(3))]
MIT License