proxpero

public func ack(_ m: Int, _ n: Int) -> Int {
    if m == 0 { return n + 1 }
    if n == 0 { return ack(m - 1, 1) }
    return ack(m - 1, ack(m, n - 1))
}

for i in (0...5) {
    for j in (0...5) {
        print("ack(\(i), \(j)) is \(ack(i, j))")
    }

proxpero

// Part 1

extension String {
    var characterCounts: [Character: Int] {
        return self.reduce(into: [Character: Int]()) { $0[$1, default: 0] += 1 }
    }
}

extension Bool {
    var intValue: Int {

proxpero

// prepare the puzzle input
let input = loadFile(named: "day1") // convenience function in resources
    .split(separator: "\n")
    .compactMap(Int.init) // extension on Int to init? with String.Subsequence

// part 1
let part1 = input.reduce(0, +)

// part 2

proxpero

// taken 2018-03-19 from wikipedia. https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2

enum Iso3166_1a2: String {
    case af = "AF"
    case ax = "AX"
    case al = "AL"
    case dz = "DZ"
    case `as` = "AS"
    case ad = "AD"
    case ao = "AO"

proxpero

// taken 2018-03-19 from wikipedia. https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes

public enum Iso639_1: String {
    case ab = "AB"
    case aa = "AA"
    case af = "AF"
    case ak = "AK"
    case sq = "SQ"
    case am = "AM"
    case ar = "AR"

proxpero

/// Creates a sequence of tuple-3s built out of three underlying sequences.
/// Based on Zip2Seqence from the Swift Standard Library.
/// https://github.com/apple/swift/blob/9361a6b66f6f8351e89c090f604d7e1f42e2a045/stdlib/public/core/Zip.swift
///
/// - Parameters:
///   - sequence1: The first sequence or collection to zip.
///   - sequence2: The second sequence or collection to zip.
///   - sequence3: The third sequence or collection to zip.
/// - Returns: A sequence of tuple triples, where the elements of each triplet are
///   corresponding elements of `sequence1`, `sequence2`, and `sequence3`.

proxpero

// Accompanying blog post: http://127.0.0.1:4000/2017/07/11/encoding-and-decoding-custom-enums-with-associated-values-in-swift-4
// Also: https://gist.github.com/proxpero/189a723fb96bb88fac5bf9e11d6cf9e2
enum Barcode {
    case upc(Int, Int, Int, Int)
    case qrCode(String)
}

extension Barcode: Codable {

    private enum CodingKeys: String, CodingKey {

proxpero

// See http://proxpero.com/2017/07/11/encoding-and-decoding-custom-enums-with-associated-values-in-swift-4/
enum Barcode {
    case upc(Int, Int, Int, Int)
    case qrCode(String)
}

extension Barcode: Codable {
    init(from decoder: Decoder) throws {
        self = try Barcode.Coding.init(from: decoder).barcode()
    }

proxpero

Keybase proof

I hereby claim:

• I am proxpero on github.
• I am proxpero (https://keybase.io/proxpero) on keybase.
• I have a public key whose fingerprint is ABAF 07DE 0D7E EA58 7C60 1131 CB36 31B5 E8CA 11C7

To claim this, I am signing this object:

proxpero

// As described in: http://proxpero.com/2017/02/14/an-implementation-of-md5/

extension Collection where Iterator.Element == UInt8 {

    /// Returns the md5 hash of self.
    public var md5: String {
        return self.md5Digest.lazy.reduce("") {
            var s = String($1, radix: 16)
            if s.characters.count == 1 {
                s = "0" + s