koher’s gists

koher / each-pair-without-any-sequence.md

Created March 3, 2017 03:12

`eachPair` without `AnySequence`

eachPair without AnySequence

extension Sequence where Self.SubSequence: Sequence {
  func eachPair() -> Zip2Sequence<Self, Self.SubSequence> {
    return zip(self, self.dropFirst())
  }
}

(1...10).eachPair().forEach { print($0) }

koher / decode-json.md

Created March 8, 2017 07:59

// Argo
struct User {
  let id: Int
  let name: String
  let email: String?
  let role: Role
  let companyName: String
  let friends: [User]
}

koher / variance.swift

Created May 14, 2017 22:01

	class Animal {}
	class Cat: Animal {}

	let cats: Array<Cat> = [Cat()]
	let animals: Array<Animal> = cats // OK

	let cat: Optional<Cat> = .some(Cat())
	let animal: Optional<Animal> = cat // OK

	struct Box<Value> {

koher / variance.kt

Created May 14, 2017 22:07

	open class Animal
	class Cat: Animal()

	class Box<out Value> ( // `out` for covariance
	val value: Value
	)

	fun main(args: Array<String>) {
	val catBox: Box<Cat> = Box(Cat())
	val animalBox: Box<Animal> = catBox // OK

koher / RangeContains.swift

Last active August 4, 2017 08:25

	extension CountableRange {
	public func contains(_ range: CountableRange<Bound>) -> Bool {
	return lowerBound <= range.lowerBound && range.upperBound <= upperBound
	}

	public func contains(_ range: CountableClosedRange<Bound>) -> Bool {
	return lowerBound <= range.lowerBound && range.upperBound < upperBound
	}

	public func contains(_ range: Range<Bound>) -> Bool {

koher / BoxEq.kt

Created July 7, 2017 00:30

	val a: Int = 999
	val b: Int? = a
	val c: Int? = a
	println(b === c) // false

koher / destroy.swift

Created July 22, 2017 15:04

	// destroyed by `-Ounchecked`
	import Foundation

	let a: Int

	switch arc4random() % 3 {
	case 0:
	print("0")
	a = 111
	case 1:

koher / swift4-dictionary-subscript-with-default.swift

Last active September 25, 2017 00:15

	let array = [2, 3, 3, 4, 7, 2, 1, 4, 0, 9, 1, 2]

	// array の要素の値ごとに集計
	// 2 が 3 個、 3 が 2 個などを知りたい
	var nToCount = [Int: Int]()
	for n in array {
	nToCount[n, default: 0] += 1
	}

	// 結果を表示

koher / swift4-dictionary-subscript-with-default-2.swift

Last active September 25, 2017 01:24

	let array = [2, 3, 3, 4, 7, 2, 1, 4, 0, 9, 1, 2]

	// array の要素の値ごとに集計
	// 2 が 3 個、 3 が 2 個などを知りたい
	let nToCount: [Int: Int] = array.reduce(into: [:]) { nToCount, n in
	nToCount[n, default: 0] += 1
	}

	// 結果を表示
	for (n, count) in (nToCount.sorted { $0.key < $1.key }) {

koher / swift-type-erasure-pattern.swift

Created October 6, 2017 07:35 — forked from omochi/swift-type-erasure-pattern.swift

	protocol CatProtocol {
	var name: String { get set }
	func nya() -> String
	mutating func sleep()
	func clone() -> Self
	func cast<T>(to: T.Type) -> T?
	}

	class Cat : CatProtocol {
	required init() {}

Yuta Koshizawa koher