rizumita

var i: Character?
test("Optional Binding") {
    for _ in 0...repeatCount {
        if let us = s {
            i = us.first
        } else {
            i = "i".first
        }
    }
}

rizumita

test("Optional Binding") {
    for _ in 0...repeatCount {
        let unrapped: String
        if let tmp = s {
            unrapped = tmp
        } else {
            unrapped = "default"
        }
    }
}

rizumita

func runSpeedTests() {
    let s: String? = "test"
    let repeatCount = 10000000000

    var i = 0
    test("Optional Binding") {
        for _ in 0...repeatCount {
            if let _ = s { i += 1 }
        }
    }

rizumita

func runSpeedTests() {
    let s: String? = "test"
    let repeatCount = 100000000

    test("Optional Binding") {
        for _ in 0...repeatCount {
            if let _ = s {}
        }
    }

rizumita

struct AnyCodingKeys: CodingKey {
    var stringValue: String
    var intValue: Int?

    init?(stringValue: String) { self.stringValue = stringValue }
    
    init?(intValue: Int) {
        self.stringValue = String(intValue)
        self.intValue = intValue
    }

rizumita

struct Permission<Holder: PermissionHolder> {
    let holder: Holder
}

protocol PermissionHolder {
    var can: Permission<Self> { get }
}

extension PermissionHolder {
    var can: Permission<Self> { return Permission(holder: self) }

rizumita

let json = """
{
"id": 1,
"url":"",
"size":{ "width": 100, "height": 50 }
}
""".data(using: .utf8)!

protocol MyCodable: Codable {
    static func decode(from decoder: Decoder) throws -> Self

rizumita

func const<A, B>(_ value: A) -> (B) -> A {
    return { _ in value }
}

let f_const: (String) -> () = { const(())(foo("bar")($0)) }
f_const("hoge") // 返値がVoidなのでWarningが発生しない

rizumita

func foo(_ string: String) -> (String) -> String {
    return { s in
        let result = string + " " + s
        print(result)
        return result
    }
}

let f: (String) -> String = foo("bar")
f("baz")        // result of call is unused が発生

rizumita

func operation(_ sub1: () -> (), _ sub2: () -> ()) {
    sub1()
    sub2()
}