Yuka Ezura ezura

Typed error can be useful in certain cases, especially when accompanied with NoError type.

For example, in reactive programming, https://github.com/ReactiveCocoa/ReactiveSwift (typed error) allows us to create UI bindings only if Error is NoError, i.e.:

static func <~ <Source: BindingSource> (provider: Self, source: Source) -> Disposable? 
    where Source.Value == Value, Source.Error == NoError { ... }
    
// example
let alphaSignal: Signal = ...

	import Foundation

	func f() {
	unowned var unownedValue: NSDate?
	unownedValue = NSDate()
	}

	void main() {
	var tmp = "tmp";
	final finalVar = tmp;
	// Const variables must be initialized with a constant value.
	// const constVar = tmp;
	const _constVar = "const";
	const constVar = _constVar;
	print(finalVar + constVar);
	}

	void main() {
	for (int i = 0; i < 5; i++) {
	print('hello ${i + 1}');
	}

	for (var i in ["1", false]) {
	print(convertToBool(i));
	}
	}

	v1 + v2 + v3
	// evaluation order: v1 v2 v3

	v1 + v2 * v3
	// evaluation order: v1 v2 v3

	v1 + v2 * (v3 + v4) + v5
	// evaluation order: v1 v2 v3 v4 v5

	enum N {
	case never(Never)
	}

	func f(_ v: N) {
	switch v {
	case .never(let naver):
	print(naver)
	}
	}

	var v: Int?
	if (a?.v = 1) == nil {
	// if a is nil, do something
	}

	var global: Any? = nil

	class A {
	deinit {
	global = self
	}
	}

	do {
	_ = A()

	/*
	event \| without didSet \| have didSet
	start 0 0
	0 0
	set 1 1
	1 0
	1 0
	1 0
	end 1 1
	--- 1

	int v = 0;

	// 意図しているコード
	if(v == 0) { ... } // `if(1)` と評価

	// `==` と `=` を書き間違えたコード
	if(v = 0) { ... } // `if(0)` と評価