sidepelican’s gists

sidepelican / TaskScope.swift

Created October 25, 2025 12:58

TaskScope.swift

	import Synchronization

	public final class TaskScope: Sendable {
	public typealias Job = @Sendable () async -> ()

	private let stream: AsyncStream<Job>
	private let continuation: AsyncStream<Job>.Continuation
	private let isRunning = Atomic<Bool>(false)

	public init() {

sidepelican / ComposableViewModel.swift

Created October 6, 2025 00:13

	@MainActor protocol ComposableViewModel: DynamicProperty {
	associatedtype Body: View
	@ViewBuilder @MainActor func build(content: NonVisibleView) -> Self.Body
	}

	struct NonVisibleView: View {
	var body: some View {
	EmptyView()
	}
	}

sidepelican / concat.swift

Last active June 5, 2024 08:27

resultBuilderと雪だるまジェネリクスで型の組み立て

	import Foundation

	@dynamicMemberLookup
	struct Concat<L: Decodable, R: Decodable>: Decodable {
	init(left: L, right: R) {
	self.left = left
	self.right = right
	}
	private var left: L
	private var right: R

sidepelican / RandomUInt8Sequence.swift

Created June 1, 2024 00:48

	public struct RandomUInt8Sequence: Sequence {
	@usableFromInline var count: Int
	public init(count: Int) {
	self.count = count
	}
	public func makeIterator() -> Iterator {
	Iterator(self)
	}

	public struct Iterator: IteratorProtocol {

sidepelican / test.swift

Last active May 23, 2024 00:44

子タスクがキャンセルハンドルしなくても元スコープを抜け出せるtimeout

	import Foundation

	func brokenTask() async {
	await withCheckedContinuation { (c) in
	// キャンセルシグナルが握りつぶされていて正しく中断しない処理
	Task {
	try await Task.sleep(for: .seconds(5))
	c.resume()
	}
	}

sidepelican / main.swift

Created September 18, 2023 09:33

Taskはキャンセルされても明示的にtry Task.checkCancellation()などで抜けない限り最後まで走り抜ける

	import Foundation

	func mySleep(seconds: Int) async {
	await withCheckedContinuation { c in
	DispatchQueue.global().asyncAfter(deadline: .now() + TimeInterval(seconds)) {
	c.resume()
	}
	}
	}

sidepelican / main.swift

Created September 18, 2023 09:08

TaskLocalの引き継ぎはasync letやTask {}では行われる

	import Foundation

	enum MyValue {
	@TaskLocal static var foo: Int = 0
	}

	func myFunc(@_inheritActorContext _ op: @Sendable @escaping () async -> ()) async {
	await withCheckedContinuation { c in
	DispatchQueue.global().async {
	Task {

sidepelican / main.swift

Created February 22, 2023 02:18

Task.detachedはTask.initとは別のスレッドプールを持つが、無限に伸びるわけではない

	var greeting = "Hello, playground"
	print(greeting, ProcessInfo.processInfo.processorCount)
	defer {
	print(greeting)
	}

	for i in 0..<30 {
	Task.detached {
	print("detached", i)
	sleep(1)

sidepelican / ThreadLocal.swift

Created November 3, 2022 08:30

@ThreadLocal property wrapper

	import Foundation

	@propertyWrapper
	public struct ThreadLocal<Value> {
	private let defaultValue: () -> Value
	private let name: String

	public init(wrappedValue: @autoclosure @escaping () -> Value) {
	self.defaultValue = wrappedValue
	self.name = UUID().uuidString

sidepelican / app_preview.md

Last active February 1, 2022 14:07

動画の長さに合わせて無音ファイルをカット

$ ffmpeg -ss 0 -i mute30.wav -t 16.45 mute.wav

無音ファイルと動画を結合

$ ffmpeg -i in.mp4 -i mute.wav -vf scale=886:1920,setsar=1:1 out.mp4

Iceman sidepelican