Denis Lebedev delebedev

Leyline Conformance Audit — 2026-03-22

TL;DR

The 6 "levers" in docs/conformance/levers.md are detection infrastructure — they help find gaps faster but don't close them. Building a better microscope doesn't fix the specimen. The actual conformance improvements come from fixing known protocol gaps.

What exists today

libdispatch efficiency tips

I suspect most developers are using the libdispatch inefficiently due to the way it was presented to us at the time it was introduced and for many years after that, and due to the confusing documentation and API. I realized this after reading the 'concurrency' discussion on the swift-evolution mailing-list, in particular the messages from Pierre Habouzit (who is the libdispatch maintainer at Apple) are quite enlightening (and you can also find many tweets from him on the subject).

My take-aways are:

Javascript is fun

a = new Date('2019-03-31T00:00:00.000Z');
a.setDate(a.getDate() + 1);
console.log(a);

Firefox macos	Safari macos	chrome macos

Types

A type is a collection of possible values. An integer can have values 0, 1, 2, 3, etc.; a boolean can have values true and false. We can imagine any type we like: for example, a HighFive type that allows the values "hi" or 5, but nothing else. It's not a string and it's not an integer; it's its own, separate type.

Statically typed languages constrain variables' types: the programming language might know, for example, that x is an Integer. In that case, the programmer isn't allowed to say x = true; that would be an invalid program. The compiler will refuse to compile it, so we can't even run it.

	#!/bin/bash
	# Leyline client setup for macOS.
	# Patches the Arena client to connect to the Leyline game server.
	#
	# Usage:
	# ./setup.sh on — patch Arena to connect to leyline.games
	# ./setup.sh off — restore Arena to stock (removes services.conf)
	#
	# Override MTGA path: MTGA_PATH="/path/to/MTGA.app" ./setup.sh on

	#!/usr/bin/env python

	import lldb

	def process(debugger, command, result, internal_dict):
	lldb.debugger.HandleCommand("""
	expr -l swift --
	func $process(_ request: URLRequest) {
	func curl(_ request: URLRequest) -> String {
	guard let url = request.url?.absoluteString else {

	struct MinimalDecoder : Decoder {
	var codingPath = [CodingKey?]()
	var userInfo = [CodingUserInfoKey : Any]()

	public func container<Key>(keyedBy type: Key.Type) throws -> KeyedDecodingContainer<Key> {
	return KeyedDecodingContainer(MinimalKeyedDecodingContainer<Key>(decoder: self))
	}

	public func unkeyedContainer() throws -> UnkeyedDecodingContainer {
	return DecodingContainer(decoder: self)

	// Class Keyword: NSManagedObject is defined in objective-c (not sure if it matters)
	// .keywords is CoreData to-many relationship pointing to "Keyword" objects.

	// How do I convert .keywords to [Keyword]?

	po type(of: keywords)
	_NSFaultingMutableOrderedSet

	po keywords is NSOrderedSet
	true

	Adyen Test Card Numbers
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	For all cards use the following expiration and CVV2/CVC2/or CID for Amex.

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	Expiration Dates CVV2 / CVC3 CID (American Express)
	06/2016 OR 08/2018 737 7373

	import Result
	import Unbox

	public enum Method: String { // Bluntly stolen from Alamofire
	case OPTIONS = "OPTIONS"
	case GET = "GET"
	case HEAD = "HEAD"
	case POST = "POST"
	case PUT = "PUT"
	case PATCH = "PATCH"