tclementdev

libdispatch efficiency tips

The libdispatch is one of the most misused API due to the way it was presented to us when it was introduced and for many years after that, and due to the confusing documentation and API. This page is a compilation of important things to know if you're going to use this library. Many references are available at the end of this document pointing to comments from Apple's very own libdispatch maintainer (Pierre Habouzit).

My take-aways are:

• You should create very few, long-lived, well-defined queues. These queues should be seen as execution contexts in your program (gui, background work, ...) that benefit from executing in parallel. An important thing to note is that if these queues are all active at once, you will get as many threads running. In most apps, you probably do not need to create more than 3 or 4 queues.

• Go serial first, and as you find performance bottle necks, measure why, and if concurrency helps, apply with care, always validating under system pressure. Reuse

entone

def get_ipv4_address() do
  :inet.getifaddrs()
  |> elem(1)
  |> Enum.find(fn {_interface, attr} ->
    case attr |> Keyword.get_values(:addr) do
      [] -> false
      list -> list |> Enum.find(fn(addr) ->
        case addr do
          nil -> false
          {127, 0, 0, 1} -> false

lattner

Swift Concurrency Manifesto

Author: Chris Lattner

Chinese Translation by Jason Yu

Contents

• Introduction
• Overall Vision

rob-brown

//
// Actor.Swift
//
// Copyright (c) 2017 Robert Brown
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is

danielberkompas

defmodule MyApp.Scheduler do
  @moduledoc """
  Schedules a Mix task to be run at a given interval in milliseconds.

  ## Options

  - `:task`: The name of the Mix task to run.
  - `:args`: A list of arguments to pass to the Mix task's `run/1` function.
  - `:interval`: The time interval in millisconds to rerun the task.

mcmurrym

public extension CustomDebugStringConvertible {
    var debugDescription: String {
        return debugDescription()
    }
    
    func debugDescription(_ indentationLevel: Int = 0, includeType: Bool = true) -> String {
        
        let indentString = (0..<indentationLevel).reduce("") { tabs, _ in tabs + "\t" }
        
        var s: String

jarsen

import Foundation

//
// MARK: - JSONError Type
//

public enum JSONError: ErrorType, CustomStringConvertible {
    case KeyNotFound(key: JSONKeyType)
    case NullValue(key: JSONKeyType)
    case TypeMismatch(expected: Any, actual: Any)

gaearon

function mapValues(obj, fn) {
  return Object.keys(obj).reduce((result, key) => {
    result[key] = fn(obj[key], key);
    return result;
  }, {});
}

function pick(obj, fn) {
  return Object.keys(obj).reduce((result, key) => {
    if (fn(obj[key])) {

jarsen

// Playground - noun: a place where people can play

import UIKit
import CoreGraphics

public enum Result<T> {
    case Success(@autoclosure () -> T)
    case Failure(String)
    
    init(_ value:T) {

jarsen

// Playground - noun: a place where people can play

import Foundation

infix operator >>- { associativity left precedence 150 } // Bind
infix operator <^> { associativity left } // Functor's fmap (usually <$>)
infix operator <*> { associativity left } // Applicative's apply

public typealias JSON = AnyObject
public typealias JSONObject = Dictionary<String, JSON>