staltz

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

---

romaonthego

 a:  AM/PM
 A:	0~86399999 (Millisecond of Day)
 
 c/cc:	1~7 (Day of Week)
 ccc:	Sun/Mon/Tue/Wed/Thu/Fri/Sat
 cccc:	Sunday/Monday/Tuesday/Wednesday/Thursday/Friday/Saturday
 
 d:	1~31 (0 padded Day of Month)
 D:	1~366 (0 padded Day of Year) 
 

andymatuschak

A composable pattern for pure state machines with effects

State machines are everywhere in interactive systems, but they're rarely defined clearly and explicitly. Given some big blob of code including implicit state machines, which transitions are possible and under what conditions? What effects take place on what transitions?

There are existing design patterns for state machines, but all the patterns I've seen complect side effects with the structure of the state machine itself. Instances of these patterns are difficult to test without mocking, and they end up with more dependencies. Worse, the classic patterns compose poorly: hierarchical state machines are typically not straightforward extensions. The functional programming world has solutions, but they don't transpose neatly enough to be broadly usable in mainstream languages.

Here I present a composable pattern for pure state machiness with effects,

jagregory

So you've cloned somebody's repo from github, but now you want to fork it and contribute back. Never fear!

Technically, when you fork "origin" should be your fork and "upstream" should be the project you forked; however, if you're willing to break this convention then it's easy.

* Off the top of my head *

1. Fork their repo on Github
2. In your local, add a new remote to your fork; then fetch it, and push your changes up to it

    git remote add my-fork git@github...my-fork.git

codeinthehole

#!/usr/bin/env bash
# 
# Bootstrap script for setting up a new OSX machine
# 
# This should be idempotent so it can be run multiple times.
#
# Some apps don't have a cask and so still need to be installed by hand. These
# include:
#
# - Twitter (app store)

aras-p

// Just before switching jobs:
// Add one of these.
// Preferably into the same commit where you do a large merge.
//
// This started as a tweet with a joke of "C++ pro-tip: #define private public",
// and then it quickly escalated into more and more evil suggestions.
// I've tried to capture interesting suggestions here.
//
// Contributors: @r2d2rigo, @joeldevahl, @msinilo, @_Humus_,
// @YuriyODonnell, @rygorous, @cmuratori, @mike_acton, @grumpygiant,

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

msrose

Combining two git repositories

Use case: You have repository A with remote location rA, and repository B (which may or may not have remote location rB). You want to do one of two things:

• preserve all commits of both repositories, but replace everything from A with the contents of B, and use rA as your remote location
• actually combine the two repositories, as if they are two branches that you want to merge, using rA as the remote location

NB: Check out git subtree/git submodule and this Stack Overflow question before going through the steps below. This gist is just a record of how I solved this problem on my own one day.

Before starting, make sure your local and remote repositories are up-to-date with all changes you need. The following steps use the general idea of changing the remote origin and renaming the local master branch of one of the repos in order to combine the two master branches.

ollieatkinson

public struct Tuple<each T> {
    public private(set) var value: (repeat each T)
    public init(_ value: repeat each T) { self.value = (repeat each value) }
}

extension Tuple {

    public func map<each U>(
        _ transform: (repeat each T) throws -> (repeat each U)
    ) rethrows -> (repeat each U) {

davidbalbert

// Cursed! Do not use!

// Supports most, but not all Text initializers.

import SwiftUI

extension FormatStyle {
    func format(any value: Any) -> FormatOutput? {
        if let v = value as? FormatInput {
            return format(v)