william-reed

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,

Option 1: Command-line download extension as zip and extract

extension_id=jifpbeccnghkjeaalbbjmodiffmgedin   # change this ID
curl -L -o "$extension_id.zip" "https://clients2.google.com/service/update2/crx?response=redirect&os=mac&arch=x86-64&nacl_arch=x86-64&prod=chromecrx&prodchannel=stable&prodversion=44.0.2403.130&x=id%3D$extension_id%26uc" 
unzip -d "$extension_id-source" "$extension_id.zip"

Thx to crxviewer for the magic download URL.

	/**
	* Navigates only if this is safely possible; when this Fragment is still the current destination.
	*/
	fun Fragment.navigateSafe(
	@IdRes resId: Int,
	args: Bundle? = null,
	navOptions: NavOptions? = null,
	navigatorExtras: Navigator.Extras? = null
	) {
	if (mayNavigate()) findNavController().navigate(

	function morning
	# homebrew
	brew update
	brew upgrade
	brew outdated
	brew cleanup

	# sdkman
	echo "Y" \| sdk update

	// Spark 2.1
	val spark = SparkSession.builder().master("local").getOrCreate()

	// Given a list of mixture of strings in integers
	val values = List("20030100013280", 1.0)

	// Create `Row` from `Seq`
	val row = Row.fromSeq(values)

	// Create `RDD` from `Row`

	#!/bin/bash

	# Thanks to https://gist.github.com/wenzhixin/43cf3ce909c24948c6e7
	# Execute this script in your home directory. Lines 17 and 21 will prompt you for a y/n

	# Install Oracle JDK 8
	add-apt-repository ppa:webupd8team/java
	apt-get update
	apt-get install -y oracle-java8-installer
	apt-get install -y unzip make # NDK stuff

	# The command finds the most recent tag that is reachable from a commit.
	# If the tag points to the commit, then only the tag is shown.
	# Otherwise, it suffixes the tag name with the number of additional commits on top of the tagged object
	# and the abbreviated object name of the most recent commit.
	git describe

	# With --abbrev set to 0, the command can be used to find the closest tagname without any suffix:
	git describe --abbrev=0

	# other examples

william-reed

A composable pattern for pure state machines with effects

Option 1: Command-line download extension as zip and extract

Default

Powerlevel10k

-# delete local tag '12345'
-git tag -d 12345
-# delete remote tag '12345' (eg, GitHub version too)
-git push origin :refs/tags/12345
-# alternative approach
-git push --delete origin tagName
-git tag -d tagName