Lucas Romero luqasn

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,

I wanted this capability for various reasons. It's not necessarily stable, because uap0 has to use the same channel as wlan0, and if you're traveling/mobile, wifi channels aren't necessarily predictable.

This is not a guide. This is just so I remember how to get back where I started, in case I wipe this thing. =)

Extremely helpful guides that got me here:

Exporting your 2FA tokens from Authy to transfer them into another 2FA application

IMPORTANT - Update regarding deprecation of Authy desktop apps

Past August 2024, Authy stopped supported the desktop version of their apps:
See Authy is shutting down its desktop app | The 2FA app Authy will only be available on Android and iOS starting in August for details.

And indeed, after a while, Authy changed something in their backend which now prevents the old desktop app from logging in. If you are already logged in, then you are in luck, and you can follow the instructions below to export your tokens.

If you are not logged in anymore, but can find a backup of the necessary files, then restore those files, and re-install Authy 2.2.3 following the instructions below, and it should work as expected.

Linting your code, the vanilla way

You may want a linter plugin to lint your code in Vim but you probably don't need it. At least try the built-in way before jumping on the plugin bandwagon.

Defining `makeprg`

autocmd FileType <filetype> setlocal makeprg=<external command>

This autocommand tells Vim to use <external command> when invoking :make % in a <filetype> buffer. You can add as many similar lines as needed for other languages.

58 bytes of CSS to look great nearly everywhere

When making this website, i wanted a simple, reasonable way to make it look good on most displays. Not counting any minimization techniques, the following 58 bytes worked well for me:

main {
  max-width: 38rem;
  padding: 2rem;
  margin: auto;
}

	using System;
	using Foundation;
	using UIKit;
	using System.Collections.Generic;
	using System.Diagnostics;
	using CoreGraphics;

	namespace iOS
	{
	/// <summary>

	#!/bin/bash
	## this little Gist is for Copy the Letsencrypt Cert from an Linux machine (e.g. Raspberry PI or Synology NAS)
	## to the router (Fritzbox).
	## It is usefull to be able to speak to the Router over DDNS without any Cert issue in the Browser.
	## thanks to https://gist.github.com/mahowi for the perfect Idea
	## put it in /etc/letsencrypt/renewal-hooks/post so it gets run after every renewal.
	## since Fritz OS 7.25 it is needed to select a Username, from a security point of view
	## it is always a good idea to have a non default user name. And as normaly a Fritz Box
	## is connected to the Internet, the prefered method should be WITH Username.

	#!/bin/bash

	#
	# NOTE: specify the absolutepath to the directory to use when
	# loading a plugin. '~' expansion is supported.
	#

	chunkc core::plugin_dir /usr/local/opt/chunkwm/share/chunkwm/plugins

	#

	package statemachine

	import debug
	import fail
	import io.reactivex.Observable
	import kotlinx.coroutines.experimental.channels.Channel
	import kotlinx.coroutines.experimental.channels.produce
	import kotlinx.coroutines.experimental.delay
	import kotlinx.coroutines.experimental.launch
	import kotlinx.coroutines.experimental.runBlocking

	{ hostName, pkgs, ... }:
	{
	imports = [
	./hardware.nix
	];

	networking.hostName = hostName;
	time.timeZone = "America/Los_Angeles";

	system.copySystemConfiguration = true;