Stanislav Pankevich stanislaw

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,

Опции bash для разработки

Разрабатывайте скрипты с опциями set -eu

set -e - падать на ошибках
set -u - считать ошибкой обращение к неопределенной переменной
set -o pipefail - заставить пайпы перестать скрывать ошибки предыдущих команд

Профиты

максимально быстрое выявление скрытых ошибок в коде.
не надо самому писать многие проверки значений.
Это сделает shell-код похожим на нормальный язык программирования, а не на набор последовательно выполняющихся команд, которым на всё пофиг.

Mastering Programming - by Kent Beck

From years of watching master programmers, I have observed certain common patterns in their workflows. From years of coaching skilled journeyman programmers, I have observed the absence of those patterns. I have seen what a difference introducing the patterns can make. Here are ways effective programmers get the most out of their precious 3e9 seconds on the planet. The theme here is scaling your brain. The journeyman learns to solve bigger problems by solving more problems at once. The master learns to solve even bigger problems than that by solving fewer problems at once. Part of the wisdom is subdividing so that integrating the separate solutions will be a smaller problem than just solving them together.

Time

Slicing - Take a big project, cut it into thin slices, and rearrange the slices to suit your context. I can always slice projects finer and I can always find new permutations of the slices that meet different needs

Things to remember when compiling/linking C/C++ software

by Angel Leon. March 17, 2015;

Last update on December 14, 2023

Updated on February 27, 2023

Updated August 29, 2019.

Videos

Introduction to Functional Programming Johannes Weiß - https://vimeo.com/100786088
ReactiveCocoa at MobiDevDay Andrew Sardone - https://vimeo.com/65637501
The Future Of ReactiveCocoa Justin Spahr-Summers - https://www.youtube.com/watch?v=ICNjRS2X8WM
Enemy of the State Justin Spahr-Summers - https://www.youtube.com/watch?v=7AqXBuJOJkY
WWDC 2014 Session 229 - Advanced iOS Application Architecture and Patterns Andy Matuschak - https://developer.apple.com/videos/play/wwdc2014/229/
Functioning as a Functionalist Andy Matuschak - https://www.youtube.com/watch?v=rJosPrqBqrA
Controlling Complexity in Swift Andy Matuschak - https://realm.io/news/andy-matuschak-controlling-complexity/

The three design patterns (Adapter, Facade and Bridge) all produce the result of a clean public API. The difference between the patterns are usually due to a subtle context shift (and in some cases, a behavioural requirement).

Adapter

The primary function of an Adapter is to produce a unified interface for a number of underlying and unrelated objects.

You will notice this pattern being utilised in many applications. For example, ActiveRecord (the popular Ruby ORM; object-relational mapping) creates a unified interface as part of its API but the code underneath the interface is able to communicate with many different types of databases. Allowing the consumer of the API to not have to worry about specific database implementation details.

The principle structure of this pattern is:

	%% The typical answer for how to eliminate white space in wrapfigure doesn't work for me (I'm using a SIGGRAPH style sheet):
	%% http://tex.stackexchange.com/questions/111393/too-much-space-around-wrap-figure
	%% Instead, let's just offset the image.
	%% The horizontal white space is \columnsep and the vertical white space is \intextsep.
	%% Subtract them from the column width and offset the image accordingly.
	%% How to move an image:
	%% http://tex.stackexchange.com/questions/107340/how-to-shift-graphics-adjust-placement-of-figure-with-includegraphics
	\begin{wrapfigure}[11]{R}{1in - .75\columnsep}
	%\centering
	\vspace{-\intextsep}

	Ну условно говоря:
	Модеь: АААА! Давление 1960 на 1230!!!
	Viewmodel : состояние лампочки: красное
	View; Окей, отобразим ! красным


	# и в обратную сторону
	(Пользователь жмет педальку)
	View : -> ViewModel
	Слушай, тут пользователь жмякнул педальку.

	#!/bin/sh

	#
	# Converts branch name 'MAPP-452_how-is-it-going' into a commit message 'MAPP-452 How is it going'
	#

	if ! [ -z $2 ]
	then
	if ! [ "message" == $2 ]
	then

	#!/usr/bin/env bash

	declare -i ERRORS=0

	if git rev-parse --verify HEAD > /dev/null 2>&1
	then
	AGAINST=HEAD
	else
	AGAINST=4b825dc642cb6eb9a060e54bf8d69288fbee4904
	fi