jdrew1303

module GameState
    exposing
        ( Game(..)
        , GameDefinition
        , PlayState
        , loading
        , updateGameDefinition
        , updatePlayState
        , updateScore
        , toReady

jdrew1303

Implementing State Machine On Eloquent Model*

* Update (12.09.2017): I have improved the trait so that it can be used with objects other than Eloquent Models.

Some days ago I came across a task where I needed to implement managable state for an Eloquent model. This is a common task, actually there is a mathematical model called "Finite-state Machine". The concept is that the state machine (SM) "can be in exactly one of the finite number of states at any given time". Also changing from one state to another (called transition) depends on fulfilling the conditions defined by its configuration.

Practically this means you define each state that the SM can be in and the possible transitions. To define a transition you set the states on which the transition can be applied (initial conditions) and the only state in which the SM should be after the transition.

That's the theory, let's get to the work.

jdrew1303

FiniteAuditTrail Trait

Support for keeping an audit trail for any state machine, borrowed from the Ruby StateMachine audit trail gem. Having an audit trail gives you a complete history of the state changes in your model. This history allows you to investigate incidents or perform analytics, like: “How long does it take on average to go from state a to state b?”, or “What percentage of cases goes from state a to b via state c?”

Requirements

1. PHP >= 5.4
2. Laravel 4 framework

jdrew1303

This is my short example of creating a an Indexed State Monad

[Raw Code] (https://gist.github.com/smurphy8/8e0eb2923a2784ea8acd)

Indexed State Monads are different from the standard state Monad because the type of the state is transformable. This is awesome and really nice for creating statemachines that prohibit invalid transitions at the type level.

Here is the thing I read about [Indexed Monads] (http://blog.sigfpe.com/2009/02/beyond-monads.html)

jdrew1303

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

jdrew1303

var moment = require('moment');

module.exports = function(/* orbit, [Date, time String], [format String], [etc] */){

  // Takes an orbit definition of the kind used in GEOF stellar-objects and
  // remaining arguments as moment arguments, returning heliocentric
  // rectangular coordinates in α's unit (probably AU).

  // TODO: Does not yet take into account changes in orbit over time.
  // TODO: Converts between degrees and radians too often, I think.

jdrew1303

      /*
       * The parser is now in one of the following three states:
       *
       * 1. The parser successfully parsed the whole input.
       *
       *    - |result !== null|
       *    - |pos === input.length|
       *    - |rightmostMatchFailuresExpected| may or may not contain something
       *
       * 2. The parser successfully parsed only a part of the input.

jdrew1303

/*
 * PEG.js грамматика парсера фильтра результатов сравнения метрик
 * Как обновлять грамматику:
 *    1. Скопипастить исходник в http://pegjs.org/online
 *    2. Указать Parser variable: window.filter_parser
 *    3. Download parser
 *    4. Минифицировать скачанный js код через: http://jscompress.com
 *    5. Обновить файл filter_parser.pegjs.min.js
 *    6. Запустить js unit-тесты: mocha filter_parser.pegjs.test.js
 *    7. Обновить исходник в этом файле filter_parser.pegjs

jdrew1303

{
  function joinNested(x) {
    return x.map(function(y) {
      return Array.isArray(y) ? joinNested(y) : y
    }).join('')
  }
}

// match all rules, consuming the entire input
root = a:all EOF { return a }

jdrew1303

/*
 * Task: Parse even numbers in PEG.js (http://pegjs.majda.cz).
 *
 * Solution: Let's parse all numbers and reject odd ones using a semantic
 * predicate -- an arbitrary piece of code that returns true (meaning "continue
 * parsing") or false (meaning "halt parsing").
 *
 * This solution wouldn't work before commit a2af1fe612 because predicates
 * didn't have access to labeled expressions in the grammar as variables
 * (without ugly workarounds). But they have the access now and the solution