vahidk

// This code is based on https://en.wikipedia.org/wiki/HSL_and_HSV
// Free to use for any purpose. No attribution needed.

function rgbToHsl(r, g, b) {
  r /= 255; g /= 255; b /= 255;
  let max = Math.max(r, g, b);
  let min = Math.min(r, g, b);
  let d = max - min;
  let h;
  if (d === 0) h = 0;

WaldoJeffers

const compose = (...fns) => fns.reduce((f, g) => (...args) => f(g(...args)))

// Usage : compose functions right to left
// compose(minus8, add10, multiply10)(4) === 42
//
// The resulting function can accept as many arguments as the first function does
// compose(add2, multiply)(4, 10) === 42

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,

yang-wei

Should be work with 0.18

Destructuring(or pattern matching) is a way used to extract data from a data structure(tuple, list, record) that mirros the construction. Compare to other languages, Elm support much less destructuring but let's see what it got !

Tuple

myTuple = ("A", "B", "C")
myNestedTuple = ("A", "B", "C", ("X", "Y", "Z"))

flbuddymooreiv

The following shell transcript shows how to:

• Create a GPG key
• Create a pass database
• Add git support to the pass database
• Create a remote git repository
• Push the pass database to the remote git repository
• Fetch and display your passwords from another host

It is assumed that the pass package has been installed on both the first and second computers.

ohanhi

Learning FP the hard way: Experiences on the Elm language

by Ossi Hanhinen, @ohanhi

with the support of Futurice 💚.

Licensed under CC BY 4.0.

Editorial note

austinhyde

Observables

You don't really need a framework or fancy cutting-edge JavaScript features to do two-way data binding. Let's start basic - first and foremost, you need a way to tell when data changes. Traditionally, this is done via an Observer pattern, but a full-blown implementation of that is a little clunky for nice, lightweight JavaScript. So, if native getters/setters are out, the only mechanism we have are accessors:

var n = 5;
function getN() { return n; }
function setN(newN) { n = newN; }

console.log(getN()); // 5

setN(10);

evancz

Architecture in Elm

This document is a collection of concepts and strategies to make large Elm projects modular and extensible.

We will start by thinking about the structure of signals in our program. Broadly speaking, your application state should live in one big foldp. You will probably merge a bunch of input signals into a single stream of updates. This sounds a bit crazy at first, but it is in the same ballpark as Om or Facebook's Flux. There are a couple major benefits to having a centralized home for your application state:

1. There is a single source of truth. Traditional approaches force you to write a decent amount of custom and error prone code to synchronize state between many different stateful components. (The state of this widget needs to be synced with the application state, which needs to be synced with some other widget, etc.) By placing all of your state in one location, you eliminate an entire class of bugs in which two components get into inconsistent states. We also think yo

6174

 //http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript
 Math.random().toString(36).substring(2, 15) + Math.random().toString(36).substring(2, 15);

mjackson

/**
 * Converts an RGB color value to HSL. Conversion formula
 * adapted from http://en.wikipedia.org/wiki/HSL_color_space.
 * Assumes r, g, and b are contained in the set [0, 255] and
 * returns h, s, and l in the set [0, 1].
 *
 * @param   Number  r       The red color value
 * @param   Number  g       The green color value
 * @param   Number  b       The blue color value
 * @return  Array           The HSL representation