SimplicityJS

Pattern matching in JavaScript

A port of Simplicity for C# to JavaScript.

Installation

npm install --save-dev simplicityjs

Note that the NPM package name is simplicityjs, not simplicity (which was already taken). Add a reference to ./node_modules/simplicityjs/dist/simplicity.js.

Usage

These examples are in ES6.

import match from 'simplicityjs'

var letter = 'f';
var result = match(letter)
	.with('a', 'Letter is A')
	.with('b', 'Letter is B')
	.with(x => 'c' <= x && x <= 'h', x => 'Letter ' + x + ' is between c and h')
	.else(x => 'Letter ' + x + ' is out of range')
	.do();

// result = 'Letter f is between c and h'

Call it without a value and call toFunc() at the end of the method chain to get a function value that can be reused:

var formatFuzzyAmount = match()
	.with(0, 'None')
	.with(x => 0 < x && x <= 0.125, 'Just a bit')
	.with(x => 0.125 < x && x <= 0.29, 'About one quarter')
	.with(x => 0.29 < x && x <= 0.41, 'About one third')
	.with(x => 0.41 < x && x <= 0.58, 'About half')
	.with(x => 0.58 < x && x <= 0.7, 'About two thirds')
	.with(x => 0.7 < x && x <= 0.875, 'About three quarters')
	.with(x => 0.875 < x && x < 1, 'Almost all')
	.else('All')
	.toFunc();

var oneQuarter = formatFuzzyAmount(0.25);
var twoThirds = formatFuzzyAmount(0.66);

// oneQuarter = 'About one quarter'
// twoThirds = 'About two thirds'

Building and contributing

1. Install NPM
2. Clone the SimplicityJS repo
3. npm install

SimplicityJS's source is in ES6, transpiled to ES5 (the widely currently supported version of JavaScript in browsers) using Babel via a Gulp script. To build, install Gulp globally (sudo npm install -g gulp) and run gulp from the repo root. The default Gulp task will run Babel and write the result to ./dist/simplicity.js.

Deploying to NPN

These are instructions to myself ;-)

1. npm login, provide creds
2. npm publish

that was easy

Versions

• 3.0.1 - sigh need to export default not just export. if only someone had written a test suite for this library.
• 3.0.0 - Whoops, didn't actually build the dist js... Also removed support for distribution via Bower
• 2.0.0 - use ES6 export, don't add it to window - breaking change
• 1.0.0 - version bump because yay NPM publishing!
• 0.1.0 - first version, port of Simplicity for C#