mori

A simple bridge to ClojureScript's persistent data structures and supporting APIs for vanilla JavaScript. Pull requests welcome.

Getting it

You can install the latest release via npm:

npm install mori

The installed package contains a single optimized JavaScript file mori.js.

Load mori in your Node.js programs as you would any other module:

var mori = require("mori");

In a browser, you can load mori with a script tag, as you would any other JavaScript library:

<script src="mori.js" type="text/javascript"></script>

You can also load it as an AMD module, e.g. with RequireJS.

Build

Prerequisites

You will first need to install the Java SDK, if it's not already installed on your system.

On Windows, you will need to manually install Leiningen. On UNIX-like systems, Leiningen will be installed within the project automatically if the lein executable is not found on your path or if your lein version predates 2.0.0.

Clone the repo

git clone https://github.com/swannodette/mori.git
cd mori

On a UNIX-like system build with

./scripts/build.sh

Alternatively using npm

npm run-script build

On Windows

./scripts/build.ps1

The build process will generate an optimized JavaScript file mori.js, which is suitable for use with Node.js, or in a Web browser or other JavaScript environments. You can also load it as an AMD module.

Usage

You can use it from your projects like so:

var inc = function(n) {
  return n+1;
};

mori.into_array(mori.map(inc, mori.vector(1,2,3,4,5)));
// => [2,3,4,5,6]

Efficient non-destructive updates!

var v1 = mori.vector(1,2,3);
var v2 = mori.conj(v1, 4);
v1.toString(); // => '[1 2 3]'
v2.toString(); // => '[1 2 3 4]'

var sum = function(a, b) {
  return a + b;
};
mori.reduce(sum, mori.vector(1, 2, 3, 4)); // => 10

Lazy sequences!

var _ = mori;
_.into_array(_.interpose("foo", _.vector(1, 2, 3, 4)));
// => [1, "foo", 2, "foo", 3, "foo", 4]

Or if it's more your speed, use it from CoffeeScript!

inc = (x) -> x+1  
r = mori.map inc, mori.vector(1,2,3,4,5)
mori.into_array r

Documentation

You can find extensive documentation and examples here.

More Examples

Efficient Freeze/Thaw

For vectors and maps we provide an efficient thaw and freeze operations:

var m = mori;

// ~330ms with v8 3.22.11 MBA 1.7ghz
for(var j = 0; j < 10; j++) {
  var s = new Date();
  var arr = [];
  for(var i = 0; i < 10000000; i++) {
    arr.push(i);
  }
  print("Array push " + arr.length + " items " + ((new Date())-s));
  gc();
}

// ~360ms
for(var j = 0; j < 10; j++) {
  s = new Date();
  var mv = m.mutable.thaw(m.vector());
  for(var i = 0; i < 10000000; i++) {
    mv = m.mutable.conj1(mv, i);
  }
  var v = m.mutable.freeze(mv);
  print("Mutable vector conj " + m.count(v) + " items " + ((new Date())-s));
  gc();
}

ES6 Map/Set inspired interfaces

All Mori maps and sets support all the non-mutating methods of the proposed ES6 Map and Set interfaces. The main difference with the spec is that key lookup is based on value not reference. keys, values, and entries methods return the proposed mutable iterators:

var m = mori;
var h = m.hash_map("foo", 1, "bar", 2);

h.has("foo"); // => true
h.get("foo"); // => 1

var iter = h.keys();
iter.next(); // => {done: false, value: "foo"}

This feature is subject to changes in the ES6 proposal.

Reducers

Mori includes the new Clojure reducers framework. Zero allocation collection operations FTW:

var m = mori;
var a = [];

for(var i = 0; i < 1000000; i++) {
  a.push(i);
}

// make it immutable
var v = m.into(m.vector(), a);

var mul3 = function(n) {
  return n*3;
}

function time(f) {
  var s = new Date();
  f();
  console.log(((new Date())-s)+"ms");
}

// 87ms 3.5ghz iMac recent V8 build
time(function() {
  m.reduce(m.sum, 0, m.rmap(m.inc, m.rmap(m.inc, m.rmap(m.inc, v))));
});

// 365ms
time(function() {
  a.map(m.inc).map(m.inc).map(m.inc).reduce(function(a,b){return a+b;}, 0);
})

Pipelines

mori.pipeline(mori.vector(1,2,3),
              function(v) { return mori.conj(v,4) },
              function(v) { return mori.drop(2, v) });

// => [3 4]

Currying

mori.pipeline(mori.vector(1,2,3),
              mori.curry(mori.conj, 4),
              mori.curry(mori.conj, 5));

// => [1 2 3 4 5]

Partial Application

mori.pipeline(mori.vector(1,2,3),
              mori.curry(mori.conj, 4),
              mori.partial(mori.drop, 2));

// => (3 4)

Function Composition

var second = mori.comp(mori.first, mori.rest);

second(mori.vector(1,2,3));
// => 2

Juxtaposition

var pos_and_neg = mori.juxt(mori.identity, function (v) { return -v; });
pos_and_neg(1);
// => [1 -1]

mori.knit(mori.inc, mori.dec)(pos_and_neg(1));
// => [2 -2]

Copyright (C) 2014 David Nolen and contributors

Distributed under the Eclipse Public License, the same as Clojure.