mori

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

Getting it

You can download the latest prebuilt version of Mori from the downloads tab.

It's also available for Node.js via npm:

npm install mori

Caveats

Pre-pre-pre alpha. ClojureScript is constantly being improved, especially in terms of performance. That said, it's probably still already useful.

Build

Make a folder in the repo folder called checkouts, clone the ClojureScript repo into it.

Install Leiningen.

Grab dependencies:

lein deps

On a UNIX-like system build with:

./scripts/build.sh

On Windows:

./scripts/build.ps1

This will produce a file mori.js. You can include this like any other JavaScript library.

Note: If you are using leiningen 2, use this for your project.clj

(defproject mori "0.1.0-SNAPSHOT"
  :description "Persistent Data Structures for JavaScript"
  :dependencies [[org.clojure/clojure "1.4.0"]]
  :profiles {:dev 
             {:source-paths 
              ["comp/clojurescript/src/clj"   
               "comp/clojurescript/src/cljs"]}}
  :cljsbuild {:builds {:tmp {:source-path "src"
                             :compiler {:optimizations :advanced
                                        :output-to "tmp.js"}}}})

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

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");
}

// 513ms
time(function() {
  m.reduce(m.sum, 0, m.rmap(m.inc, m.rfilter(m.is_even, m.rmap(mul3, v))));
});

// 254ms
time(function() {
  a.map(mul3).filter(m.is_even).map(m.inc).reduce(m.sum);
})

// impressive given the level of abstraction
// expect us to get more competitive :D

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) 2012 David Nolen and contributors

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