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var sharpLabels = ["A", "A♯", "B", "C", "C♯", "D", "D♯", "E", "F", "F♯", "G", "G♯"];
var flatLabels = ["A", "B♭", "B", "C", "D♭", "D", "E♭", "E", "F", "G♭", "G", "A♭"];

function pitchClass(freq_Hz, labels) {
    var cents = Math.round(1200 * Math.log(freq_Hz/440) / Math.log(2));
    var semitones = Math.round(cents / 100);

    var pclass = (((semitones % 12) + 12) % 12);
    var octave = 4 + Math.floor(semitones / 12);

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Basics

• Elm code is written as expressions. The end goal of an Elm programm is to specify a main expression which will be a Signal of Html values.
• Line comments in Elm are marked using -- and are equivalent to // in JS.
• Block comments in Elm are marked using {- and -} which are equivalent to /* and */ in JS.

Modules

module ModuleName where

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function makeBigObject() {
    var big = new Float64Array(10000000); // Allocate big object.
    return {
        one: function () { return big.length; }, // Has ref to big object.
        two: function () { return "hello"; } // Doesn't have ref to big object.
    };
}

function leak() {
    var l = makeBigObject();   // l has ref to big object via "one".

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module StartAppAutomaton where

import Graphics.Element exposing (..)
import Window
import Time
import Automaton as Auto

dt = Time.fps 60

type alias Model = {count : Int}

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module VirtualDomFailure where

import Window
import Time
import Html exposing (..)
import Html.Attributes exposing (..)
import Graphics.Element exposing (..)
import Signal exposing (..)

googleLogo = "https://www.google.co.in/images/srpr/logo11w.png"

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// The problem is to write sum() such that it produces the following output -
// console.log(sum(2,3)); // Produces 5
// console.log(sum(2)(3)); // Produces 5

function sum() {
    var s = Array.prototype.reduce.call(arguments, function (x, y) { return x + y; }, 0);
    var f = function () {
        var a = Array.prototype.slice.call(arguments);
        a.push(s);
        return sum.apply(null, a);

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function stddev(values) {
  return Math.sqrt(mean(values.map(square)) - square(mean(values)));
}

function mean(values) {
  return values.reduce(add, 0) / values.length;
}

function add(x, y) {
  return x + y;

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// Here is a possible pure-functional implementation of stateful signals.

function makeSound(signal, currState, result, endCondition) {
    return endCondition(currState) ?  reverse(result, null) : signal(currState, function (nextState, val) {
        return makeSound(signal, nextState, pair(val, result), endCondition);
    });
}

// A simple implementation of pair
function pair(val, list) {

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// Takes a file produced by sweet.js and minimally renames
// all the identifiers that have been hygienified by the macro
// expansion. Run using -
//    node /path/to/rename_sweet.js file1.js > fileout.js
var fs = require('fs');

var code = fs.readFileSync(process.argv[2], 'utf8');

var idRE = /[A-Za-z_][A-Za-z0-9_\$]*/g;

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// (Syntax) -> String
function resolveCtx(originalName, ctx, stop_spine, stop_branch) {
    if (ctx instanceof Mark) {
        return resolveCtx(originalName, ctx.context, stop_spine, stop_branch);
    }
    if (ctx instanceof Def) {
        if (stop_spine.indexOf(ctx.defctx) !== -1) {
            return resolveCtx(originalName, ctx.context, stop_spine, stop_branch);
        }
        return resolveCtx(originalName, renames(ctx.defctx, ctx.context, originalName), stop_spine, unionEl(stop_branch, ctx.defctx));