140byt.es -- Functional programming: map a function to arguments

README.md

140byt.es

A tweet-sized, fork-to-play, community-curated collection of JavaScript.

How to play

1. Click the button above to fork this gist.
2. Modify all the files to according to the rules below.
3. Save your entry and tweet it up!

Rules

All entries must exist in an index.js file, whose contents are

1. a valid Javascript function expression, that
2. optionally self-executes,
3. contains no more than 140 bytes, and
4. does not pollute global scope.

All entries must also be licensed under the MIT license.

For more information

The 140byt.es site hasn't launched yet, but for now follow @140bytes on Twitter.

To learn about byte-saving hacks for your own code, or to contribute what you've learned, head to the wiki.

140byt.es is brought to you by Jed Schmidt. It was inspired by work from Thomas Fuchs and Dustin Diaz.

annotated.js

/* Functional map - constructs a new array by calling a function with each argument
 *
 * Usage:
 * map(fn, array)
 * map(fn, object)
 * map(fn, arg1, arg2, argn)
 *
 * Always returns an array
 */
var map =
function(){
    var r=[],
        e,                          // used for attribute names
        a=r.slice.call(arguments),  // r is shorter than Array.prototype
        f=a.shift();                // get the function
    if(a.length<2&&a[0]){a=a[0];}   // if(t==='object'||t==='string'){a=a[0];} would be cleaner but longer
    for(e in a){
        r.push(f.call(null,a[e]));  // construct the result array by applying the function iteratively
    }
    return r;
};

index.js

function(){var r=[],e,a=r.slice.call(arguments),f=a.shift();if(a.length<2&&a[0]){a=a[0];}for(e in a){r.push(f.call(null,a[e]));}return r;};

LICENSE.txt

Copyright (c) 2011 Peter Hillerström, http://peter.vasb.fi/
 
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
 
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

package.json

{
  // [REQUIRED] A name for your library.
  // This must match /^[a-z_]\w*$/i
  "name": "140bytes-peterhil-map",

  // [OPTIONAL] A description of your library, phrased as a verb predicate.
  // The gist description is used by default.
  "description": "Functional map - constructs a new array by calling a function with each argument.",

  // [OPTIONAL] Up to 5 keywords used for indexing.
  "keywords": [
    "140bytes",
    "functional",
    "map"
  ]
}

This works with string too – a simple ROT-13:
map(String.fromCharCode, map(function(c){return (c.toUpperCase().charCodeAt(0)+13-65)%26+65}, "HELLO World!"))
-> ["U", "R", "Y", "Y", "B", "-", "J", "B", "E", "Y", "Q", "."]