All that’s great about CoffeeScript in 40 characters

OP's example in coffeescript:

  Array::compact = -> x for x in @ when x?

In es6:

  Array.prototype.compact = function() {
    return this.filter(x => x !== null);
  }

I find it easier to read than OP's example, but I would like to see non-lexically bound this function shorthand in es6/7. I see a mention of it at the bottom of this spec[1], but not sure what they mean by "Initializer opt". Maybe like this:

  Array.prototype.compact = this => this.filter(x => x !== null)

[1] http://tc39wiki.calculist.org/es6/arrow-functions/

Sure, that is a nice one liner, but the reason that JavaScript code is so ugly is because it's what the CoffeeScript function compiled to.

Array.prototype.compact = function( list) { for ( var i = list.length; i >= 0; i--) { if ( list[ i ] == null) results.splice( i, 1); }

Ah yes the argument by neat one-liner.

Now let's move on to the truly relevant and constructive activity: comparing which language has best-looking toy quicksort implementation