Dynamically generating functions with Coffeescript

translator.coffee

lines = -> Array::join.call arguments, '\n' # joins arguments into a newline separated string

# helper function, generates instructions to put base+index into D
load_from_base = (base) -> (idx) -> lines "@#{base}", "D=M", "@#{idx}", "A=D+A", "D=M"

push_segment = # returns instructions to load value to push into D given index
	constant: (idx) -> lines "@#{idx}" 'D=A'
	argument: load_from_base 'ARG'
	local: load_from_base 'LCL'
	this: load_from_base 'THIS'
	that: load_from_base 'THAT'
	temp: (idx) -> lines '@5', 'D=A', "@#{idx}", 'A=D+A', 'D=M'
	pointer: (idx) -> lines '@3', 'D=A', "@#{idx}", 'A=D+A', 'D=M'
	static: (idx) -> lines "@#{filename}.#{idx}", 'D=M'

translator.js

var lines, load_from_base, push_segment;
lines = function(){
  return Array.prototype.join.call(arguments, '\n');
};
load_from_base = function(base){
  return function(idx){
    return lines("@" + base, "D=M", "@" + idx, "A=D+A", "D=M");
  };
};
push_segment = {
  constant: function(idx){
    return lines("@" + idx, 'D=A');
  },
  argument: load_from_base('ARG'),
  local: load_from_base('LCL'),
  'this': load_from_base('THIS'),
  that: load_from_base('THAT'),
  temp: function(idx){
    return lines('@5', 'D=A', "@" + idx, 'A=D+A', 'D=M');
  },
  pointer: function(idx){
    return lines('@3', 'D=A', "@" + idx, 'A=D+A', 'D=M');
  },
  'static': function(idx){
    return lines("@" + filename + "." + idx, 'D=M');
  }
};