rf-

~/bin/src/coffee-script $ coffee -pe "thing[stuff()] ?= 5"
(function() {
  var _a, _b;
  thing[(_a = stuff())] = (typeof (_b = thing[(_a = stuff())]) !== "undefined" && _b !== null) ? thing[_a] : 5;
})();

should be

~/bin/src/coffee-script $ coffee -pe "thing[stuff()] ?= 5"
(function() {

rf-

~ $ cat > test.coffee
a: 3
b: 4
c: a + b


~ $ coffee -p test.coffee 
(function() {
  {
    a: 3,

rf-

~ $ coffee -pe "a: 3"
(function() {
  {
    a: 3
  };
})();

rf-

~/bin/src/node $ coffee -pe "i in [0..10]"
(function() {
  var _a, _b, _c, _d, _e;
  !!(function(){ for (var _d=0, _e=(_a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]).length; _d<_e; _d++) if (_a[_d] === i) return true; }).call(this);
})();

rf-

~/bin/src/node $ coffee -pe "x: [0..10]"
(function() {
  var _a, _b;
  {
    x: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
  };
})();