I'm glad to see the tighter code being generated for keyword arguments, but I'm afraid there's a problem. If a default value is provided, it is now being evaluated whether it's needed or not: (defun blah (&key (param (long-running-computation))) (foo param)) => function blah() { var param = longRunningComputation(); var _js10 = arguments.length; // ... return foo(param); }; Compare this to: (defun blah (&optional (param (long-running-computation))) (foo param)) => function blah(param) { if (param === undefined) { param = longRunningComputation(); }; return foo(param); }; I think the above keyword behavior is incorrect and the optionals have it right. Yet I like the fact that all the sludge of the "if variable remains undefined after sucking out the optional arguments then set it to null" sort has been removed. Is there a compromise? For example, could we do it the simpler way where the default value is a constant? Daniel