Re: [parenscript-devel] Bug: &optional arguments stay undefined when they shouldn't

Daniel Gackle wrote:

PS' implementation of &optional function arguments breaks because of JS's weird short-circuiting. For example,

(ps (defun blah (&optional (x 0)) (return x))) => "function blah(x) { x = undefined === x && 0 || x; return x; };"

With this implementation, blah() is undefined when it should return 0.

You may have noticed this, but for passer-bys I'll note that the reason for this is actually a bit nuanced. You'll notice this only occurs when your default value for x is zero. Zero is false in JS, so 0 || x always returns x even if x is undefined.

Thanks for the report. I've pushed a fix for this that should be more robust to this type of thing.

Cheers,

-- Travis