Er, what?<p>OS X is Clozure&#x27;s home platform and in my experience where it works best. The project has all those Cocoa bindings and grew out of Macintosh Common Lisp; it&#x27;s definitely an OS X friendly Common Lisp.<p>CMUCL is...if not precisely <i>dead</i>, certainly moribund. It&#x27;s been ported all over the place and the OS X port is certainly credible, but I wouldn&#x27;t call it a first class Common Lisp for the Mac platform.