Add #'constantly, as specified by ANSI Common Lisp. 2010-02-22 Aidan Kehoe <kehoea@parhasard.net> * cl-extra.el (constantly): Add this function, from ANSI Common Lisp, using the SBCL extension that extra arguments to it are passed back as multiple values in the constructed function. * cl-macs.el (constantly): In the compiler macro for #'constantly, construct a compiled-function object almost every time, at compile time when all arguments are constant, and at runtime when they vary.