I'm a fan of Norvig's LOOP implementation from PAIP: http://www.norvig.com/paip/loop.lisp http://www.norvig.com/paip/loop.lisp It's missing some things from the

I'm a fan of Norvig's LOOP implementation from PAIP: http://www.norvig.com/paip/loop.lisp http://www.norvig.com/paip/loop.lisp It's missing some things from the full ANSI CL loop but it's just 223 code lines, and importantly not particularly clever code lines so that it serves as great instruction material for a method on how one could write one's own macro as complex as loop is.