Subject: lambda list in MULTIPLE-VALUE-BIND? From: Erik Naggum <firstname.lastname@example.org> Date: 1998/03/07 Newsgroups: comp.lang.lisp Message-ID: <email@example.com> lately, I have been annoyed by a what I think is a limitation in the usability of multiple values. in particular, I need to know whether I got a NIL back as a value or didn't get anything. MULTIPLE-VALUE-BIND is insufficient in keeping track of the number of values involed. in my view, it is as much an error for a function to return too few or too many values as it was to pass it the wrong number of arguments -- when those values are actually needed. now I wonder -- why was MULTIPLE-VALUE-BIND defined so simplistically? with just a list of symbols to be bound, it sort of defeats the purpose of a variable number of returned values, doesn't it? I can obtain the desired behavior with either of these macros (except that MULTIPLE-VALUE-DESTRUCTURING-BIND is a bad name): (defmacro multiple-value-destructuring-bind (lambda-list value-form &body body) `(destructuring-bind ,lambda-list (multiple-value-list ,value-form) ,@body)) (defmacro multiple-value-destructuring-bind (lambda-list value-form &body body) `(multiple-value-call (lambda ,lambda-list ,@body) ,value-form)) these are fairly expensive when the function receiving multiple values from some other function _already_ knows how many values it receives and could signal an error when the number doesn't match expectations. is there a better way to check the number of returned values than with MULTIPLE-VALUE-CALL, or is that the only special operator of consequence? #:Erik -- God grant me serenity to accept the code I cannot change, courage to change the code I can, and wisdom to know the difference.