Re: Macros: Scheme vs Common Lisp

MS> Your example evaluates BAR at macro-definition time which surely MS> is not what you intended. (I.e., (foo) expands to 23, MS> regardless.) What I want is: MS> (setq 23) MS> (defmacro foo () 'bar) MS> (foo) => 23 MS> (let ((bar 42)) (foo)) => 23 [note: CL actually yields 42] MS> (setq bar 57) MS> (foo) => 57 MS> (let ((bar 42)) (foo)) => 57 [note: CL actually yields 42] Holger> But exactly this behaviour is what you get when you use Holger> (defmacro foo () bar) instead of (defmacro foo () 'bar): Holger> USER(2): (setq bar 23) Holger> 23 Holger> USER(9): (defmacro foo () bar) Holger> FOO Holger> USER(10): (foo) Holger> 23 Holger> USER(11): (let ((bar 42)) (foo)) Holger> 23 Holger> USER(12): (setq bar 57) Holger> 57 Holger> USER(13): (let ((bar 42)) (foo)) Holger> 57 Holger> USER(14): Another problem with this approach is that it breaks in the following case: (setq bar 23) (defmacro foo () bar) (defun baz () (foo)) (baz) => 23 (setq bar 42) (baz) => [still ...] 23 This makes obvious that the macro dereferences the binding too early. (Namely, at expansion time.) -- Cheers =8-} Chipsy Friede, Völkerverständigung und überhaupt blabla