Re: Macros: Scheme vs Common Lisp

MS> Can you explain to me why the above should lead to a different MS> result? CLISP's output is exactly what I expected it to be: MS>(setq bar 23) MS>(defmacro foo () bar) ; this means (foo) expands to the value of BAR Isn't this meant to mean to refer to the current binding of bar, which in this case happens to be 23 ? MS>(defun baz () (foo)) ; this therefore expands to (defun baz () 23) MS>(baz) => 23 ; indeed MS>(setq baz 42) ; the definition of FOO is unchanged (I guess you mean bar, not baz). You are right, the definition of FOO is unchanged, it still refers to the current binding of bar - which now happens to be 42. MS>(foo) => 23 ; presto Hence, (foo) should give 42. USER(29): (setq gee 23) 23 USER(30): (let ((gee 42)) (defmacro fun () gee)) FUN USER(31): (fun) 42 USER(32): gee 23 USER(37): (let ((gee 42)) (defmacro fun2 () gee) (setq gee 57) (fun2)) 57 MS> I have to admit, though, that this thread is furthering my MS> conviction that using CL macros right is something fairly MS> difficult :-) Didn't I say this right from the start ? ;-) However, it also furthers my conviction that refering to non-special, non-local variables should best be avoided (this applies of course to CL-macros. But I am still not convinced that this is a useful construct in general, anyway. Disclaimer: YMMV). Holger -- --- http://www.coling.uni-freiburg.de/~schauer --- ">grep schauer passwd "Das ist nur eine Shell. Bedenklich waere, wenn Dein LILO /vmunix.el bootet." -- Kristian und Holger in de.comp.os.linux.misc