Re: Macros: Scheme vs Common Lisp

From: sperber(a)informatik.uni-tuebingen.de (Michael Sperber [Mr. Preprocessor]) Date: 24 Aug 1998 11:14:43 +0200 No. I think the problem is that many C and Common Lisp programmers confuse the concepts of "binding" and "assignment." In my experience this is far more common among C programmers than CL programmers. . . . and in Common Lisp, assignment (via setq) may create the binding if it doesn't exist yet. Thus, in your example, (setq bar 23) Of course, many consider this sloppy. CMUCL issues a warning at this point. What I want is: (setq 23) (defmacro foo () 'bar) (foo) => 23 (let ((bar 42)) (foo)) => 23 [note: CL actually yields 42] (setq bar 57) (foo) => 57 (let ((bar 42)) (foo)) => 57 [note: CL actually yields 42] For what it's worth, CMUCL gives the values that you want, assuming that you meant (setq bar 23) as the first form rather than (setq 23). Rick CMU Common Lisp 18a x86-linux 1.4.0 cvs, running on germs Send bug reports and questions to cmucl-bugs(a)cs.cmu.edu. Loaded subsystems: Python 1.0, target Intel x86 CLOS based on PCL version: September 16 92 PCL (f) * * (setq bar 23) Warning: Declaring Bar special. 23 * (defmacro foo () bar) Foo * (foo) 23 * (let ((bar 42)) (foo)) 23 * (setq bar 57) 57 * (foo) 57 * (let ((bar 42)) (foo)) 57 * (quit) done. Mapping 5021696 bytes at 0x1000000. Mapping 7991296 bytes at 0x5000000.