Hrvoje> sperber(a)Informatik.Uni-Tuebingen.De (Michael Sperber [Mr. Preprocessor]) writes: Hrvoje> It has been discussed multiple times in the past. In fact, it would Hrvoje> have already been done if the fate hadn't transpired against Chuck and Hrvoje> Ben working on XEmacs. Hrvoje> Can you explain what you mean by incompatible? Old code will obviously not run under the new Elisp engine, because it may intrinsically use dynamic binding for non-DEFVAR'ed names. New code will not run under the old engine because that does not support static binding, even if it syntactically is totally acceptable to the old engine. Also, the Elisp compiler does not reliably detect which variables should be DEFVAR'ed which aren't already. Consider the following program fragment which has different semantics depending on the interpretation of LET: (defun f (g) (let ((x 2)) (funcall g))) (let ((x 1)) (f #'(lambda () x))) ... and watch what sort of (bogus) message the compiler produces. -- Cheers =8-} Chipsy Friede, Völkerverständigung und überhaupt blabla