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Re: weird desktop.el change
From: |
Markus Triska |
Subject: |
Re: weird desktop.el change |
Date: |
Fri, 13 Apr 2007 19:02:07 +0200 |
Miles Bader <address@hidden> writes:
> The process of substituting "mapc" for "mapcar" when the result
> isn't used is not only a hugely widespread tweak in the lisp
> community (a "no brainer" as you might call it), indeed it's an
> obvious optimization for even a very stupid lisp compiler...
Available with this patch:
2007-04-13 Markus Triska <address@hidden>
* emacs-lisp/byte-opt.el (byte-optimize-form-code-walker): rewrite
`mapcar' to `mapc' when called for effect
Index: byte-opt.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/emacs-lisp/byte-opt.el,v
retrieving revision 1.94
diff -c -r1.94 byte-opt.el
*** byte-opt.el 11 Apr 2007 17:10:42 -0000 1.94
--- byte-opt.el 13 Apr 2007 16:48:08 -0000
***************
*** 408,413 ****
--- 408,418 ----
(prin1-to-string clause))
clause))
(cdr form))))
+ ((and for-effect (eq fn 'mapcar))
+ (when (/= (length form) 3)
+ (byte-compile-warn "wrong number of arguments for `mapcar'"))
+ (byte-compile-warn "`mapcar' called for effect; using `mapc'")
+ (byte-optimize-form (cons 'mapc (cdr form)) for-effect))
((eq fn 'progn)
;; as an extra added bonus, this simplifies (progn <x>) --> <x>
(if (cdr (cdr form))
- weird desktop.el change, Miles Bader, 2007/04/10
- Re: weird desktop.el change, Juanma Barranquero, 2007/04/10
- Re: weird desktop.el change, Miles Bader, 2007/04/10
- Re: weird desktop.el change, Chong Yidong, 2007/04/10
- Re: weird desktop.el change, Stephen J. Turnbull, 2007/04/11
- Re: weird desktop.el change, Richard Matthew Stallman, 2007/04/11
- Re: weird desktop.el change, Miles Bader, 2007/04/11
- Re: weird desktop.el change,
Markus Triska <=
- Re: weird desktop.el change, Stefan Monnier, 2007/04/13
- Re: weird desktop.el change, Markus Triska, 2007/04/13
- Re: weird desktop.el change, Richard Stallman, 2007/04/13
- Re: weird desktop.el change, Markus Triska, 2007/04/14
- Re: weird desktop.el change, Richard Stallman, 2007/04/15