GNU bug report logs - #16936
24.3; lexical-let does not take function arguments into account when creating closures

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jordon Biondo <jordonbiondo <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.3; lexical-let does not take function arguments into account when
 creating closures
Date: Tue, 4 Mar 2014 11:54:24 -0500

[Message part 1 (text/plain, inline)]

;; here is code to test by, description in comments
(require 'cl)

;; lexical let is supposed to use fake lexical binding
;; to imitate closure behavior in CL
;; so, this in emacs lisp:
(apply (lexical-let ((x 3) (y 4))
    (lambda (x) (+ x y))) '(1)) ;; in EL returns 7

;; should behave like this in CL
(apply (let ((x 3) (y 4))
 (lambda (x) (+ x y))) '(1)) ;; in CL returns 5 (SBCL)

;; however in emacs lisp, the lambda arg x is forgetton and
;; the lexical-let bound x is used in the lambda, not the arg.

I assume this is not the desired behavior.


In GNU Emacs 24.3.1 (i386-mingw-nt6.2.9200)
 of 2013-03-17 on MARVIN
Windowing system distributor `Microsoft Corp.', version 6.2.9200
Configured using:
 `configure --with-gcc (4.7) --cflags
 -ID:/devel/emacs/libs/libXpm-3.5.8/include
 -ID:/devel/emacs/libs/libXpm-3.5.8/src
 -ID:/devel/emacs/libs/libpng-dev_1.4.3-1/include
 -ID:/devel/emacs/libs/zlib-dev_1.2.5-2/include
 -ID:/devel/emacs/libs/giflib-4.1.4-1/include
 -ID:/devel/emacs/libs/jpeg-6b-4/include
 -ID:/devel/emacs/libs/tiff-3.8.2-1/include
 -ID:/devel/emacs/libs/gnutls-3.0.9/include
 -ID:/devel/emacs/libs/libiconv-1.13.1-1-dev/include
 -ID:/devel/emacs/libs/libxml2-2.7.8/include/libxml2'

Important settings:
  value of $LANG: ENU
  locale-coding-system: cp1252
  default enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
d SPC b a h a <backspace> <backspace> <backspace> e
h a v e SPC l i k e SPC t h i s SPC i n SPC C : <backspace>
l <backspace> L C-n C-n C-e <return> <return> ; ; SPC
h o w e v e r SPC i n SPC e m a c s SPC l i s p , SPC
t h e SPC l a m b d a SPC a r e <backspace> g SPC x
SPC i s SPC f o r g e t t o n SPC a n d <return> <tab>
; ; SPC t h e SPC l e x i c a l - l e t SPC b o u n
d SPC x SPC i s SPC u s e d SPC i n SPC t h e SPC l
a m b d a . C-p C-p C-e C-p C-e SPC ; ; SPC i n SPC
C L S-SPC r e t u r n s SPC 5 C-p C-p C-p C-p C-p C-n
C-e SPC ; ; SPC i n SPC E L SPC r e t u r n s SPC 7
C-p C-p C-p C-p C-n C-n C-n C-n C-n C-n C-n C-n C-n
C-n C-n C-n C-p C-e <backspace> SPC n o t SPC t h e
SPC a r g . C-b C-b C-b C-b C-b C-b C-b C-b C-b C-b
C-b C-b C-b , C-e M-x C-g C-p C-p C-p C-e SPC ( S B
C L ) C-n C-n C-n C-n C-e M-x e m a c s - b u <tab>
<tab> <backspace> <backspace> r e <tab> <tab> <tab>
<backspace> <backspace> <tab> <tab> <tab> C-a C-k r
e p o <tab> <tab> r <tab> <return>

Recent messages:
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[Message part 2 (text/html, inline)]

Message #8 received at 16936 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Jordon Biondo <jordonbiondo <at> gmail.com>
Cc: 16936 <at> debbugs.gnu.org
Subject: Re: bug#16936: 24.3;
 lexical-let does not take function arguments into account when
 creating closures
Date: Fri, 07 Mar 2014 17:26:06 -0500

> I assume this is not the desired behavior.

Indeed.  If you use `lexical-binding' instead of `lexical-let' you won't
suffer from those problems.

`lexical-let' is on the way to deprecation and the problem you describe
has affected `lexical-let' "for ever", so I don't think anyone will
care to fix it.


        Stefan

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