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[PATCH] Implement letrec without backquote?

From: Tino Calancha
Subject: [PATCH] Implement letrec without backquote?
Date: Sat, 05 Nov 2016 02:39:00 +0900


i am sorry if this question results naive.
Is there any advantage on this patch?

*) I don't see significant differences neither in performance
   nor readability: in the patch, the macro expands to just
   one setq call.  Initially, i thought this could be an advantage,
   but after running some checks i don't see differences.

*) This patch doesn't use backquote, but as longer as `letrec' is
   not used in an early stage of the bootstrap this doesn't matter.

Thank you.

>From e11cb762efa4ab7e6ea9bdc755d95d4275c6b715 Mon Sep 17 00:00:00 2001
From: Tino Calancha <address@hidden>
Date: Sat, 5 Nov 2016 02:12:28 +0900
Subject: [PATCH] * lisp/subr.el (letrec):  Reimplement it without backquote

 lisp/subr.el | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lisp/subr.el b/lisp/subr.el
index fba43be..e667e85 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -1529,9 +1529,9 @@ letrec
   ;; As a special-form, we could implement it more efficiently (and cleanly,
   ;; making the vars actually unbound during evaluation of the binders).
   (declare (debug let) (indent 1))
-  `(let ,(mapcar #'car binders)
-     ,@(mapcar (lambda (binder) `(setq ,@binder)) binders)
-     ,@body))
+  (nconc (list 'let (mapcar #'car binders)
+               (apply #'append (cons '(setq) binders)))
+         body))
 (defmacro with-wrapper-hook (hook args &rest body)
   "Run BODY, using wrapper functions from HOOK with additional ARGS.

In GNU Emacs (x86_64-pc-linux-gnu, GTK+ Version 3.22.2)
 of 2016-11-03 built on calancha-pc
Repository revision: abe594c0990a4e6bc72b20b7ff06b4b0c01a682c

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