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[PATCH] Fix and-let*.
From: |
Taylan Ulrich Bayırlı/Kammer |
Subject: |
[PATCH] Fix and-let*. |
Date: |
Fri, 02 Oct 2015 23:18:53 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Our and-let* wasn't entirely conformant to SRFI-2. It would return #t
for a variety of forms where it should return the last evaluated
expression's value instead.
Here's a patch. Is the copyright a problem?
>From e08e9a7e1048c8e0ad58e09585e4b6a071906db3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Taylan=20Ulrich=20Bay=C4=B1rl=C4=B1/Kammer?=
<address@hidden>
Date: Fri, 2 Oct 2015 22:56:04 +0200
Subject: [PATCH] Fix and-let*.
---
module/ice-9/and-let-star.scm | 50 ++++++++++++++++++++++++++++++++-----------
1 file changed, 38 insertions(+), 12 deletions(-)
diff --git a/module/ice-9/and-let-star.scm b/module/ice-9/and-let-star.scm
index ff15a7a..0c12f16 100644
--- a/module/ice-9/and-let-star.scm
+++ b/module/ice-9/and-let-star.scm
@@ -1,6 +1,7 @@
;;;; and-let-star.scm --- and-let* syntactic form (SRFI-2) for Guile
;;;;
;;;; Copyright (C) 1999, 2001, 2004, 2006, 2013 Free Software Foundation, Inc.
+;;;; Copyright (C) 2015 Taylan Ulrich Bayırlı/Kammer <address@hidden>
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
@@ -22,20 +23,45 @@
(define-syntax %and-let*
(lambda (form)
(syntax-case form ()
- ((_ orig-form ())
- #'#t)
- ((_ orig-form () body bodies ...)
- #'(begin body bodies ...))
- ((_ orig-form ((var exp) c ...) body ...)
+
+ ;; Handle zero-clauses special-case.
+ ((_ orig-form () . body)
+ #'(begin #t . body))
+
+ ;; Reduce clauses down to one regardless of body.
+ ((_ orig-form ((var expr) rest . rest*) . body)
+ (identifier? #'var)
+ #'(let ((var expr))
+ (and var (%and-let* (rest . rest*) . body))))
+ ((_ orig-form ((expr) rest . rest*) . body)
+ #'(and expr (%and-let* (rest . rest*) . body)))
+ ((_ orig-form (var rest . rest*) . body)
+ (identifier? #'var)
+ #'(and var (%and-let* (rest . rest*) . body)))
+
+ ;; Handle 1-clause cases without a body.
+ ((_ orig-form ((var expr)))
(identifier? #'var)
- #'(let ((var exp))
- (and var (%and-let* orig-form (c ...) body ...))))
- ((_ orig-form ((exp) c ...) body ...)
- #'(and exp (%and-let* orig-form (c ...) body ...)))
- ((_ orig-form (var c ...) body ...)
+ #'expr)
+ ((_ orig-form ((expr)))
+ #'expr)
+ ((_ orig-form (var))
(identifier? #'var)
- #'(and var (%and-let* orig-form (c ...) body ...)))
- ((_ orig-form (bad-clause c ...) body ...)
+ #'var)
+
+ ;; Handle 1-clause cases with a body.
+ ((_ orig-form ((var expr)) . body)
+ (identifier? #'var)
+ #'(let ((var expr))
+ (and var (begin . body))))
+ ((_ orig-form ((expr)) . body)
+ #'(and expr (begin . body)))
+ ((_ orig-form (var) . body)
+ (identifier? #'var)
+ #'(and var (begin . body)))
+
+ ;; Handle bad clauses.
+ ((_ orig-form (bad-clause . rest) . body)
(syntax-violation 'and-let* "Bad clause" #'orig-form #'bad-clause)))))
(define-syntax and-let*
--
2.5.0
- [PATCH] Fix and-let*.,
Taylan Ulrich Bayırlı/Kammer <=