Fixes <http://bugs.gnu.org/17147>
* module/ice-9/boot-9.scm (and, or): Add syntax rules that only do one
pattern matching operation per and/or rather than per argument.
Signed-off-by: David Kastrup <d...@gnu.org>
---
module/ice-9/boot-9.scm | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/module/ice-9/boot-9.scm b/module/ice-9/boot-9.scm
index 7f38c4b..d2f34d9 100644
--- a/module/ice-9/boot-9.scm
+++ b/module/ice-9/boot-9.scm
@@ -426,6 +426,8 @@ file with the given name already exists, the effect is
unspecified."
;; The binding for `macroexpand' has now been overridden, making psyntax the
;; expander now.
+;; quasisyntax requires simple definitions of and/or for bootstrapping.
+
(define-syntax and
(syntax-rules ()
((_) #t)
@@ -440,6 +442,30 @@ file with the given name already exists, the effect is
unspecified."
(include-from-path "ice-9/quasisyntax")
+;; Don't use syntactically recursive definitions of and/or for speed
+;; reasons as they need to match the whole argument list for each
+;; iteration.
+
+(define-syntax and
+ (lambda (expr)
+ (syntax-case expr ()
+ ((_) #'#t)
+ ((_ x y ...)
+ (let loop ((x #'x) (y #'(y ...)))
+ (if (null? y)
+ x
+ #`(if #,x #,(loop (car y) (cdr y)) #f)))))))
+
+(define-syntax or
+ (lambda (expr)
+ (syntax-case expr ()
+ ((_) #'#f)
+ ((_ x y ...)
+ (let loop ((x #'x) (y #'(y ...)))
+ (if (null? y)
+ x
+ #`(let ((t #,x)) (if t t #,(loop (car y) (cdr y))))))))))
+
(define-syntax-rule (when test stmt stmt* ...)
(if test (begin stmt stmt* ...)))
--
1.9.1
