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authorLudovic Courtès <ludo@gnu.org>2020-06-17 17:33:28 +0200
committerLudovic Courtès <ludo@gnu.org>2020-06-17 17:33:28 +0200
commitcd4c747fb8cd6c65f18471aad54427d87b884ebc (patch)
tree08423f26595d6f1aa5e5ca44576e9930e15e243c /module/srfi/srfi-1.scm
parent0360843acee98f26598d8f77eda880a03ea3be93 (diff)
downloadguile-cd4c747fb8cd6c65f18471aad54427d87b884ebc.tar.gz
srfi-1: Rewrite 'find-tail' in Scheme.
* libguile/srfi-1.c (scm_srfi1_find_tail): Remove. * libguile/srfi-1.h (scm_srfi1_find_tail): Likewise. * module/srfi/srfi-1.scm (find-tail): New procedure.
Diffstat (limited to 'module/srfi/srfi-1.scm')
-rw-r--r--module/srfi/srfi-1.scm11
1 files changed, 11 insertions, 0 deletions
diff --git a/module/srfi/srfi-1.scm b/module/srfi/srfi-1.scm
index e5b28e777..1fc7a0e26 100644
--- a/module/srfi/srfi-1.scm
+++ b/module/srfi/srfi-1.scm
@@ -731,6 +731,17 @@ the list returned."
head
(loop (cdr lst)))))))
+(define (find-tail pred lst)
+ "Return the first pair of @var{lst} whose @sc{car} satisfies the
+predicate @var{pred}, or return @code{#f} if no such element is found."
+ (check-arg procedure? pred find)
+ (let loop ((lst lst))
+ (and (not (null? lst))
+ (let ((head (car lst)))
+ (if (pred head)
+ lst
+ (loop (cdr lst)))))))
+
(define (take-while pred ls)
"Return a new list which is the longest initial prefix of LS whose
elements all satisfy the predicate PRED."