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-rw-r--r--module/rnrs/base.scm39
1 files changed, 38 insertions, 1 deletions
diff --git a/module/rnrs/base.scm b/module/rnrs/base.scm
index 499a22444..9fedac01d 100644
--- a/module/rnrs/base.scm
+++ b/module/rnrs/base.scm
@@ -73,7 +73,7 @@
let-syntax letrec-syntax
syntax-rules identifier-syntax)
- (import (rename (except (guile) error raise map)
+ (import (rename (except (guile) error raise map string-for-each)
(log log-internal)
(euclidean-quotient div)
(euclidean-remainder mod)
@@ -86,6 +86,43 @@
(inexact->exact exact))
(srfi srfi-11))
+ (define string-for-each
+ (case-lambda
+ ((proc string)
+ (let ((end (string-length string)))
+ (let loop ((i 0))
+ (unless (= i end)
+ (proc (string-ref string i))
+ (loop (+ i 1))))))
+ ((proc string1 string2)
+ (let ((end1 (string-length string1))
+ (end2 (string-length string2)))
+ (unless (= end1 end2)
+ (assertion-violation 'string-for-each
+ "string arguments must all have the same length"
+ string1 string2))
+ (let loop ((i 0))
+ (unless (= i end1)
+ (proc (string-ref string1 i)
+ (string-ref string2 i))
+ (loop (+ i 1))))))
+ ((proc string . strings)
+ (let ((end (string-length string))
+ (ends (map string-length strings)))
+ (for-each (lambda (x)
+ (unless (= end x)
+ (apply assertion-violation
+ 'string-for-each
+ "string arguments must all have the same length"
+ string strings)))
+ ends)
+ (let loop ((i 0))
+ (unless (= i end)
+ (apply proc
+ (string-ref string i)
+ (map (lambda (s) (string-ref s i)) strings))
+ (loop (+ i 1))))))))
+
(define map
(case-lambda
((f l)