add repeat

3 files changed, 31 insertions, 1 deletions

diff --git a/mew.scm b/mew.scm
index f170273..7de52f0 100644
--- a/mew.scm
+++ b/mew.scm
@@ -17,7 +17,7 @@
      negate nth-accumulator
      odometer one-of op op*
      per pop! prn proj push! puts
-     rand range rep
+     rand range rep repeat
      sample scan scan-right sing? search seq set set-at sgn
      shuffle shuffle! str slurp
      tally-accumulator tbl time
@@ -46,6 +46,7 @@
           (chicken random)
           (chicken repl)
           (chicken syntax)
+          utf8-srfi-13
           srfi-17
           (rename (srfi-69)
              (hash-table-keys keys)
@@ -1280,6 +1281,20 @@
            (list knil)
            lists))
 
+  (define (repeat o n)
+    (cond ((list? o) (concatenate (make-list n o)))
+          ((vector? o) (let* ((l (vector-length o))
+                              (size (* l n))
+                              (v (make-vector size)))
+                         (let loop ((i 0))
+                           (when (< i size)
+                             (vector-set! v i (vector-ref o (mod i l)))
+                             (loop (+ i 1))))
+                         v))
+          ((string? o) (string-concatenate (repeat (list o) n)))
+          ((char? o) (make-string n o))
+          (#t (error "no repeat defined"))))
+
   (let ((old-repl-prompt (repl-prompt)))
     (repl-prompt (lambda ()
                    (let ((old-prompt (old-repl-prompt)))
diff --git a/mew.svnwiki b/mew.svnwiki
index 92ed78d..dce8f34 100644
--- a/mew.svnwiki
+++ b/mew.svnwiki
@@ -422,6 +422,10 @@ in the sequence {{<haystack>}},
 starting no earlier than {{<offset>>}} (default: 0).
 Returns false if the sequence cannot be found.
 
+<procedure>(repeat <val> <n>)</procedure>
+
+Repeat the list/vector/string/char {{<val>}} {{<n>}} times.
+
 
 == Generators and Accumulators
 
diff --git a/tests/test.mew b/tests/test.mew
index d2eacbd..96f0764 100644
--- a/tests/test.mew
+++ b/tests/test.mew
@@ -718,3 +718,14 @@
   (test 42 (imp #t #t #t 42))
   (test 42 (imp 39 40 41 42))
   (test #t (imp 39 #f 41 42)))
+
+(test-group "repeat"
+  (test '(1 2 3 1 2 3 1 2 3 1 2 3) (repeat '(1 2 3) 4))
+  (test #(1 2 3 1 2 3 1 2 3 1 2 3) (repeat #(1 2 3) 4))
+  (test "123123123123" (repeat "123" 4))
+  (test "xxxx" (repeat #\x 4))
+
+  (test '() (repeat '(1 2 3) 0))
+  (test #() (repeat #(1 2 3) 0))
+  (test "" (repeat "123" 0))
+  (test "" (repeat #\x 0)))