Define helper intercalate.

1 files changed, 12 insertions, 2 deletions

diff --git a/list.csc b/list.csc
index c4bc013..799b070 100644
--- a/list.csc
+++ b/list.csc
@@ -1,9 +1,12 @@
 (define-library (csc list)
   (export
+    intercalate
     revappend
     split-at
     take)
-  (import (scheme base))
+  (import (scheme base)
+          (only (csc match)
+            match))
   (begin
 
 
@@ -30,4 +33,11 @@
                  (acc b))
         (if (null? xs)
             acc
-          (loop (cdr xs) (cons (car xs) acc)))))))
+          (loop (cdr xs) (cons (car xs) acc)))))
+
+
+    (define (intercalate x l)
+      (match l
+        ('() '())
+        ((_) l)
+        ((head . tail) (cons head (cons x (intercalate x tail))))))))