Added (length)

[scheme.forth.jl.git] / scheme-library.scm

diff --git a/scheme-library.scm b/scheme-library.scm
index f95ed65..484f500 100644 (file)
--- a/scheme-library.scm
+++ b/scheme-library.scm
@@ -13,6 +13,14 @@
 (define (cddr l) (cdr (cdr l)))
 (define (cadar l) (car (cdr (car l))))
 
 (define (cddr l) (cdr (cdr l)))
 (define (cadar l) (car (cdr (car l))))
 

+; Return number of items in list
+(define (length l)
+  (define (iter a count)
+    (if (null? a)
+      count
+      (iter (cdr a) (+ count 1))))
+  (iter l 0))
+

 ; Join two lists together
 (define (join l1 l2)
   (if (null? l1)
 ; Join two lists together
 (define (join l1 l2)
   (if (null? l1)