X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme-library.scm;h=1a68a10d43a56e08ad417787677fe2629f3809d7;hb=fa6316fc696ddda325b2e2a8af83f4024ddf32bd;hp=b92795dfd03f29005d13aa3ac9eb57e5abadbfb3;hpb=050cc9a7e651ba8eacb054283307f4d06141c302;p=scheme.forth.jl.git

diff --git a/scheme-library.scm b/scheme-library.scm
index b92795d..1a68a10 100644
--- a/scheme-library.scm
+++ b/scheme-library.scm
@@ -29,11 +29,25 @@
 
 ;; LIBRARY FORMS
 
+(define-macro (while condition . body)
+              `(begin
+                 (define (loop)
+                   (if ,condition
+                     (begin ,@body (loop))))
+                 (loop)))
+
 ;; TESTING
 
 (define-macro (backwards . body)
               (cons 'begin (reverse body)))
 
+; Test for the while macro.
+(define (count)
+  (define counter 10)
+  (while (> counter 0)
+         (display counter) (newline)
+         (set! counter (- counter 1))))
+
 ; Basic iterative summation.  Run this on large numbers to
 ; test garbage collection and tail-call optimization.
 (define (sum n)