X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme-library.scm;h=62a7aa3513148f2bb39eaed311f2d7fb2d0297c4;hb=82b93d081309895fe1a8e446daad5b8a75896fa3;hp=207bb30062fe236189c9b49b402462b934af5255;hpb=480095585b96fbcc5a4fb58fb57188609aadb6e5;p=scheme.forth.jl.git

diff --git a/scheme-library.scm b/scheme-library.scm
index 207bb30..62a7aa3 100644
--- a/scheme-library.scm
+++ b/scheme-library.scm
@@ -21,13 +21,36 @@
       (car lists)
       (join (car lists) (apply append (cdr lists))))))
 
+; Reverse the contents of a list
+(define (reverse l)
+  (if (null? l)
+    ()
+    (append (reverse (cdr l)) (list (car l)))))
 
 ;; LIBRARY FORMS
-(define-macro (let value . body )
-              (list (list 'lambda (list (car value)) body)) (cdr value))
+
+(define-macro (while condition . body)
+              `(begin
+                 (define (loop)
+                   (if ,condition
+                     (begin ,@body (loop))))
+                 (loop)))
 
 ;; TESTING
 
+(define-macro (backwards . body)
+              (cons 'begin (reverse body)))
+
+(define method '(while (> counter 0)
+                       (display counter) (newline)
+                       (set! counter (- counter 1))))
+
+(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)