X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=scheme.forth.jl.git;a=blobdiff_plain;f=scheme-library.scm;h=aad91f426c85c5c250e59adb22b65470163dec7a;hp=ffe02ea14b441741b8b4b90a98dc6f01a40e4e30;hb=749dd8439730c404058c7a672252ab19967268ac;hpb=1d07170e70db6f42a900ea918ac22cce65345f2f

diff --git a/scheme-library.scm b/scheme-library.scm
index ffe02ea..aad91f4 100644
--- a/scheme-library.scm
+++ b/scheme-library.scm
@@ -87,6 +87,35 @@
                 (error "cond requires at least one clause.")
                 (expand-clauses clauses)))
 
+; and
+
+(define (expand-and-expressions expressions)
+  (if (null? expressions)
+    #t
+    (let ((first (car expressions))
+          (rest (cdr expressions)))
+      `(if ,first
+         ,(expand-and-expressions rest)
+         #f))))
+
+(define-macro (and . expressions)
+              (expand-and-expressions expressions))
+
+; or
+
+(define (expand-or-expressions expressions)
+  (if (null? expressions)
+    #f
+    (let ((first (car expressions))
+          (rest (cdr expressions)))
+      `(if ,first
+         #t
+         ,(expand-or-expressions rest)))))
+
+(define-macro (or . expressions)
+              (expand-or-expressions expressions))
+
+
 ;; TESTING
 
 (define-macro (backwards . body)