base: New `until' macro does the obvious thing.

[lisp] / mdw-base.lisp

diff --git a/mdw-base.lisp b/mdw-base.lisp
index 37a30684330953cea4daaa00702f2fb116be4e32..e87c51191ab1e155c07758839b8b1c9ba26c7efc 100644 (file)
--- a/mdw-base.lisp
+++ b/mdw-base.lisp
@@ -33,7 +33,7 @@ (defpackage #:mdw.base
           #:stringify #:mappend #:listify #:fix-pair #:pairify #:parse-body
           #:whitespace-char-p
           #:slot-uninitialized
           #:stringify #:mappend #:listify #:fix-pair #:pairify #:parse-body
           #:whitespace-char-p
           #:slot-uninitialized

-          #:nlet #:while #:case2 #:ecase2
+          #:nlet #:while #:until #:case2 #:ecase2

           #:with-gensyms #:let*/gensyms #:with-places
           #:locp #:locf #:ref #:with-locatives
           #:update-place #:update-place-after
           #:with-gensyms #:let*/gensyms #:with-places
           #:locp #:locf #:ref #:with-locatives
           #:update-place #:update-place-after


@@ -189,9 +189,11 @@ (defmacro nlet (name binds &body body)
 
 (defmacro while (cond &body body)
   "If COND is false, evaluate to nil; otherwise evaluate BODY and try again."
 
 (defmacro while (cond &body body)
   "If COND is false, evaluate to nil; otherwise evaluate BODY and try again."

-  `(loop
-     (unless ,cond (return))
-     ,@body))
+  `(loop (unless ,cond (return)) (progn ,@body)))
+
+(defmacro until (cond &body body)
+  "If COND is true, evaluate to nil; otherwise evaluate BODY and try again."
+  `(loop (when ,cond (return)) (progn ,@body)))

 
 (compile-time-defun do-case2-like (kind vform clauses)
   "Helper function for `case2' and `ecase2'."
 
 (compile-time-defun do-case2-like (kind vform clauses)
   "Helper function for `case2' and `ecase2'."