Import Upstream version 3a1upstream/3a1

1 files changed, 9 insertions, 6 deletions

diff --git a/promise.scm b/promise.scm
index f38aebf..44ffea1 100644
--- a/promise.scm
+++ b/promise.scm
@@ -1,5 +1,5 @@
 ;;;"promise.scm" promise for force and delay
-;;; From Revised^4 Report on the Algorithmic Language Scheme
+;;; From Revised^5 Report on the Algorithmic Language Scheme
 ;;; Editors: William Clinger and Jonathon Rees
 ;
 ; We intend this report to belong to the entire Scheme community, and so
@@ -7,9 +7,9 @@
 ; particular, we encourage implementors of Scheme to use this report as
 ; a starting point for manuals and other documentation, modifying it as
 ; necessary.
-
-(define promise:force (lambda (object) (object)))
-
+;@
+(define force (lambda (object) (object)))
+;@
 (define make-promise
   (lambda (proc)
     (let ((result-ready? #f)
@@ -23,7 +23,10 @@
 		  (begin (set! result-ready? #t)
 			 (set! result x)
 			 result))))))))
-
 ;;; change occurences of (DELAY <expression>) to
 ;;; (MAKE-PROMISE (LAMBDA () <expression>))
-;;; and (define force promise:force)
+;@
+(define-syntax delay
+  (syntax-rules ()
+    ((delay expression)
+     (make-promise (lambda () expression)))))