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authorelioat <elioat@tilde.institute>2023-08-23 07:52:19 -0400
committerelioat <elioat@tilde.institute>2023-08-23 07:52:19 -0400
commit562a9a52d599d9a05f871404050968a5fd282640 (patch)
tree7d3305c1252c043bfe246ccc7deff0056aa6b5ab /js/games/nluqo.github.io/~bh/61a-pages/Lectures/3.2/prev5.scm
parent5d012c6c011a9dedf7d0a098e456206244eb5a0f (diff)
downloadtour-562a9a52d599d9a05f871404050968a5fd282640.tar.gz
*
Diffstat (limited to 'js/games/nluqo.github.io/~bh/61a-pages/Lectures/3.2/prev5.scm')
-rw-r--r--js/games/nluqo.github.io/~bh/61a-pages/Lectures/3.2/prev5.scm19
1 files changed, 19 insertions, 0 deletions
diff --git a/js/games/nluqo.github.io/~bh/61a-pages/Lectures/3.2/prev5.scm b/js/games/nluqo.github.io/~bh/61a-pages/Lectures/3.2/prev5.scm
new file mode 100644
index 0000000..b2a6c27
--- /dev/null
+++ b/js/games/nluqo.github.io/~bh/61a-pages/Lectures/3.2/prev5.scm
@@ -0,0 +1,19 @@
+(define make-previous
+  (let ((glob 'first-time))
+    (lambda ()
+      (let ((old 'first-time))
+	(lambda (msg)
+	  (cond ((eq? msg 'local)
+		 (lambda (arg)
+		   (let ((result old))
+		     (set! old arg)
+		     result)))
+		((eq? msg 'global)
+		 (lambda (arg)
+		   (let ((result glob))
+		     (set! glob arg)
+		     result)))
+		(else (error "No such method" msg)) ))))))
+
+
+