X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=lambda_library.mdwn;h=423ad596c0d342875fe370f23df095bff93cc88c;hp=579668bed6323e3a976b8a70d599f537a82fbcca;hb=35ab33cfa5ca8a4460068037b52fa088783d09df;hpb=8ef02c87c6608f870322ca38033c372b50890ef2

diff --git a/lambda_library.mdwn b/lambda_library.mdwn
index 579668be..423ad596 100644
--- a/lambda_library.mdwn
+++ b/lambda_library.mdwn
@@ -65,9 +65,9 @@ and all sorts of other places. Others of them are our own handiwork.
 	; more efficient reverse builds a left-fold instead
 	; make_left_list a (make_left_list b (make_left_list c empty)) ~~> \f z. f c (f b (f a z))
 	let reverse = (\make_left_list lst. lst make_left_list empty) (\h t f z. t f (f h z))  in
-	; most elegant
+	; from Oleg, of course it's the most elegant
 	; revappend [a;b;c] [x;y] ~~> [c;b;a;x;y]
-	let revappend = \lst. lst (\hd sofar. \lst. sofar (make_list hd lst)) I  in
+	let revappend = \left. left (\hd sofar. \right. sofar (make_list hd right)) I  in
 	let rev = \lst. revappend lst empty  in
 	; zip [a;b;c] [x;y;z] ~~> [(a,x);(b,y);(c,z)]
 	let zip = \left right. (\base build. reverse left build base (\x y. reverse x))
@@ -329,5 +329,9 @@ let list_equal =
                 )
                 ; when fold is finished, check sofar-pair
                 (\might_be_equal right_tail. and might_be_equal (isempty right_tail))
+
+; most elegant
+let list_equal = \left. left (\hd sofar. \right. and (and (not (isempty right)) (eq hd (head right))) (sofar (tail right))) isempty
+
 -->