tweak Oleg's rev,list_equal

[lambda.git] / lambda_library.mdwn

diff --git a/lambda_library.mdwn b/lambda_library.mdwn
index 0c00c45..423ad59 100644 (file)
--- 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
        ; 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]
        ; 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))
        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))


@@ -331,7 +331,7 @@ let list_equal =
                 (\might_be_equal right_tail. and might_be_equal (isempty right_tail))
 
 ; most elegant
                 (\might_be_equal right_tail. and might_be_equal (isempty right_tail))
 
 ; most elegant

-let list_equal = \lst. lst (\hd sofar. \lst. and (and (not (isempty lst)) (eq hd (head lst))) (sofar (tail lst))) isempty
+let list_equal = \left. left (\hd sofar. \right. and (and (not (isempty right)) (eq hd (head right))) (sofar (tail right))) isempty

 
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