From: Chris Barker <barker@omega.(none)>
Date: Tue, 7 Dec 2010 13:11:55 +0000 (-0500)
Subject: edits
X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=2cf860e245af53cbd58f88575f6f9f3a9884be40

edits
---

diff --git a/using_continuations_to_solve_same_fringe.mdwn b/using_continuations_to_solve_same_fringe.mdwn
index b65add60..1c980a4b 100644
--- a/using_continuations_to_solve_same_fringe.mdwn
+++ b/using_continuations_to_solve_same_fringe.mdwn
@@ -58,15 +58,15 @@ the thunk by applying it to the unit:
 
 <pre>
 # let rec make_int_stream i = Next (i, fun () -> make_int_stream (i + 1));;
-val make_int_stream : int -> int stream = <fun>
+val make_int_stream : int -> int stream = [fun]
 # let int_stream = make_int_stream 1;;
-val int_stream : int stream = Next (1, <fun>)         (* First element: 1 *)
+val int_stream : int stream = Next (1, [fun])         (* First element: 1 *)
 # match int_stream with Next (i, rest) -> rest;;      
-- : unit -> int stream = <fun>                        (* Rest: a thunk *)
+- : unit -> int stream = [fun]                        (* Rest: a thunk *)
 
 (* Force the thunk to compute the second element *)
 # (match int_stream with Next (i, rest) -> rest) ();;
-- : int stream = Next (2, <fun>)      
+- : int stream = Next (2, [fun])      
 </pre>
 
 You can think of `int_stream` as a functional object that provides
@@ -115,11 +115,14 @@ Notice the forcing of the thunks in the recursive call to
 - : bool = false
 </pre>
 
-Now, this implementation is a bit silly, since in order to convert the
-trees to leaf streams, our tree_monadizer function has to visit every
-node in the tree.  But if we needed to compare each tree to a large
-set of other trees, we could arrange to monadize each tree only once,
-and then run compare_streams on the monadized trees.
+Now, you might think that this implementation is a bit silly, since in
+order to convert the trees to leaf streams, our tree_monadizer
+function has to visit every node in the tree, so we'd have to traverse
+the entire tree at some point.  But you'd be wrong: part of what gets
+suspended in the thunking of the stream is the computation of the rest
+of the monadized tree.  Proving this claim requires adding print
+statements (or other tracing technology) within the tree monadizer
+function.
 
 By the way, what if you have reason to believe that the fringes of
 your trees are more likely to differ near the right edge than the left