X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=week11.mdwn;h=0128a5da9bbc933e7b961aa64a2685dec8ace7cc;hp=1857d8b988836b22dc691e2238a5d69e6cf9e65a;hb=339b62e48b39fadd325d9e0dc903430c4a896870;hpb=21d43bf1749e0f6329a481ab8d4c5726a13e7011

diff --git a/week11.mdwn b/week11.mdwn
index 1857d8b9..0128a5da 100644
--- a/week11.mdwn
+++ b/week11.mdwn
@@ -1,22 +1,11 @@
 These notes may change in the next few days (today is 30 Nov 2010).
 The material here benefited from many discussions with Ken Shan.
 
-[[!toc]]
+##[[Tree and List Zippers]]##
 
-##List Zippers##
+##[[Coroutines and Aborts]]##
 
-Say you've got some moderately-complex function for searching through a list, for example:
-
-	let find_nth (test : 'a -> bool) (n : int) (lst : 'a list) : (int * 'a) ->
-		let rec helper (position : int) n lst =
-			match lst with
-			| [] -> failwith "not found"
-			| x :: xs when test x -> (if n = 1
-				then (position, x)
-				else helper (position + 1) (n - 1) xs
-			)
-			| x :: xs -> helper (position + 1) n xs
-		in helper 0 n lst;;
+##[[From Lists to Continuations]]##
 
 This searches for the `n`th element of a list that satisfies the predicate `test`, and returns a pair containing the position of that element, and the element itself. Good. But now what if you wanted to retrieve a different kind of information, such as the `n`th element matching `test`, together with its preceding and succeeding elements? In a real situation, you'd want to develop some good strategy for reporting when the target element doesn't have a predecessor and successor; but we'll just simplify here and report them as having some default value:
 
@@ -1760,4 +1749,7 @@ called a
 that is intended to 
 represent non-deterministic computations as a tree.
 
+##[[List Monad as Continuation Monad]]##
+
+##[[Manipulating Trees with Monads]]##