X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?a=blobdiff_plain;ds=sidebyside;f=assignment8.mdwn;h=5a2780d8459e95e45fa07ea0de4ce26c26a88a76;hb=1c203e3ca6a3b29830af36ea6f6b3a86be93675f;hp=a66c26ae54b9b4e1dc5a86428ed7d5eabeed6c27;hpb=57e4fb87e24913780f5ed25f975986775adc068a;p=lambda.git

diff --git a/assignment8.mdwn b/assignment8.mdwn
index a66c26ae..5a2780d8 100644
--- a/assignment8.mdwn
+++ b/assignment8.mdwn
@@ -2,9 +2,10 @@
 
 		type 'a tree = Leaf of 'a | Node of ('a tree * 'a tree)
 
-		type 'a starred_tree = Root | Starring_Left of 'a starred_pair | Starring_Right of 'a starred_pair
-		and 'a starred_pair = { parent : 'a starred_tree; sibling: 'a tree }
-		and 'a zipper = { tree : 'a starred_tree; filler: 'a tree };;
+		type 'a starred_level = Root | Starring_Left of 'a starred_nonroot | Starring_Right of 'a starred_nonroot
+		and 'a starred_nonroot = { parent : 'a starred_level; sibling: 'a tree };;
+
+		type 'a zipper = { level : 'a starred_level; filler: 'a tree };;
 
 		let rec move_botleft (z : 'a zipper) : 'a zipper =
 			(* returns z if the targetted node in z has no children *)
@@ -22,7 +23,7 @@
 
 
 		let new_zipper (t : 'a tree) : 'a zipper =
-			{tree = Root; filler = t}
+			{level = Root; filler = t}
 			;;
 
 	 
@@ -64,7 +65,7 @@
 			;;
 
 
-2.	Here's another implementation of the same-fringe function, in Scheme. It's taken from <http://c2.com/cgi/wiki?SameFringeProblem>. It uses thunks to delay the evaluation of code that computes the tail of a list of a tree's fringe. It also involves passing continuations as arguments. Your assignment is to fill in the blanks in the code, **and also to supply comments to the code,** to explain what every significant piece is doing. Don't forget to supply the comments, this is an important part of the assignment.
+2.	Here's another implementation of the same-fringe function, in Scheme. It's taken from <http://c2.com/cgi/wiki?SameFringeProblem>. It uses thunks to delay the evaluation of code that computes the tail of a list of a tree's fringe. It also involves passing continuations (`tailk`s) as arguments. Your assignment is to fill in the blanks in the code, **and also to supply comments to the code,** to explain what every significant piece is doing. Don't forget to supply the comments, this is an important part of the assignment.
 
 	This code uses Scheme's `cond` construct. That works like this;