From: Jim Pryor <profjim@jimpryor.net>
Date: Tue, 30 Nov 2010 16:28:33 +0000 (-0500)
Subject: week11 tweaks
X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=1c203e3ca6a3b29830af36ea6f6b3a86be93675f

week11 tweaks

Signed-off-by: Jim Pryor <profjim@jimpryor.net>
---

diff --git a/assignment8.mdwn b/assignment8.mdwn
index 59e0090b..5a2780d8 100644
--- a/assignment8.mdwn
+++ b/assignment8.mdwn
@@ -5,7 +5,7 @@
 		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 = { tree : 'a starred_level; filler: '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 *)
@@ -23,7 +23,7 @@
 
 
 		let new_zipper (t : 'a tree) : 'a zipper =
-			{tree = Root; filler = t}
+			{level = Root; filler = t}
 			;;
 
 	&nbsp;
diff --git a/week11.mdwn b/week11.mdwn
index 14d5eed2..c20bc1f9 100644
--- a/week11.mdwn
+++ b/week11.mdwn
@@ -327,18 +327,18 @@ Anyway, using record types, we might define the tree zipper interface like so:
 	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 = { tree : 'a starred_level; filler: '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 *)
 	    (* else returns move_botleft (zipper which results from moving down and left in z) *)
 
 <!--
-	    let {tree; filler} = z
+	    let {level; filler} = z
 	    in match filler with
 	    | Leaf _ -> z
 	    | Node(left, right) ->
-	        let zdown = {tree = Starring_Left {parent = tree; sibling = right}; filler = left}
+	        let zdown = {level = Starring_Left {parent = level; sibling = right}; filler = left}
 	        in move_botleft zdown
 	    ;;
 -->
@@ -349,12 +349,12 @@ Anyway, using record types, we might define the tree zipper interface like so:
 	    (* else returns move_right_or_up (result of moving up in z) *)
 
 <!--
-	    let {tree; filler} = z
-	    in match tree with
-	    | Starring_Left {parent; sibling = right} -> Some {tree = Starring_Right {parent; sibling = filler}; filler = right}
+	    let {level; filler} = z
+	    in match level with
+	    | Starring_Left {parent; sibling = right} -> Some {level = Starring_Right {parent; sibling = filler}; filler = right}
 	    | Root -> None
 	    | Starring_Right {parent; sibling = left} ->
-	        let z' = {tree = parent; filler = Node(left, filler)}
+	        let z' = {level = parent; filler = Node(left, filler)}
 	        in move_right_or_up z'
 	    ;;
 -->
@@ -362,7 +362,7 @@ Anyway, using record types, we might define the tree zipper interface like so:
 The following function takes an 'a tree and returns an 'a zipper focused on its root:
 
 	let new_zipper (t : 'a tree) : 'a zipper =
-	    {tree = Root; filler = t}
+	    {level = Root; filler = t}
 	    ;;
 
 Finally, we can use a mutable reference cell to define a function that enumerates a tree's fringe until it's exhausted: