From: Jim Pryor Date: Mon, 4 Oct 2010 01:07:16 +0000 (-0400) Subject: Merge branch 'pryor' X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=50a9ebe3ecc8c1b392c8118546ded369fe39d1d4;hp=72c0c8340fbb4f71beef958e74950db4cd677087 Merge branch 'pryor' --- diff --git a/assignment4.mdwn b/assignment4.mdwn index 8b8a19dc..cd927873 100644 --- a/assignment4.mdwn +++ b/assignment4.mdwn @@ -34,9 +34,14 @@ First, read this: [[Implementing trees]]
  1. Write an implementation of leaf-labeled trees. You can do something v3-like, or use the Y combinator, as you prefer. - You'll need an operation `make_leaf` that turns a label into a new leaf. You'll need an operation `make_node` that takes two subtrees (perhaps leaves, perhaps other nodes) and joins them into a new tree. You'll need an operation `isleaf` that tells you whether a given tree is a leaf. And an operation `extract_label` that tells you what value is associated with a given leaf. - -
  2. The **fringe** of a leaf-labeled tree is the list of values at its leaves, ordered from left to right. For example, the fringe of this tree: +You'll need an operation `make_leaf` that turns a label into a new leaf. You'll +need an operation `make_node` that takes two subtrees (perhaps leaves, perhaps +other nodes) and joins them into a new tree. You'll need an operation `isleaf` +that tells you whether a given tree is a leaf. And an operation `extract_label` +that tells you what value is associated with a given leaf. + +
  3. The **fringe** of a leaf-labeled tree is the list of values at its leaves, +ordered from left to right. For example, the fringe of this tree: . / \