From: Ramakrishnan Muthukrishnan <vu3rdd@gmail.com>
Date: Thu, 22 Jul 2010 19:51:50 +0000 (+0530)
Subject: text examples upto 2.2.3
X-Git-Url: https://git.rkrishnan.org/listings/specifications/frontends/FTP-and-SFTP.rst?a=commitdiff_plain;h=542fc334464dfade8fe5517b8756f67b82679c3e;p=sicp.git

text examples upto 2.2.3
---

diff --git a/src/sicp/ch2_2.clj b/src/sicp/ch2_2.clj
index 2fd2f9e..e0107f5 100644
--- a/src/sicp/ch2_2.clj
+++ b/src/sicp/ch2_2.clj
@@ -1,4 +1,5 @@
-(ns sicp.ch2_2)
+(ns sicp.ch2_2
+  (:refer-clojure :exclude (map)))
 
 (cons 1
       (cons 2
@@ -88,4 +89,19 @@
   (cond (nil? coll)       0
 	(not (seq? coll)) 1
 	:else (+ (count-leaves (first coll))
-		 (count-leaves (next coll)))))
\ No newline at end of file
+		 (count-leaves (next coll)))))
+
+;; mapping over trees
+(defn scale-tree [tree factor]
+  (cond (nil? tree) nil
+	(not (seq? tree)) (* tree factor)
+	:else (cons (scale-tree (first tree) factor)
+		    (scale-tree (next tree) factor))))
+
+;; using map
+(defn scale-tree-with-map [tree factor]
+  (map (fn [sub-tree]
+	 (if (seq? sub-tree)
+	   (scale-tree-with-map sub-tree factor)
+	   (* sub-tree factor)))
+       tree))
\ No newline at end of file