From: Ramakrishnan Muthukrishnan <vu3rdd@gmail.com>
Date: Sat, 10 Jul 2010 12:38:46 +0000 (+0530)
Subject: solution to 2.28. Really interesting..
X-Git-Url: https://git.rkrishnan.org/pf/content/%22news.html/frontends//%22%22?a=commitdiff_plain;h=a8bf474c88c23078f2f789a7d24bbd25a89e63b2;p=sicp.git

solution to 2.28. Really interesting..
---

diff --git a/src/sicp/ex2_28.clj b/src/sicp/ex2_28.clj
new file mode 100644
index 0000000..027b285
--- /dev/null
+++ b/src/sicp/ex2_28.clj
@@ -0,0 +1,19 @@
+(ns sicp.ex2_28
+  (:use [clojure.test]))
+
+;; take a list of nested lists and return a flat list with elements
+;; in the same left-to-right order
+(defn fringe [lst]
+  (cond (not (seq? lst)) (list lst)
+	(empty? lst)     nil
+	:else (concat (fringe (first lst))
+		      (fringe (rest lst)))))
+
+(deftest test-fringe-with-simple-list
+  (is (= (fringe '(1 2 3 4)) '(1 2 3 4))))
+
+(deftest test-fringe-with-nested-list
+  (are [x y] [= x y]
+       (fringe '((1 2) 3 4))   '(1 2 3 4)
+       (fringe '(1 2 (3 4)))   '(1 2 3 4)
+       (fringe '((1 2) (3 4))) '(1 2 3 4)))