Adapt palindrome into a ttd approach

1 files changed, 21 insertions, 0 deletions

diff --git a/palindrome/palindrome.scm b/palindrome/palindrome.scm
new file mode 100755
index 0000000..276e628
--- /dev/null
+++ b/palindrome/palindrome.scm
@@ -0,0 +1,21 @@
+(define-module (palindrome))
+
+
+(define-public (pp str)
+  "Pretty-printer wrapper for
+palindrome?"
+  (format #f "String ~a is ~aa palindrome!\n"
+          str
+          (if (palindrome? str)
+              "" "not ")))
+
+(define-public (palindrome? str)
+  "Returns #t if STR is a palindrome, false
+otherwise. Ignores casing and non-alphabetic
+characters."
+  (let ((clean (cleanup str)))
+    (equal? clean (string-reverse clean))))
+
+(define (cleanup str)
+  (string-downcase (string-filter
+                    char-set:letter str)))