March 2014 update

Task/Caesar-cipher/Scala/caesar-cipher-3.scala

@@ -0,0 +1,12 @@
+class Caeser(val key: Int) {
+  @annotation.tailrec
+  private def rotate(p: Int, s: IndexedSeq[Char]): IndexedSeq[Char] = if (p < 0) rotate(s.length + p, s) else s.drop(p) ++ s.take(p)
+
+  val uc = 'A' to 'Z'
+  val lc = 'a' to 'z'
+  val as = uc ++ lc
+  val bs = rotate(key, uc) ++ rotate(key, lc)
+
+  def encode(c: Char) = if (as.contains(c)) bs(as.indexOf(c)) else c
+  def decode(c: Char) = if (bs.contains(c)) as(bs.indexOf(c)) else c
+}

Task/Caesar-cipher/Scala/caesar-cipher-4.scala

@@ -0,0 +1,6 @@
+val text = "The five boxing wizards jump quickly"
+val myCaeser = new Caeser(3)
+val encoded = text.map(c => myCaeser.encode(c))
+println("Plaintext => " + text)
+println("Ciphertext => " + encoded)
+println("Decrypted => " + encoded.map(c => myCaeser.decode(c)))

Task/Caesar-cipher/Scheme/caesar-cipher.ss

@@ -0,0 +1,27 @@
+;
+; Works with R7RS-compatible Schemes (e.g. Chibi).
+; Also current versions of Chicken, Gauche and Kawa.
+;
+(cond-expand
+  (chicken (use srfi-13))
+  (gauche  (use srfi-13))
+  (kawa    (import (srfi :13)))
+  (else    (import (scheme base) (scheme write)))) ; R7RS
+
+
+(define msg "The quick brown fox jumps over the lazy dog.")
+(define key 13)
+
+(define (caesar char)
+  (define A (char->integer #\A))
+  (define Z (char->integer #\Z))
+  (define a (char->integer #\a))
+  (define z (char->integer #\z))
+  (define c (char->integer char))
+  (integer->char
+    (cond ((<= A c Z) (+ A (modulo (+ key (- c A)) 26)))
+          ((<= a c z) (+ a (modulo (+ key (- c a)) 26)))
+          (else c)))) ; Return other characters verbatim.
+
+(display (string-map caesar msg))
+(newline)

Task/Caesar-cipher/TXR/caesar-cipher.txr

@@ -13,7 +13,7 @@
                  (e (tostringp (+ #\a (mod (+ i k) 26))))
                  (P (upcase-str p))
                  (E (upcase-str e)))
-            '(((,p ,e) (,P ,E))
+            ^(((,p ,e) (,P ,E))
               ((,e ,p) (,E ,P))))))
 @(deffilter enc . @(mappend (fun first) enc-dec))
 @(deffilter dec . @(mappend (fun second) enc-dec))