Data commit

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)