langs a-z

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

@@ -0,0 +1,23 @@
+@(next :args)
+@(cases)
+@{key /[0-9]+/}
+@text
+@(or)
+@  (throw error "specify <key-num> <text>")
+@(end)
+@(do
+   (defvar k (int-str key 10)))
+@(bind enc-dec
+       @(collect-each ((i (range 0 25)))
+          (let* ((p (tostringp (+ #\a i)))
+                 (e (tostringp (+ #\a (mod (+ i k) 26))))
+                 (P (upcase-str p))
+                 (E (upcase-str e)))
+            '(((,p ,e) (,P ,E))
+              ((,e ,p) (,E ,P))))))
+@(deffilter enc . @(mappend (fun first) enc-dec))
+@(deffilter dec . @(mappend (fun second) enc-dec))
+@(output)
+encoded: @{text :filter enc}
+decoded: @{text :filter dec}
+@(end)