June 2018 Update

Task/Caesar-cipher/Factor/caesar-cipher.factor

@@ -0,0 +1,18 @@
+USING: io kernel locals math sequences unicode.categories ;
+IN: rosetta-code.caesar-cipher
+
+:: cipher ( n s -- s' )
+    [| c |
+        c Letter? [
+            c letter? CHAR: a CHAR: A ? :> a
+            c a - n + 26 mod a +
+        ]
+        [ c ] if
+    ] :> shift
+    s [ shift call ] map ;
+
+: encrypt ( n s -- s' ) cipher ;
+: decrypt ( n s -- s' ) [ 26 swap - ] dip cipher ;
+
+11 "Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozr." decrypt print
+11 "The quick brown fox jumped over the lazy dog." encrypt print