tasks a-s

Task/Rot-13/Factor/rot-13.factor

@@ -0,0 +1,24 @@
+#! /usr/bin/env factor
+
+USING: kernel io ascii math combinators sequences ;
+IN: rot13
+
+: rot-base ( ch ch -- ch ) [ - 13 + 26 mod ] keep + ;
+
+: rot13-ch ( ch -- ch )
+    {
+        { [ dup letter? ] [ CHAR: a rot-base ] }
+        { [ dup LETTER? ] [ CHAR: A rot-base ] }
+        [ ]
+    }
+    cond ;
+
+: rot13 ( str -- str ) [ rot13-ch ] map ;
+
+: main ( -- )
+    [ readln dup ]
+    [ rot13 print flush ]
+    while
+    drop ;
+
+MAIN: main