#!/usr/local/bin/slate

ch@(String Character traits) rot13
[| value |
  upper ::= ch isUppercase.
  value := ch toLowercase as: Integer.
  (value >= 97) /\ [value < 110]
    ifTrue: [value += 13]
    ifFalse: [(value > 109) /\ [value <= 122]
                ifTrue: [value -= 13]].
  upper
    ifTrue: [(value as: String Character) toUppercase]
    ifFalse: [value as: String Character]
].

lobby define: #Rot13Encoder &parents: {Encoder}.

c@(Rot13Encoder traits) convert
[
  [c in isAtEnd] whileFalse: [c out nextPut: c in next rot13].
].

(Rot13Encoder newFrom: Console reader to: Console writer) convert.