val .rot = fn(.s, .key) {
    cp2s map(fn(.c) rotate(rotate(.c, .key, 'a'..'z'), .key, 'A'..'Z'), s2cp .s)
}

val .s = "A quick brown fox jumped over something."
val .key = 3

writeln " original: ", .s
writeln "encrypted: ", .rot(.s, .key)
writeln "decrypted: ", .rot(.rot(.s, .key), -.key)