substitution-cipher.rant

# Constructs a substitution cipher function
[%make-cipher: alphabet] {
  <
    $letters = [split: <alphabet>];
    $sub-letters = [shuffled: <letters>];
    $cipher = [assoc: <letters>; <sub-letters>];
    $cipher-rev = [assoc: <sub-letters>; <letters>];
  >
  # Return cipher functions
  (::
    encode = [?: message] {
      [split: <message> |> translate: <cipher> |> sum]
    };
    decode = [?: message] {
      [split: <message> |> translate: <cipher-rev> |> sum]
    };
  )
}

# Create a cipher and encode/decode a message
<$cipher = [make-cipher: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"]>
<$secret-message = "The quick brown fox jumps over the lazy dog.">
<$encoded-message = [cipher/encode: <secret-message>]>
<$decoded-message = [cipher/decode: <encoded-message>]>

# Finally, print the result
Original: \"<secret-message>\"\n
Encoded: \"<encoded-message>\"\n
Decoded: \"<decoded-message>\"\n