gistfile1.idr

confoundMessage : (StreamCipher k, Serializable i, Serializable o) =>
                  k -> i -> o
confoundMessage key message =
  let encodedMsg = encode message
  in decode (zipWith xor
                     (Prelude.Stream.take (length encodedMsg)
                                          (generateKeystream key))
                     encodedMsg)

-- When elaborating an application of function Prelude.Vect.zipWith:
--         Unifying n and length (encode message) would lead to infinite value

------------------
-- second attempt:

confoundMsg : StreamCipher k => k -> Vect m (Bits n) -> Vect m (Bits n)
confoundMsg {m=m} key = zipWith xor (take m (generateKeystream key))
confoundMessage : (StreamCipher k, Serializable i, Serializable o) =>
                  k -> i -> o
confoundMessage key message = decode (confoundMsg key (encode message))

-- ./Data/Crypto/Encryption/StreamCipher.idr:27:17:Incomplete term decode (confoundMsg key (encode message))