Discussion on: "Parse, don't validate" using ViewPatterns

readOp :: Word8 -> ByteString -> Maybe Opcode
readOp word bs =
  readDUP word
    <|> readSWAP word
    <|> readLOG word
    <|> readPUSH word bs
    <|> case word of
      0x00 -> pure STOP
      ...
      _ -> Nothing