Converting type <=> Int for byte-based communication

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Background:

I have a project where I need to communicate with bytes (serial protocol, using ports) where I wanted to send and receive bytes to & from ports. I’m currently using List Int because it’s easy to send over the js bridge (not sure if I can do that with Bytes)

The communication is a Request/OKResponse/Error protocol where each of them has commands associated. The structure is pretty much like this:

Request = 0x1

OKResponse= 0x2

Error = 0x3

(in reality they have parameters and all, omitted for the post).

where cmd is a byte, so we can correlate response and commands.

For example:

CmdFoo = 0x11

CmdBar = 0x22

So, when I want to request Foo, I would write [Request CmdFoo] in bytes [0x1, 0x11]

and wait until I got a response. If I get [0x2, 0x11], I know that it’s a successful response for foo [OKResponse, CmdFoo].

Questions:

How would you make conversions between those commands and the byte representation? Would you do

type CommandByte = Byte Int

type Command = CmdFoo | CmdBar

commandToCommandByte : Command -> CommandByte
commandToCommandByte cmd = case cmd of 
                             CmdFoo -> 0x11
                             CmdBar -> 0x22

commandByteToCommand : CommandByte -> Maybe Command

-- same idea, in reverse

or would you maintain

mapping : List (Command, CommandByte)

but you’re forced to write List.filter followed by `List.Maybe for either direction…

let me know, how would you approach this? Would you have used Bytes.Encode? I would’ve used if I knew it existed ( I didn’t know as I’m starting out) and I don’t know if it can be sent over ports…
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