Re: [Caml-list] Pattern matching question

["Seth J. Fogarty" <sfogarty@gmail.com>]

On 7/19/06, Jim Miller <gordon.j.miller@gmail.com> wrote:
> I'm trying to use an OCaml program to form an umambiguous protocol
> specification.  I've convinced myself that by proper definition of my types,
> and avoiding using the _ in matches, I can get OCaml to help me verify that
> I have a complete specification.  I'm doing this by defining a function that
> specifies the behavior of one of the protocol partners when it receives a
> message.  Here is an example of what I have.
>
>  let requestOp = REQUEST_KEY | SUCCESS;;
>
>  let message = None | Register of requestOp * int;;
>
>  let receive idList msg =
>    match message with
>       None -> None
>
>  |    Register( REQUEST_KEY, id ) -> begin
>           match idList with
>               [] -> Register(SUCCESS, id)
>           |   l when (List.mem id l) -> Register(Success, (next_available_id
> l))
>           |  _ -> Register(Success, id)
>  ;;


Try something like

match idList with
     [] -> Register(SUCCESS, id)
   | l -> if List.mem id l then Register(foo) else Register(bar)

And replace the guard with an if statement.

-- 
Seth Fogarty             sfogarty@[gmail.com|rice.edu|livejournal]
Neep-neep at large    AIM: Sorrath
"I know there are people in this world who do not love their fellow
human beings - and I hate people like that" --Tom Lehrer.