Re: [Caml-list] Pattern matching of records

[Thibault Suzanne <thi.suzanne@gmail.com>]

There is no need to specify the origin module in front of each field :

match s0 with
| { S.a = 0; b = 0 } -> true
| _ -> false

Le 16/09/2015 14:19, Leonardo Laguna Ruiz a écrit :
>
> I have the following type
>
> (* File: S.ml *)
> module S = struct
>    type s =
>       {
>          a : int;
>          b : int;
>       }
> end
>
>
> I I have found that for creating records I can do as follows:
>
> (* File: main.ml *)
> open S
> let s0 = S.{ a = 0; b = 0}
>
>
> However this does not work for pattern matching:
>
> (* this does not work *)
> match s0 with
> | S.{ a = 0 ; b = 0 } -> true
> | _ -> false
>
>
> These two alternatives work, but one with a warning and the other 
> (depending on the type) is too verbose:
>
> (* this produces a warning *)
> match s0 with
> | { a = 0 ; b = 0 } -> true
> | _ -> false
>
> (* this works *)
> match s0 with
> | { S.a = 0 ; S.b = 0 } -> true
> | _ -> false
>
>
> Is there any other way of writing pattern matches as compact as S.{ a 
> = 0 ; b = 0 } ? (which is consistent to the construction of the same 
> value)
>
> I know that it's possible to do:
>
> let open S in
> match s0 with
> | { a = 0 ; b = 0 } -> true
> | _ -> false
>
> but the main reason I don't do it is because I have more records like:
>
> match s0,k0 with
> | { S.a = 0 }, {K.a = 0 } -> true
>
>
>
> Best regards,
>
> Leonardo
>
>
>