Re: [Caml-list] module type and record

[Xavier Leroy <xavier.leroy@inria.fr>]

> hello,
> I need to declare a record type in a field like :
> 
> module A : ( MY_TYPE with type t = { label1 : int ; label2 : string } ) =
> struct
> ....
> end
> 
> but the compiler seems to refuse this declaration.

Currently, only type abbreviations can be added with the "with type"
construct:  MODTYPE with type t = some_type_expression.

This restriction is somewhat artificial and I'm considering lifting it.

> Could you give me a solution for this problem ?

Currently, you need to expand "MY_TYPE with..." by hand into

        sig
          type t = { label1 : int ; label2 : string }
          (* other elements of signature MY_TYPE
        end

An alternative is to declare the record type separately:

        type my_rec = { label1 : int ; label2 : string }

        module A : (MY_TYPE with type t = my_rec) = ...

- Xavier Leroy

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