Re: [Caml-list] Records

[Sven LUTHER <luther@dpt-info.u-strasbg.fr>]

On Thu, Mar 22, 2001 at 01:34:04PM +0100, Alex Baretta wrote:
> Basically I'm trying to define two record type as sharing some
> field names. I have tried twice, apparently in the same way, and
> obtained two different error messages, which seem to contradict
> one another. Could anyone explain to me what is happening here?
> 
> 
>         Objective Caml version 3.00
> 
> # type rec1 = { field1 : int }
>   type rec2 = { field1 : int ; field2 : int };; <--- Here I define
> my two record types
> type rec1 = { field1 : int; } 
> type rec2 = { field1 : int; field2 : int; } 
> # { field1 = 1 };; <--- This is supposed to be a correct rec1

no, it is a rec2 record, since field1 was lastly defined for rec2.

One workaround would be :

module Rec1 = struct
  type t = {field1 : int}
end
module Rec2 = struct
  type t = { field1 : int; field2 : int; } 
end

Then you can do :

{Rec1.field1 = 1} : Rec1.t

or 

{Rec2.field1 = 1; Rec2.field2 = 2} : Rec2.t

If you are interrestedin more such things, i remember a discution about such
things some time ago on this list, please look at the mailing list archive for
more details.

Friendly,

Sven Luther
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