RE: [Caml-list] "type foo = Foo | Bar | Baz" vs. "type foo = Foo | Baz | Bar"

[David Allsopp <dra-news@metastack.com>]

Oliver Bandel wrote:
> Hello,
> 
> I got an error message when the ml-file and the mli-file have a sum-type,
> where the order of the type definitionis different.
> This seems to be new, at least I did not found such an error message
> before.
> 
> ==========================================================================
> =
> File "foo.ml", line 1:
> Error: The implementation foo.ml does not match the interface foo.cmi:
>         Type declarations do not match:
>           type foo = Foo | Bar | Baz
>         is not included in
>           type foo = Foo | Baz | Bar
>         File "foo.ml", line 1, characters 0-26: Actual declaration
>         Fields number 2 have different names, Bar and Baz.
> ==========================================================================
> =

It has always been the case, but I think the error message used to be much less clear.

> I looked for warning-/error-codes, to look, if checking the order of the
> definition of a type can be switched on and off.
> 
> But I didn't found a number, that I can use with -w-switch.

It's not a warning, so you can't switch it off - having a different order of constructors makes the type different (it changes the runtime representation).


David