Re: The constructor XX is defined in both types

There is no risk. This is warning 30, which was meant to avoid user
confusions before type-based disambiguation of fields and constructors
was implemented. It should not be a default warning anymore (feel free
to open an issue on the bugtracker for this), and you can safely
disable it.

In recent versions of OCaml (since 4.01.0), there are better warnings
to control the readability risks of disambiguation of fields and
constructor names:
- warning 40 warns if disambiguation selects a name inside a module
that is not opened in the current scope (I recommend using it)
- warning 41 warns if a choice was made in absence of type information
(defaulting to last-defined-name wins, not robust to addition of type
annotations) (I recommend using it)
- warning 42 warns if a type-directed disambiguation choice was
different from what the last-defined-wins would have selected (this
should be useful only when you want to make sure that your code will
also compile with older OCaml versions that did not support
typed-directed disambiguation)

On Sat, Aug 1, 2015 at 9:55 AM, Sébastien Dailly
[email protected] [ocaml_beginners]
<[email protected]> wrote:
> Hello,
>
> I'm tring to translate the xml schema in term of OCaml types :
>
>> type element = string Xml.Attributes.t
>> and group = string Xml.Attributes.t * sub_group option
>> and choice = string Xml.Attributes.t * sub_choice list
>> and sequence = string Xml.Attributes.t * sub_choice list
>>
>>
>> and sub_choice =
>>   | Element of element
>>   | Group of group
>>   | Choice of choice
>>   | Sequence of sequence
>>
>> and sub_group =
>>   | Choice of choice
>>   | Sequence of sequence
>>
>
> The compilation give me the warning :
>
>> the constructor Choice is defined in both types sub_choice and sub_group
>
>> the constructor Sequence is defined in both types sub_choice and sub_group.
>
> I know I could use polymorphic variants to prevent this, but I want to
> restrict each type with the contructors defined in the schema. (I also
> want to be as close as possible with the xsd names types).
>
> My question is : what do I risks ? I did some tests and this seems to
> work correctly in pattern matching and I did not see where it could
> break the code.
>
> Thank you
>
>
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