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[Jacques-Henri Jourdan <jacques-henri.jourdan AT normalesup.org>]

Hi,

What's strange, to my point of view, is that list is template universe
polymorphic. My interpretation is that it does mean that any use of list
(and of nil) after its definition should not create new constraints of
list's own universe variable, but rather create a fresh universe
variable and add constraints on this variable.

-- 
JH

Le 06/09/2017 à 07:49, Guillaume Melquiond a écrit :
> On 06/09/2017 01:14, Jan-Oliver Kaiser wrote:
>> Hey everyone,
>>
>> List.tl and List.repeat are outliers in the List module as they
>> introduce new universes which upper-bound list's own universe variable
>> in the global graph. Why is that?
> Good catch. They are created because of the implicit argument of nil,
> which is of type Type. I have no idea whether this deficiency of Coq is
> easily fixed, but we can at least remove these superfluous universes by
> explicit setting the argument of nil in the definitions of tl and repeat.
>
> Best regards,
>
> Guillaume

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