Le 30 oct. 07 à 18:56, skaller a écrit :

> On Tue, 2007-10-30 at 12:08 -0500, Edgar Friendly wrote:
>> Brian Hurt wrote:
>>> Chung-chieh Shan wrote:
>>>
>>>> Any tips on how (and perhaps how not) to teach functors?
>
> The problem teaching functors is that the essential feature
> of functors is missing -- a functor is a structure preserving
> map but there's no way to specify any structure other than
> in comments.

Indeed, I don't really see the link between Ocaml functors and  
Category ones (???). Could someone explain this ?

Classically, types would be the objects and functions would be the  
arrows. But then a functor does not map a type to each original type  
neither a function to each original function. So what ?

Maybe we could see all the module structures associated to a module  
signature form a category ? And then a (ocaml) functor would indeed  
be a (category) functor from the category associated to the signature  
of the parameter to the category of its returned module type. (?)

Is this the way to go ? I thing I've read once that it was linked  
with "institutions" theory (of Goguen), is this right ?

Thanks for answers,
Vincent