>
> On 06/17/2016 02:13 PM, oldk1331 wrote:
> > Type is a category, but Type is the domain of types:
>
> To be honest, I also find this confusing. What I heard from Stephen Watt
> the other day was that Type is something like the type of all types
> (even of itself). Of course, that is somewhat contradicting, but "Type"
> was convenient to introduce technically.
>
> In fact, there is the hierarchy
>
> domains < categories < Category
>
> where "<" denotes the type hierarchy level. In Aldor/FriCAS it stops at
> "Category", but Type would be at the end of an infinite type hierarchy
> chain going beyond "Category".
>
> However, the actual implementation claims that Type is of type Category.
> Now what is the type of the (constant) "Category"? I don't know.
FriCAS is somewhat inconsistent here:
(2) -> Integer
(2) Integer
Type: Type
(3) -> typeOf(Integer)
(3) Type
Type: Category
(4) -> typeOf(typeOf(Integer))
(4) Category
Type: Type
(5) -> typeOf(typeOf(typeOf(Integer)))
(5) Category
Type: Type
So 'typeOf' says that Category is of type Category, while printer
says it is of type Type...
--
Waldek Hebisch
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