[Hugs-users] explicit kind information; other question

[luc.duponcheel at accenture.com]

Hi all,

as an addition to my previous email about dealing with

> ...

> type C ct23 ct12 c1 x y = ct23 (ct12 c1) x y in ...

> here is what hugs infers

> :info C
> -- type constructor with kind (* -> * -> * -> *) -> (* -> *) -> * -> * -> * -> *
> type C a b c d e = <restricted>

>...


I see that, from the definition of C only,
one cannot really infer a more specific kind than the one inferred above.

But, if' C ct23 ct12 c1 x y' (as a synonym for 'ct23 (ct12 c1) x y')
is used in a context where the expressions 'ct12 c1 x y' and 'c1 x y' are used as well,
then, the kind inferencer can infer that c1 has kind (* -> * -> *),
ct12 has kind ((* -> * -> *) -> * -> * -> *), ct12 c1 has kind (* -> * -> *),
and ct23 has kind ((* -> * -> *) -> * -> * -> *).

So, explicit kind information is not needed if the kind inferencer is a bit smarter.

Any comments?

Luc Duponcheel

 



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