Mmmmh... no, to do that you need ImpredicativeTypes (which is I believe
about to be deprecated).
You have to declare Job a data, not a type, and use
ExistentialQuantification.
2012/6/13 Ismael Figueroa Palet
Do you want to hide the specific types of the job? Presumably to then define a type JobList = [Job] ? You can do that with the ExistentialQuantification extension.
type Job = forall k a. Map k a type JobList = [Job]
?? Note you can't unpack the types k a once you have hidden them. But the typechecker can use it to ensure some static property. Also you could use unsafeCoerce to do some casts, but *only if you are *sure* that things will go OK*.
2012/6/13 Magicloud Magiclouds
Hi, I've forgotten this. This is OK: type Job k a = Map k a And this is OK: {-# LANGUAGE RankNTypes #-} -- or LiberalTypeSynonyms? type Job = forall a. forall k. Map k a
Then how to write it like this? type Job = Map k a -- 竹密岂妨流水过 山高哪阻野云飞
And for G+, please use magiclouds#gmail.com.
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-- Ismael
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