Merge Full/:-> into a single type

[oliver-batchelor]

For your interest, this seems to compile with minimal changes. I've left alone classes like Syntactic for the most part, and simply restricted the kind where necessary to Sig Type -> Type, for example in the eval class, where the AST data type itself is still kind polymorphic.

The only casualty is Functor (AST sym) which I guess is now some other type of functor potentially? Any ideas there?

[oliver-batchelor]

Still doesn't compile on 7.10 because base 4.9 now has polykinded Const :: Type -> k -> Type where 4.7 is Const :: Type -> Type -> Type

[emilaxelsson]

Thank you for this PR! I want to see how this plays out in raw-feldspar. This will take some time, but I'll try to be quick.

I think we should define our own poly-kinded Const then. I wouldn't want to drop 7.10 support.

I guess 7.8 is out of question? (Can never remember which features were introduced when.)

[oliver-batchelor]

Seems 7.8 is failing for a different reason (something about Typeable 'Full), I'll see if it can be fixed up.

[emilaxelsson]

Wow, this too way longer than expected... For some reason I was expecting to have to make changes in RAW-Feldspar, but all I needed was to turn on DataKinds and PolyKinds and everything works fine. Sorry it took so long.

I'll be happy to merge. Could you perhaps just smash the commits into a single one with a more descriptive message?

Thanks

[emilaxelsson]

Oh right, there was also the 7.8 issue. Any progress on that?