Commits on Dec 10, 2020

1. Make the TH machinery handle PolyKinds more robustly …

   This is a collection of various Template Haskell–related fixes that, when all
   put together, fixes #917. This does the following:
   
   * Rather than use `th-abstraction`'s `datatypeType` function, which strips off
     important kind information from type arguments, I defined a similar
     `datatypeTypeKinded` function that preserves kinds when reasonable.
   * `Control.Lens.Internal.{FieldTH,PrismTH}` is now more careful to use
     `freeVariablesWellScoped` (from `th-abstraction`) instead of `typeVars`
     to ensure that the resulting types are well scoped. This is particularly
     important for poly-kinded types, as the kind variables must always appear
     before the type variables.
   * I deleted the `close` function from `Control.Lens.Internal.PrismTH` in favor
     of `quantifyType` and `quantifyType'`, which I have moved to
     `Control.Lens.Internal.TH` so that they may be used by `FieldTH` and
     `PrismTH` alike. Moreover, I now use `quantifyType'` in the definition of
     `PrismTH.makeClassyPrismClass` so that any type variables bound by the class
     itself do not get requantified in any class methods. The previous code was
     not doing this at all, which was just plain wrong.

   

   RyanGlScott committed Dec 10, 2020
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