Recover role of a type variable in source Haskell

[Ryan Scott]

It depends on what you mean by "source Haskell". If you're willing to
consider including Template Haskell in your definition of "source", then
the answer is yes, since there is a reifyRoles function [1] which gives you
this information.

I'm not aware of another way to accomplish this (without resorting to
something like the GHC API).

Ryan S.
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[1]
https://hackage.haskell.org/package/template-haskell-2.14.0.0/docs/Language-Haskell-TH.html#v:reifyRoles
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