Request for feedback: deriving strategies syntax

[Ryan Scott]

Sorry for not including the full context on that link. It's part of a
Summer of Haskell 2016 project called Native Metaprogramming in
Haskell [1] (a.k.a. Introspective Template Haskell [2]), aiming to fix
Trac #11081 [3].

Ryan S.
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[1] https://github.com/shayan-najd/NativeMetaprogramming
[2] https://ghc.haskell.org/trac/ghc/wiki/TemplateHaskell/Introspective
[3] https://ghc.haskell.org/trac/ghc/ticket/11081