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danidiaz/ReifyExceptions.hs

Created August 10, 2023 13:31
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ReifyExceptions.hs
-- code by mniip
types :: [String]
types = $(
do
insts <- reifyInstances ''Exception [VarT (mkName "a")]
let
tyConOf (AppT ty _) = tyConOf ty
tyConOf (ConT con) = Just con
tyConOf _ = Nothing
tyCons <- for insts \case
InstanceD _ _ (AppT (ConT exc) ty) _
| exc == ''Exception
, Just tyCon <- tyConOf ty
-> pure tyCon
Language.Haskell.TH.Syntax.lift $ show <$> filter ((Just "base" ==) . namePackage) tyCons
)
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