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{-# LANGUAGE DeriveFunctor, DeriveFoldable, DeriveTraversable #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE FlexibleContexts, DatatypeContexts #-}
module ShouldCompile where
import Data.Foldable
import Data.Traversable
data Trivial a = Trivial
deriving (Functor,Foldable,Traversable)
-- lots of different things
data Strange a b c
= T1 a b c
| T2 c c c
| T3 [a] [b] [c] -- lists
| T4 [[a]] [[b]] [[c]] -- nested lists
| T5 (c,(b,b),(c,c)) -- tuples
| T6 ([c],Strange a b c) -- tycons
deriving (Functor,Foldable,Traversable)
data NotPrimitivelyRecursive a
= S1 (NotPrimitivelyRecursive (a,a))
| S2 a
deriving (Functor,Foldable,Traversable)
data Eq a => StupidConstraint a b = Stupid a b
deriving (Functor,Foldable,Traversable)
-- requires Foldable/Traversable constraint on f and g
data Compose f g a = Compose (f (g a))
deriving (Functor,Foldable,Traversable)
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