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{- The purpose of this is to test that record update is
sufficiently polymorphic. See comments with
tcExpr (RecordUpd) in TcExpr.lhs
-}
module Main where
data T a b c d = MkT1 { op1 :: a, op2 :: b }
| MkT2 { op1 :: a, op3 :: c }
| MkT3 { op4 :: a, op5 :: d }
update1 :: a2 -> T a b c d -> T a2 b c d2
update1 x t = t { op1 = x }
-- NB: the MkT3.op4 case doesn't constrain the result because
-- it doesn't have an op1 field
update2 :: a2 -> T a b c d -> T a2 b2 c2 d
update2 x t = t { op4 = x }
main = print (op4 $
update2 True $
MkT3 { op4 = op2 $
update1 (1::Int) $
MkT1 { op1 = True }
})
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