Deriving instance conditionally compiles
{-# LANGUAGE GADTs #-}
{-# LANGUAGE StandaloneDeriving #-}
data Abstract
data Reified
data Player
data Elect p a where
ElectRefAsTypeOf :: Int -> Elect Abstract a -> Elect Abstract a
ElectHandle :: a -> Elect Reified a
Controller :: Elect Abstract Player
Owner :: Elect Abstract Player
You :: Elect Abstract Player
deriving instance (Eq a) => Eq (Elect p a)
deriving instance (Ord a) => Ord (Elect p a)
As is, the above code fails to compile. But if I move ElectRefAsTypeOf
to be the last constructor for the GADT, the code does compile. If I remove one of the Elect Abstract Player
constructors, the code still won't compile even if the ElectRefAsTypeOf
is moved.
Trac metadata
Trac field | Value |
---|---|
Version | 7.6.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | MacOS X |
Architecture |