#4093: compiler hangs (type checking?)
-----------------------+----------------------------------------------------
Reporter: dias | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.13 | Keywords:
Os: Linux | Testcase:
Architecture: x86 | Failure: Compile-time crash
-----------------------+----------------------------------------------------
The compiler hangs while compiling the following program, probably during
type checking. Perhaps it has something to do with type functions?
Note: I can give you several variations of the same program that also
hang. Let me know if you want them.
{{{
{-# LANGUAGE GADTs, EmptyDataDecls, ScopedTypeVariables, TypeFamilies #-}
module Test () where
data C
data O
type family EitherCO e a b :: *
type instance EitherCO C a b = a
type instance EitherCO O a b = b
data MaybeC ex t where
JustC :: t -> MaybeC C t
NothingC :: MaybeC O t
data Block (n :: * -> * -> *) e x
blockToNodeList ::
forall n e x. (EitherCO e (A C O n) (A O O n) ~ A e O n,
EitherCO x (A C C n) (A C O n) ~ A C x n) =>
Block n e x -> A e x n
type A e x n = (MaybeC e (n C O), MaybeC x (n O C))
blockToNodeList b = foldBlockNodesF (f, l) b z
where
z :: EitherCO e (EitherCO e (A C O n) (A O O n)) (EitherCO e (A C O n)
(A O O n))
z = undefined
f :: n C O -> EitherCO e (A C O n) (A O O n) -> EitherCO e (A C O n)
(A O O n)
f n _ = (JustC n, NothingC)
l :: n O C -> EitherCO e (A C O n) (A O O n) -> EitherCO e (A C C n)
(A O C n)
l _ = undefined
foldBlockNodesF :: forall n a b c e x .
( n C O -> a -> b
, n O C -> b -> c)
-> (Block n e x -> EitherCO e a b -> EitherCO x c b)
foldBlockNodesF _ = undefined
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4093>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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