zonkQuantifiedTyVar panic
Small program (extracted from the dev version of vector):
{-# LANGUAGE Rank2Types, MultiParamTypeClasses, FlexibleContexts, TypeFamilies, ScopedTypeVariables #-}
module T where
type family Mutable (v :: * -> *) :: * -> * -> *
class MVector (v :: * -> * -> *) a
class MVector (Mutable v) a => Vector v a where
copy :: Monad m => Mutable v s a -> v a -> m ()
data Chunk v s a = Chunk (forall m. (Monad m, Vector v a) => Mutable v s a -> m ())
vstep (v:vs) = Chunk (\mv -> copy mv v)When I compile this, I get:
ghc: panic! (the 'impossible' happened)
(GHC version 7.6.1 for x86_64-unknown-linux):
zonkQuantifiedTyVar f_afr{tv} [fsk]Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.6.1 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
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| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |