Type Family panic

The following code produces the ghc panic below.

{-# LANGUAGE RankNTypes, TypeFamilies #-}
import Data.VectorSpace 

data I  = I { integral :: (VectorSpace v, Scalar v ~ Double) => v
            }

-- This works
-- integral :: (VectorSpace v, Scalar v ~ Double) => v
-- integral = undefined

-- type BallAnim = Input -> Behavior Ball

followMouse i = integral undefined undefined

ff>ghci GhcBug.hs
GHCi, version 6.10.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Main             ( GhcBug.hs, interpreted )
: panic! (the 'impossible' happened)
  (GHC version 6.10.1 for i386-unknown-mingw32):
        applyTypeToArgs
    ipv{v B4} [lid]
      @ (a{tv arL} [sk] -> t_arM{tv} [sk])
      $dVectorSpace{v arP} [lid]
      (base:GHC.Err.undefined{v rdH} [gid] @ a{tv arL} [sk])
    (vector-space-0.5:Data.VectorSpace.Scalar{tc rgl}
       (a{tv arL} [sk] -> t_arM{tv} [sk])
       ~
     ghc-prim:GHC.Types.Double{(w) tc 3u}) =>
    a{tv arL} [sk] -> t_arM{tv} [sk]

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

Trac metadata

Trac field	Value
Version	6.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Windows
Architecture	x86