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 |