id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
6141,ghc: panic! (the 'impossible' happened),aSect,,"i tried to load the following code in ghci:

{-# OPTIONS_GHC -Wall -O2 #-}

module Main where

import Data.Map (Map)
import qualified Data.Map as Map

data Vertex a
   = Vertex { vname :: a }
   deriving (Show, Read, Eq)

data Edge a
   = Edge { xedge :: a
          , yedge :: a }
   deriving (Show, Read, Eq)

data Graph a
   = Graph { vertexes  :: [Vertex a]
           , edges     :: [Edge a]
           , adjacents :: Vertex a -> [Vertex a]
           } deriving (show, Read, Eq)


and then i got the following error:

ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for x86_64-unknown-linux):
	nameModule show{tv a25N}
",bug,closed,normal,,Compiler,7.4.1,invalid,,,Linux,x86_64 (amd64),GHC rejects valid program,,,,,