enerate the string for a *runtime* error message
matchContextErrString :: Outputable id
                      => HsMatchContext id -> SDoc
matchContextErrString (FunRhs (L _ fun) _) = text "function" <+> ppr fun
matchContex
matchContextErrString :: Outputable id
                      => HsMatchContext id -> SDoc
matchContextErrString (FunRhs (L _ fun) _) = text "function" <+> ppr fun
matchContextErrString (FunRhs (L _ fun) _) = text "function" <+> ppr fun