mkDictSelRhs :: Class
             -> Int         -- 0-indexed selector among (superclasses ++ methods)
             -> CoreExpr
mkDictSelRhs clas val_index
  = mkLams tyvars (Lam dict_id rhs_body)
  where
    tycon          = classTyCon clas
    new_tycon      = isNewTyCon tycon
    [data_con]     = tyConDataCons tycon
    tyvars         = dataConUnivTyVars data_con
    arg_tys        = dataConRepArgTys data_con  -- Includes the dictionary superclasses

    the_arg_id     = getNth arg_ids val_index
    pred           = mkClassPred clas (mkTyVarTys tyvars)
    dict_id        = mkTemplateLocal 1 pred
    arg_ids        = mkTemplateLocalsNum 2 arg_tys

    rhs_body | new_tycon = unwrapNewTypeBody tycon (map mkTyVarTy tyvars) (Var dict_id)
             | otherwise = Case (Var dict_id) dict_id (idType the_arg_id)
                                [(DataAlt data_con, arg_ids, varToCoreExpr the_arg_id)]
                                -- varToCoreExpr needed for equality superclass selectors
                                --   sel a b d = case x of { MkC _ (g:a~b) _ -> CO g }
mkDictSelRhs :: Class
             -> Int         -- 0-indexed selector among (superclasses ++ methods)
             -> CoreExpr
mkDictSelRhs clas val_index
  = mkLams tyvars (Lam dict_id rhs_body)
  where
    tycon          = classTyCon clas
    new_tycon      = isNewTyCon tycon
    [data_con]     = tyConDataCons tycon
    tyvars         = dataConUnivTyVars data_con
    arg_tys        = dataConRepArgTys data_con  -- Includes the dictionary superclasses

    the_arg_id     = getNth arg_ids val_index
    pred           = mkClassPred clas (mkTyVarTys tyvars)
    dict_id        = mkTemplateLocal 1 pred
    arg_ids        = mkTemplateLocalsNum 2 arg_tys

    rhs_body | new_tycon = unwrapNewTypeBody tycon (map mkTyVarTy tyvars) (Var dict_id)
             | otherwise = Case (Var dict_id) dict_id (idType the_arg_id)
                                [(DataAlt data_con, arg_ids, varToCoreExpr the_arg_id)]
                                -- varToCoreExpr needed for equality superclass selectors
                                --   sel a b d = case x of { MkC _ (g:a~b) _ -> CO g }
mkDictSelRhs clas val_index
  = mkLams tyvars (Lam dict_id rhs_body)
  where
    tycon          = classTyCon clas
    new_tycon      = isNewTyCon tycon
    [data_con]     = tyConDataCons tycon
    tyvars         = dataConUnivTyVars data_con
    arg_tys        = dataConRepArgTys data_con  -- Includes the dictionary superclasses

    the_arg_id     = getNth arg_ids val_index
    pred           = mkClassPred clas (mkTyVarTys tyvars)
    dict_id        = mkTemplateLocal 1 pred
    arg_ids        = mkTemplateLocalsNum 2 arg_tys

    rhs_body | new_tycon = unwrapNewTypeBody tycon (map mkTyVarTy tyvars) (Var dict_id)
             | otherwise = Case (Var dict_id) dict_id (idType the_arg_id)
                                [(DataAlt data_con, arg_ids, varToCoreExpr the_arg_id)]
                                -- varToCoreExpr needed for equality superclass selectors
                                --   sel a b d = case x of { MkC _ (g:a~b) _ -> CO g }