get_unused_cons :: [Pat Id] -> [DataCon]
get_unused_cons used_cons = unused_cons
where
- (ConPatOut { pat_ty = ty }) = head used_cons
- ty_con = tcTyConAppTyCon ty -- Newtype observable
- all_cons = tyConDataCons ty_con
- used_cons_as_id = map (\ (ConPatOut{ pat_con = L _ d}) -> d) used_cons
- unused_cons = uniqSetToList
- (mkUniqSet all_cons `minusUniqSet` mkUniqSet used_cons_as_id)
+ (ConPatOut { pat_con = l_con, pat_ty = ty }) = head used_cons
+ ty_con = dataConTyCon (unLoc l_con) -- Newtype observable
+ all_cons = tyConDataCons ty_con
+ used_cons_as_id = map (\ (ConPatOut{ pat_con = L _ d}) -> d) used_cons
+ unused_cons = uniqSetToList
+ (mkUniqSet all_cons `minusUniqSet` mkUniqSet used_cons_as_id)
all_vars :: [Pat Id] -> Bool
all_vars [] = True
the_rhs = mkHsConApp cls_data_con cls_inst_tys $
map HsVar (sc_dict_ids ++ op_ids)
+ -- Warning: this HsCase scrutinises a value with a PredTy, which is
+ -- never otherwise seen in Haskell source code. It'd be
+ -- nicer to generate Core directly!
; return (HsCase (noLoc coerced_rep_dict) $
MatchGroup [the_match] (mkFunTy inst_head_ty inst_head_ty)) }
where
-
+%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcType]{Types used in the typechecker}
-----------------------
tcTyConAppTyCon :: Type -> TyCon
-tcTyConAppTyCon ty = fst (tcSplitTyConApp ty)
+tcTyConAppTyCon ty = case tcSplitTyConApp_maybe ty of
+ Just (tc, _) -> tc
+ Nothing -> pprPanic "tcTyConAppTyCon" (pprType ty)
tcTyConAppArgs :: Type -> [Type]
-tcTyConAppArgs ty = snd (tcSplitTyConApp ty)
+tcTyConAppArgs ty = case tcSplitTyConApp_maybe ty of
+ Just (_, args) -> args
+ Nothing -> pprPanic "tcTyConAppArgs" (pprType ty)
tcSplitTyConApp :: Type -> (TyCon, [Type])
tcSplitTyConApp ty = case tcSplitTyConApp_maybe ty of
tcSplitTyConApp_maybe ty | Just ty' <- tcView ty = tcSplitTyConApp_maybe ty'
tcSplitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
tcSplitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
-tcSplitTyConApp_maybe (AppTy arg res) = Just (funTyCon, [arg,res])
-- Newtypes are opaque, so they may be split
-- However, predicates are not treated
-- as tycon applications by the type checker
-
--- XXX - 2006-09-24: This case is hard-coded in (rendering predicates opaque as well)
--- to make the newly reworked newtype-deriving work on the trivial case:
--- newtype T = T () deriving (Eq, Ord)
--- Please remove this if the newtype-deriving scheme no longer produces a PredTy.
-tcSplitTyConApp_maybe (PredTy (ClassP _ [ty'])) = tcSplitTyConApp_maybe ty'
-
tcSplitTyConApp_maybe other = Nothing
-----------------------