\begin{code}
module Type (
-- re-exports from TypeRep:
- Type, PredType, ThetaType,
+ TyThing(..),
+ Type, PredType(..), ThetaType,
Kind, TyVarSubst,
superKind, superBoxity, -- KX and BX respectively
applyTy, applyTys, isForAllTy, dropForAlls,
-- Source types
- SourceType(..), sourceTypeRep, mkPredTy, mkPredTys,
+ isPredTy, predTypeRep, mkPredTy, mkPredTys,
-- Newtypes
- splitNewType_maybe,
+ splitRecNewType_maybe,
-- Lifting and boxity
- isUnLiftedType, isUnboxedTupleType, isAlgType, isStrictType, isPrimitiveType,
+ isUnLiftedType, isUnboxedTupleType, isAlgType, isPrimitiveType,
+ isStrictType, isStrictPred,
-- Free variables
tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
-- Other imports:
-import {-# SOURCE #-} PprType( pprType ) -- Only called in debug messages
import {-# SOURCE #-} Subst ( substTyWith )
-- friends:
-import Var ( Id, TyVar, tyVarKind, tyVarName, setTyVarName )
+import Var ( TyVar, tyVarKind, tyVarName, setTyVarName )
import VarEnv
import VarSet
mkTyVarTys = map mkTyVarTy -- a common use of mkTyVarTy
getTyVar :: String -> Type -> TyVar
-getTyVar msg (TyVarTy tv) = tv
-getTyVar msg (SourceTy p) = getTyVar msg (sourceTypeRep p)
-getTyVar msg (NoteTy _ t) = getTyVar msg t
-getTyVar msg other = panic ("getTyVar: " ++ msg)
-
-getTyVar_maybe :: Type -> Maybe TyVar
-getTyVar_maybe (TyVarTy tv) = Just tv
-getTyVar_maybe (NoteTy _ t) = getTyVar_maybe t
-getTyVar_maybe (SourceTy p) = getTyVar_maybe (sourceTypeRep p)
-getTyVar_maybe other = Nothing
+getTyVar msg ty = case getTyVar_maybe ty of
+ Just tv -> tv
+ Nothing -> panic ("getTyVar: " ++ msg)
isTyVarTy :: Type -> Bool
-isTyVarTy (TyVarTy tv) = True
-isTyVarTy (NoteTy _ ty) = isTyVarTy ty
-isTyVarTy (SourceTy p) = isTyVarTy (sourceTypeRep p)
-isTyVarTy other = False
+isTyVarTy ty = isJust (getTyVar_maybe ty)
+
+getTyVar_maybe :: Type -> Maybe TyVar
+getTyVar_maybe (TyVarTy tv) = Just tv
+getTyVar_maybe (NoteTy _ t) = getTyVar_maybe t
+getTyVar_maybe (PredTy p) = getTyVar_maybe (predTypeRep p)
+getTyVar_maybe (NewTcApp tc tys) = getTyVar_maybe (newTypeRep tc tys)
+getTyVar_maybe other = Nothing
\end{code}
\begin{code}
mkAppTy orig_ty1 orig_ty2
- = ASSERT( not (isSourceTy orig_ty1) ) -- Source types are of kind *
+ = ASSERT2( not (isPredTy orig_ty1), crudePprType orig_ty1 ) -- Source types are of kind *
mk_app orig_ty1
where
mk_app (NoteTy _ ty1) = mk_app ty1
+ mk_app (NewTcApp tc tys) = NewTcApp tc (tys ++ [orig_ty2])
mk_app (TyConApp tc tys) = mkGenTyConApp tc (tys ++ [orig_ty2])
mk_app ty1 = AppTy orig_ty1 orig_ty2
-- We call mkGenTyConApp because the TyConApp could be an
-- returns to (Ratio Integer), which has needlessly lost
-- the Rational part.
mkAppTys orig_ty1 orig_tys2
- = ASSERT( not (isSourceTy orig_ty1) ) -- Source types are of kind *
+ = ASSERT( not (isPredTy orig_ty1) ) -- Source types are of kind *
mk_app orig_ty1
where
mk_app (NoteTy _ ty1) = mk_app ty1
+ mk_app (NewTcApp tc tys) = NewTcApp tc (tys ++ orig_tys2)
mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ orig_tys2)
+ -- Use mkTyConApp in case tc is (->)
mk_app ty1 = foldl AppTy orig_ty1 orig_tys2
splitAppTy_maybe :: Type -> Maybe (Type, Type)
splitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2)
splitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2)
splitAppTy_maybe (NoteTy _ ty) = splitAppTy_maybe ty
-splitAppTy_maybe (SourceTy p) = splitAppTy_maybe (sourceTypeRep p)
+splitAppTy_maybe (PredTy p) = splitAppTy_maybe (predTypeRep p)
+splitAppTy_maybe (NewTcApp tc tys) = splitAppTy_maybe (newTypeRep tc tys)
splitAppTy_maybe (TyConApp tc tys) = case snocView tys of
Nothing -> Nothing
- Just (tys',ty') -> Just (TyConApp tc tys', ty')
+ Just (tys',ty') -> Just (mkGenTyConApp tc tys', ty')
+ -- mkGenTyConApp just in case the tc is a newtype
+
splitAppTy_maybe other = Nothing
splitAppTy :: Type -> (Type, Type)
where
split orig_ty (AppTy ty arg) args = split ty ty (arg:args)
split orig_ty (NoteTy _ ty) args = split orig_ty ty args
- split orig_ty (SourceTy p) args = split orig_ty (sourceTypeRep p) args
+ split orig_ty (PredTy p) args = split orig_ty (predTypeRep p) args
+ split orig_ty (NewTcApp tc tc_args) args = split orig_ty (newTypeRep tc tc_args) args
+ split orig_ty (TyConApp tc tc_args) args = (mkGenTyConApp tc [], tc_args ++ args)
+ -- mkGenTyConApp just in case the tc is a newtype
split orig_ty (FunTy ty1 ty2) args = ASSERT( null args )
(TyConApp funTyCon [], [ty1,ty2])
- split orig_ty (TyConApp tc tc_args) args = (TyConApp tc [], tc_args ++ args)
split orig_ty ty args = (orig_ty, args)
\end{code}
isFunTy ty = isJust (splitFunTy_maybe ty)
splitFunTy :: Type -> (Type, Type)
-splitFunTy (FunTy arg res) = (arg, res)
-splitFunTy (NoteTy _ ty) = splitFunTy ty
-splitFunTy (SourceTy p) = splitFunTy (sourceTypeRep p)
+splitFunTy (FunTy arg res) = (arg, res)
+splitFunTy (NoteTy _ ty) = splitFunTy ty
+splitFunTy (PredTy p) = splitFunTy (predTypeRep p)
+splitFunTy (NewTcApp tc tys) = splitFunTy (newTypeRep tc tys)
+splitFunTy other = pprPanic "splitFunTy" (crudePprType other)
splitFunTy_maybe :: Type -> Maybe (Type, Type)
-splitFunTy_maybe (FunTy arg res) = Just (arg, res)
-splitFunTy_maybe (NoteTy _ ty) = splitFunTy_maybe ty
-splitFunTy_maybe (SourceTy p) = splitFunTy_maybe (sourceTypeRep p)
-splitFunTy_maybe other = Nothing
+splitFunTy_maybe (FunTy arg res) = Just (arg, res)
+splitFunTy_maybe (NoteTy _ ty) = splitFunTy_maybe ty
+splitFunTy_maybe (PredTy p) = splitFunTy_maybe (predTypeRep p)
+splitFunTy_maybe (NewTcApp tc tys) = splitFunTy_maybe (newTypeRep tc tys)
+splitFunTy_maybe other = Nothing
splitFunTys :: Type -> ([Type], Type)
splitFunTys ty = split [] ty ty
where
- split args orig_ty (FunTy arg res) = split (arg:args) res res
- split args orig_ty (NoteTy _ ty) = split args orig_ty ty
- split args orig_ty (SourceTy p) = split args orig_ty (sourceTypeRep p)
- split args orig_ty ty = (reverse args, orig_ty)
+ split args orig_ty (FunTy arg res) = split (arg:args) res res
+ split args orig_ty (NoteTy _ ty) = split args orig_ty ty
+ split args orig_ty (PredTy p) = split args orig_ty (predTypeRep p)
+ split args orig_ty (NewTcApp tc tys) = split args orig_ty (newTypeRep tc tys)
+ split args orig_ty ty = (reverse args, orig_ty)
zipFunTys :: Outputable a => [a] -> Type -> ([(a,Type)], Type)
zipFunTys orig_xs orig_ty = split [] orig_xs orig_ty orig_ty
where
- split acc [] nty ty = (reverse acc, nty)
- split acc (x:xs) nty (FunTy arg res) = split ((x,arg):acc) xs res res
- split acc xs nty (NoteTy _ ty) = split acc xs nty ty
- split acc xs nty (SourceTy p) = split acc xs nty (sourceTypeRep p)
- split acc (x:xs) nty ty = pprPanic "zipFunTys" (ppr orig_xs <+> pprType orig_ty)
+ split acc [] nty ty = (reverse acc, nty)
+ split acc (x:xs) nty (FunTy arg res) = split ((x,arg):acc) xs res res
+ split acc xs nty (NoteTy _ ty) = split acc xs nty ty
+ split acc xs nty (PredTy p) = split acc xs nty (predTypeRep p)
+ split acc xs nty (NewTcApp tc tys) = split acc xs nty (newTypeRep tc tys)
+ split acc (x:xs) nty ty = pprPanic "zipFunTys" (ppr orig_xs <+> crudePprType orig_ty)
funResultTy :: Type -> Type
-funResultTy (FunTy arg res) = res
-funResultTy (NoteTy _ ty) = funResultTy ty
-funResultTy (SourceTy p) = funResultTy (sourceTypeRep p)
-funResultTy ty = pprPanic "funResultTy" (pprType ty)
+funResultTy (FunTy arg res) = res
+funResultTy (NoteTy _ ty) = funResultTy ty
+funResultTy (PredTy p) = funResultTy (predTypeRep p)
+funResultTy (NewTcApp tc tys) = funResultTy (newTypeRep tc tys)
+funResultTy ty = pprPanic "funResultTy" (crudePprType ty)
funArgTy :: Type -> Type
-funArgTy (FunTy arg res) = arg
-funArgTy (NoteTy _ ty) = funArgTy ty
-funArgTy (SourceTy p) = funArgTy (sourceTypeRep p)
-funArgTy ty = pprPanic "funArgTy" (pprType ty)
+funArgTy (FunTy arg res) = arg
+funArgTy (NoteTy _ ty) = funArgTy ty
+funArgTy (PredTy p) = funArgTy (predTypeRep p)
+funArgTy (NewTcApp tc tys) = funArgTy (newTypeRep tc tys)
+funArgTy ty = pprPanic "funArgTy" (crudePprType ty)
\end{code}
---------------------------------------------------------------------
TyConApp
~~~~~~~~
-@mkTyConApp@ is a key function, because it builds a TyConApp, FunTy or SourceTy,
+@mkTyConApp@ is a key function, because it builds a TyConApp, FunTy or PredTy,
as apppropriate.
\begin{code}
| isFunTyCon tycon, [ty1,ty2] <- tys
= FunTy ty1 ty2
- | isNewTyCon tycon, -- A saturated newtype application;
- not (isRecursiveTyCon tycon), -- Not recursive (we don't use SourceTypes for them)
- tys `lengthIs` tyConArity tycon -- use the SourceType form
- = SourceTy (NType tycon tys)
+ | isNewTyCon tycon
+ = NewTcApp tycon tys
| otherwise
= ASSERT(not (isSynTyCon tycon))
TyConApp tycon tys
mkTyConTy :: TyCon -> Type
-mkTyConTy tycon = ASSERT( not (isSynTyCon tycon) )
- TyConApp tycon []
+mkTyConTy tycon = mkTyConApp tycon []
-- splitTyConApp "looks through" synonyms, because they don't
-- mean a distinct type, but all other type-constructor applications
splitTyConApp :: Type -> (TyCon, [Type])
splitTyConApp ty = case splitTyConApp_maybe ty of
Just stuff -> stuff
- Nothing -> pprPanic "splitTyConApp" (pprType ty)
+ Nothing -> pprPanic "splitTyConApp" (crudePprType ty)
splitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
splitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
splitTyConApp_maybe (NoteTy _ ty) = splitTyConApp_maybe ty
-splitTyConApp_maybe (SourceTy p) = splitTyConApp_maybe (sourceTypeRep p)
+splitTyConApp_maybe (PredTy p) = splitTyConApp_maybe (predTypeRep p)
+splitTyConApp_maybe (NewTcApp tc tys) = splitTyConApp_maybe (newTypeRep tc tys)
splitTyConApp_maybe other = Nothing
\end{code}
(e) [recursive] newtypes
It's useful in the back end.
-Remember, non-recursive newtypes get expanded as part of the SourceTy case,
-but recursive ones are represented by TyConApps and have to be expanded
-by steam.
-
\begin{code}
repType :: Type -> Type
+-- Only applied to types of kind *; hence tycons are saturated
repType (ForAllTy _ ty) = repType ty
repType (NoteTy _ ty) = repType ty
-repType (SourceTy p) = repType (sourceTypeRep p)
-repType (TyConApp tc tys) | isNewTyCon tc && tys `lengthIs` tyConArity tc
- = repType (newTypeRep tc tys)
+repType (PredTy p) = repType (predTypeRep p)
+repType (NewTcApp tc tys) = ASSERT( tys `lengthIs` tyConArity tc )
+ repType (new_type_rep tc tys)
repType ty = ty
FunTy _ _ -> PtrRep
AppTy _ _ -> PtrRep -- ??
TyVarTy _ -> PtrRep
+ other -> pprPanic "typePrimRep" (crudePprType ty)
\end{code}
splitForAllTy_maybe ty = splitFAT_m ty
where
splitFAT_m (NoteTy _ ty) = splitFAT_m ty
- splitFAT_m (SourceTy p) = splitFAT_m (sourceTypeRep p)
+ splitFAT_m (PredTy p) = splitFAT_m (predTypeRep p)
+ splitFAT_m (NewTcApp tc tys) = splitFAT_m (newTypeRep tc tys)
splitFAT_m (ForAllTy tyvar ty) = Just(tyvar, ty)
splitFAT_m _ = Nothing
splitForAllTys :: Type -> ([TyVar], Type)
splitForAllTys ty = split ty ty []
where
- split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs)
- split orig_ty (NoteTy _ ty) tvs = split orig_ty ty tvs
- split orig_ty (SourceTy p) tvs = split orig_ty (sourceTypeRep p) tvs
- split orig_ty t tvs = (reverse tvs, orig_ty)
+ split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs)
+ split orig_ty (NoteTy _ ty) tvs = split orig_ty ty tvs
+ split orig_ty (PredTy p) tvs = split orig_ty (predTypeRep p) tvs
+ split orig_ty (NewTcApp tc tys) tvs = split orig_ty (newTypeRep tc tys) tvs
+ split orig_ty t tvs = (reverse tvs, orig_ty)
dropForAlls :: Type -> Type
dropForAlls ty = snd (splitForAllTys ty)
\begin{code}
applyTy :: Type -> Type -> Type
-applyTy (SourceTy p) arg = applyTy (sourceTypeRep p) arg
-applyTy (NoteTy _ fun) arg = applyTy fun arg
-applyTy (ForAllTy tv ty) arg = substTyWith [tv] [arg] ty
-applyTy other arg = panic "applyTy"
+applyTy (PredTy p) arg = applyTy (predTypeRep p) arg
+applyTy (NewTcApp tc tys) arg = applyTy (newTypeRep tc tys) arg
+applyTy (NoteTy _ fun) arg = applyTy fun arg
+applyTy (ForAllTy tv ty) arg = substTyWith [tv] [arg] ty
+applyTy other arg = panic "applyTy"
applyTys :: Type -> [Type] -> Type
-- This function is interesting because
= substTyWith (take n_args tvs) arg_tys
(mkForAllTys (drop n_args tvs) rho_ty)
| otherwise -- Too many type args
- = ASSERT2( n_tvs > 0, pprType orig_fun_ty ) -- Zero case gives infnite loop!
+ = ASSERT2( n_tvs > 0, crudePprType orig_fun_ty ) -- Zero case gives infnite loop!
applyTys (substTyWith tvs (take n_tvs arg_tys) rho_ty)
(drop n_tvs arg_tys)
where
Source types are always lifted.
-The key function is sourceTypeRep which gives the representation of a source type:
+The key function is predTypeRep which gives the representation of a source type:
\begin{code}
mkPredTy :: PredType -> Type
-mkPredTy pred = SourceTy pred
+mkPredTy pred = PredTy pred
mkPredTys :: ThetaType -> [Type]
-mkPredTys preds = map SourceTy preds
-
-sourceTypeRep :: SourceType -> Type
--- Convert a predicate to its "representation type";
--- the type of evidence for that predicate, which is actually passed at runtime
-sourceTypeRep (IParam _ ty) = ty
-sourceTypeRep (ClassP clas tys) = mkTyConApp (classTyCon clas) tys
- -- Note the mkTyConApp; the classTyCon might be a newtype!
-sourceTypeRep (NType tc tys) = newTypeRep tc tys
- -- ToDo: Consider caching this substitution in a NType
-
-isSourceTy :: Type -> Bool
-isSourceTy (NoteTy _ ty) = isSourceTy ty
-isSourceTy (SourceTy sty) = True
-isSourceTy _ = False
+mkPredTys preds = map PredTy preds
+
+predTypeRep :: PredType -> Type
+-- Convert a PredType to its "representation type";
+-- the post-type-checking type used by all the Core passes of GHC.
+predTypeRep (IParam _ ty) = ty
+predTypeRep (ClassP clas tys) = mkTyConApp (classTyCon clas) tys
+ -- Result might be a NewTcApp, but the consumer will
+ -- look through that too if necessary
+
+isPredTy :: Type -> Bool
+isPredTy (NoteTy _ ty) = isPredTy ty
+isPredTy (PredTy sty) = True
+isPredTy _ = False
+\end{code}
-splitNewType_maybe :: Type -> Maybe Type
--- Newtypes that are recursive are reprsented by TyConApp, just
--- as they always were. Occasionally we want to find their representation type.
--- NB: remember that in this module, non-recursive newtypes are transparent
+%************************************************************************
+%* *
+ NewTypes
+%* *
+%************************************************************************
-splitNewType_maybe ty
- = case splitTyConApp_maybe ty of
- Just (tc,tys) | isNewTyCon tc -> ASSERT( tys `lengthIs` tyConArity tc )
- -- The assert should hold because repType should
- -- only be applied to *types* (of kind *)
- Just (newTypeRep tc tys)
- other -> Nothing
+\begin{code}
+splitRecNewType_maybe :: Type -> Maybe Type
+-- Newtypes are always represented by a NewTcApp
+-- Sometimes we want to look through a recursive newtype, and that's what happens here
+-- Only applied to types of kind *, hence the newtype is always saturated
+splitRecNewType_maybe (NoteTy _ ty) = splitRecNewType_maybe ty
+splitRecNewType_maybe (NewTcApp tc tys)
+ | isRecursiveTyCon tc
+ = ASSERT( tys `lengthIs` tyConArity tc && isNewTyCon tc )
+ -- The assert should hold because repType should
+ -- only be applied to *types* (of kind *)
+ Just (new_type_rep tc tys)
+splitRecNewType_maybe other = Nothing
+-----------------------------
+newTypeRep :: TyCon -> [Type] -> Type
-- A local helper function (not exported)
-newTypeRep new_tycon tys = case newTyConRep new_tycon of
- (tvs, rep_ty) -> substTyWith tvs tys rep_ty
+-- Expands a newtype application to
+-- *either* a vanilla TyConApp (recursive newtype, or non-saturated)
+-- *or* the newtype representation (otherwise)
+-- Either way, the result is not a NewTcApp
+--
+-- NB: the returned TyConApp is always deconstructed immediately by the
+-- caller... a TyConApp with a newtype type constructor never lives
+-- in an ordinary type
+newTypeRep tc tys
+ | not (isRecursiveTyCon tc), -- Not recursive and saturated
+ tys `lengthIs` tyConArity tc -- treat as equivalent to expansion
+ = new_type_rep tc tys
+ | otherwise
+ = TyConApp tc tys
+ -- ToDo: Consider caching this substitution in a NType
+
+----------------------------
+-- new_type_rep doesn't ask any questions:
+-- it just expands newtype, whether recursive or not
+new_type_rep new_tycon tys = ASSERT( tys `lengthIs` tyConArity new_tycon )
+ case newTyConRep new_tycon of
+ (tvs, rep_ty) -> substTyWith tvs tys rep_ty
\end{code}
typeKind (TyVarTy tyvar) = tyVarKind tyvar
typeKind (TyConApp tycon tys) = foldr (\_ k -> funResultTy k) (tyConKind tycon) tys
+typeKind (NewTcApp tycon tys) = foldr (\_ k -> funResultTy k) (tyConKind tycon) tys
typeKind (NoteTy _ ty) = typeKind ty
-typeKind (SourceTy _) = liftedTypeKind -- Predicates are always
+typeKind (PredTy _) = liftedTypeKind -- Predicates are always
-- represented by lifted types
typeKind (AppTy fun arg) = funResultTy (typeKind fun)
tyVarsOfType :: Type -> TyVarSet
tyVarsOfType (TyVarTy tv) = unitVarSet tv
tyVarsOfType (TyConApp tycon tys) = tyVarsOfTypes tys
+tyVarsOfType (NewTcApp tycon tys) = tyVarsOfTypes tys
tyVarsOfType (NoteTy (FTVNote tvs) ty2) = tvs
tyVarsOfType (NoteTy (SynNote ty1) ty2) = tyVarsOfType ty2 -- See note [Syn] below
-tyVarsOfType (SourceTy sty) = tyVarsOfSourceType sty
+tyVarsOfType (PredTy sty) = tyVarsOfPred sty
tyVarsOfType (FunTy arg res) = tyVarsOfType arg `unionVarSet` tyVarsOfType res
tyVarsOfType (AppTy fun arg) = tyVarsOfType fun `unionVarSet` tyVarsOfType arg
tyVarsOfType (ForAllTy tyvar ty) = tyVarsOfType ty `minusVarSet` unitVarSet tyvar
tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys
tyVarsOfPred :: PredType -> TyVarSet
-tyVarsOfPred = tyVarsOfSourceType -- Just a subtype
-
-tyVarsOfSourceType :: SourceType -> TyVarSet
-tyVarsOfSourceType (IParam _ ty) = tyVarsOfType ty
-tyVarsOfSourceType (ClassP _ tys) = tyVarsOfTypes tys
-tyVarsOfSourceType (NType _ tys) = tyVarsOfTypes tys
+tyVarsOfPred (IParam _ ty) = tyVarsOfType ty
+tyVarsOfPred (ClassP _ tys) = tyVarsOfTypes tys
tyVarsOfTheta :: ThetaType -> TyVarSet
-tyVarsOfTheta = foldr (unionVarSet . tyVarsOfSourceType) emptyVarSet
+tyVarsOfTheta = foldr (unionVarSet . tyVarsOfPred) emptyVarSet
-- Add a Note with the free tyvars to the top of the type
addFreeTyVars :: Type -> Type
Just tv' -> TyVarTy tv'
go (TyConApp tycon tys) = let args = map go tys
in args `seqList` TyConApp tycon args
+ go (NewTcApp tycon tys) = let args = map go tys
+ in args `seqList` NewTcApp tycon args
go (NoteTy note ty) = (NoteTy $! (go_note note)) $! (go ty)
- go (SourceTy sty) = SourceTy (tidySourceType env sty)
+ go (PredTy sty) = PredTy (tidyPred env sty)
go (AppTy fun arg) = (AppTy $! (go fun)) $! (go arg)
go (FunTy fun arg) = (FunTy $! (go fun)) $! (go arg)
go (ForAllTy tv ty) = ForAllTy tvp $! (tidyType envp ty)
tidyTypes env tys = map (tidyType env) tys
-tidyPred :: TidyEnv -> SourceType -> SourceType
-tidyPred = tidySourceType
-
-tidySourceType :: TidyEnv -> SourceType -> SourceType
-tidySourceType env (IParam n ty) = IParam n (tidyType env ty)
-tidySourceType env (ClassP clas tys) = ClassP clas (tidyTypes env tys)
-tidySourceType env (NType tc tys) = NType tc (tidyTypes env tys)
+tidyPred :: TidyEnv -> PredType -> PredType
+tidyPred env (IParam n ty) = IParam n (tidyType env ty)
+tidyPred env (ClassP clas tys) = ClassP clas (tidyTypes env tys)
\end{code}
-- They are pretty bogus types, mind you. It would be better never to
-- construct them
-isUnLiftedType (ForAllTy tv ty) = isUnLiftedType ty
-isUnLiftedType (NoteTy _ ty) = isUnLiftedType ty
-isUnLiftedType (TyConApp tc _) = isUnLiftedTyCon tc
-isUnLiftedType (SourceTy _) = False -- All source types are lifted
-isUnLiftedType other = False
+isUnLiftedType (ForAllTy tv ty) = isUnLiftedType ty
+isUnLiftedType (NoteTy _ ty) = isUnLiftedType ty
+isUnLiftedType (TyConApp tc _) = isUnLiftedTyCon tc
+isUnLiftedType (PredTy _) = False -- All source types are lifted
+isUnLiftedType (NewTcApp tc tys) = isUnLiftedType (newTypeRep tc tys)
+isUnLiftedType other = False
isUnboxedTupleType :: Type -> Bool
isUnboxedTupleType ty = case splitTyConApp_maybe ty of
which is below TcType in the hierarchy, so it's convenient to put it here.
\begin{code}
-isStrictType (ForAllTy tv ty) = isStrictType ty
-isStrictType (NoteTy _ ty) = isStrictType ty
-isStrictType (TyConApp tc _) = isUnLiftedTyCon tc
-isStrictType (SourceTy (ClassP clas _)) = opt_DictsStrict && not (isNewTyCon (classTyCon clas))
+isStrictType (ForAllTy tv ty) = isStrictType ty
+isStrictType (NoteTy _ ty) = isStrictType ty
+isStrictType (TyConApp tc _) = isUnLiftedTyCon tc
+isStrictType (NewTcApp tc tys) = isStrictType (newTypeRep tc tys)
+isStrictType (PredTy pred) = isStrictPred pred
+isStrictType other = False
+
+isStrictPred (ClassP clas _) = opt_DictsStrict && not (isNewTyCon (classTyCon clas))
+isStrictPred other = False
-- We may be strict in dictionary types, but only if it
-- has more than one component.
-- [Being strict in a single-component dictionary risks
-- poking the dictionary component, which is wrong.]
-isStrictType other = False
\end{code}
\begin{code}
seqType (AppTy t1 t2) = seqType t1 `seq` seqType t2
seqType (FunTy t1 t2) = seqType t1 `seq` seqType t2
seqType (NoteTy note t2) = seqNote note `seq` seqType t2
-seqType (SourceTy p) = seqPred p
+seqType (PredTy p) = seqPred p
seqType (TyConApp tc tys) = tc `seq` seqTypes tys
+seqType (NewTcApp tc tys) = tc `seq` seqTypes tys
seqType (ForAllTy tv ty) = tv `seq` seqType ty
seqTypes :: [Type] -> ()
seqNote (SynNote ty) = seqType ty
seqNote (FTVNote set) = sizeUniqSet set `seq` ()
-seqPred :: SourceType -> ()
+seqPred :: PredType -> ()
seqPred (ClassP c tys) = c `seq` seqTypes tys
-seqPred (NType tc tys) = tc `seq` seqTypes tys
seqPred (IParam n ty) = n `seq` seqType ty
\end{code}
eq_ty env (NoteTy _ t1) t2 = eq_ty env t1 t2
eq_ty env t1 (NoteTy _ t2) = eq_ty env t1 t2
--- Look through SourceTy. This is where the looping danger comes from
-eq_ty env (SourceTy sty1) t2 = eq_ty env (sourceTypeRep sty1) t2
-eq_ty env t1 (SourceTy sty2) = eq_ty env t1 (sourceTypeRep sty2)
+-- Look through PredTy and NewTcApp. This is where the looping danger comes from.
+-- We don't bother to check for the PredType/PredType case, no good reason
+-- Hmm: maybe there is a good reason: see the notes below about newtypes
+eq_ty env (PredTy sty1) t2 = eq_ty env (predTypeRep sty1) t2
+eq_ty env t1 (PredTy sty2) = eq_ty env t1 (predTypeRep sty2)
+
+-- NB: we *cannot* short-cut the newtype comparison thus:
+-- eq_ty env (NewTcApp tc1 tys1) (NewTcApp tc2 tys2)
+-- | (tc1 == tc2) = (eq_tys env tys1 tys2)
+--
+-- Consider:
+-- newtype T a = MkT [a]
+-- newtype Foo m = MkFoo (forall a. m a -> Int)
+-- w1 :: Foo []
+-- w1 = ...
+--
+-- w2 :: Foo T
+-- w2 = MkFoo (\(MkT x) -> case w1 of MkFoo f -> f x)
+--
+-- We end up with w2 = w1; so we need that Foo T = Foo []
+-- but we can only expand saturated newtypes, so just comparing
+-- T with [] won't do.
+
+eq_ty env (NewTcApp tc1 tys1) t2 = eq_ty env (newTypeRep tc1 tys1) t2
+eq_ty env t1 (NewTcApp tc2 tys2) = eq_ty env t1 (newTypeRep tc2 tys2)
-- The rest is plain sailing
eq_ty env (TyVarTy tv1) (TyVarTy tv2) = case lookupVarEnv env tv1 of
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