\begin{code}
module Type (
- -- re-exports from TypeRep:
- Type, PredType, ThetaType,
- Kind, TyVarSubst,
-
- TyThing(..), isTyClThing,
-
- superKind, superBoxity, -- KX and BX respectively
- liftedBoxity, unliftedBoxity, -- :: BX
- openKindCon, -- :: KX
- typeCon, -- :: BX -> KX
- liftedTypeKind, unliftedTypeKind, openTypeKind, -- :: KX
- mkArrowKind, mkArrowKinds, -- :: KX -> KX -> KX
- isTypeKind, isAnyTypeKind,
+ -- re-exports from TypeRep
+ TyThing(..), Type, PredType(..), ThetaType, TyVarSubst,
funTyCon,
- usageKindCon, -- :: KX
- usageTypeKind, -- :: KX
- usOnceTyCon, usManyTyCon, -- :: $
- usOnce, usMany, -- :: $
+ -- Re-exports from Kind
+ module Kind,
- -- exports from this module:
- hasMoreBoxityInfo, defaultKind,
+ -- Re-exports from TyCon
+ PrimRep(..),
mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, isTyVarTy,
applyTy, applyTys, isForAllTy, dropForAlls,
-- Source types
- SourceType(..), sourceTypeRep, mkPredTy, mkPredTys,
+ 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,
tidyTopType, tidyPred,
-- Comparison
- eqType, eqKind, eqUsage,
+ eqType,
-- Seq
- seqType, seqTypes
+ seqType, seqTypes,
+ -- Pretty-printing
+ pprType, pprParendType,
+ pprPred, pprTheta, pprThetaArrow, pprClassPred
) where
#include "HsVersions.h"
-- Other imports:
-import {-# SOURCE #-} PprType( pprType ) -- Only called in debug messages
import {-# SOURCE #-} Subst ( substTyWith )
-- friends:
-import Var ( Id, TyVar, tyVarKind, tyVarName, setTyVarName )
+import Kind
+import Var ( TyVar, tyVarKind, tyVarName, setTyVarName )
import VarEnv
import VarSet
import Class ( Class, classTyCon )
import TyCon ( TyCon, isRecursiveTyCon, isPrimTyCon,
isUnboxedTupleTyCon, isUnLiftedTyCon,
- isFunTyCon, isNewTyCon, newTyConRep,
+ isFunTyCon, isNewTyCon, newTyConRep, newTyConRhs,
isAlgTyCon, isSynTyCon, tyConArity,
- tyConKind, getSynTyConDefn,
- tyConPrimRep,
+ tyConKind, getSynTyConDefn, PrimRep(..), tyConPrimRep,
)
-- others
import CmdLineOpts ( opt_DictsStrict )
import SrcLoc ( noSrcLoc )
-import PrimRep ( PrimRep(..) )
import Unique ( Uniquable(..) )
-import Util ( mapAccumL, seqList, lengthIs )
+import Util ( mapAccumL, seqList, lengthIs, snocView )
import Outputable
import UniqSet ( sizeUniqSet ) -- Should come via VarSet
import Maybe ( isJust )
%************************************************************************
%* *
- TyThing
-%* *
-%************************************************************************
-
-\begin{code}
-data TyThing = AnId Id
- | ATyCon TyCon
- | AClass Class
-
-isTyClThing :: TyThing -> Bool
-isTyClThing (ATyCon _) = True
-isTyClThing (AClass _) = True
-isTyClThing (AnId _) = False
-
-instance NamedThing TyThing where
- getName (AnId id) = getName id
- getName (ATyCon tc) = getName tc
- getName (AClass cl) = getName cl
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Stuff to do with kinds.}
-%* *
-%************************************************************************
-
-\begin{code}
-hasMoreBoxityInfo :: Kind -> Kind -> Bool
--- (k1 `hasMoreBoxityInfo` k2) checks that k1 <: k2
-hasMoreBoxityInfo k1 k2
- | k2 `eqKind` openTypeKind = isAnyTypeKind k1
- | otherwise = k1 `eqKind` k2
- where
-
-isAnyTypeKind :: Kind -> Bool
--- True of kind * and *# and ?
-isAnyTypeKind (TyConApp tc _) = tc == typeCon || tc == openKindCon
-isAnyTypeKind (NoteTy _ k) = isAnyTypeKind k
-isAnyTypeKind other = False
-
-isTypeKind :: Kind -> Bool
--- True of kind * and *#
-isTypeKind (TyConApp tc _) = tc == typeCon
-isTypeKind (NoteTy _ k) = isTypeKind k
-isTypeKind other = False
-
-defaultKind :: Kind -> Kind
--- Used when generalising: default kind '?' to '*'
-defaultKind kind | kind `eqKind` openTypeKind = liftedTypeKind
- | otherwise = kind
-\end{code}
-
-
-%************************************************************************
-%* *
\subsection{Constructor-specific functions}
%* *
%************************************************************************
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 *
- mk_app orig_ty1
+ = 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 *
- mk_app orig_ty1
+ = 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 (TyConApp tc []) = Nothing
-splitAppTy_maybe (TyConApp tc tys) = split tys []
- where
- split [ty2] acc = Just (TyConApp tc (reverse acc), ty2)
- split (ty:tys) acc = split tys (ty:acc)
+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 (mkGenTyConApp tc tys', ty')
+ -- mkGenTyConApp just in case the tc is a newtype
-splitAppTy_maybe other = Nothing
+splitAppTy_maybe other = Nothing
splitAppTy :: Type -> (Type, Type)
splitAppTy ty = case splitAppTy_maybe ty of
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" (ppr 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 <+> ppr 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" (ppr 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" (ppr 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" (ppr 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
+-- ToDo: this could be moved to the code generator, using splitTyConApp instead
+-- of inspecting the type directly.
typePrimRep :: Type -> PrimRep
typePrimRep ty = case repType ty of
TyConApp tc _ -> tyConPrimRep tc
FunTy _ _ -> PtrRep
- AppTy _ _ -> PtrRep -- ??
+ AppTy _ _ -> PtrRep -- See note below
TyVarTy _ -> PtrRep
+ other -> pprPanic "typePrimRep" (ppr ty)
+ -- Types of the form 'f a' must be of kind *, not *#, so
+ -- we are guaranteed that they are represented by pointers.
+ -- The reason is that f must have kind *->*, not *->*#, because
+ -- (we claim) there is no way to constrain f's kind any other
+ -- way.
+
+-- 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}
-
---------------------------------------------------------------------
ForAllTy
~~~~~~~~
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)
-- (mkPiType now in CoreUtils)
-Applying a for-all to its arguments. Lift usage annotation as required.
+applyTy, applyTys
+~~~~~~~~~~~~~~~~~
+Instantiate a for-all type with one or more type arguments.
+Used when we have a polymorphic function applied to type args:
+ f t1 t2
+Then we use (applyTys type-of-f [t1,t2]) to compute the type of
+the expression.
\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
-applyTys orig_fun_ty arg_tys
- = substTyWith tvs arg_tys ty
- where
- (tvs, ty) = split orig_fun_ty arg_tys
-
- split fun_ty [] = ([], fun_ty)
- split (NoteTy _ fun_ty) args = split fun_ty args
- split (SourceTy p) args = split (sourceTypeRep p) args
- split (ForAllTy tv fun_ty) (arg:args) = case split fun_ty args of
- (tvs, ty) -> (tv:tvs, ty)
- split other_ty args = panic "applyTys"
- -- No show instance for Type yet
+-- This function is interesting because
+-- a) the function may have more for-alls than there are args
+-- b) less obviously, it may have fewer for-alls
+-- For case (b) think of
+-- applyTys (forall a.a) [forall b.b, Int]
+-- This really can happen, via dressing up polymorphic types with newtype
+-- clothing. Here's an example:
+-- newtype R = R (forall a. a->a)
+-- foo = case undefined :: R of
+-- R f -> f ()
+
+applyTys orig_fun_ty [] = orig_fun_ty
+applyTys orig_fun_ty arg_tys
+ | n_tvs == n_args -- The vastly common case
+ = substTyWith tvs arg_tys rho_ty
+ | n_tvs > n_args -- Too many for-alls
+ = substTyWith (take n_args tvs) arg_tys
+ (mkForAllTys (drop n_args tvs) rho_ty)
+ | otherwise -- Too many type args
+ = ASSERT2( n_tvs > 0, ppr orig_fun_ty ) -- Zero case gives infnite loop!
+ applyTys (substTyWith tvs (take n_tvs arg_tys) rho_ty)
+ (drop n_tvs arg_tys)
+ where
+ (tvs, rho_ty) = splitForAllTys orig_fun_ty
+ n_tvs = length tvs
+ n_args = length arg_tys
\end{code}
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.
+-- Unwraps only the outermost level; for example, the result might
+-- be a NewTcApp; c.f. newTypeRep
+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
+\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
+-- It only strips *one layer* off, so the caller will usually call itself recursively
+-- Only applied to types of kind *, hence the newtype is always saturated
+splitRecNewType_maybe (NoteTy _ ty) = splitRecNewType_maybe ty
+splitRecNewType_maybe (PredTy p) = splitRecNewType_maybe (predTypeRep p)
+splitRecNewType_maybe (NewTcApp tc tys)
+ | isRecursiveTyCon tc
+ = ASSERT( tys `lengthIs` tyConArity tc && isNewTyCon tc )
+ -- The assert should hold because splitRecNewType_maybe
+ -- should only be applied to *types* (of kind *)
+ Just (new_type_rhs 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 *the outermoset level of* a newtype application to
+-- *either* a vanilla TyConApp (recursive newtype, or non-saturated)
+-- *or* the newtype representation (otherwise), meaning the
+-- type written in the RHS of the newtype decl,
+-- which may itself be a newtype
+--
+-- Example: newtype R = MkR S
+-- newtype S = MkS T
+-- newtype T = MkT (T -> T)
+-- newTypeRep on R gives NewTcApp S
+-- on S gives NewTcApp T
+-- on T gives TyConApp T
+--
+-- 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_rhs tc tys
+ | otherwise
+ = TyConApp tc tys
+ -- ToDo: Consider caching this substitution in a NType
+
+-- new_type_rhs doesn't ask any questions:
+-- it just expands newtype one level, whether recursive or not
+new_type_rhs tc tys
+ = case newTyConRhs tc of
+ (tvs, rep_ty) -> substTyWith tvs tys rep_ty
\end{code}
typeKind :: Type -> Kind
typeKind (TyVarTy tyvar) = tyVarKind tyvar
-typeKind (TyConApp tycon tys) = foldr (\_ k -> funResultTy k) (tyConKind tycon) tys
+typeKind (TyConApp tycon tys) = foldr (\_ k -> kindFunResult k) (tyConKind tycon) tys
+typeKind (NewTcApp tycon tys) = foldr (\_ k -> kindFunResult 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)
-
-typeKind (FunTy arg res) = fix_up (typeKind res)
- where
- fix_up (TyConApp tycon _) | tycon == typeCon
- || tycon == openKindCon = liftedTypeKind
- fix_up (NoteTy _ kind) = fix_up kind
- fix_up kind = kind
- -- The basic story is
- -- typeKind (FunTy arg res) = typeKind res
- -- But a function is lifted regardless of its result type
- -- Hence the strange fix-up.
- -- Note that 'res', being the result of a FunTy, can't have
- -- a strange kind like (*->*).
-
+typeKind (AppTy fun arg) = kindFunResult (typeKind fun)
+typeKind (FunTy arg res) = liftedTypeKind
typeKind (ForAllTy tv ty) = typeKind ty
\end{code}
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
tidyTyVarBndr :: TidyEnv -> TyVar -> (TidyEnv, TyVar)
tidyTyVarBndr (tidy_env, subst) tyvar
= case tidyOccName tidy_env (getOccName name) of
- (tidy', occ') -> -- New occname reqd
- ((tidy', subst'), tyvar')
+ (tidy', occ') -> ((tidy', subst'), tyvar')
where
subst' = extendVarEnv subst tyvar tyvar'
tyvar' = setTyVarName tyvar name'
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}
\begin{code}
eqType t1 t2 = eq_ty emptyVarEnv t1 t2
-eqKind = eqType -- No worries about looking
-eqUsage = eqType -- through source types for these two
-- Look through Notes
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
projects / ghc-hetmet.git / blobdiff