\begin{code}
module Type (
- GenType(..), Type,
+ GenType(..), TyNote(..), -- Representation visible to friends
+ Type, GenKind, Kind,
+ TyVarSubst, GenTyVarSubst,
+
+ funTyCon, boxedKindCon, unboxedKindCon, openKindCon,
+
+ boxedTypeKind, unboxedTypeKind, openTypeKind, mkArrowKind, mkArrowKinds,
+ hasMoreBoxityInfo, superKind,
mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, isTyVarTy,
- mkAppTy, mkAppTys, splitAppTy, splitAppTys,
+ mkAppTy, mkAppTys, splitAppTy, splitAppTys, splitAppTy_maybe,
- mkFunTy, mkFunTys, splitFunTy_maybe, splitFunTys,
+ mkFunTy, mkFunTys, splitFunTy_maybe, splitFunTys, funResultTy,
mkTyConApp, mkTyConTy, splitTyConApp_maybe,
splitAlgTyConApp_maybe, splitAlgTyConApp,
mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys,
applyTy, applyTys, isForAllTy,
+ mkPiType,
TauType, RhoType, SigmaType, ThetaType,
isTauTy,
mkRhoTy, splitRhoTy,
mkSigmaTy, splitSigmaTy,
- isUnpointedType, isUnboxedType, typePrimRep,
-
- matchTy, matchTys,
+ isUnLiftedType, isUnboxedType, isUnboxedTupleType, isAlgType,
+ typePrimRep,
tyVarsOfType, tyVarsOfTypes, namesOfType, typeKind,
+ addFreeTyVars,
- instantiateTy, instantiateTauTy, instantiateThetaTy, applyToTyVars,
+ substTy, fullSubstTy, substTyVar,
+ substFlexiTy, substFlexiTheta,
showTypeCategory
) where
#include "HsVersions.h"
-import {-# SOURCE #-} Id ( Id )
+import {-# SOURCE #-} DataCon( DataCon )
-- friends:
+import Var ( Id, TyVar, GenTyVar, IdOrTyVar,
+ removeTyVarFlexi,
+ tyVarKind, isId, idType
+ )
+import VarEnv
+import VarSet
+
+import Name ( NamedThing(..), Provenance(..), ExportFlag(..),
+ mkWiredInTyConName, mkGlobalName, varOcc
+ )
+import NameSet
import Class ( classTyCon, Class )
-import Kind ( mkBoxedTypeKind, resultKind, Kind )
-import TyCon ( mkFunTyCon, isFunTyCon, isEnumerationTyCon, isTupleTyCon, maybeTyConSingleCon,
+import TyCon ( TyCon, Boxity(..),
+ mkFunTyCon, mkKindCon, superKindCon,
+ matchesTyCon, isUnboxedTupleTyCon, isUnLiftedTyCon,
+ isFunTyCon, isEnumerationTyCon,
+ isTupleTyCon, maybeTyConSingleCon,
isPrimTyCon, isAlgTyCon, isSynTyCon, tyConArity,
tyConKind, tyConDataCons, getSynTyConDefn,
- tyConPrimRep, tyConClass_maybe, TyCon )
-import TyVar ( GenTyVarSet, TyVarEnv, GenTyVar, TyVar,
- tyVarKind, tyVarFlexi, emptyTyVarSet, unionTyVarSets, minusTyVarSet,
- unitTyVarSet, lookupTyVarEnv, delFromTyVarEnv, zipTyVarEnv, mkTyVarEnv,
- emptyTyVarEnv, isEmptyTyVarEnv, addToTyVarEnv )
-import Name ( NamedThing(..),
- NameSet,
- unionNameSets, emptyNameSet, unitNameSet, minusNameSet
+ tyConPrimRep, tyConClass_maybe
)
-- others
-import BasicTypes ( Unused )
-import Maybes ( maybeToBool, assocMaybe )
-import PrimRep ( PrimRep(..) )
-import Unique -- quite a few *Keys
-import Util ( thenCmp, panic, assertPanic )
+import BasicTypes ( Unused )
+import SrcLoc ( mkBuiltinSrcLoc )
+import PrelMods ( pREL_GHC )
+import Maybes ( maybeToBool )
+import PrimRep ( PrimRep(..), isFollowableRep )
+import Unique -- quite a few *Keys
+import Util ( thenCmp )
+import Outputable
+
\end{code}
+%************************************************************************
+%* *
+\subsection{Type Classifications}
+%* *
+%************************************************************************
+
+A type is
+
+ *unboxed* iff its representation is other than a pointer
+ Unboxed types cannot instantiate a type variable
+ Unboxed types are always unlifted.
+
+ *lifted* A type is lifted iff it has bottom as an element.
+ Closures always have lifted types: i.e. any
+ let-bound identifier in Core must have a lifted
+ type. Operationally, a lifted object is one that
+ can be entered.
+ (NOTE: previously "pointed").
+ *algebraic* A type with one or more constructors. An algebraic
+ type is one that can be deconstructed with a case
+ expression. *NOT* the same as lifted types,
+ because we also include unboxed tuples in this
+ classification.
+
+ *primitive* iff it is a built-in type that can't be expressed
+ in Haskell.
+
+Currently, all primitive types are unlifted, but that's not necessarily
+the case. (E.g. Int could be primitive.)
+
+Some primitive types are unboxed, such as Int#, whereas some are boxed
+but unlifted (such as ByteArray#). The only primitive types that we
+classify as algebraic are the unboxed tuples.
+
+examples of type classifications:
+
+Type primitive boxed lifted algebraic
+-----------------------------------------------------------------------------
+Int#, Yes No No No
+ByteArray# Yes Yes No No
+(# a, b #) Yes No No Yes
+( a, b ) No Yes Yes Yes
+[a] No Yes Yes Yes
%************************************************************************
%* *
\begin{code}
type Type = GenType Unused -- Used after typechecker
+type GenKind flexi = GenType flexi
+type Kind = Type
+
+type TyVarSubst = TyVarEnv Type
+type GenTyVarSubst flexi = TyVarEnv (GenType flexi)
+
data GenType flexi -- Parameterised over the "flexi" part of a type variable
= TyVarTy (GenTyVar flexi)
(GenType flexi)
(GenType flexi)
- | SynTy -- Saturated application of a type synonym
- (GenType flexi) -- The unexpanded version; always a TyConTy
+ | NoteTy -- Saturated application of a type synonym
+ (TyNote flexi)
(GenType flexi) -- The expanded version
| ForAllTy
(GenTyVar flexi)
(GenType flexi) -- TypeKind
+
+data TyNote flexi
+ = SynNote (GenType flexi) -- The unexpanded version of the type synonym; always a TyConApp
+ | FTVNote (GenTyVarSet flexi) -- The free type variables of the noted expression
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Wired-in type constructors
+%* *
+%************************************************************************
+
+We define a few wired-in type constructors here to avoid module knots
+
+\begin{code}
+funTyConName = mkWiredInTyConName funTyConKey pREL_GHC SLIT("->") funTyCon
+funTyCon = mkFunTyCon funTyConName (mkArrowKinds [boxedTypeKind, boxedTypeKind] boxedTypeKind)
+\end{code}
+
+\begin{code}
+mk_kind_name key str = mkGlobalName key pREL_GHC (varOcc str)
+ (LocalDef mkBuiltinSrcLoc NotExported)
+ -- mk_kind_name is a bit of a hack
+ -- The LocalDef means that we print the name without
+ -- a qualifier, which is what we want for these kinds.
+
+boxedKindConName = mk_kind_name boxedKindConKey SLIT("*")
+boxedKindCon = mkKindCon boxedKindConName superKind Boxed
+
+unboxedKindConName = mk_kind_name unboxedKindConKey SLIT("*#")
+unboxedKindCon = mkKindCon unboxedKindConName superKind Unboxed
+
+openKindConName = mk_kind_name openKindConKey SLIT("*?")
+openKindCon = mkKindCon openKindConName superKind Open
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Kinds}
+%* *
+%************************************************************************
+
+\begin{code}
+superKind :: GenKind flexi -- Box, the type of all kinds
+superKind = TyConApp superKindCon []
+
+boxedTypeKind, unboxedTypeKind, openTypeKind :: GenKind flexi
+boxedTypeKind = TyConApp boxedKindCon []
+unboxedTypeKind = TyConApp unboxedKindCon []
+openTypeKind = TyConApp openKindCon []
+
+mkArrowKind :: GenKind flexi -> GenKind flexi -> GenKind flexi
+mkArrowKind = FunTy
+
+mkArrowKinds :: [GenKind flexi] -> GenKind flexi -> GenKind flexi
+mkArrowKinds arg_kinds result_kind = foldr FunTy result_kind arg_kinds
+\end{code}
+
+\begin{code}
+hasMoreBoxityInfo :: GenKind flexi -> GenKind flexi -> Bool
+
+(NoteTy _ k1) `hasMoreBoxityInfo` k2 = k1 `hasMoreBoxityInfo` k2
+k1 `hasMoreBoxityInfo` (NoteTy _ k2) = k1 `hasMoreBoxityInfo` k2
+
+(TyConApp kc1 ts1) `hasMoreBoxityInfo` (TyConApp kc2 ts2)
+ = ASSERT( null ts1 && null ts2 )
+ kc2 `matchesTyCon` kc1 -- NB the reversal of arguments
+
+kind1@(FunTy _ _) `hasMoreBoxityInfo` kind2@(FunTy _ _)
+ = ASSERT( kind1 == kind2 )
+ True
+ -- The two kinds can be arrow kinds; for example when unifying
+ -- (m1 Int) and (m2 Int) we end up unifying m1 and m2, which should
+ -- have the same kind.
+
+-- Other cases are impossible
\end{code}
getTyVar :: String -> GenType flexi -> GenTyVar flexi
getTyVar msg (TyVarTy tv) = tv
-getTyVar msg (SynTy _ t) = getTyVar msg t
+getTyVar msg (NoteTy _ t) = getTyVar msg t
getTyVar msg other = panic ("getTyVar: " ++ msg)
getTyVar_maybe :: GenType flexi -> Maybe (GenTyVar flexi)
getTyVar_maybe (TyVarTy tv) = Just tv
-getTyVar_maybe (SynTy _ t) = getTyVar_maybe t
+getTyVar_maybe (NoteTy _ t) = getTyVar_maybe t
getTyVar_maybe other = Nothing
isTyVarTy :: GenType flexi -> Bool
-isTyVarTy (TyVarTy tv) = True
-isTyVarTy (SynTy _ ty) = isTyVarTy ty
-isTyVarTy other = False
+isTyVarTy (TyVarTy tv) = True
+isTyVarTy (NoteTy _ ty) = isTyVarTy ty
+isTyVarTy other = False
\end{code}
\begin{code}
mkAppTy orig_ty1 orig_ty2 = mk_app orig_ty1
where
- mk_app (SynTy _ ty1) = mk_app ty1
+ mk_app (NoteTy _ ty1) = mk_app ty1
mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ [orig_ty2])
mk_app ty1 = AppTy orig_ty1 orig_ty2
-- the Rational part.
mkAppTys orig_ty1 orig_tys2 = mk_app orig_ty1
where
- mk_app (SynTy _ ty1) = mk_app ty1
+ mk_app (NoteTy _ ty1) = mk_app ty1
mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ orig_tys2)
mk_app ty1 = foldl AppTy orig_ty1 orig_tys2
-splitAppTy :: GenType flexi -> (GenType flexi, GenType flexi)
-splitAppTy (FunTy ty1 ty2) = (TyConApp mkFunTyCon [ty1], ty2)
-splitAppTy (AppTy ty1 ty2) = (ty1, ty2)
-splitAppTy (SynTy _ ty) = splitAppTy ty
-splitAppTy (TyConApp tc tys) = split tys []
+splitAppTy_maybe :: GenType flexi -> Maybe (GenType flexi, GenType flexi)
+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 (TyConApp tc []) = Nothing
+splitAppTy_maybe (TyConApp tc tys) = split tys []
where
- split [ty2] acc = (TyConApp tc (reverse acc), ty2)
+ split [ty2] acc = Just (TyConApp tc (reverse acc), ty2)
split (ty:tys) acc = split tys (ty:acc)
-splitAppTy other = panic "splitAppTy"
+
+splitAppTy_maybe other = Nothing
+
+splitAppTy :: GenType flexi -> (GenType flexi, GenType flexi)
+splitAppTy ty = case splitAppTy_maybe ty of
+ Just pr -> pr
+ Nothing -> panic "splitAppTy"
splitAppTys :: GenType flexi -> (GenType flexi, [GenType flexi])
splitAppTys ty = split ty ty []
where
split orig_ty (AppTy ty arg) args = split ty ty (arg:args)
- split orig_ty (SynTy _ ty) args = split orig_ty ty args
+ split orig_ty (NoteTy _ ty) args = split orig_ty ty args
split orig_ty (FunTy ty1 ty2) args = ASSERT( null args )
- (TyConApp mkFunTyCon [], [ty1,ty2])
+ (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}
splitFunTy_maybe :: GenType flexi -> Maybe (GenType flexi, GenType flexi)
splitFunTy_maybe (FunTy arg res) = Just (arg, res)
-splitFunTy_maybe (SynTy _ ty) = splitFunTy_maybe ty
+splitFunTy_maybe (NoteTy _ ty) = splitFunTy_maybe ty
splitFunTy_maybe other = Nothing
splitFunTys ty = split [] ty ty
where
split args orig_ty (FunTy arg res) = split (arg:args) res res
- split args orig_ty (SynTy _ ty) = split args orig_ty ty
+ split args orig_ty (NoteTy _ ty) = split args orig_ty ty
split args orig_ty ty = (reverse args, orig_ty)
+
+funResultTy :: GenType flexi -> GenType flexi
+funResultTy (FunTy arg res) = res
+funResultTy (NoteTy _ ty) = funResultTy ty
+funResultTy ty = ty
\end{code}
splitTyConApp_maybe :: GenType flexi -> Maybe (TyCon, [GenType flexi])
splitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
-splitTyConApp_maybe (FunTy arg res) = Just (mkFunTyCon, [arg,res])
-splitTyConApp_maybe (SynTy _ ty) = splitTyConApp_maybe ty
+splitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
+splitTyConApp_maybe (NoteTy _ ty) = splitTyConApp_maybe ty
splitTyConApp_maybe other = Nothing
-- splitAlgTyConApp_maybe looks for
-- "Algebraic" => newtype, data type, or dictionary (not function types)
-- We return the constructors too.
-splitAlgTyConApp_maybe :: GenType flexi -> Maybe (TyCon, [GenType flexi], [Id])
+splitAlgTyConApp_maybe :: GenType flexi -> Maybe (TyCon, [GenType flexi], [DataCon])
splitAlgTyConApp_maybe (TyConApp tc tys)
| isAlgTyCon tc &&
- tyConArity tc == length tys = Just (tc, tys, tyConDataCons tc)
-splitAlgTyConApp_maybe (SynTy _ ty) = splitAlgTyConApp_maybe ty
-splitAlgTyConApp_maybe other = Nothing
+ tyConArity tc == length tys = Just (tc, tys, tyConDataCons tc)
+splitAlgTyConApp_maybe (NoteTy _ ty) = splitAlgTyConApp_maybe ty
+splitAlgTyConApp_maybe other = Nothing
-splitAlgTyConApp :: GenType flexi -> (TyCon, [GenType flexi], [Id])
+splitAlgTyConApp :: GenType flexi -> (TyCon, [GenType flexi], [DataCon])
-- Here the "algebraic" property is an *assertion*
splitAlgTyConApp (TyConApp tc tys) = ASSERT( isAlgTyCon tc && tyConArity tc == length tys )
(tc, tys, tyConDataCons tc)
-splitAlgTyConApp (SynTy _ ty) = splitAlgTyConApp ty
+splitAlgTyConApp (NoteTy _ ty) = splitAlgTyConApp ty
\end{code}
"Dictionary" types are just ordinary data types, but you can
maybe_class = tyConClass_maybe tc
Just clas = maybe_class
-splitDictTy_maybe (SynTy _ ty) = splitDictTy_maybe ty
+splitDictTy_maybe (NoteTy _ ty) = splitDictTy_maybe ty
splitDictTy_maybe other = Nothing
isDictTy :: GenType flexi -> Bool
| maybeToBool (tyConClass_maybe tc)
&& tyConArity tc == length tys
= True
-isDictTy (SynTy _ ty) = isDictTy ty
-isDictTy other = False
+isDictTy (NoteTy _ ty) = isDictTy ty
+isDictTy other = False
\end{code}
\begin{code}
mkSynTy syn_tycon tys
= ASSERT(isSynTyCon syn_tycon)
- SynTy (TyConApp syn_tycon tys)
- (instantiateTauTy (zipTyVarEnv tyvars tys) body)
+ NoteTy (SynNote (TyConApp syn_tycon tys))
+ (substFlexiTy (zipVarEnv tyvars tys) body)
+ -- The "flexi" is needed so we can get a TcType from a synonym
where
(tyvars, body) = getSynTyConDefn syn_tycon
-isSynTy (SynTy _ _) = True
-isSynTy other = False
+isSynTy (NoteTy (SynNote _) _) = True
+isSynTy other = False
\end{code}
Notes on type synonyms
mkForAllTys tyvars ty = foldr ForAllTy ty tyvars
splitForAllTy_maybe :: GenType flexi -> Maybe (GenTyVar flexi, GenType flexi)
-splitForAllTy_maybe (SynTy _ ty) = splitForAllTy_maybe ty
+splitForAllTy_maybe (NoteTy _ ty) = splitForAllTy_maybe ty
splitForAllTy_maybe (ForAllTy tyvar ty) = Just(tyvar, ty)
splitForAllTy_maybe _ = Nothing
isForAllTy :: GenType flexi -> Bool
-isForAllTy (SynTy _ ty) = isForAllTy ty
+isForAllTy (NoteTy _ ty) = isForAllTy ty
isForAllTy (ForAllTy tyvar ty) = True
isForAllTy _ = False
splitForAllTys ty = split ty ty []
where
split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs)
- split orig_ty (SynTy _ ty) tvs = split orig_ty ty tvs
+ split orig_ty (NoteTy _ ty) tvs = split orig_ty ty tvs
split orig_ty t tvs = (reverse tvs, orig_ty)
\end{code}
+@mkPiType@ makes a (->) type or a forall type, depending on whether
+it is given a type variable or a term variable.
+
+\begin{code}
+mkPiType :: IdOrTyVar -> Type -> Type -- The more polymorphic version doesn't work...
+mkPiType v ty | isId v = mkFunTy (idType v) ty
+ | otherwise = ForAllTy v ty
+\end{code}
\begin{code}
applyTy :: GenType flexi -> GenType flexi -> GenType flexi
-applyTy (SynTy _ fun) arg = applyTy fun arg
-applyTy (ForAllTy tv ty) arg = instantiateTy (mkTyVarEnv [(tv,arg)]) ty
+applyTy (NoteTy _ fun) arg = applyTy fun arg
+applyTy (ForAllTy tv ty) arg = substTy (mkVarEnv [(tv,arg)]) ty
applyTy other arg = panic "applyTy"
applyTys :: GenType flexi -> [GenType flexi] -> GenType flexi
applyTys fun_ty arg_tys
= go [] fun_ty arg_tys
where
- go env ty [] = instantiateTy (mkTyVarEnv env) ty
- go env (SynTy _ fun) args = go env fun args
+ go env ty [] = substTy (mkVarEnv env) ty
+ go env (NoteTy _ fun) args = go env fun args
go env (ForAllTy tv ty) (arg:args) = go ((tv,arg):env) ty args
go env other args = panic "applyTys"
\end{code}
isTauTy (TyConApp _ tys) = all isTauTy tys
isTauTy (AppTy a b) = isTauTy a && isTauTy b
isTauTy (FunTy a b) = isTauTy a && isTauTy b
-isTauTy (SynTy _ ty) = isTauTy ty
+isTauTy (NoteTy _ ty) = isTauTy ty
isTauTy other = False
\end{code}
split orig_ty (FunTy arg res) ts = case splitDictTy_maybe arg of
Just pair -> split res res (pair:ts)
Nothing -> (reverse ts, orig_ty)
- split orig_ty (SynTy _ ty) ts = split orig_ty ty ts
+ split orig_ty (NoteTy _ ty) ts = split orig_ty ty ts
split orig_ty ty ts = (reverse ts, orig_ty)
\end{code}
Finding the kind of a type
~~~~~~~~~~~~~~~~~~~~~~~~~~
\begin{code}
+-- typeKind is only ever used on Types, never Kinds
+-- If it were used on Kinds, the typeKind of FunTy would not be boxedTypeKind;
+-- yet at the type level functions are boxed even if neither argument nor
+-- result are boxed. This seems pretty fishy to me.
+
typeKind :: GenType flexi -> Kind
typeKind (TyVarTy tyvar) = tyVarKind tyvar
-typeKind (TyConApp tycon tys) = foldr (\_ k -> resultKind k) (tyConKind tycon) tys
-typeKind (SynTy _ ty) = typeKind ty
-typeKind (FunTy fun arg) = mkBoxedTypeKind
-typeKind (AppTy fun arg) = resultKind (typeKind fun)
-typeKind (ForAllTy _ _) = mkBoxedTypeKind
+typeKind (TyConApp tycon tys) = foldr (\_ k -> funResultTy k) (tyConKind tycon) tys
+typeKind (NoteTy _ ty) = typeKind ty
+typeKind (FunTy fun arg) = boxedTypeKind
+typeKind (AppTy fun arg) = funResultTy (typeKind fun)
+typeKind (ForAllTy _ _) = boxedTypeKind
\end{code}
\begin{code}
tyVarsOfType :: GenType flexi -> GenTyVarSet flexi
-tyVarsOfType (TyVarTy tv) = unitTyVarSet tv
+tyVarsOfType (TyVarTy tv) = unitVarSet tv
tyVarsOfType (TyConApp tycon tys) = tyVarsOfTypes tys
-tyVarsOfType (SynTy ty1 ty2) = tyVarsOfType ty1
-tyVarsOfType (FunTy arg res) = tyVarsOfType arg `unionTyVarSets` tyVarsOfType res
-tyVarsOfType (AppTy fun arg) = tyVarsOfType fun `unionTyVarSets` tyVarsOfType arg
-tyVarsOfType (ForAllTy tyvar ty) = tyVarsOfType ty `minusTyVarSet` unitTyVarSet tyvar
+tyVarsOfType (NoteTy (FTVNote tvs) ty2) = tvs
+tyVarsOfType (NoteTy (SynNote ty1) ty2) = tyVarsOfType ty1
+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 :: [GenType flexi] -> GenTyVarSet flexi
-tyVarsOfTypes tys = foldr (unionTyVarSets.tyVarsOfType) emptyTyVarSet tys
+tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys
+
+-- Add a Note with the free tyvars to the top of the type
+addFreeTyVars :: GenType flexi -> GenType flexi
+addFreeTyVars ty@(NoteTy (FTVNote _) _) = ty
+addFreeTyVars ty = NoteTy (FTVNote (tyVarsOfType ty)) ty
-- Find the free names of a type, including the type constructors and classes it mentions
namesOfType :: GenType flexi -> NameSet
namesOfType (TyVarTy tv) = unitNameSet (getName tv)
namesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets`
namesOfTypes tys
-namesOfType (SynTy ty1 ty2) = namesOfType ty1
+namesOfType (NoteTy (SynNote ty1) ty2) = namesOfType ty1
+namesOfType (NoteTy other_note ty2) = namesOfType ty2
namesOfType (FunTy arg res) = namesOfType arg `unionNameSets` namesOfType res
namesOfType (AppTy fun arg) = namesOfType fun `unionNameSets` namesOfType arg
namesOfType (ForAllTy tyvar ty) = namesOfType ty `minusNameSet` unitNameSet (getName tyvar)
%* *
%************************************************************************
+@substTy@ applies a substitution to a type. It deals correctly with name capture.
+
\begin{code}
-instantiateTy :: TyVarEnv (GenType flexi) -> GenType flexi -> GenType flexi
-instantiateTauTy :: TyVarEnv (GenType flexi2) -> GenType flexi1 -> GenType flexi2
-
-
--- instantiateTy applies a type environment to a type.
--- It can handle shadowing; for example:
--- f = /\ t1 t2 -> \ d ->
--- letrec f' = /\ t1 -> \x -> ...(f' t1 x')...
--- in f' t1
--- Here, when we clone t1 to t1', say, we'll come across shadowing
--- when applying the clone environment to the type of f'.
---
--- As a sanity check, we should also check that name capture
--- doesn't occur, but that means keeping track of the free variables of the
--- range of the TyVarEnv, which I don't do just yet.
-
-instantiateTy tenv ty
- | isEmptyTyVarEnv tenv
- = ty
+substTy :: GenTyVarSubst flexi -> GenType flexi -> GenType flexi
+substTy tenv ty = subst_ty tenv tset ty
+ where
+ tset = foldVarEnv (unionVarSet . tyVarsOfType) emptyVarSet tenv
+ -- If ty doesn't have any for-alls, then this thunk
+ -- will never be evaluated
+\end{code}
- | otherwise
- = go tenv ty
+@fullSubstTy@ is like @substTy@ except that it needs to be given a set
+of in-scope type variables. In exchange it's a bit more efficient, at least
+if you happen to have that set lying around.
+
+\begin{code}
+fullSubstTy :: GenTyVarSubst flexi -- Substitution to apply
+ -> GenTyVarSet flexi -- Superset of the free tyvars of
+ -- the range of the tyvar env
+ -> GenType flexi -> GenType flexi
+-- ASSUMPTION: The substitution is idempotent.
+-- Equivalently: No tyvar is both in scope, and in the domain of the substitution.
+fullSubstTy tenv tset ty | isEmptyVarEnv tenv = ty
+ | otherwise = subst_ty tenv tset ty
+
+-- subst_ty does the business
+subst_ty tenv tset ty
+ = go ty
where
- go tenv ty@(TyVarTy tv) = case (lookupTyVarEnv tenv tv) of
- Nothing -> ty
- Just ty -> ty
- go tenv (TyConApp tc tys) = TyConApp tc (map (go tenv) tys)
- go tenv (SynTy ty1 ty2) = SynTy (go tenv ty1) (go tenv ty2)
- go tenv (FunTy arg res) = FunTy (go tenv arg) (go tenv res)
- go tenv (AppTy fun arg) = mkAppTy (go tenv fun) (go tenv arg)
- go tenv (ForAllTy tv ty) = ForAllTy tv (go tenv' ty)
- where
- tenv' = case lookupTyVarEnv tenv tv of
- Nothing -> tenv
- Just _ -> delFromTyVarEnv tenv tv
-
--- instantiateTauTy works only (a) on types with no ForAlls,
--- and when (b) all the type variables are being instantiated
--- In return it is more polymorphic than instantiateTy
-
-instantiateTauTy tenv ty = applyToTyVars lookup ty
- where
- lookup tv = case lookupTyVarEnv tenv tv of
- Just ty -> ty -- Must succeed
-
-
-instantiateThetaTy :: TyVarEnv Type -> ThetaType -> ThetaType
-instantiateThetaTy tenv theta
- = [(clas, map (instantiateTauTy tenv) tys) | (clas, tys) <- theta]
-
-applyToTyVars :: (GenTyVar flexi1 -> GenType flexi2)
- -> GenType flexi1
- -> GenType flexi2
-applyToTyVars f ty = go ty
+ go (TyConApp tc tys) = TyConApp tc (map go tys)
+ go (NoteTy (SynNote ty1) ty2) = NoteTy (SynNote (go ty1)) (go ty2)
+ go (NoteTy (FTVNote _) ty2) = go ty2 -- Discard the free tyvar note
+ go (FunTy arg res) = FunTy (go arg) (go res)
+ go (AppTy fun arg) = mkAppTy (go fun) (go arg)
+ go ty@(TyVarTy tv) = case (lookupVarEnv tenv tv) of
+ Nothing -> ty
+ Just ty' -> ty'
+ go (ForAllTy tv ty) = case substTyVar tenv tset tv of
+ (tenv', tset', tv') -> ForAllTy tv' (subst_ty tenv' tset' ty)
+
+substTyVar :: GenTyVarSubst flexi -> GenTyVarSet flexi -> GenTyVar flexi
+ -> (GenTyVarSubst flexi, GenTyVarSet flexi, GenTyVar flexi)
+
+substTyVar tenv tset tv
+ | not (tv `elemVarSet` tset) -- No need to clone
+ -- But must delete from substitution
+ = (tenv `delVarEnv` tv, tset `extendVarSet` tv, tv)
+
+ | otherwise -- The forall's variable is in scope so
+ -- we'd better rename it away from the in-scope variables
+ -- Extending the substitution to do this renaming also
+ -- has the (correct) effect of discarding any existing
+ -- substitution for that variable
+ = (extendVarEnv tenv tv (TyVarTy tv'), tset `extendVarSet` tv', tv')
where
- go (TyVarTy tv) = f tv
- go (TyConApp tc tys) = TyConApp tc (map go tys)
- go (SynTy ty1 ty2) = SynTy (go ty1) (go ty2)
- go (FunTy arg res) = FunTy (go arg) (go res)
- go (AppTy fun arg) = mkAppTy (go fun) (go arg)
- go (ForAllTy tv ty) = panic "instantiateTauTy"
+ tv' = uniqAway tset tv
\end{code}
-%************************************************************************
-%* *
-\subsection{Boxedness and pointedness}
-%* *
-%************************************************************************
+@substFlexiTy@ applies a substitution to a (GenType flexi1) returning
+a (GenType flexi2). Note that we convert from one flexi status to another.
-A type is
- *unboxed* iff its representation is other than a pointer
- Unboxed types cannot instantiate a type variable
- Unboxed types are always unpointed.
+Two assumptions, for (substFlexiTy env ty)
+ (a) the substitution, env, must cover all free tyvars of the type, ty
+ (b) the free vars of the range of the substitution must be
+ different than any of the forall'd variables in the type, ty
- *unpointed* iff it can't be a thunk, and cannot have value bottom
- An unpointed type may or may not be unboxed.
- (E.g. Array# is unpointed, but boxed.)
- An unpointed type *can* instantiate a type variable,
- provided it is boxed.
-
- *primitive* iff it is a built-in type that can't be expressed
- in Haskell
-
-Currently, all primitive types are unpointed, but that's not necessarily
-the case. (E.g. Int could be primitive.)
+The latter assumption is reasonable because, after all, ty has a different
+type to the range of the substitution.
\begin{code}
-isUnboxedType :: Type -> Bool
-isUnboxedType ty = case typePrimRep ty of
- PtrRep -> False
- other -> True
-
--- Danger! Currently the unpointed types are precisely
--- the primitive ones, but that might not always be the case
-isUnpointedType :: Type -> Bool
-isUnpointedType ty = case splitTyConApp_maybe ty of
- Just (tc, ty_args) -> isPrimTyCon tc
- other -> False
-
-typePrimRep :: Type -> PrimRep
-typePrimRep ty = case splitTyConApp_maybe ty of
- Just (tc, ty_args) -> tyConPrimRep tc
- other -> PtrRep
+substFlexiTy :: GenTyVarSubst flexi2 -> GenType flexi1 -> GenType flexi2
+substFlexiTy env ty = go ty
+ where
+ go (TyVarTy tv) = case lookupVarEnv env tv of
+ Just ty -> ty
+ Nothing -> pprPanic "substFlexiTy" (ppr tv)
+ go (TyConApp tc tys) = TyConApp tc (map go tys)
+ go (NoteTy (SynNote ty1) ty2) = NoteTy (SynNote (go ty1)) (go ty2)
+ go (NoteTy (FTVNote _) ty2) = go ty2 -- Discard free tyvar note
+ go (FunTy arg res) = FunTy (go arg) (go res)
+ go (AppTy fun arg) = mkAppTy (go fun) (go arg)
+ go (ForAllTy tv ty) = ForAllTy tv' (substFlexiTy env' ty)
+ where
+ tv' = removeTyVarFlexi tv
+ env' = extendVarEnv env tv (TyVarTy tv')
+
+substFlexiTheta :: GenTyVarSubst flexi2 -> [(Class, [GenType flexi1])]
+ -> [(Class, [GenType flexi2])]
+substFlexiTheta env theta = [(clas, map (substFlexiTy env) tys) | (clas,tys) <- theta]
\end{code}
%************************************************************************
%* *
-\subsection{Matching on types}
+\subsection{Boxedness and liftedness}
%* *
%************************************************************************
-Matching is a {\em unidirectional} process, matching a type against a
-template (which is just a type with type variables in it). The
-matcher assumes that there are no repeated type variables in the
-template, so that it simply returns a mapping of type variables to
-types. It also fails on nested foralls.
+\begin{code}
+isUnboxedType :: GenType flexi -> Bool
+isUnboxedType ty = not (isFollowableRep (typePrimRep ty))
-@matchTys@ matches corresponding elements of a list of templates and
-types.
+isUnLiftedType :: GenType flexi -> Bool
+isUnLiftedType ty = case splitTyConApp_maybe ty of
+ Just (tc, ty_args) -> isUnLiftedTyCon tc
+ other -> False
-\begin{code}
-matchTy :: GenType Bool -- Template
- -> GenType flexi -- Proposed instance of template
- -> Maybe (TyVarEnv (GenType flexi)) -- Matching substitution
-
-
-matchTys :: [GenType Bool] -- Templates
- -> [GenType flexi] -- Proposed instance of template
- -> Maybe (TyVarEnv (GenType flexi), -- Matching substitution
- [GenType flexi]) -- Left over instance types
-
-matchTy ty1 ty2 = match ty1 ty2 (\s -> Just s) emptyTyVarEnv
-matchTys tys1 tys2 = match_list tys1 tys2 (\pr -> Just pr) emptyTyVarEnv
-\end{code}
+isUnboxedTupleType :: GenType flexi -> Bool
+isUnboxedTupleType ty = case splitTyConApp_maybe ty of
+ Just (tc, ty_args) -> isUnboxedTupleTyCon tc
+ other -> False
-@match@ is the main function.
+isAlgType :: GenType flexi -> Bool
+isAlgType ty = case splitTyConApp_maybe ty of
+ Just (tc, ty_args) -> isAlgTyCon tc
+ other -> False
-\begin{code}
-match :: GenType Bool -> GenType flexi -- Current match pair
- -> (TyVarEnv (GenType flexi) -> Maybe result) -- Continuation
- -> TyVarEnv (GenType flexi) -- Current substitution
- -> Maybe result
-
--- When matching against a type variable, see if the variable
--- has already been bound. If so, check that what it's bound to
--- is the same as ty; if not, bind it and carry on.
-
-match (TyVarTy v) ty k = \s -> if tyVarFlexi v then
- -- v is a template variable
- case lookupTyVarEnv s v of
- Nothing -> k (addToTyVarEnv s v ty)
- Just ty' | ty' == ty -> k s -- Succeeds
- | otherwise -> Nothing -- Fails
- else
- -- v is not a template variable; ty had better match
- -- Can't use (==) because types differ
- case ty of
- TyVarTy v' | uniqueOf v == uniqueOf v'
- -> k s -- Success
- other -> Nothing -- Failure
-
-match (FunTy arg1 res1) (FunTy arg2 res2) k = match arg1 arg2 (match res1 res2 k)
-match (AppTy fun1 arg1) (AppTy fun2 arg2) k = match fun1 fun2 (match arg1 arg2 k)
-match (TyConApp tc1 tys1) (TyConApp tc2 tys2) k | tc1 == tc2
- = match_list tys1 tys2 ( \(s,tys2') ->
- if null tys2' then
- k s -- Succeed
- else
- Nothing -- Fail
- )
-
- -- With type synonyms, we have to be careful for the exact
- -- same reasons as in the unifier. Please see the
- -- considerable commentary there before changing anything
- -- here! (WDP 95/05)
-match (SynTy _ ty1) ty2 k = match ty1 ty2 k
-match ty1 (SynTy _ ty2) k = match ty1 ty2 k
-
--- Catch-all fails
-match _ _ _ = \s -> Nothing
-
-match_list [] tys2 k = \s -> k (s, tys2)
-match_list (ty1:tys1) [] k = \s -> Nothing -- Not enough arg tys => failure
-match_list (ty1:tys1) (ty2:tys2) k = match ty1 ty2 (match_list tys1 tys2 k)
+typePrimRep :: GenType flexi -> PrimRep
+typePrimRep ty = case splitTyConApp_maybe ty of
+ Just (tc, ty_args) -> tyConPrimRep tc
+ other -> PtrRep
\end{code}
%************************************************************************
cmpTy :: GenType flexi -> GenType flexi -> Ordering
cmpTy ty1 ty2
- = cmp emptyTyVarEnv ty1 ty2
+ = cmp emptyVarEnv ty1 ty2
where
-- The "env" maps type variables in ty1 to type variables in ty2
-- So when comparing for-alls.. (forall tv1 . t1) (forall tv2 . t2)
-- we in effect substitute tv2 for tv1 in t1 before continuing
- lookup env tv1 = case lookupTyVarEnv env tv1 of
+ lookup env tv1 = case lookupVarEnv env tv1 of
Just tv2 -> tv2
Nothing -> tv1
- -- Get rid of SynTy
- cmp env (SynTy _ ty1) ty2 = cmp env ty1 ty2
- cmp env ty1 (SynTy _ ty2) = cmp env ty1 ty2
+ -- Get rid of NoteTy
+ cmp env (NoteTy _ ty1) ty2 = cmp env ty1 ty2
+ cmp env ty1 (NoteTy _ ty2) = cmp env ty1 ty2
-- Deal with equal constructors
cmp env (TyVarTy tv1) (TyVarTy tv2) = lookup env tv1 `compare` tv2
cmp env (AppTy f1 a1) (AppTy f2 a2) = cmp env f1 f2 `thenCmp` cmp env a1 a2
cmp env (FunTy f1 a1) (FunTy f2 a2) = cmp env f1 f2 `thenCmp` cmp env a1 a2
cmp env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` (cmps env tys1 tys2)
- cmp env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmp (addToTyVarEnv env tv1 tv2) t1 t2
+ cmp env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmp (extendVarEnv env tv1 tv2) t1 t2
-- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy
cmp env (AppTy _ _) (TyVarTy _) = GT
else '.'
Just (tycon, _) ->
- let utc = uniqueOf tycon in
+ let utc = getUnique tycon in
if utc == charDataConKey then 'C'
else if utc == intDataConKey then 'I'
else if utc == floatDataConKey then 'F'
projects / ghc-hetmet.git / blobdiff