\begin{code}
module Type (
- -- re-exports from TypeRep:
- Type,
- Kind, TyVarSubst,
-
- superKind, superBoxity, -- KX and BX respectively
- boxedBoxity, unboxedBoxity, -- :: BX
- openKindCon, -- :: KX
- typeCon, -- :: BX -> KX
- boxedTypeKind, unboxedTypeKind, openTypeKind, -- :: KX
- mkArrowKind, mkArrowKinds, -- :: KX -> KX -> KX
-
+ -- re-exports from TypeRep
+ TyThing(..), Type, PredType(..), ThetaType, TyVarSubst,
funTyCon,
- -- exports from this module:
- hasMoreBoxityInfo, defaultKind,
+ -- Re-exports from Kind
+ module Kind,
+
+ -- Re-exports from TyCon
+ PrimRep(..),
mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, isTyVarTy,
mkAppTy, mkAppTys, splitAppTy, splitAppTys, splitAppTy_maybe,
- mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, splitFunTys, splitFunTysN,
- funResultTy, funArgTy, zipFunTys,
-
- mkTyConApp, mkTyConTy, splitTyConApp_maybe,
- splitAlgTyConApp_maybe, splitAlgTyConApp,
+ mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, splitFunTys,
+ funResultTy, funArgTy, zipFunTys, isFunTy,
- -- Predicates and the like
- mkDictTy, mkDictTys, mkPredTy, splitPredTy_maybe,
- splitDictTy_maybe, isDictTy, predRepTy,
+ mkGenTyConApp, mkTyConApp, mkTyConTy,
+ tyConAppTyCon, tyConAppArgs,
+ splitTyConApp_maybe, splitTyConApp,
- mkSynTy, isSynTy, deNoteType,
+ mkSynTy,
- repType, splitRepFunTys, splitNewType_maybe, typePrimRep,
-
- UsageAnn(..), mkUsgTy, isUsgTy{- dont use -}, isNotUsgTy, splitUsgTy, unUsgTy, tyUsg,
- mkUsForAllTy, mkUsForAllTys, splitUsForAllTys, substUsTy,
+ repType, typePrimRep,
mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys,
- applyTy, applyTys, hoistForAllTys,
+ applyTy, applyTys, isForAllTy, dropForAlls,
+
+ -- Source types
+ predTypeRep, mkPredTy, mkPredTys,
- TauType, RhoType, SigmaType, PredType(..), ThetaType,
- ClassPred, ClassContext, mkClassPred,
- getClassTys_maybe, ipName_maybe, classesToPreds, classesOfPreds,
- isTauTy, mkRhoTy, splitRhoTy,
- mkSigmaTy, isSigmaTy, splitSigmaTy,
- getDFunTyKey,
+ -- Newtypes
+ splitRecNewType_maybe,
-- Lifting and boxity
- isUnLiftedType, isUnboxedType, isUnboxedTupleType, isAlgType, isDataType, isNewType,
+ isUnLiftedType, isUnboxedTupleType, isAlgType, isPrimitiveType,
+ isStrictType, isStrictPred,
-- Free variables
tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
- namesOfType, typeKind, addFreeTyVars,
+ typeKind, addFreeTyVars,
-- Tidying up for printing
- tidyType, tidyTypes,
- tidyOpenType, tidyOpenTypes,
- tidyTyVar, tidyTyVars,
- tidyTopType,
+ tidyType, tidyTypes,
+ tidyOpenType, tidyOpenTypes,
+ tidyTyVarBndr, tidyFreeTyVars,
+ tidyOpenTyVar, tidyOpenTyVars,
+ tidyTopType, tidyPred,
+
+ -- Comparison
+ eqType,
-- Seq
- seqType, seqTypes
+ seqType, seqTypes,
+ -- Pretty-printing
+ pprType, pprParendType,
+ pprPred, pprTheta, pprThetaArrow, pprClassPred
) where
#include "HsVersions.h"
-- Other imports:
-import {-# SOURCE #-} DataCon( DataCon, dataConRepType )
-import {-# SOURCE #-} PprType( pprType ) -- Only called in debug messages
-import {-# SOURCE #-} Subst ( mkTyVarSubst, substTy )
+import {-# SOURCE #-} Subst ( substTyWith )
-- friends:
-import Var ( TyVar, Var, UVar,
- tyVarKind, tyVarName, setTyVarName, isId, idType,
- )
+import Kind
+import Var ( TyVar, tyVarKind, tyVarName, setTyVarName )
import VarEnv
import VarSet
-import Name ( Name, NamedThing(..), OccName, mkLocalName, tidyOccName )
-import NameSet
-import Class ( classTyCon, Class, ClassPred, ClassContext )
-import TyCon ( TyCon,
+import Name ( NamedThing(..), mkInternalName, tidyOccName )
+import Class ( Class, classTyCon )
+import TyCon ( TyCon, isRecursiveTyCon, isPrimTyCon,
isUnboxedTupleTyCon, isUnLiftedTyCon,
- isFunTyCon, isDataTyCon, isNewTyCon, newTyConRep,
- isAlgTyCon, isSynTyCon, tyConArity,
- tyConKind, tyConDataCons, getSynTyConDefn,
- tyConPrimRep
+ isFunTyCon, isNewTyCon, newTyConRep, newTyConRhs,
+ isAlgTyCon, isSynTyCon, tyConArity,
+ tyConKind, getSynTyConDefn, PrimRep(..), tyConPrimRep,
)
-- others
+import CmdLineOpts ( opt_DictsStrict )
import SrcLoc ( noSrcLoc )
-import PrimRep ( PrimRep(..), isFollowableRep )
import Unique ( Uniquable(..) )
-import Util ( mapAccumL, seqList, thenCmp )
+import Util ( mapAccumL, seqList, lengthIs, snocView )
import Outputable
import UniqSet ( sizeUniqSet ) -- Should come via VarSet
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Stuff to do with kinds.}
-%* *
-%************************************************************************
-
-\begin{code}
-hasMoreBoxityInfo :: Kind -> Kind -> Bool
-hasMoreBoxityInfo k1 k2
- | k2 == openTypeKind = True
- | otherwise = k1 == k2
-
-defaultKind :: Kind -> Kind
--- Used when generalising: default kind '?' to '*'
-defaultKind kind | kind == openTypeKind = boxedTypeKind
- | otherwise = kind
+import Maybe ( isJust )
\end{code}
mkTyVarTys = map mkTyVarTy -- a common use of mkTyVarTy
getTyVar :: String -> Type -> TyVar
-getTyVar msg (TyVarTy tv) = tv
-getTyVar msg (PredTy p) = getTyVar msg (predRepTy 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 (PredTy p) = getTyVar_maybe (predRepTy 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 (PredTy p) = isTyVarTy (predRepTy 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
- = ASSERT2( isNotUsgTy orig_ty1 && isNotUsgTy orig_ty2, pprType orig_ty1 <+> text "to" <+> pprType orig_ty2 )
- ASSERT( not (isPredTy orig_ty1) ) -- Predicates are of kind *
- mk_app orig_ty1
+ = mk_app orig_ty1
where
mk_app (NoteTy _ ty1) = mk_app ty1
- mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ [orig_ty2])
+ 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
+ -- under-saturated type synonym. GHC allows that; e.g.
+ -- type Foo k = k a -> k a
+ -- type Id x = x
+ -- foo :: Foo Id -> Foo Id
+ --
+ -- Here Id is partially applied in the type sig for Foo,
+ -- but once the type synonyms are expanded all is well
mkAppTys :: Type -> [Type] -> Type
mkAppTys orig_ty1 [] = orig_ty1
-- This check for an empty list of type arguments
- -- avoids the needless of a type synonym constructor.
+ -- avoids the needless loss of a type synonym constructor.
-- For example: mkAppTys Rational []
-- returns to (Ratio Integer), which has needlessly lost
-- the Rational part.
mkAppTys orig_ty1 orig_tys2
- = ASSERT2( isNotUsgTy orig_ty1, pprType orig_ty1 )
- ASSERT( not (isPredTy orig_ty1) ) -- Predicates 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)
- mk_app ty1 = ASSERT2( all isNotUsgTy orig_tys2, pprType orig_ty1 <+> text "to" <+> hsep (map pprType orig_tys2) )
- foldl AppTy orig_ty1 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 (PredTy p) = splitAppTy_maybe (predRepTy 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 (PredTy p) args = split orig_ty (predRepTy 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}
mkFunTys :: [Type] -> Type -> Type
mkFunTys tys ty = foldr FunTy ty tys
+isFunTy :: Type -> Bool
+isFunTy ty = isJust (splitFunTy_maybe ty)
+
splitFunTy :: Type -> (Type, Type)
-splitFunTy (FunTy arg res) = (arg, res)
-splitFunTy (NoteTy _ ty) = splitFunTy ty
-splitFunTy (PredTy p) = splitFunTy (predRepTy 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 (PredTy p) = splitFunTy_maybe (predRepTy 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 (PredTy p) = split args orig_ty (predRepTy p)
- split args orig_ty ty = (reverse args, orig_ty)
-
-splitFunTysN :: String -> Int -> Type -> ([Type], Type)
-splitFunTysN msg orig_n orig_ty = split orig_n [] orig_ty orig_ty
- where
- split 0 args syn_ty ty = (reverse args, syn_ty)
- split n args syn_ty (FunTy arg res) = split (n-1) (arg:args) res res
- split n args syn_ty (NoteTy _ ty) = split n args syn_ty ty
- split n args syn_ty (PredTy p) = split n args syn_ty (predRepTy p)
- split n args syn_ty ty = pprPanic ("splitFunTysN: " ++ msg) (int orig_n <+> pprType 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 (PredTy p) = split acc xs nty (predRepTy 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 (PredTy p) = funResultTy (predRepTy 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 (PredTy p) = funArgTy (predRepTy 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 PredTy,
+as apppropriate.
\begin{code}
+mkGenTyConApp :: TyCon -> [Type] -> Type
+mkGenTyConApp tc tys
+ | isSynTyCon tc = mkSynTy tc tys
+ | otherwise = mkTyConApp tc tys
+
mkTyConApp :: TyCon -> [Type] -> Type
+-- Assumes TyCon is not a SynTyCon; use mkSynTy instead for those
mkTyConApp tycon tys
- | isFunTyCon tycon && length tys == 2
- = case tys of
- (ty1:ty2:_) -> FunTy ty1 ty2
+ | isFunTyCon tycon, [ty1,ty2] <- tys
+ = FunTy ty1 ty2
+
+ | 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
-- including functions are returned as Just ..
+tyConAppTyCon :: Type -> TyCon
+tyConAppTyCon ty = fst (splitTyConApp ty)
+
+tyConAppArgs :: Type -> [Type]
+tyConAppArgs ty = snd (splitTyConApp ty)
+
+splitTyConApp :: Type -> (TyCon, [Type])
+splitTyConApp ty = case splitTyConApp_maybe ty of
+ Just stuff -> stuff
+ 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 (PredTy p) = splitTyConApp_maybe (predRepTy p)
+splitTyConApp_maybe (PredTy p) = splitTyConApp_maybe (predTypeRep p)
+splitTyConApp_maybe (NewTcApp tc tys) = splitTyConApp_maybe (newTypeRep tc tys)
splitTyConApp_maybe other = Nothing
-
--- splitAlgTyConApp_maybe looks for
--- *saturated* applications of *algebraic* data types
--- "Algebraic" => newtype, data type, or dictionary (not function types)
--- We return the constructors too, so there had better be some.
-
-splitAlgTyConApp_maybe :: Type -> Maybe (TyCon, [Type], [DataCon])
-splitAlgTyConApp_maybe (TyConApp tc tys)
- | isAlgTyCon tc &&
- tyConArity tc == length tys = Just (tc, tys, tyConDataCons tc)
-splitAlgTyConApp_maybe (NoteTy _ ty) = splitAlgTyConApp_maybe ty
-splitAlgTyConApp_maybe (PredTy p) = splitAlgTyConApp_maybe (predRepTy p)
-splitAlgTyConApp_maybe other = Nothing
-
-splitAlgTyConApp :: Type -> (TyCon, [Type], [DataCon])
- -- Here the "algebraic" property is an *assertion*
-splitAlgTyConApp (TyConApp tc tys) = ASSERT( isAlgTyCon tc && tyConArity tc == length tys )
- (tc, tys, tyConDataCons tc)
-splitAlgTyConApp (NoteTy _ ty) = splitAlgTyConApp ty
-splitAlgTyConApp (PredTy p) = splitAlgTyConApp (predRepTy p)
-#ifdef DEBUG
-splitAlgTyConApp ty = pprPanic "splitAlgTyConApp" (pprType ty)
-#endif
\end{code}
~~~~~
\begin{code}
-mkSynTy syn_tycon tys
- = ASSERT( isSynTyCon syn_tycon )
- ASSERT( isNotUsgTy body )
- ASSERT( length tyvars == length tys )
- NoteTy (SynNote (TyConApp syn_tycon tys))
- (substTy (mkTyVarSubst tyvars tys) body)
+mkSynTy tycon tys
+ | n_args == arity -- Exactly saturated
+ = mk_syn tys
+ | n_args > arity -- Over-saturated
+ = case splitAt arity tys of { (as,bs) -> mkAppTys (mk_syn as) bs }
+ -- Its important to use mkAppTys, rather than (foldl AppTy),
+ -- because (mk_syn as) might well return a partially-applied
+ -- type constructor; indeed, usually will!
+ | otherwise -- Un-saturated
+ = TyConApp tycon tys
+ -- For the un-saturated case we build TyConApp directly
+ -- (mkTyConApp ASSERTs that the tc isn't a SynTyCon).
+ -- Here we are relying on checkValidType to find
+ -- the error. What we can't do is use mkSynTy with
+ -- too few arg tys, because that is utterly bogus.
+
where
- (tyvars, body) = getSynTyConDefn syn_tycon
-
-isSynTy (NoteTy (SynNote _) _) = True
-isSynTy other = False
-
-deNoteType :: Type -> Type
- -- Remove synonyms, but not Preds
-deNoteType ty@(TyVarTy tyvar) = ty
-deNoteType (TyConApp tycon tys) = TyConApp tycon (map deNoteType tys)
-deNoteType (PredTy p) = PredTy p
-deNoteType (NoteTy _ ty) = deNoteType ty
-deNoteType (AppTy fun arg) = AppTy (deNoteType fun) (deNoteType arg)
-deNoteType (FunTy fun arg) = FunTy (deNoteType fun) (deNoteType arg)
-deNoteType (ForAllTy tv ty) = ForAllTy tv (deNoteType ty)
+ mk_syn tys = NoteTy (SynNote (TyConApp tycon tys))
+ (substTyWith tyvars tys body)
+
+ (tyvars, body) = ASSERT( isSynTyCon tycon ) getSynTyConDefn tycon
+ arity = tyConArity tycon
+ n_args = length tys
\end{code}
Notes on type synonyms
Representation types
~~~~~~~~~~~~~~~~~~~~
-
repType looks through
(a) for-alls, and
- (b) newtypes
- (c) synonyms
- (d) predicates
-It's useful in the back end where we're not
-interested in newtypes anymore.
+ (b) synonyms
+ (c) predicates
+ (d) usage annotations
+ (e) [recursive] newtypes
+It's useful in the back end.
\begin{code}
repType :: Type -> Type
-repType (ForAllTy _ ty) = repType ty
-repType (NoteTy _ ty) = repType ty
-repType (PredTy p) = repType (predRepTy p)
-repType ty = case splitNewType_maybe ty of
- Just ty' -> repType ty' -- Still re-apply repType in case of for-all
- Nothing -> ty
-
-splitRepFunTys :: Type -> ([Type], Type)
--- Like splitFunTys, but looks through newtypes and for-alls
-splitRepFunTys ty = split [] (repType ty)
- where
- split args (FunTy arg res) = split (arg:args) (repType res)
- split args ty = (reverse args, ty)
+-- Only applied to types of kind *; hence tycons are saturated
+repType (ForAllTy _ ty) = repType ty
+repType (NoteTy _ ty) = repType ty
+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
-
-splitNewType_maybe :: Type -> Maybe Type
--- Find the representation of a newtype, if it is one
--- Looks through multiple levels of newtype, but does not look through for-alls
-splitNewType_maybe (NoteTy _ ty) = splitNewType_maybe ty
-splitNewType_maybe (PredTy p) = splitNewType_maybe (predRepTy p)
-splitNewType_maybe (TyConApp tc tys) = case newTyConRep tc of
- Just rep_ty -> ASSERT( length tys == tyConArity tc )
- -- The assert should hold because repType should
- -- only be applied to *types* (of kind *)
- Just (applyTys rep_ty tys)
- Nothing -> Nothing
-splitNewType_maybe other = Nothing
-\end{code}
-
-
-
----------------------------------------------------------------------
- UsgNote
- ~~~~~~~
-
-NB: Invariant: if present, usage note is at the very top of the type.
-This should be carefully preserved.
-
-In some parts of the compiler, comments use the _Once Upon a
-Polymorphic Type_ (POPL'99) usage of "rho = generalised
-usage-annotated type; sigma = usage-annotated type; tau =
-usage-annotated type except on top"; unfortunately this conflicts with
-the rho/tau/theta/sigma usage in the rest of the compiler. (KSW
-1999-07)
-
-\begin{code}
-mkUsgTy :: UsageAnn -> Type -> Type
-#ifndef USMANY
-mkUsgTy UsMany ty = ASSERT2( isNotUsgTy ty, pprType ty )
- ty
-#endif
-mkUsgTy usg ty = ASSERT2( isNotUsgTy ty, pprType ty )
- NoteTy (UsgNote usg) ty
-
--- The isUsgTy function is utterly useless if UsManys are omitted.
--- Be warned! KSW 1999-04.
-isUsgTy :: Type -> Bool
-#ifndef USMANY
-isUsgTy _ = True
-#else
-isUsgTy (NoteTy (UsgForAll _) ty) = isUsgTy ty
-isUsgTy (NoteTy (UsgNote _) _ ) = True
-isUsgTy other = False
-#endif
-
--- The isNotUsgTy function may return a false True if UsManys are omitted;
--- in other words, A SSERT( isNotUsgTy ty ) may be useful but
--- A SSERT( not (isNotUsg ty) ) is asking for trouble. KSW 1999-04.
-isNotUsgTy :: Type -> Bool
-isNotUsgTy (NoteTy (UsgForAll _) _) = False
-isNotUsgTy (NoteTy (UsgNote _) _) = False
-isNotUsgTy other = True
-
--- splitUsgTy_maybe is not exported, since it is meaningless if
--- UsManys are omitted. It is used in several places in this module,
--- however. KSW 1999-04.
-splitUsgTy_maybe :: Type -> Maybe (UsageAnn,Type)
-splitUsgTy_maybe (NoteTy (UsgNote usg) ty2) = ASSERT( isNotUsgTy ty2 )
- Just (usg,ty2)
-splitUsgTy_maybe ty@(NoteTy (UsgForAll _) _) = pprPanic "splitUsgTy_maybe:" $ pprType ty
-splitUsgTy_maybe ty = Nothing
-
-splitUsgTy :: Type -> (UsageAnn,Type)
-splitUsgTy ty = case splitUsgTy_maybe ty of
- Just ans -> ans
- Nothing ->
-#ifndef USMANY
- (UsMany,ty)
-#else
- pprPanic "splitUsgTy: no usage annot:" $ pprType ty
-#endif
-
-tyUsg :: Type -> UsageAnn
-tyUsg = fst . splitUsgTy
-
-unUsgTy :: Type -> Type
--- strip outer usage annotation if present
-unUsgTy ty = case splitUsgTy_maybe ty of
- Just (_,ty1) -> ASSERT2( isNotUsgTy ty1, pprType ty )
- ty1
- Nothing -> ty
-
-mkUsForAllTy :: UVar -> Type -> Type
-mkUsForAllTy uv ty = NoteTy (UsgForAll uv) ty
-
-mkUsForAllTys :: [UVar] -> Type -> Type
-mkUsForAllTys uvs ty = foldr (NoteTy . UsgForAll) ty uvs
-
-splitUsForAllTys :: Type -> ([UVar],Type)
-splitUsForAllTys ty = split ty []
- where split (NoteTy (UsgForAll u) ty) uvs = split ty (u:uvs)
- split other_ty uvs = (reverse uvs, other_ty)
-
-substUsTy :: VarEnv UsageAnn -> Type -> Type
--- assumes range is fresh uvars, so no conflicts
-substUsTy ve (NoteTy note@(UsgNote (UsVar u))
- ty ) = NoteTy (case lookupVarEnv ve u of
- Just ua -> UsgNote ua
- Nothing -> note)
- (substUsTy ve ty)
-substUsTy ve (NoteTy (SynNote ty1) ty2) = NoteTy (SynNote (substUsTy ve ty1)) (substUsTy ve ty2)
-substUsTy ve (NoteTy note ty) = NoteTy note (substUsTy ve ty)
-
-substUsTy ve (PredTy (Class c tys)) = PredTy (Class c (map (substUsTy ve) tys))
-substUsTy ve (PredTy (IParam n ty)) = PredTy (IParam n (substUsTy ve ty))
-substUsTy ve (TyVarTy tv) = TyVarTy tv
-substUsTy ve (AppTy ty1 ty2) = AppTy (substUsTy ve ty1) (substUsTy ve ty2)
-substUsTy ve (FunTy ty1 ty2) = FunTy (substUsTy ve ty1) (substUsTy ve ty2)
-substUsTy ve (TyConApp tyc tys) = TyConApp tyc (map (substUsTy ve) tys)
-substUsTy ve (ForAllTy yv ty ) = ForAllTy yv (substUsTy ve ty)
+ 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
~~~~~~~~
-We need to be clever here with usage annotations; they need to be
-lifted or lowered through the forall as appropriate.
-
\begin{code}
mkForAllTy :: TyVar -> Type -> Type
-mkForAllTy tyvar ty = case splitUsgTy_maybe ty of
- Just (usg,ty') -> NoteTy (UsgNote usg)
- (ForAllTy tyvar ty')
- Nothing -> ForAllTy tyvar ty
+mkForAllTy tyvar ty
+ = mkForAllTys [tyvar] ty
mkForAllTys :: [TyVar] -> Type -> Type
-mkForAllTys tyvars ty = case splitUsgTy_maybe ty of
- Just (usg,ty') -> NoteTy (UsgNote usg)
- (foldr ForAllTy ty' tyvars)
- Nothing -> foldr ForAllTy ty tyvars
+mkForAllTys tyvars ty = foldr ForAllTy ty tyvars
+
+isForAllTy :: Type -> Bool
+isForAllTy (NoteTy _ ty) = isForAllTy ty
+isForAllTy (ForAllTy _ _) = True
+isForAllTy other_ty = False
splitForAllTy_maybe :: Type -> Maybe (TyVar, Type)
-splitForAllTy_maybe ty = case splitUsgTy_maybe ty of
- Just (usg,ty') -> do (tyvar,ty'') <- splitFAT_m ty'
- return (tyvar, NoteTy (UsgNote usg) ty'')
- Nothing -> splitFAT_m ty
+splitForAllTy_maybe ty = splitFAT_m ty
where
splitFAT_m (NoteTy _ ty) = splitFAT_m ty
- splitFAT_m (PredTy p) = splitFAT_m (predRepTy 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 = case splitUsgTy_maybe ty of
- Just (usg,ty') -> let (tvs,ty'') = split ty' ty' []
- in (tvs, NoteTy (UsgNote usg) ty'')
- Nothing -> split ty ty []
+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 (PredTy p) tvs = split orig_ty (predRepTy 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)
\end{code}
-- (mkPiType now in CoreUtils)
-Applying a for-all to its arguments
+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 (NoteTy note@(UsgNote _) fun) arg = NoteTy note (applyTy fun arg)
-applyTy (NoteTy note@(UsgForAll _) fun) arg = NoteTy note (applyTy fun arg)
-applyTy (PredTy p) arg = applyTy (predRepTy p) arg
-applyTy (NoteTy _ fun) arg = applyTy fun arg
-applyTy (ForAllTy tv ty) arg = ASSERT( isNotUsgTy arg )
- substTy (mkTyVarSubst [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 fun_ty arg_tys
- = substTy (mkTyVarSubst tvs arg_tys) ty
- where
- (tvs, ty) = split fun_ty arg_tys
-
- split fun_ty [] = ([], fun_ty)
- split (NoteTy note@(UsgNote _) fun_ty)
- args = case split fun_ty args of
- (tvs, ty) -> (tvs, NoteTy note ty)
- split (NoteTy note@(UsgForAll _) fun_ty)
- args = case split fun_ty args of
- (tvs, ty) -> (tvs, NoteTy note ty)
- split (NoteTy _ fun_ty) args = split fun_ty args
- split (PredTy p) args = split (predRepTy p) args
- split (ForAllTy tv fun_ty) (arg:args) = ASSERT2( isNotUsgTy arg, vcat (map pprType arg_tys) $$
- text "in application of" <+> pprType fun_ty)
- case split fun_ty args of
- (tvs, ty) -> (tv:tvs, ty)
- split other_ty args = panic "applyTys"
-\end{code}
-
-Note that we allow applications to be of usage-annotated- types, as an
-extension: we handle them by lifting the annotation outside. The
-argument, however, must still be unannotated.
-
-\begin{code}
-hoistForAllTys :: Type -> Type
- -- Move all the foralls to the top
- -- e.g. T -> forall a. a ==> forall a. T -> a
-hoistForAllTys ty
- = case hoist ty of { (tvs, body) -> mkForAllTys tvs body }
+-- 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
- hoist :: Type -> ([TyVar], Type)
- hoist ty = case splitFunTys ty of { (args, res) ->
- case splitForAllTys res of {
- ([], body) -> ([], ty) ;
- (tvs1, body1) -> case hoist body1 of { (tvs2,body2) ->
- (tvs1 ++ tvs2, mkFunTys args body2)
- }}}
+ (tvs, rho_ty) = splitForAllTys orig_fun_ty
+ n_tvs = length tvs
+ n_args = length arg_tys
\end{code}
%************************************************************************
%* *
-\subsection{Stuff to do with the source-language types}
-
-PredType and ThetaType are used in types for expressions and bindings.
-ClassPred and ClassContext are used in class and instance declarations.
+\subsection{Source types}
%* *
%************************************************************************
-"Dictionary" types are just ordinary data types, but you can
-tell from the type constructor whether it's a dictionary or not.
-
-\begin{code}
-mkClassPred clas tys = Class clas tys
+A "source type" is a type that is a separate type as far as the type checker is
+concerned, but which has low-level representation as far as the back end is concerned.
-mkDictTy :: Class -> [Type] -> Type
-mkDictTy clas tys = mkPredTy (Class clas tys)
+Source types are always lifted.
-mkDictTys :: ClassContext -> [Type]
-mkDictTys cxt = [mkDictTy cls tys | (cls,tys) <- cxt]
+The key function is predTypeRep which gives the representation of a source type:
+\begin{code}
mkPredTy :: PredType -> Type
mkPredTy pred = PredTy pred
-predRepTy :: PredType -> Type
--- Convert a predicate to its "representation type";
--- the type of evidence for that predicate, which is actually passed at runtime
-predRepTy (Class clas tys) = TyConApp (classTyCon clas) tys
-predRepTy (IParam n ty) = ty
-
-isPredTy :: Type -> Bool
-isPredTy (NoteTy _ ty) = isPredTy ty
-isPredTy (PredTy _) = True
-isPredTy _ = False
-
-isDictTy :: Type -> Bool
-isDictTy (NoteTy _ ty) = isDictTy ty
-isDictTy (PredTy (Class _ _)) = True
-isDictTy other = False
-
-splitPredTy_maybe :: Type -> Maybe PredType
-splitPredTy_maybe (NoteTy _ ty) = splitPredTy_maybe ty
-splitPredTy_maybe (PredTy p) = Just p
-splitPredTy_maybe other = Nothing
-
-splitDictTy_maybe :: Type -> Maybe (Class, [Type])
-splitDictTy_maybe ty = case splitPredTy_maybe ty of
- Just p -> getClassTys_maybe p
- Nothing -> Nothing
-
-getClassTys_maybe :: PredType -> Maybe ClassPred
-getClassTys_maybe (Class clas tys) = Just (clas, tys)
-getClassTys_maybe _ = Nothing
-
-ipName_maybe :: PredType -> Maybe Name
-ipName_maybe (IParam n _) = Just n
-ipName_maybe _ = Nothing
-
-classesToPreds :: ClassContext -> ThetaType
-classesToPreds cts = map (uncurry Class) cts
-
-classesOfPreds :: ThetaType -> ClassContext
-classesOfPreds theta = [(clas,tys) | Class clas tys <- theta]
+mkPredTys :: ThetaType -> [Type]
+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}
-@isTauTy@ tests for nested for-alls.
-
-\begin{code}
-isTauTy :: Type -> Bool
-isTauTy (TyVarTy v) = True
-isTauTy (TyConApp _ tys) = all isTauTy tys
-isTauTy (AppTy a b) = isTauTy a && isTauTy b
-isTauTy (FunTy a b) = isTauTy a && isTauTy b
-isTauTy (PredTy p) = isTauTy (predRepTy p)
-isTauTy (NoteTy _ ty) = isTauTy ty
-isTauTy other = False
-\end{code}
-\begin{code}
-mkRhoTy :: [PredType] -> Type -> Type
-mkRhoTy theta ty = foldr (\p r -> FunTy (mkPredTy p) r) ty theta
-
-splitRhoTy :: Type -> ([PredType], Type)
-splitRhoTy ty = split ty ty []
- where
- split orig_ty (FunTy arg res) ts = case splitPredTy_maybe arg of
- Just p -> split res res (p:ts)
- Nothing -> (reverse ts, orig_ty)
- split orig_ty (NoteTy _ ty) ts = split orig_ty ty ts
- split orig_ty ty ts = (reverse ts, orig_ty)
-\end{code}
-
-
-isSigmaType returns true of any qualified type. It doesn't *necessarily* have
-any foralls. E.g.
- f :: (?x::Int) => Int -> Int
-
-\begin{code}
-mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkRhoTy theta tau)
-
-isSigmaTy :: Type -> Bool
-isSigmaTy (ForAllTy tyvar ty) = True
-isSigmaTy (FunTy a b) = isPredTy a
-isSigmaTy (NoteTy _ ty) = isSigmaTy ty
-isSigmaTy _ = False
-
-splitSigmaTy :: Type -> ([TyVar], [PredType], Type)
-splitSigmaTy ty =
- (tyvars, theta, tau)
- where
- (tyvars,rho) = splitForAllTys ty
- (theta,tau) = splitRhoTy rho
-\end{code}
+%************************************************************************
+%* *
+ NewTypes
+%* *
+%************************************************************************
\begin{code}
-getDFunTyKey :: Type -> OccName -- Get some string from a type, to be used to
- -- construct a dictionary function name
-getDFunTyKey (TyVarTy tv) = getOccName tv
-getDFunTyKey (TyConApp tc _) = getOccName tc
-getDFunTyKey (AppTy fun _) = getDFunTyKey fun
-getDFunTyKey (NoteTy _ t) = getDFunTyKey t
-getDFunTyKey (FunTy arg _) = getOccName funTyCon
-getDFunTyKey (ForAllTy _ t) = getDFunTyKey t
--- PredTy shouldn't happen
+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)
+-- 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 (PredTy _) = boxedTypeKind -- Predicates are always
- -- represented by boxed 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 = boxedTypeKind
- 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 boxed 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 (PredTy _) = liftedTypeKind -- Predicates are always
+ -- represented by lifted types
+typeKind (AppTy fun arg) = kindFunResult (typeKind fun)
+typeKind (FunTy arg res) = liftedTypeKind
typeKind (ForAllTy tv ty) = typeKind ty
\end{code}
Free variables of a type
~~~~~~~~~~~~~~~~~~~~~~~~
\begin{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 ty1
-tyVarsOfType (NoteTy (UsgNote _) ty) = tyVarsOfType ty
-tyVarsOfType (NoteTy (UsgForAll _) ty) = tyVarsOfType ty
-tyVarsOfType (PredTy p) = tyVarsOfPred p
+tyVarsOfType (NoteTy (SynNote ty1) ty2) = tyVarsOfType ty2 -- See note [Syn] below
+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
+-- Note [Syn]
+-- Consider
+-- type T a = Int
+-- What are the free tyvars of (T x)? Empty, of course!
+-- Here's the example that Ralf Laemmel showed me:
+-- foo :: (forall a. C u a -> C u a) -> u
+-- mappend :: Monoid u => u -> u -> u
+--
+-- bar :: Monoid u => u
+-- bar = foo (\t -> t `mappend` t)
+-- We have to generalise at the arg to f, and we don't
+-- want to capture the constraint (Monad (C u a)) because
+-- it appears to mention a. Pretty silly, but it was useful to him.
+
+
tyVarsOfTypes :: [Type] -> TyVarSet
tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys
tyVarsOfPred :: PredType -> TyVarSet
-tyVarsOfPred (Class clas tys) = tyVarsOfTypes tys
-tyVarsOfPred (IParam n ty) = tyVarsOfType ty
+tyVarsOfPred (IParam _ ty) = tyVarsOfType ty
+tyVarsOfPred (ClassP _ tys) = tyVarsOfTypes tys
tyVarsOfTheta :: ThetaType -> TyVarSet
tyVarsOfTheta = foldr (unionVarSet . tyVarsOfPred) emptyVarSet
-- Add a Note with the free tyvars to the top of the type
--- (but under a usage if there is one)
addFreeTyVars :: Type -> Type
-addFreeTyVars (NoteTy note@(UsgNote _) ty) = NoteTy note (addFreeTyVars ty)
-addFreeTyVars (NoteTy note@(UsgForAll _) ty) = NoteTy note (addFreeTyVars ty)
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 :: Type -> NameSet
-namesOfType (TyVarTy tv) = unitNameSet (getName tv)
-namesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets`
- namesOfTypes tys
-namesOfType (NoteTy (SynNote ty1) ty2) = namesOfType ty1
-namesOfType (NoteTy other_note ty2) = namesOfType ty2
-namesOfType (PredTy p) = namesOfType (predRepTy p)
-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)
-
-namesOfTypes tys = foldr (unionNameSets . namesOfType) emptyNameSet tys
\end{code}
-
%************************************************************************
%* *
\subsection{TidyType}
It doesn't change the uniques at all, just the print names.
\begin{code}
-tidyTyVar :: TidyEnv -> TyVar -> (TidyEnv, TyVar)
-tidyTyVar env@(tidy_env, subst) tyvar
- = case lookupVarEnv subst tyvar of
-
- Just tyvar' -> -- Already substituted
- (env, tyvar')
-
- Nothing -> -- Make a new nice name for it
-
- case tidyOccName tidy_env (getOccName name) of
- (tidy', occ') -> -- New occname reqd
- ((tidy', subst'), tyvar')
- where
- subst' = extendVarEnv subst tyvar tyvar'
- tyvar' = setTyVarName tyvar name'
- name' = mkLocalName (getUnique name) occ' noSrcLoc
- -- Note: make a *user* tyvar, so it printes nicely
- -- Could extract src loc, but no need.
+tidyTyVarBndr :: TidyEnv -> TyVar -> (TidyEnv, TyVar)
+tidyTyVarBndr (tidy_env, subst) tyvar
+ = case tidyOccName tidy_env (getOccName name) of
+ (tidy', occ') -> ((tidy', subst'), tyvar')
+ where
+ subst' = extendVarEnv subst tyvar tyvar'
+ tyvar' = setTyVarName tyvar name'
+ name' = mkInternalName (getUnique name) occ' noSrcLoc
+ -- Note: make a *user* tyvar, so it printes nicely
+ -- Could extract src loc, but no need.
where
name = tyVarName tyvar
-tidyTyVars env tyvars = mapAccumL tidyTyVar env tyvars
+tidyFreeTyVars :: TidyEnv -> TyVarSet -> TidyEnv
+-- Add the free tyvars to the env in tidy form,
+-- so that we can tidy the type they are free in
+tidyFreeTyVars env tyvars = fst (tidyOpenTyVars env (varSetElems tyvars))
+
+tidyOpenTyVars :: TidyEnv -> [TyVar] -> (TidyEnv, [TyVar])
+tidyOpenTyVars env tyvars = mapAccumL tidyOpenTyVar env tyvars
+
+tidyOpenTyVar :: TidyEnv -> TyVar -> (TidyEnv, TyVar)
+-- Treat a new tyvar as a binder, and give it a fresh tidy name
+tidyOpenTyVar env@(tidy_env, subst) tyvar
+ = case lookupVarEnv subst tyvar of
+ Just tyvar' -> (env, tyvar') -- Already substituted
+ Nothing -> tidyTyVarBndr env tyvar -- Treat it as a binder
tidyType :: TidyEnv -> Type -> Type
tidyType env@(tidy_env, subst) ty
Just tv' -> TyVarTy tv'
go (TyConApp tycon tys) = let args = map go tys
in args `seqList` TyConApp tycon args
- go (NoteTy note ty) = (NoteTy SAPPLY (go_note note)) SAPPLY (go ty)
- go (PredTy p) = PredTy (go_pred p)
- go (AppTy fun arg) = (AppTy SAPPLY (go fun)) SAPPLY (go arg)
- go (FunTy fun arg) = (FunTy SAPPLY (go fun)) SAPPLY (go arg)
- go (ForAllTy tv ty) = ForAllTy tvp SAPPLY (tidyType envp ty)
+ 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 (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)
where
- (envp, tvp) = tidyTyVar env tv
+ (envp, tvp) = tidyTyVarBndr env tv
- go_note (SynNote ty) = SynNote SAPPLY (go ty)
+ go_note (SynNote ty) = SynNote $! (go ty)
go_note note@(FTVNote ftvs) = note -- No need to tidy the free tyvars
- go_note note@(UsgNote _) = note -- Usage annotation is already tidy
- go_note note@(UsgForAll _) = note -- Uvar binder is already tidy
-
- go_pred (Class c tys) = Class c (tidyTypes env tys)
- go_pred (IParam n ty) = IParam n (go ty)
tidyTypes env tys = map (tidyType 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}
tidyOpenType env ty
= (env', tidyType env' ty)
where
- env' = foldl go env (varSetElems (tyVarsOfType ty))
- go env tyvar = fst (tidyTyVar env tyvar)
+ env' = tidyFreeTyVars env (tyVarsOfType ty)
tidyOpenTypes :: TidyEnv -> [Type] -> (TidyEnv, [Type])
tidyOpenTypes env tys = mapAccumL tidyOpenType env tys
%************************************************************************
%* *
-\subsection{Boxedness and liftedness}
+\subsection{Liftedness}
%* *
%************************************************************************
\begin{code}
-isUnboxedType :: Type -> Bool
-isUnboxedType ty = not (isFollowableRep (typePrimRep ty))
-
isUnLiftedType :: Type -> Bool
-- isUnLiftedType returns True for forall'd unlifted types:
-- x :: forall a. Int#
-- 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 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
-- Should only be applied to *types*; hence the assert
isAlgType :: Type -> Bool
isAlgType ty = case splitTyConApp_maybe ty of
- Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc )
+ Just (tc, ty_args) -> ASSERT( ty_args `lengthIs` tyConArity tc )
isAlgTyCon tc
other -> False
+\end{code}
--- Should only be applied to *types*; hence the assert
-isDataType :: Type -> Bool
-isDataType ty = case splitTyConApp_maybe ty of
- Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc )
- isDataTyCon tc
- other -> False
+@isStrictType@ computes whether an argument (or let RHS) should
+be computed strictly or lazily, based only on its type.
+Works just like isUnLiftedType, except that it has a special case
+for dictionaries. Since it takes account of ClassP, you might think
+this function should be in TcType, but isStrictType is used by DataCon,
+which is below TcType in the hierarchy, so it's convenient to put it here.
-isNewType :: Type -> Bool
-isNewType ty = case splitTyConApp_maybe ty of
- Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc )
- isNewTyCon tc
+\begin{code}
+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.]
+\end{code}
+
+\begin{code}
+isPrimitiveType :: Type -> Bool
+-- Returns types that are opaque to Haskell.
+-- Most of these are unlifted, but now that we interact with .NET, we
+-- may have primtive (foreign-imported) types that are lifted
+isPrimitiveType ty = case splitTyConApp_maybe ty of
+ Just (tc, ty_args) -> ASSERT( ty_args `lengthIs` tyConArity tc )
+ isPrimTyCon tc
other -> False
\end{code}
seqType (NoteTy note t2) = seqNote note `seq` seqType t2
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 :: TyNote -> ()
seqNote (SynNote ty) = seqType ty
seqNote (FTVNote set) = sizeUniqSet set `seq` ()
-seqNote (UsgNote usg) = usg `seq` ()
seqPred :: PredType -> ()
-seqPred (Class c tys) = c `seq` seqTypes tys
-seqPred (IParam n ty) = n `seq` seqType ty
+seqPred (ClassP c tys) = c `seq` seqTypes tys
+seqPred (IParam n ty) = n `seq` seqType ty
\end{code}
%* *
%************************************************************************
+Comparison; don't use instances so that we know where it happens.
+Look through newtypes but not usage types.
-For the moment at least, type comparisons don't work if
-there are embedded for-alls.
+Note that eqType can respond 'False' for partial applications of newtypes.
+Consider
+ newtype Parser m a = MkParser (Foogle m a)
-\begin{code}
-instance Eq Type where
- ty1 == ty2 = case ty1 `compare` ty2 of { EQ -> True; other -> False }
-
-instance Ord Type where
- compare ty1 ty2 = cmpTy emptyVarEnv ty1 ty2
-
-cmpTy :: TyVarEnv TyVar -> Type -> Type -> Ordering
- -- 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
-
- -- Get rid of NoteTy
-cmpTy env (NoteTy _ ty1) ty2 = cmpTy env ty1 ty2
-cmpTy env ty1 (NoteTy _ ty2) = cmpTy env ty1 ty2
-
- -- Get rid of PredTy
-cmpTy env (PredTy p1) (PredTy p2) = cmpPred env p1 p2
-cmpTy env (PredTy p1) ty2 = cmpTy env (predRepTy p1) ty2
-cmpTy env ty1 (PredTy p2) = cmpTy env ty1 (predRepTy p2)
-
- -- Deal with equal constructors
-cmpTy env (TyVarTy tv1) (TyVarTy tv2) = case lookupVarEnv env tv1 of
- Just tv1a -> tv1a `compare` tv2
- Nothing -> tv1 `compare` tv2
-
-cmpTy env (AppTy f1 a1) (AppTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2
-cmpTy env (FunTy f1 a1) (FunTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2
-cmpTy env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` (cmpTys env tys1 tys2)
-cmpTy env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmpTy (extendVarEnv env tv1 tv2) t1 t2
-
- -- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy
-cmpTy env (AppTy _ _) (TyVarTy _) = GT
-
-cmpTy env (FunTy _ _) (TyVarTy _) = GT
-cmpTy env (FunTy _ _) (AppTy _ _) = GT
-
-cmpTy env (TyConApp _ _) (TyVarTy _) = GT
-cmpTy env (TyConApp _ _) (AppTy _ _) = GT
-cmpTy env (TyConApp _ _) (FunTy _ _) = GT
-
-cmpTy env (ForAllTy _ _) other = GT
-
-cmpTy env _ _ = LT
+Does
+ Monad (Parser m) `eqType` Monad (Foogle m)
-
-cmpTys env [] [] = EQ
-cmpTys env (t:ts) [] = GT
-cmpTys env [] (t:ts) = LT
-cmpTys env (t1:t1s) (t2:t2s) = cmpTy env t1 t2 `thenCmp` cmpTys env t1s t2s
-\end{code}
+Well, yes, but eqType won't see that they are the same.
+I don't think this is harmful, but it's soemthing to watch out for.
\begin{code}
-instance Eq PredType where
- p1 == p2 = case p1 `compare` p2 of { EQ -> True; other -> False }
-
-instance Ord PredType where
- compare p1 p2 = cmpPred emptyVarEnv p1 p2
-
-cmpPred :: TyVarEnv TyVar -> PredType -> PredType -> Ordering
-cmpPred env (IParam n1 t) (IParam n2 t2) = n1 `compare` n2
- -- Just compare the names!
-cmpPred env (Class c1 tys1) (Class c2 tys2) = (c1 `compare` c2) `thenCmp` (cmpTys env tys1 tys2)
-cmpPred env (IParam _ _) (Class _ _) = LT
-cmpPred env (Class _ _) (IParam _ _) = GT
+eqType t1 t2 = eq_ty emptyVarEnv t1 t2
+
+-- 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 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
+ Just tv1a -> tv1a == tv2
+ Nothing -> tv1 == tv2
+eq_ty env (ForAllTy tv1 t1) (ForAllTy tv2 t2)
+ | tv1 == tv2 = eq_ty (delVarEnv env tv1) t1 t2
+ | otherwise = eq_ty (extendVarEnv env tv1 tv2) t1 t2
+eq_ty env (AppTy s1 t1) (AppTy s2 t2) = (eq_ty env s1 s2) && (eq_ty env t1 t2)
+eq_ty env (FunTy s1 t1) (FunTy s2 t2) = (eq_ty env s1 s2) && (eq_ty env t1 t2)
+eq_ty env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 == tc2) && (eq_tys env tys1 tys2)
+eq_ty env t1 t2 = False
+
+eq_tys env [] [] = True
+eq_tys env (t1:tys1) (t2:tys2) = (eq_ty env t1 t2) && (eq_tys env tys1 tys2)
+eq_tys env tys1 tys2 = False
\end{code}
+
projects / ghc-hetmet.git / blobdiff