-\begin{code}
-#include "HsVersions.h"
+%
+% (c) The GRASP/AQUA Project, Glasgow University, 1998
+%
+\section[Type]{Type - public interface}
+\begin{code}
module Type (
- GenType(..), SYN_IE(Type), SYN_IE(TauType),
- mkTyVarTy, mkTyVarTys,
- getTyVar, getTyVar_maybe, isTyVarTy,
- mkAppTy, mkAppTys, splitAppTy,
- mkFunTy, mkFunTys,
- splitFunTy, splitFunTyExpandingDicts, splitFunTyExpandingDictsAndPeeking,
- getFunTy_maybe, getFunTyExpandingDicts_maybe,
- mkTyConTy, getTyCon_maybe, applyTyCon,
- mkSynTy,
- mkForAllTy, mkForAllTys, getForAllTy_maybe, getForAllTyExpandingDicts_maybe, splitForAllTy,
- mkForAllUsageTy, getForAllUsageTy,
- applyTy,
-#ifdef DEBUG
- expandTy, -- only let out for debugging (ToDo: rm?)
-#endif
- isPrimType, isUnboxedType, typePrimRep,
+ -- re-exports from TypeRep
+ TyThing(..), Type, PredType(..), ThetaType,
+ funTyCon,
+
+ -- 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, isFunTy,
+
+ mkTyConApp, mkTyConTy,
+ tyConAppTyCon, tyConAppArgs,
+ splitTyConApp_maybe, splitTyConApp,
+
+ repType, typePrimRep, coreView, tcView,
+
+ mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys,
+ applyTy, applyTys, isForAllTy, dropForAlls,
+
+ -- Source types
+ predTypeRep, mkPredTy, mkPredTys,
- SYN_IE(RhoType), SYN_IE(SigmaType), SYN_IE(ThetaType),
- mkDictTy,
- mkRhoTy, splitRhoTy, mkTheta, isDictTy,
- mkSigmaTy, splitSigmaTy,
+ -- Newtypes
+ splitRecNewType_maybe,
- maybeAppTyCon, getAppTyCon,
- maybeAppDataTyCon, getAppDataTyCon, getAppSpecDataTyCon,
- maybeAppDataTyConExpandingDicts, maybeAppSpecDataTyConExpandingDicts,
- getAppDataTyConExpandingDicts, getAppSpecDataTyConExpandingDicts,
- maybeBoxedPrimType,
+ -- Lifting and boxity
+ isUnLiftedType, isUnboxedTupleType, isAlgType, isPrimitiveType,
+ isStrictType, isStrictPred,
- matchTy, matchTys, eqTy, eqSimpleTy, eqSimpleTheta,
+ -- Free variables
+ tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
+ typeKind, addFreeTyVars,
- instantiateTy, instantiateTauTy, instantiateUsage,
- applyTypeEnvToTy,
+ -- Tidying up for printing
+ tidyType, tidyTypes,
+ tidyOpenType, tidyOpenTypes,
+ tidyTyVarBndr, tidyFreeTyVars,
+ tidyOpenTyVar, tidyOpenTyVars,
+ tidyTopType, tidyPred,
+ tidyKind,
- isTauTy,
+ -- Comparison
+ coreEqType, tcEqType, tcEqTypes, tcCmpType, tcCmpTypes,
+ tcEqPred, tcCmpPred, tcEqTypeX,
- tyVarsOfType, tyVarsOfTypes, namesOfType, typeKind
+ -- Seq
+ seqType, seqTypes,
+
+ -- Type substitutions
+ TvSubstEnv, emptyTvSubstEnv, -- Representation widely visible
+ TvSubst(..), emptyTvSubst, -- Representation visible to a few friends
+ mkTvSubst, mkOpenTvSubst, zipOpenTvSubst, zipTopTvSubst, mkTopTvSubst, notElemTvSubst,
+ getTvSubstEnv, setTvSubstEnv, getTvInScope, extendTvInScope,
+ extendTvSubst, extendTvSubstList, isInScope, composeTvSubst, zipTyEnv,
+
+ -- Performing substitution on types
+ substTy, substTys, substTyWith, substTheta,
+ substPred, substTyVar, substTyVarBndr, deShadowTy, lookupTyVar,
+
+ -- Pretty-printing
+ pprType, pprParendType, pprTyThingCategory,
+ pprPred, pprTheta, pprThetaArrow, pprClassPred
) where
-IMP_Ubiq()
---IMPORT_DELOOPER(IdLoop) -- for paranoia checking
-IMPORT_DELOOPER(TyLoop)
---IMPORT_DELOOPER(PrelLoop) -- for paranoia checking
+#include "HsVersions.h"
+
+-- We import the representation and primitive functions from TypeRep.
+-- Many things are reexported, but not the representation!
+
+import TypeRep
-- friends:
-import Class ( classSig, classOpLocalType, GenClass{-instances-} )
-import Kind ( mkBoxedTypeKind, resultKind, notArrowKind, Kind )
-import TyCon ( mkFunTyCon, isFunTyCon,
- isPrimTyCon, isDataTyCon, isSynTyCon, maybeNewTyCon, isNewTyCon,
- tyConKind, tyConDataCons, getSynTyConDefn, TyCon )
-import TyVar ( tyVarKind, GenTyVar{-instances-}, SYN_IE(GenTyVarSet),
- emptyTyVarSet, unionTyVarSets, minusTyVarSet,
- unitTyVarSet, nullTyVarEnv, lookupTyVarEnv, delFromTyVarEnv,
- addOneToTyVarEnv, SYN_IE(TyVarEnv), SYN_IE(TyVar) )
-import Usage ( usageOmega, GenUsage, SYN_IE(Usage), SYN_IE(UVar), SYN_IE(UVarEnv),
- nullUVarEnv, addOneToUVarEnv, lookupUVarEnv, eqUVar,
- eqUsage )
-
-import Name ( NamedThing(..),
- NameSet(..), unionNameSets, emptyNameSet, unitNameSet, minusNameSet
+import Kind
+import Var ( Var, TyVar, tyVarKind, tyVarName, setTyVarName, mkTyVar )
+import VarEnv
+import VarSet
+
+import OccName ( tidyOccName )
+import Name ( NamedThing(..), mkInternalName, tidyNameOcc )
+import Class ( Class, classTyCon )
+import TyCon ( TyCon, isRecursiveTyCon, isPrimTyCon,
+ isUnboxedTupleTyCon, isUnLiftedTyCon,
+ isFunTyCon, isNewTyCon, newTyConRep, newTyConRhs,
+ isAlgTyCon, tyConArity,
+ tcExpandTyCon_maybe, coreExpandTyCon_maybe,
+ tyConKind, PrimRep(..), tyConPrimRep,
)
-- others
-import Maybes ( maybeToBool, assocMaybe )
-import PrimRep ( PrimRep(..) )
-import Unique -- quite a few *Keys
-import Util ( thenCmp, zipEqual, assoc,
- panic, panic#, assertPanic, pprPanic,
- Ord3(..){-instances-}
- )
--- ToDo:rm all these
---import {-mumble-}
--- Pretty
---import {-mumble-}
--- PprStyle
---import {-mumble-}
--- PprType --(pprType )
---import {-mumble-}
--- UniqFM (ufmToList )
---import {-mumble-}
--- Outputable
---import PprEnv
+import StaticFlags ( opt_DictsStrict )
+import SrcLoc ( noSrcLoc )
+import Util ( mapAccumL, seqList, lengthIs, snocView, thenCmp, isEqual, all2 )
+import Outputable
+import UniqSet ( sizeUniqSet ) -- Should come via VarSet
+import Maybe ( isJust )
\end{code}
-Data types
-~~~~~~~~~~
-\begin{code}
-type Type = GenType TyVar UVar -- Used after typechecker
-
-data GenType tyvar uvar -- Parameterised over type and usage variables
- = TyVarTy tyvar
-
- | AppTy
- (GenType tyvar uvar)
- (GenType tyvar uvar)
-
- | TyConTy -- Constants of a specified kind
- TyCon -- Must *not* be a SynTyCon
- (GenUsage uvar) -- Usage gives uvar of the full application,
- -- iff the full application is of kind Type
- -- c.f. the Usage field in TyVars
-
- | SynTy -- Synonyms must be saturated, and contain their expansion
- TyCon -- Must be a SynTyCon
- [GenType tyvar uvar]
- (GenType tyvar uvar) -- Expansion!
-
- | ForAllTy
- tyvar
- (GenType tyvar uvar) -- TypeKind
-
- | ForAllUsageTy
- uvar -- Quantify over this
- [uvar] -- Bounds; the quantified var must be
- -- less than or equal to all these
- (GenType tyvar uvar)
-
- -- Two special cases that save a *lot* of administrative
- -- overhead:
-
- | FunTy -- BoxedTypeKind
- (GenType tyvar uvar) -- Both args are of TypeKind
- (GenType tyvar uvar)
- (GenUsage uvar)
-
- | DictTy -- TypeKind
- Class -- Class
- (GenType tyvar uvar) -- Arg has kind TypeKind
- (GenUsage uvar)
-\end{code}
+%************************************************************************
+%* *
+ Type representation
+%* *
+%************************************************************************
+
+In Core, we "look through" non-recursive newtypes and PredTypes.
\begin{code}
-type RhoType = Type
-type TauType = Type
-type ThetaType = [(Class, Type)]
-type SigmaType = Type
+{-# INLINE coreView #-}
+coreView :: Type -> Maybe Type
+-- Srips off the *top layer only* of a type to give
+-- its underlying representation type.
+-- Returns Nothing if there is nothing to look through.
+--
+-- In the case of newtypes, it returns
+-- *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)
+-- expandNewTcApp on R gives Just S
+-- on S gives Just T
+-- on T gives Nothing (no expansion)
+
+-- By being non-recursive and inlined, this case analysis gets efficiently
+-- joined onto the case analysis that the caller is already doing
+coreView (NoteTy _ ty) = Just ty
+coreView (PredTy p) = Just (predTypeRep p)
+coreView (TyConApp tc tys) | Just (tenv, rhs, tys') <- coreExpandTyCon_maybe tc tys
+ = Just (mkAppTys (substTy (mkTopTvSubst tenv) rhs) tys')
+ -- Its important to use mkAppTys, rather than (foldl AppTy),
+ -- because the function part might well return a
+ -- partially-applied type constructor; indeed, usually will!
+coreView ty = Nothing
+
+-----------------------------------------------
+{-# INLINE tcView #-}
+tcView :: Type -> Maybe Type
+-- Same, but for the type checker, which just looks through synonyms
+tcView (NoteTy _ ty) = Just ty
+tcView (TyConApp tc tys) | Just (tenv, rhs, tys') <- tcExpandTyCon_maybe tc tys
+ = Just (mkAppTys (substTy (mkTopTvSubst tenv) rhs) tys')
+tcView ty = Nothing
\end{code}
-Expand abbreviations
-~~~~~~~~~~~~~~~~~~~~
-Removes just the top level of any abbreviations.
+%************************************************************************
+%* *
+\subsection{Constructor-specific functions}
+%* *
+%************************************************************************
+
+---------------------------------------------------------------------
+ TyVarTy
+ ~~~~~~~
\begin{code}
-expandTy :: Type -> Type -- Restricted to Type due to Dict expansion
+mkTyVarTy :: TyVar -> Type
+mkTyVarTy = TyVarTy
+
+mkTyVarTys :: [TyVar] -> [Type]
+mkTyVarTys = map mkTyVarTy -- a common use of mkTyVarTy
-expandTy (FunTy t1 t2 u) = AppTy (AppTy (TyConTy mkFunTyCon u) t1) t2
-expandTy (SynTy _ _ t) = expandTy t
-expandTy (DictTy clas ty u)
- = case all_arg_tys of
+getTyVar :: String -> Type -> TyVar
+getTyVar msg ty = case getTyVar_maybe ty of
+ Just tv -> tv
+ Nothing -> panic ("getTyVar: " ++ msg)
- [] -> voidTy -- Empty dictionary represented by Void
+isTyVarTy :: Type -> Bool
+isTyVarTy ty = isJust (getTyVar_maybe ty)
- [arg_ty] -> expandTy arg_ty -- just the <whatever> itself
+getTyVar_maybe :: Type -> Maybe TyVar
+getTyVar_maybe ty | Just ty' <- coreView ty = getTyVar_maybe ty'
+getTyVar_maybe (TyVarTy tv) = Just tv
+getTyVar_maybe other = Nothing
+\end{code}
- -- The extra expandTy is to make sure that
- -- the result isn't still a dict, which it might be
- -- if the original guy was a dict with one superdict and
- -- no methods!
- other -> ASSERT(not (null all_arg_tys))
- foldl AppTy (TyConTy (tupleTyCon (length all_arg_tys)) u) all_arg_tys
+---------------------------------------------------------------------
+ AppTy
+ ~~~~~
+We need to be pretty careful with AppTy to make sure we obey the
+invariant that a TyConApp is always visibly so. mkAppTy maintains the
+invariant: use it.
- -- A tuple of 'em
- -- Note: length of all_arg_tys can be 0 if the class is
- -- CCallable, CReturnable (and anything else
- -- *really weird* that the user writes).
+\begin{code}
+mkAppTy orig_ty1 orig_ty2
+ = mk_app orig_ty1
where
- (tyvar, super_classes, ops) = classSig clas
- super_dict_tys = map mk_super_ty super_classes
- class_op_tys = map mk_op_ty ops
- all_arg_tys = super_dict_tys ++ class_op_tys
- mk_super_ty sc = DictTy sc ty usageOmega
- mk_op_ty op = instantiateTy [(tyvar,ty)] (classOpLocalType op)
-
-expandTy ty = ty
+ 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
+ -- Note that 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 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
+ = mk_app orig_ty1
+ where
+ mk_app (NoteTy _ ty1) = mk_app ty1
+ mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ orig_tys2)
+ -- mkTyConApp: see notes with mkAppTy
+ mk_app ty1 = foldl AppTy orig_ty1 orig_tys2
+
+splitAppTy_maybe :: Type -> Maybe (Type, Type)
+splitAppTy_maybe ty | Just ty' <- coreView ty = splitAppTy_maybe ty'
+splitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2)
+splitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2)
+splitAppTy_maybe (TyConApp tc tys) = case snocView tys of
+ Nothing -> Nothing
+ Just (tys',ty') -> Just (TyConApp tc tys', ty')
+splitAppTy_maybe other = Nothing
+
+splitAppTy :: Type -> (Type, Type)
+splitAppTy ty = case splitAppTy_maybe ty of
+ Just pr -> pr
+ Nothing -> panic "splitAppTy"
+
+splitAppTys :: Type -> (Type, [Type])
+splitAppTys ty = split ty ty []
+ where
+ split orig_ty ty args | Just ty' <- coreView ty = split orig_ty ty' args
+ split orig_ty (AppTy ty arg) args = split ty ty (arg:args)
+ split orig_ty (TyConApp tc tc_args) args = (TyConApp tc [], tc_args ++ args)
+ split orig_ty (FunTy ty1 ty2) args = ASSERT( null args )
+ (TyConApp funTyCon [], [ty1,ty2])
+ split orig_ty ty args = (orig_ty, args)
\end{code}
-Simple construction and analysis functions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-mkTyVarTy :: t -> GenType t u
-mkTyVarTys :: [t] -> [GenType t y]
-mkTyVarTy = TyVarTy
-mkTyVarTys = map mkTyVarTy -- a common use of mkTyVarTy
-getTyVar :: String -> GenType t u -> t
-getTyVar msg (TyVarTy tv) = tv
-getTyVar msg (SynTy _ _ t) = getTyVar msg t
-getTyVar msg other = panic ("getTyVar: " ++ msg)
+---------------------------------------------------------------------
+ FunTy
+ ~~~~~
-getTyVar_maybe :: GenType t u -> Maybe t
-getTyVar_maybe (TyVarTy tv) = Just tv
-getTyVar_maybe (SynTy _ _ t) = getTyVar_maybe t
-getTyVar_maybe other = Nothing
+\begin{code}
+mkFunTy :: Type -> Type -> Type
+mkFunTy arg res = FunTy arg res
-isTyVarTy :: GenType t u -> Bool
-isTyVarTy (TyVarTy tv) = True
-isTyVarTy (SynTy _ _ t) = isTyVarTy t
-isTyVarTy other = False
-\end{code}
+mkFunTys :: [Type] -> Type -> Type
+mkFunTys tys ty = foldr FunTy ty tys
-\begin{code}
-mkAppTy = AppTy
+isFunTy :: Type -> Bool
+isFunTy ty = isJust (splitFunTy_maybe ty)
+
+splitFunTy :: Type -> (Type, Type)
+splitFunTy ty | Just ty' <- coreView ty = splitFunTy ty'
+splitFunTy (FunTy arg res) = (arg, res)
+splitFunTy other = pprPanic "splitFunTy" (ppr other)
-mkAppTys :: GenType t u -> [GenType t u] -> GenType t u
-mkAppTys t ts = foldl AppTy t ts
+splitFunTy_maybe :: Type -> Maybe (Type, Type)
+splitFunTy_maybe ty | Just ty' <- coreView ty = splitFunTy_maybe ty'
+splitFunTy_maybe (FunTy arg res) = Just (arg, res)
+splitFunTy_maybe other = Nothing
-splitAppTy :: GenType t u -> (GenType t u, [GenType t u])
-splitAppTy t = go t []
+splitFunTys :: Type -> ([Type], Type)
+splitFunTys ty = split [] ty ty
+ where
+ split args orig_ty ty | Just ty' <- coreView ty = split args orig_ty ty'
+ split args orig_ty (FunTy arg res) = split (arg:args) res res
+ split args orig_ty ty = (reverse args, orig_ty)
+
+splitFunTysN :: Int -> Type -> ([Type], Type)
+-- Split off exactly n arg tys
+splitFunTysN 0 ty = ([], ty)
+splitFunTysN n ty = case splitFunTy ty of { (arg, res) ->
+ case splitFunTysN (n-1) res of { (args, res) ->
+ (arg:args, res) }}
+
+zipFunTys :: Outputable a => [a] -> Type -> ([(a,Type)], Type)
+zipFunTys orig_xs orig_ty = split [] orig_xs orig_ty orig_ty
where
- go (AppTy t arg) ts = go t (arg:ts)
- go (FunTy fun arg u) ts = (TyConTy mkFunTyCon u, fun:arg:ts)
- go (SynTy _ _ t) ts = go t ts
- go t ts = (t,ts)
+ split acc [] nty ty = (reverse acc, nty)
+ split acc xs nty ty
+ | Just ty' <- coreView ty = split acc xs nty ty'
+ split acc (x:xs) nty (FunTy arg res) = split ((x,arg):acc) xs res res
+ split acc (x:xs) nty ty = pprPanic "zipFunTys" (ppr orig_xs <+> ppr orig_ty)
+
+funResultTy :: Type -> Type
+funResultTy ty | Just ty' <- coreView ty = funResultTy ty'
+funResultTy (FunTy arg res) = res
+funResultTy ty = pprPanic "funResultTy" (ppr ty)
+
+funArgTy :: Type -> Type
+funArgTy ty | Just ty' <- coreView ty = funArgTy ty'
+funArgTy (FunTy arg res) = arg
+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}
--- NB mkFunTy, mkFunTys puts in Omega usages, for now at least
-mkFunTy arg res = FunTy arg res usageOmega
-
-mkFunTys :: [GenType t u] -> GenType t u -> GenType t u
-mkFunTys ts t = foldr (\ f a -> FunTy f a usageOmega) t ts
-
- -- getFunTy_maybe and splitFunTy *must* have the general type given, which
- -- means they *can't* do the DictTy jiggery-pokery that
- -- *is* sometimes required. Hence we also have the ExpandingDicts variants
- -- The relationship between these
- -- two functions is like that between eqTy and eqSimpleTy.
- -- ToDo: NUKE when we do dicts via newtype
-
-getFunTy_maybe :: GenType t u -> Maybe (GenType t u, GenType t u)
-getFunTy_maybe (FunTy arg result _) = Just (arg,result)
-getFunTy_maybe (AppTy (AppTy (TyConTy tycon _) arg) res)
- | isFunTyCon tycon = Just (arg, res)
-getFunTy_maybe (SynTy _ _ t) = getFunTy_maybe t
-getFunTy_maybe other = Nothing
-
-getFunTyExpandingDicts_maybe :: Bool -- True <=> peek inside newtype applicatons
- -> Type
- -> Maybe (Type, Type)
-
-getFunTyExpandingDicts_maybe peek (FunTy arg result _) = Just (arg,result)
-getFunTyExpandingDicts_maybe peek
- (AppTy (AppTy (TyConTy tycon _) arg) res) | isFunTyCon tycon = Just (arg, res)
-getFunTyExpandingDicts_maybe peek (SynTy _ _ t) = getFunTyExpandingDicts_maybe peek t
-getFunTyExpandingDicts_maybe peek ty@(DictTy _ _ _) = getFunTyExpandingDicts_maybe peek (expandTy ty)
-
-getFunTyExpandingDicts_maybe True (ForAllTy _ ty) = getFunTyExpandingDicts_maybe True ty
- -- Ignore for-alls when peeking. See note with defn of getFunTyExpandingDictsAndPeeking
-
-getFunTyExpandingDicts_maybe peek other
- | not peek = Nothing -- that was easy
+mkTyConApp :: TyCon -> [Type] -> Type
+mkTyConApp tycon tys
+ | isFunTyCon tycon, [ty1,ty2] <- tys
+ = FunTy ty1 ty2
+
| otherwise
- = case (maybeAppTyCon other) of
- Nothing -> Nothing
- Just (tc, arg_tys)
- | not (isNewTyCon tc) -> Nothing
- | otherwise ->
- let
- [newtype_con] = tyConDataCons tc -- there must be exactly one...
- [inside_ty] = dataConArgTys newtype_con arg_tys
- in
- getFunTyExpandingDicts_maybe peek inside_ty
-
-splitFunTy :: GenType t u -> ([GenType t u], GenType t u)
-splitFunTyExpandingDicts :: Type -> ([Type], Type)
-splitFunTyExpandingDictsAndPeeking :: Type -> ([Type], Type)
-
-splitFunTy t = split_fun_ty getFunTy_maybe t
-splitFunTyExpandingDicts t = split_fun_ty (getFunTyExpandingDicts_maybe False) t
-splitFunTyExpandingDictsAndPeeking t = split_fun_ty (getFunTyExpandingDicts_maybe True) t
- -- This "peeking" stuff is used only by the code generator.
- -- It's interested in the representation type of things, ignoring:
- -- newtype
- -- foralls
- -- expanding dictionary reps
- -- synonyms, of course
-
-split_fun_ty get t = go t []
- where
- go t ts = case (get t) of
- Just (arg,res) -> go res (arg:ts)
- Nothing -> (reverse ts, t)
-\end{code}
+ = TyConApp tycon tys
-\begin{code}
--- NB applyTyCon puts in usageOmega, for now at least
-mkTyConTy tycon
- = ASSERT(not (isSynTyCon tycon))
- TyConTy tycon usageOmega
-
-applyTyCon :: TyCon -> [GenType t u] -> GenType t u
-applyTyCon tycon tys
- = ASSERT (not (isSynTyCon tycon))
- --(if (not (isSynTyCon tycon)) then \x->x else pprTrace "applyTyCon:" (pprTyCon PprDebug tycon)) $
- foldl AppTy (TyConTy tycon usageOmega) tys
-
-getTyCon_maybe :: GenType t u -> Maybe TyCon
---getTyConExpandingDicts_maybe :: Type -> Maybe TyCon
-
-getTyCon_maybe (TyConTy tycon _) = Just tycon
-getTyCon_maybe (SynTy _ _ t) = getTyCon_maybe t
-getTyCon_maybe other_ty = Nothing
-
---getTyConExpandingDicts_maybe (TyConTy tycon _) = Just tycon
---getTyConExpandingDicts_maybe (SynTy _ _ t) = getTyConExpandingDicts_maybe t
---getTyConExpandingDicts_maybe ty@(DictTy _ _ _) = getTyConExpandingDicts_maybe (expandTy ty)
---getTyConExpandingDicts_maybe other_ty = Nothing
-\end{code}
+mkTyConTy :: TyCon -> Type
+mkTyConTy tycon = mkTyConApp tycon []
-\begin{code}
-mkSynTy syn_tycon tys
- = ASSERT(isSynTyCon syn_tycon)
- SynTy syn_tycon tys (instantiateTauTy (zipEqual "mkSynTy" tyvars tys) body)
- where
- (tyvars, body) = getSynTyConDefn syn_tycon
-\end{code}
+-- splitTyConApp "looks through" synonyms, because they don't
+-- mean a distinct type, but all other type-constructor applications
+-- including functions are returned as Just ..
-Tau stuff
-~~~~~~~~~
-\begin{code}
-isTauTy :: GenType t u -> Bool
-isTauTy (TyVarTy v) = True
-isTauTy (TyConTy _ _) = True
-isTauTy (AppTy a b) = isTauTy a && isTauTy b
-isTauTy (FunTy a b _) = isTauTy a && isTauTy b
-isTauTy (SynTy _ _ ty) = isTauTy ty
-isTauTy other = False
+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 ty | Just ty' <- coreView ty = splitTyConApp_maybe ty'
+splitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
+splitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res])
+splitTyConApp_maybe other = Nothing
\end{code}
-Rho stuff
-~~~~~~~~~
-NB mkRhoTy and mkDictTy put in usageOmega, for now at least
+
+---------------------------------------------------------------------
+ SynTy
+ ~~~~~
+
+Notes on type synonyms
+~~~~~~~~~~~~~~~~~~~~~~
+The various "split" functions (splitFunTy, splitRhoTy, splitForAllTy) try
+to return type synonyms whereever possible. Thus
+
+ type Foo a = a -> a
+
+we want
+ splitFunTys (a -> Foo a) = ([a], Foo a)
+not ([a], a -> a)
+
+The reason is that we then get better (shorter) type signatures in
+interfaces. Notably this plays a role in tcTySigs in TcBinds.lhs.
+
+
+ Representation types
+ ~~~~~~~~~~~~~~~~~~~~
+repType looks through
+ (a) for-alls, and
+ (b) synonyms
+ (c) predicates
+ (d) usage annotations
+ (e) all newtypes, including recursive ones
+It's useful in the back end.
\begin{code}
-mkDictTy :: Class -> GenType t u -> GenType t u
-mkDictTy clas ty = DictTy clas ty usageOmega
-
-mkRhoTy :: [(Class, GenType t u)] -> GenType t u -> GenType t u
-mkRhoTy theta ty =
- foldr (\(c,t) r -> FunTy (DictTy c t usageOmega) r usageOmega) ty theta
-
-splitRhoTy :: GenType t u -> ([(Class,GenType t u)], GenType t u)
-splitRhoTy t =
- go t []
- where
- go (FunTy (DictTy c t _) r _) ts = go r ((c,t):ts)
- go (AppTy (AppTy (TyConTy tycon _) (DictTy c t _)) r) ts
- | isFunTyCon tycon
- = go r ((c,t):ts)
- go (SynTy _ _ t) ts = go t ts
- go t ts = (reverse ts, t)
-
-
-mkTheta :: [Type] -> ThetaType
- -- recover a ThetaType from the types of some dictionaries
-mkTheta dict_tys
- = map cvt dict_tys
- where
- cvt (DictTy clas ty _) = (clas, ty)
- cvt other = panic "Type.mkTheta" -- pprPanic "mkTheta:" (pprType PprDebug other)
+repType :: Type -> Type
+-- Only applied to types of kind *; hence tycons are saturated
+repType ty | Just ty' <- coreView ty = repType ty'
+repType (ForAllTy _ ty) = repType ty
+repType (TyConApp tc tys)
+ | isNewTyCon tc = -- Recursive newtypes are opaque to coreView
+ -- but we must expand them here. Sure to
+ -- be saturated because repType is only applied
+ -- to types of kind *
+ ASSERT( isRecursiveTyCon tc &&
+ tys `lengthIs` tyConArity tc )
+ repType (new_type_rep tc tys)
+repType ty = ty
+
+-- 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
+
+-- 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 -- 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.
-isDictTy (DictTy _ _ _) = True
-isDictTy (SynTy _ _ t) = isDictTy t
-isDictTy _ = False
\end{code}
-Forall stuff
-~~~~~~~~~~~~
+---------------------------------------------------------------------
+ ForAllTy
+ ~~~~~~~~
+
\begin{code}
-mkForAllTy = ForAllTy
+mkForAllTy :: TyVar -> Type -> Type
+mkForAllTy tyvar ty
+ = mkForAllTys [tyvar] ty
-mkForAllTys :: [t] -> GenType t u -> GenType t u
+mkForAllTys :: [TyVar] -> Type -> Type
mkForAllTys tyvars ty = foldr ForAllTy ty tyvars
-getForAllTy_maybe :: GenType t u -> Maybe (t,GenType t u)
-getForAllTy_maybe (SynTy _ _ t) = getForAllTy_maybe t
-getForAllTy_maybe (ForAllTy tyvar t) = Just(tyvar,t)
-getForAllTy_maybe _ = Nothing
-
-getForAllTyExpandingDicts_maybe :: Type -> Maybe (TyVar, Type)
-getForAllTyExpandingDicts_maybe (SynTy _ _ t) = getForAllTyExpandingDicts_maybe t
-getForAllTyExpandingDicts_maybe (ForAllTy tyvar t) = Just(tyvar,t)
-getForAllTyExpandingDicts_maybe ty@(DictTy _ _ _) = getForAllTyExpandingDicts_maybe (expandTy ty)
-getForAllTyExpandingDicts_maybe _ = Nothing
-
-splitForAllTy :: GenType t u-> ([t], GenType t u)
-splitForAllTy t = go t []
- where
- go (ForAllTy tv t) tvs = go t (tv:tvs)
- go (SynTy _ _ t) tvs = go t tvs
- go t tvs = (reverse tvs, t)
+isForAllTy :: Type -> Bool
+isForAllTy (NoteTy _ ty) = isForAllTy ty
+isForAllTy (ForAllTy _ _) = True
+isForAllTy other_ty = False
+
+splitForAllTy_maybe :: Type -> Maybe (TyVar, Type)
+splitForAllTy_maybe ty = splitFAT_m ty
+ where
+ splitFAT_m ty | Just ty' <- coreView ty = splitFAT_m ty'
+ splitFAT_m (ForAllTy tyvar ty) = Just(tyvar, ty)
+ splitFAT_m _ = Nothing
+
+splitForAllTys :: Type -> ([TyVar], Type)
+splitForAllTys ty = split ty ty []
+ where
+ split orig_ty ty tvs | Just ty' <- coreView ty = split orig_ty ty' tvs
+ split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs)
+ split orig_ty t tvs = (reverse tvs, orig_ty)
+
+dropForAlls :: Type -> Type
+dropForAlls ty = snd (splitForAllTys ty)
\end{code}
-\begin{code}
-mkForAllUsageTy :: u -> [u] -> GenType t u -> GenType t u
-mkForAllUsageTy = ForAllUsageTy
+-- (mkPiType now in CoreUtils)
-getForAllUsageTy :: GenType t u -> Maybe (u,[u],GenType t u)
-getForAllUsageTy (ForAllUsageTy uvar bounds t) = Just(uvar,bounds,t)
-getForAllUsageTy (SynTy _ _ t) = getForAllUsageTy t
-getForAllUsageTy _ = Nothing
-\end{code}
+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.
-Applied tycons (includes FunTyCons)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\begin{code}
-maybeAppTyCon
- :: GenType tyvar uvar
- -> Maybe (TyCon, -- the type constructor
- [GenType tyvar uvar]) -- types to which it is applied
-
-maybeAppTyCon ty
- = case (getTyCon_maybe app_ty) of
- Nothing -> Nothing
- Just tycon -> Just (tycon, arg_tys)
+applyTy :: Type -> Type -> Type
+applyTy ty arg | Just ty' <- coreView ty = applyTy ty' arg
+applyTy (ForAllTy tv ty) arg = substTyWith [tv] [arg] ty
+applyTy other arg = panic "applyTy"
+
+applyTys :: Type -> [Type] -> Type
+-- 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
- (app_ty, arg_tys) = splitAppTy ty
-
+ (tvs, rho_ty) = splitForAllTys orig_fun_ty
+ n_tvs = length tvs
+ n_args = length arg_tys
+\end{code}
-getAppTyCon
- :: GenType tyvar uvar
- -> (TyCon, -- the type constructor
- [GenType tyvar uvar]) -- types to which it is applied
-getAppTyCon ty
- = case maybeAppTyCon ty of
- Just stuff -> stuff
-#ifdef DEBUG
- Nothing -> panic "Type.getAppTyCon" -- (ppr PprShowAll ty)
-#endif
-\end{code}
+%************************************************************************
+%* *
+\subsection{Source types}
+%* *
+%************************************************************************
-Applied data tycons (give back constrs)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-maybeAppDataTyCon
- :: GenType (GenTyVar any) uvar
- -> Maybe (TyCon, -- the type constructor
- [GenType (GenTyVar any) uvar], -- types to which it is applied
- [Id]) -- its family of data-constructors
-maybeAppDataTyConExpandingDicts, maybeAppSpecDataTyConExpandingDicts
- :: Type -> Maybe (TyCon, [Type], [Id])
-
-maybeAppDataTyCon ty = maybe_app_data_tycon (\x->x) ty
-maybeAppDataTyConExpandingDicts ty = maybe_app_data_tycon expandTy ty
-maybeAppSpecDataTyConExpandingDicts ty = maybe_app_data_tycon expandTy ty
-
-
-maybe_app_data_tycon expand ty
- = let
- expanded_ty = expand ty
- (app_ty, arg_tys) = splitAppTy expanded_ty
- in
- case (getTyCon_maybe app_ty) of
- Just tycon | --pprTrace "maybe_app:" (ppCat [ppr PprDebug (isDataTyCon tycon), ppr PprDebug (notArrowKind (typeKind expanded_ty))]) $
- isDataTyCon tycon &&
- notArrowKind (typeKind expanded_ty)
- -- Must be saturated for ty to be a data type
- -> Just (tycon, arg_tys, tyConDataCons tycon)
-
- other -> Nothing
-
-getAppDataTyCon, getAppSpecDataTyCon
- :: GenType (GenTyVar any) uvar
- -> (TyCon, -- the type constructor
- [GenType (GenTyVar any) uvar], -- types to which it is applied
- [Id]) -- its family of data-constructors
-getAppDataTyConExpandingDicts, getAppSpecDataTyConExpandingDicts
- :: Type -> (TyCon, [Type], [Id])
-
-getAppDataTyCon ty = get_app_data_tycon maybeAppDataTyCon ty
-getAppDataTyConExpandingDicts ty = --pprTrace "getAppDataTyConEx...:" (pprType PprDebug ty) $
- get_app_data_tycon maybeAppDataTyConExpandingDicts ty
-
--- these should work like the UniTyFuns.getUniDataSpecTyCon* things of old (ToDo)
-getAppSpecDataTyCon = getAppDataTyCon
-getAppSpecDataTyConExpandingDicts = getAppDataTyConExpandingDicts
-
-get_app_data_tycon maybe ty
- = case maybe ty of
- Just stuff -> stuff
-#ifdef DEBUG
- Nothing -> panic "Type.getAppDataTyCon"-- (pprGenType PprShowAll ty)
-#endif
+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.
+Source types are always lifted.
-maybeBoxedPrimType :: Type -> Maybe (Id, Type)
+The key function is predTypeRep which gives the representation of a source type:
-maybeBoxedPrimType ty
- = case (maybeAppDataTyCon ty) of -- Data type,
- Just (tycon, tys_applied, [data_con]) -- with exactly one constructor
- -> case (dataConArgTys data_con tys_applied) of
- [data_con_arg_ty] -- Applied to exactly one type,
- | isPrimType data_con_arg_ty -- which is primitive
- -> Just (data_con, data_con_arg_ty)
- other_cases -> Nothing
- other_cases -> Nothing
+\begin{code}
+mkPredTy :: PredType -> Type
+mkPredTy pred = PredTy pred
+
+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 newtype application
+predTypeRep (IParam _ ty) = ty
+predTypeRep (ClassP clas tys) = mkTyConApp (classTyCon clas) tys
+ -- Result might be a newtype application, but the consumer will
+ -- look through that too if necessary
\end{code}
+
+%************************************************************************
+%* *
+ NewTypes
+%* *
+%************************************************************************
+
\begin{code}
-splitSigmaTy :: GenType t u -> ([t], [(Class,GenType t u)], GenType t u)
-splitSigmaTy ty =
- (tyvars, theta, tau)
- where
- (tyvars,rho) = splitForAllTy ty
- (theta,tau) = splitRhoTy rho
-
-mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkRhoTy theta tau)
+splitRecNewType_maybe :: Type -> Maybe Type
+-- 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 ty | Just ty' <- coreView ty = splitRecNewType_maybe ty'
+splitRecNewType_maybe (TyConApp tc tys)
+ | isNewTyCon tc
+ = ASSERT( tys `lengthIs` tyConArity tc ) -- splitRecNewType_maybe only be applied
+ -- to *types* (of kind *)
+ ASSERT( isRecursiveTyCon tc ) -- Guaranteed by coreView
+ case newTyConRhs tc of
+ (tvs, rep_ty) -> ASSERT( length tvs == length tys )
+ Just (substTyWith tvs tys rep_ty)
+
+splitRecNewType_maybe other = Nothing
\end{code}
-Finding the kind of a type
-~~~~~~~~~~~~~~~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Kinds and free variables}
+%* *
+%************************************************************************
+
+---------------------------------------------------------------------
+ Finding the kind of a type
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~
\begin{code}
-typeKind :: GenType (GenTyVar any) u -> Kind
-
-typeKind (TyVarTy tyvar) = tyVarKind tyvar
-typeKind (TyConTy tycon usage) = tyConKind tycon
-typeKind (SynTy _ _ ty) = typeKind ty
-typeKind (FunTy fun arg _) = mkBoxedTypeKind
-typeKind (DictTy clas arg _) = mkBoxedTypeKind
-typeKind (AppTy fun arg) = resultKind (typeKind fun)
-typeKind (ForAllTy _ _) = mkBoxedTypeKind
-typeKind (ForAllUsageTy _ _ _) = mkBoxedTypeKind
+typeKind :: Type -> Kind
+
+typeKind (TyVarTy tyvar) = tyVarKind tyvar
+typeKind (TyConApp tycon tys) = foldr (\_ k -> kindFunResult k) (tyConKind tycon) tys
+typeKind (NoteTy _ ty) = typeKind ty
+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
-~~~~~~~~~~~~~~~~~~~~~~~~
+---------------------------------------------------------------------
+ Free variables of a type
+ ~~~~~~~~~~~~~~~~~~~~~~~~
\begin{code}
-tyVarsOfType :: GenType (GenTyVar flexi) uvar -> GenTyVarSet flexi
-
-tyVarsOfType (TyVarTy tv) = unitTyVarSet tv
-tyVarsOfType (TyConTy tycon usage) = emptyTyVarSet
-tyVarsOfType (SynTy _ tys ty) = tyVarsOfTypes tys
-tyVarsOfType (FunTy arg res _) = tyVarsOfType arg `unionTyVarSets` tyVarsOfType res
-tyVarsOfType (AppTy fun arg) = tyVarsOfType fun `unionTyVarSets` tyVarsOfType arg
-tyVarsOfType (DictTy clas ty _) = tyVarsOfType ty
-tyVarsOfType (ForAllTy tyvar ty) = tyVarsOfType ty `minusTyVarSet` unitTyVarSet tyvar
-tyVarsOfType (ForAllUsageTy _ _ ty) = tyVarsOfType ty
-
-tyVarsOfTypes :: [GenType (GenTyVar flexi) uvar] -> GenTyVarSet flexi
-tyVarsOfTypes tys = foldr (unionTyVarSets.tyVarsOfType) emptyTyVarSet tys
-
--- Find the free names of a type, including the type constructors and classes it mentions
-namesOfType :: GenType (GenTyVar flexi) uvar -> NameSet
-namesOfType (TyVarTy tv) = unitNameSet (getName tv)
-namesOfType (TyConTy tycon usage) = unitNameSet (getName tycon)
-namesOfType (SynTy tycon tys ty) = unitNameSet (getName tycon) `unionNameSets`
- namesOfType ty
-namesOfType (FunTy arg res _) = namesOfType arg `unionNameSets` namesOfType res
-namesOfType (AppTy fun arg) = namesOfType fun `unionNameSets` namesOfType arg
-namesOfType (DictTy clas ty _) = unitNameSet (getName clas) `unionNameSets`
- namesOfType ty
-namesOfType (ForAllTy tyvar ty) = namesOfType ty `minusNameSet` unitNameSet (getName tyvar)
-namesOfType (ForAllUsageTy _ _ ty) = panic "forall usage"
+tyVarsOfType :: Type -> TyVarSet
+-- NB: for type synonyms tyVarsOfType does *not* expand the synonym
+tyVarsOfType (TyVarTy tv) = unitVarSet tv
+tyVarsOfType (TyConApp tycon tys) = tyVarsOfTypes tys
+tyVarsOfType (NoteTy (FTVNote tvs) ty2) = tvs
+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) = delVarSet (tyVarsOfType ty) tyvar
+
+tyVarsOfTypes :: [Type] -> TyVarSet
+tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys
+
+tyVarsOfPred :: PredType -> TyVarSet
+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
+addFreeTyVars :: Type -> Type
+addFreeTyVars ty@(NoteTy (FTVNote _) _) = ty
+addFreeTyVars ty = NoteTy (FTVNote (tyVarsOfType ty)) ty
\end{code}
-Instantiating a type
-~~~~~~~~~~~~~~~~~~~~
-\begin{code}
--- applyTy :: GenType (GenTyVar flexi) uvar
--- -> GenType (GenTyVar flexi) uvar
--- -> GenType (GenTyVar flexi) uvar
+%************************************************************************
+%* *
+\subsection{TidyType}
+%* *
+%************************************************************************
-applyTy :: Type -> Type -> Type
+tidyTy tidies up a type for printing in an error message, or in
+an interface file.
-applyTy (SynTy _ _ fun) arg = applyTy fun arg
-applyTy (ForAllTy tv ty) arg = instantiateTy [(tv,arg)] ty
-applyTy ty@(DictTy _ _ _) arg = applyTy (expandTy ty) arg
-applyTy other arg = panic "applyTy"
-\end{code}
+It doesn't change the uniques at all, just the print names.
\begin{code}
-instantiateTy :: [(GenTyVar flexi, GenType (GenTyVar flexi) uvar)]
- -> GenType (GenTyVar flexi) uvar
- -> GenType (GenTyVar flexi) uvar
+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' = tidyNameOcc name occ'
+ where
+ name = tyVarName tyvar
-instantiateTauTy :: Eq tv =>
- [(tv, GenType tv' u)]
- -> GenType tv u
- -> GenType tv' u
+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))
-applyTypeEnvToTy :: TyVarEnv Type -> SigmaType -> SigmaType
+tidyOpenTyVars :: TidyEnv -> [TyVar] -> (TidyEnv, [TyVar])
+tidyOpenTyVars env tyvars = mapAccumL tidyOpenTyVar env tyvars
--- 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
+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
-instant_help ty lookup_tv deflt_tv choose_tycon
- if_usage if_forall bound_forall_tv_BAD deflt_forall_tv
+tidyType :: TidyEnv -> Type -> Type
+tidyType env@(tidy_env, subst) ty
= go ty
where
- go (TyVarTy tv) = case (lookup_tv tv) of
- Nothing -> deflt_tv tv
- Just ty -> ty
- go ty@(TyConTy tycon usage) = choose_tycon ty tycon usage
- go (SynTy tycon tys ty) = SynTy tycon (map go tys) (go ty)
- go (FunTy arg res usage) = FunTy (go arg) (go res) usage
- go (AppTy fun arg) = AppTy (go fun) (go arg)
- go (DictTy clas ty usage) = DictTy clas (go ty) usage
- go (ForAllUsageTy uvar bds ty) = if_usage $
- ForAllUsageTy uvar bds (go ty)
- go (ForAllTy tv ty) = if_forall $
- (if (bound_forall_tv_BAD && maybeToBool (lookup_tv tv)) then
- trace "instantiateTy: unexpected forall hit"
- else
- \x->x) ForAllTy (deflt_forall_tv tv) (go ty)
-
-instantiateTy tenv ty
- = instant_help ty lookup_tv deflt_tv choose_tycon
- if_usage if_forall bound_forall_tv_BAD deflt_forall_tv
- where
- lookup_tv tv = case [ty | (tv',ty) <- tenv, tv == tv'] of
- [] -> Nothing
- [ty] -> Just ty
- _ -> panic "instantiateTy:lookup_tv"
-
- deflt_tv tv = TyVarTy tv
- choose_tycon ty _ _ = ty
- if_usage ty = ty
- if_forall ty = ty
- bound_forall_tv_BAD = True
- deflt_forall_tv tv = tv
-
-instantiateTauTy tenv ty
- = instant_help ty lookup_tv deflt_tv choose_tycon
- if_usage if_forall bound_forall_tv_BAD deflt_forall_tv
- where
- lookup_tv tv = case [ty | (tv',ty) <- tenv, tv == tv'] of
- [] -> Nothing
- [ty] -> Just ty
- _ -> panic "instantiateTauTy:lookup_tv"
-
- deflt_tv tv = panic "instantiateTauTy"
- choose_tycon _ tycon usage = TyConTy tycon usage
- if_usage ty = panic "instantiateTauTy:ForAllUsageTy"
- if_forall ty = panic "instantiateTauTy:ForAllTy"
- bound_forall_tv_BAD = panic "instantiateTauTy:bound_forall_tv"
- deflt_forall_tv tv = panic "instantiateTauTy:deflt_forall_tv"
-
-
--- applyTypeEnv 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.
---
--- We don't use instant_help because we need to carry in the environment
-
-applyTypeEnvToTy tenv ty
- = go tenv ty
- where
- go tenv ty@(TyVarTy tv) = case (lookupTyVarEnv tenv tv) of
- Nothing -> ty
- Just ty -> ty
- go tenv ty@(TyConTy tycon usage) = ty
- go tenv (SynTy tycon tys ty) = SynTy tycon (map (go tenv) tys) (go tenv ty)
- go tenv (FunTy arg res usage) = FunTy (go tenv arg) (go tenv res) usage
- go tenv (AppTy fun arg) = AppTy (go tenv fun) (go tenv arg)
- go tenv (DictTy clas ty usage) = DictTy clas (go tenv ty) usage
- go tenv (ForAllUsageTy uvar bds ty) = ForAllUsageTy uvar bds (go tenv ty)
- go tenv (ForAllTy tv ty) = ForAllTy tv (go tenv' ty)
- where
- tenv' = case lookupTyVarEnv tenv tv of
- Nothing -> tenv
- Just _ -> delFromTyVarEnv tenv tv
+ go (TyVarTy tv) = case lookupVarEnv subst tv of
+ Nothing -> TyVarTy tv
+ Just tv' -> TyVarTy tv'
+ go (TyConApp tycon tys) = let args = map go tys
+ in args `seqList` TyConApp 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) = tidyTyVarBndr env tv
+
+ go_note note@(FTVNote ftvs) = note -- No need to tidy the free tyvars
+
+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@ grabs the free type variables, tidies them
+and then uses @tidyType@ to work over the type itself
+
\begin{code}
-instantiateUsage
- :: Ord3 u => [(u, GenType t u')] -> GenType t u -> GenType t u'
+tidyOpenType :: TidyEnv -> Type -> (TidyEnv, Type)
+tidyOpenType env ty
+ = (env', tidyType env' ty)
+ where
+ env' = tidyFreeTyVars env (tyVarsOfType ty)
-instantiateUsage = panic "instantiateUsage: not implemented"
+tidyOpenTypes :: TidyEnv -> [Type] -> (TidyEnv, [Type])
+tidyOpenTypes env tys = mapAccumL tidyOpenType env tys
+
+tidyTopType :: Type -> Type
+tidyTopType ty = tidyType emptyTidyEnv ty
\end{code}
-At present there are no unboxed non-primitive types, so
-isUnboxedType is the same as isPrimType.
+%************************************************************************
+%* *
+ Tidying Kinds
+%* *
+%************************************************************************
-We're a bit cavalier about finding out whether something is
-primitive/unboxed or not. Rather than deal with the type
-arguemnts we just zoom into the function part of the type.
-That is, given (T a) we just recurse into the "T" part,
-ignoring "a".
+We use a grevious hack for tidying KindVars. A TidyEnv contains
+a (VarEnv Var) substitution, to express the renaming; but
+KindVars are not Vars. The Right Thing ultimately is to make them
+into Vars (and perhaps make Kinds into Types), but I just do a hack
+here: I make up a TyVar just to remember the new OccName for the
+renamed KindVar
\begin{code}
-isPrimType, isUnboxedType :: Type -> Bool
+tidyKind :: TidyEnv -> Kind -> (TidyEnv, Kind)
+tidyKind env@(tidy_env, subst) (KindVar kvar)
+ | Just tv <- lookupVarEnv_Directly subst uniq
+ = (env, KindVar (setKindVarOcc kvar (getOccName tv)))
+ | otherwise
+ = ((tidy', subst'), KindVar kvar')
+ where
+ uniq = kindVarUniq kvar
+ (tidy', occ') = tidyOccName tidy_env (kindVarOcc kvar)
+ kvar' = setKindVarOcc kvar occ'
+ fake_tv = mkTyVar tv_name (panic "tidyKind:fake tv kind")
+ tv_name = mkInternalName uniq occ' noSrcLoc
+ subst' = extendVarEnv subst fake_tv fake_tv
+
+tidyKind env (FunKind k1 k2)
+ = (env2, FunKind k1' k2')
+ where
+ (env1, k1') = tidyKind env k1
+ (env2, k2') = tidyKind env1 k2
+
+tidyKind env k = (env, k) -- Atomic kinds
+\end{code}
-isPrimType (AppTy ty _) = isPrimType ty
-isPrimType (SynTy _ _ ty) = isPrimType ty
-isPrimType (TyConTy tycon _) = case maybeNewTyCon tycon of
- Just (tyvars, ty) -> isPrimType ty
- Nothing -> isPrimTyCon tycon
-isPrimType _ = False
+%************************************************************************
+%* *
+\subsection{Liftedness}
+%* *
+%************************************************************************
-isUnboxedType = isPrimType
+\begin{code}
+isUnLiftedType :: Type -> Bool
+ -- isUnLiftedType returns True for forall'd unlifted types:
+ -- x :: forall a. Int#
+ -- I found bindings like these were getting floated to the top level.
+ -- They are pretty bogus types, mind you. It would be better never to
+ -- construct them
+
+isUnLiftedType ty | Just ty' <- coreView ty = isUnLiftedType ty'
+isUnLiftedType (ForAllTy tv ty) = isUnLiftedType ty
+isUnLiftedType (TyConApp tc _) = isUnLiftedTyCon tc
+isUnLiftedType other = False
+
+isUnboxedTupleType :: Type -> Bool
+isUnboxedTupleType ty = case splitTyConApp_maybe ty of
+ Just (tc, ty_args) -> isUnboxedTupleTyCon tc
+ other -> False
+
+-- Should only be applied to *types*; hence the assert
+isAlgType :: Type -> Bool
+isAlgType ty = case splitTyConApp_maybe ty of
+ Just (tc, ty_args) -> ASSERT( ty_args `lengthIs` tyConArity tc )
+ isAlgTyCon tc
+ other -> False
\end{code}
-This is *not* right: it is a placeholder (ToDo 96/03 WDP):
+@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.
+
\begin{code}
-typePrimRep :: Type -> PrimRep
+isStrictType (PredTy pred) = isStrictPred pred
+isStrictType ty | Just ty' <- coreView ty = isStrictType ty'
+isStrictType (ForAllTy tv ty) = isStrictType ty
+isStrictType (TyConApp tc _) = isUnLiftedTyCon tc
+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}
-typePrimRep (SynTy _ _ ty) = typePrimRep ty
-typePrimRep (AppTy ty _) = typePrimRep ty
-typePrimRep (TyConTy tc _)
- | isPrimTyCon tc = case (assocMaybe tc_primrep_list (uniqueOf tc)) of
- Just xx -> xx
- Nothing -> panic "Type.typePrimRep" -- pprPanic "typePrimRep:" (pprTyCon PprDebug tc)
-
- | otherwise = case maybeNewTyCon tc of
- Just (tyvars, ty) | isPrimType ty -> typePrimRep ty
- _ -> PtrRep -- Default
-
-typePrimRep _ = PtrRep -- the "default"
-
-tc_primrep_list
- = [(addrPrimTyConKey, AddrRep)
- ,(arrayPrimTyConKey, ArrayRep)
- ,(byteArrayPrimTyConKey, ByteArrayRep)
- ,(charPrimTyConKey, CharRep)
- ,(doublePrimTyConKey, DoubleRep)
- ,(floatPrimTyConKey, FloatRep)
- ,(foreignObjPrimTyConKey, ForeignObjRep)
- ,(intPrimTyConKey, IntRep)
- ,(mutableArrayPrimTyConKey, ArrayRep)
- ,(mutableByteArrayPrimTyConKey, ByteArrayRep)
- ,(stablePtrPrimTyConKey, StablePtrRep)
- ,(statePrimTyConKey, VoidRep)
- ,(synchVarPrimTyConKey, PtrRep)
- ,(voidTyConKey, VoidRep)
- ,(wordPrimTyConKey, WordRep)
- ]
+\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}
+
%************************************************************************
%* *
-\subsection{Matching on types}
+\subsection{Sequencing on types
%* *
%************************************************************************
-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.
-
-@matchTys@ matches corresponding elements of a list of templates and
-types.
-
\begin{code}
-matchTy :: GenType t1 u1 -- Template
- -> GenType t2 u2 -- Proposed instance of template
- -> Maybe [(t1,GenType t2 u2)] -- Matching substitution
-
-
-matchTys :: [GenType t1 u1] -- Templates
- -> [GenType t2 u2] -- Proposed instance of template
- -> Maybe ([(t1,GenType t2 u2)],-- Matching substitution
- [GenType t2 u2]) -- Left over instance types
-
-matchTy ty1 ty2 = match ty1 ty2 (\s -> Just s) []
-matchTys tys1 tys2 = go [] tys1 tys2
- where
- go s [] tys2 = Just (s,tys2)
- go s (ty1:tys1) [] = trace "matchTys" Nothing
- go s (ty1:tys1) (ty2:tys2) = match ty1 ty2 (\s' -> go s' tys1 tys2) s
+seqType :: Type -> ()
+seqType (TyVarTy tv) = tv `seq` ()
+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 (PredTy p) = seqPred p
+seqType (TyConApp tc tys) = tc `seq` seqTypes tys
+seqType (ForAllTy tv ty) = tv `seq` seqType ty
+
+seqTypes :: [Type] -> ()
+seqTypes [] = ()
+seqTypes (ty:tys) = seqType ty `seq` seqTypes tys
+
+seqNote :: TyNote -> ()
+seqNote (FTVNote set) = sizeUniqSet set `seq` ()
+
+seqPred :: PredType -> ()
+seqPred (ClassP c tys) = c `seq` seqTypes tys
+seqPred (IParam n ty) = n `seq` seqType ty
\end{code}
-@match@ is the main function.
+
+%************************************************************************
+%* *
+ Equality for Core types
+ (We don't use instances so that we know where it happens)
+%* *
+%************************************************************************
+
+Note that eqType works right even for partial applications of newtypes.
+See Note [Newtype eta] in TyCon.lhs
\begin{code}
-match :: GenType t1 u1 -> GenType t2 u2 -- Current match pair
- -> ([(t1, GenType t2 u2)] -> Maybe result) -- Continuation
- -> [(t1, GenType t2 u2)] -- Current substitution
- -> Maybe result
-
-match (TyVarTy v) ty k = \s -> k ((v,ty) : s)
-match (FunTy fun1 arg1 _) (FunTy fun2 arg2 _) k = match fun1 fun2 (match arg1 arg2 k)
-match (AppTy fun1 arg1) (AppTy fun2 arg2) k = match fun1 fun2 (match arg1 arg2 k)
-match (TyConTy con1 _) (TyConTy con2 _) k | con1 == con2 = k
-match (DictTy clas1 ty1 _) (DictTy clas2 ty2 _) k | clas1 == clas2 = match ty1 ty2 k
-match (SynTy _ _ ty1) ty2 k = match ty1 ty2 k
-match ty1 (SynTy _ _ ty2) k = match ty1 ty2 k
-
- -- 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)
-
--- Catch-all fails
-match _ _ _ = \s -> Nothing
+coreEqType :: Type -> Type -> Bool
+coreEqType t1 t2
+ = eq rn_env t1 t2
+ where
+ rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfType t1 `unionVarSet` tyVarsOfType t2))
+
+ eq env (TyVarTy tv1) (TyVarTy tv2) = rnOccL env tv1 == rnOccR env tv2
+ eq env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = eq (rnBndr2 env tv1 tv2) t1 t2
+ eq env (AppTy s1 t1) (AppTy s2 t2) = eq env s1 s2 && eq env t1 t2
+ eq env (FunTy s1 t1) (FunTy s2 t2) = eq env s1 s2 && eq env t1 t2
+ eq env (TyConApp tc1 tys1) (TyConApp tc2 tys2)
+ | tc1 == tc2, all2 (eq env) tys1 tys2 = True
+ -- The lengths should be equal because
+ -- the two types have the same kind
+ -- NB: if the type constructors differ that does not
+ -- necessarily mean that the types aren't equal
+ -- (synonyms, newtypes)
+ -- Even if the type constructors are the same, but the arguments
+ -- differ, the two types could be the same (e.g. if the arg is just
+ -- ignored in the RHS). In both these cases we fall through to an
+ -- attempt to expand one side or the other.
+
+ -- Now deal with newtypes, synonyms, pred-tys
+ eq env t1 t2 | Just t1' <- coreView t1 = eq env t1' t2
+ | Just t2' <- coreView t2 = eq env t1 t2'
+
+ -- Fall through case; not equal!
+ eq env t1 t2 = False
\end{code}
+
%************************************************************************
%* *
-\subsection{Equality on types}
+ Comparision for source types
+ (We don't use instances so that we know where it happens)
%* *
%************************************************************************
-The functions eqSimpleTy and eqSimpleTheta are polymorphic in the types t
-and u, but ONLY WORK FOR SIMPLE TYPES (ie. they panic if they see
-dictionaries or polymorphic types). The function eqTy has a more
-specific type, but does the `right thing' for all types.
+Note that
+ tcEqType, tcCmpType
+do *not* look through newtypes, PredTypes
+
+\begin{code}
+tcEqType :: Type -> Type -> Bool
+tcEqType t1 t2 = isEqual $ cmpType t1 t2
+
+tcEqTypes :: [Type] -> [Type] -> Bool
+tcEqTypes tys1 tys2 = isEqual $ cmpTypes tys1 tys2
+
+tcCmpType :: Type -> Type -> Ordering
+tcCmpType t1 t2 = cmpType t1 t2
+
+tcCmpTypes :: [Type] -> [Type] -> Ordering
+tcCmpTypes tys1 tys2 = cmpTypes tys1 tys2
+
+tcEqPred :: PredType -> PredType -> Bool
+tcEqPred p1 p2 = isEqual $ cmpPred p1 p2
+
+tcCmpPred :: PredType -> PredType -> Ordering
+tcCmpPred p1 p2 = cmpPred p1 p2
+
+tcEqTypeX :: RnEnv2 -> Type -> Type -> Bool
+tcEqTypeX env t1 t2 = isEqual $ cmpTypeX env t1 t2
+\end{code}
+
+Now here comes the real worker
\begin{code}
-eqSimpleTheta :: (Eq t,Eq u) =>
- [(Class,GenType t u)] -> [(Class,GenType t u)] -> Bool
+cmpType :: Type -> Type -> Ordering
+cmpType t1 t2 = cmpTypeX rn_env t1 t2
+ where
+ rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfType t1 `unionVarSet` tyVarsOfType t2))
-eqSimpleTheta [] [] = True
-eqSimpleTheta ((c1,t1):th1) ((c2,t2):th2) =
- c1==c2 && t1 `eqSimpleTy` t2 && th1 `eqSimpleTheta` th2
-eqSimpleTheta other1 other2 = False
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes ts1 ts2 = cmpTypesX rn_env ts1 ts2
+ where
+ rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfTypes ts1 `unionVarSet` tyVarsOfTypes ts2))
+
+cmpPred :: PredType -> PredType -> Ordering
+cmpPred p1 p2 = cmpPredX rn_env p1 p2
+ where
+ rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfPred p1 `unionVarSet` tyVarsOfPred p2))
+
+cmpTypeX :: RnEnv2 -> Type -> Type -> Ordering -- Main workhorse
+cmpTypeX env t1 t2 | Just t1' <- tcView t1 = cmpTypeX env t1' t2
+ | Just t2' <- tcView t2 = cmpTypeX env t1 t2'
+
+cmpTypeX env (TyVarTy tv1) (TyVarTy tv2) = rnOccL env tv1 `compare` rnOccR env tv2
+cmpTypeX env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmpTypeX (rnBndr2 env tv1 tv2) t1 t2
+cmpTypeX env (AppTy s1 t1) (AppTy s2 t2) = cmpTypeX env s1 s2 `thenCmp` cmpTypeX env t1 t2
+cmpTypeX env (FunTy s1 t1) (FunTy s2 t2) = cmpTypeX env s1 s2 `thenCmp` cmpTypeX env t1 t2
+cmpTypeX env (PredTy p1) (PredTy p2) = cmpPredX env p1 p2
+cmpTypeX env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` cmpTypesX env tys1 tys2
+cmpTypeX env t1 (NoteTy _ t2) = cmpTypeX env t1 t2
+
+ -- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy < PredTy
+cmpTypeX env (AppTy _ _) (TyVarTy _) = GT
+
+cmpTypeX env (FunTy _ _) (TyVarTy _) = GT
+cmpTypeX env (FunTy _ _) (AppTy _ _) = GT
+
+cmpTypeX env (TyConApp _ _) (TyVarTy _) = GT
+cmpTypeX env (TyConApp _ _) (AppTy _ _) = GT
+cmpTypeX env (TyConApp _ _) (FunTy _ _) = GT
+
+cmpTypeX env (ForAllTy _ _) (TyVarTy _) = GT
+cmpTypeX env (ForAllTy _ _) (AppTy _ _) = GT
+cmpTypeX env (ForAllTy _ _) (FunTy _ _) = GT
+cmpTypeX env (ForAllTy _ _) (TyConApp _ _) = GT
+
+cmpTypeX env (PredTy _) t2 = GT
+
+cmpTypeX env _ _ = LT
+
+-------------
+cmpTypesX :: RnEnv2 -> [Type] -> [Type] -> Ordering
+cmpTypesX env [] [] = EQ
+cmpTypesX env (t1:tys1) (t2:tys2) = cmpTypeX env t1 t2 `thenCmp` cmpTypesX env tys1 tys2
+cmpTypesX env [] tys = LT
+cmpTypesX env ty [] = GT
+
+-------------
+cmpPredX :: RnEnv2 -> PredType -> PredType -> Ordering
+cmpPredX env (IParam n1 ty1) (IParam n2 ty2) = (n1 `compare` n2) `thenCmp` cmpTypeX env ty1 ty2
+ -- Compare types as well as names for implicit parameters
+ -- This comparison is used exclusively (I think) for the
+ -- finite map built in TcSimplify
+cmpPredX env (ClassP c1 tys1) (ClassP c2 tys2) = (c1 `compare` c2) `thenCmp` cmpTypesX env tys1 tys2
+cmpPredX env (IParam _ _) (ClassP _ _) = LT
+cmpPredX env (ClassP _ _) (IParam _ _) = GT
\end{code}
+PredTypes are used as a FM key in TcSimplify,
+so we take the easy path and make them an instance of Ord
+
+\begin{code}
+instance Eq PredType where { (==) = tcEqPred }
+instance Ord PredType where { compare = tcCmpPred }
+\end{code}
+
+
+%************************************************************************
+%* *
+ Type substitutions
+%* *
+%************************************************************************
+
\begin{code}
-eqSimpleTy :: (Eq t,Eq u) => GenType t u -> GenType t u -> Bool
-
-(TyVarTy tv1) `eqSimpleTy` (TyVarTy tv2) =
- tv1 == tv2
-(AppTy f1 a1) `eqSimpleTy` (AppTy f2 a2) =
- f1 `eqSimpleTy` f2 && a1 `eqSimpleTy` a2
-(TyConTy tc1 u1) `eqSimpleTy` (TyConTy tc2 u2) =
- tc1 == tc2 --ToDo: later: && u1 == u2
-
-(FunTy f1 a1 u1) `eqSimpleTy` (FunTy f2 a2 u2) =
- f1 `eqSimpleTy` f2 && a1 `eqSimpleTy` a2 && u1 == u2
-(FunTy f1 a1 u1) `eqSimpleTy` t2 =
- -- Expand t1 just in case t2 matches that version
- (AppTy (AppTy (TyConTy mkFunTyCon u1) f1) a1) `eqSimpleTy` t2
-t1 `eqSimpleTy` (FunTy f2 a2 u2) =
- -- Expand t2 just in case t1 matches that version
- t1 `eqSimpleTy` (AppTy (AppTy (TyConTy mkFunTyCon u2) f2) a2)
-
-(SynTy tc1 ts1 t1) `eqSimpleTy` (SynTy tc2 ts2 t2) =
- (tc1 == tc2 && and (zipWith eqSimpleTy ts1 ts2) && length ts1 == length ts2)
- || t1 `eqSimpleTy` t2
-(SynTy _ _ t1) `eqSimpleTy` t2 =
- t1 `eqSimpleTy` t2 -- Expand the abbrevation and try again
-t1 `eqSimpleTy` (SynTy _ _ t2) =
- t1 `eqSimpleTy` t2 -- Expand the abbrevation and try again
-
-(DictTy _ _ _) `eqSimpleTy` _ = panic "eqSimpleTy: got DictTy"
-_ `eqSimpleTy` (DictTy _ _ _) = panic "eqSimpleTy: got DictTy"
-
-(ForAllTy _ _) `eqSimpleTy` _ = panic "eqSimpleTy: got ForAllTy"
-_ `eqSimpleTy` (ForAllTy _ _) = panic "eqSimpleTy: got ForAllTy"
-
-(ForAllUsageTy _ _ _) `eqSimpleTy` _ = panic "eqSimpleTy: got ForAllUsageTy"
-_ `eqSimpleTy` (ForAllUsageTy _ _ _) = panic "eqSimpleTy: got ForAllUsageTy"
-
-_ `eqSimpleTy` _ = False
+data TvSubst
+ = TvSubst InScopeSet -- The in-scope type variables
+ TvSubstEnv -- The substitution itself
+ -- See Note [Apply Once]
+
+{- ----------------------------------------------------------
+ Note [Apply Once]
+
+We use TvSubsts to instantiate things, and we might instantiate
+ forall a b. ty
+\with the types
+ [a, b], or [b, a].
+So the substition might go [a->b, b->a]. A similar situation arises in Core
+when we find a beta redex like
+ (/\ a /\ b -> e) b a
+Then we also end up with a substition that permutes type variables. Other
+variations happen to; for example [a -> (a, b)].
+
+ ***************************************************
+ *** So a TvSubst must be applied precisely once ***
+ ***************************************************
+
+A TvSubst is not idempotent, but, unlike the non-idempotent substitution
+we use during unifications, it must not be repeatedly applied.
+-------------------------------------------------------------- -}
+
+
+type TvSubstEnv = TyVarEnv Type
+ -- A TvSubstEnv is used both inside a TvSubst (with the apply-once
+ -- invariant discussed in Note [Apply Once]), and also independently
+ -- in the middle of matching, and unification (see Types.Unify)
+ -- So you have to look at the context to know if it's idempotent or
+ -- apply-once or whatever
+emptyTvSubstEnv :: TvSubstEnv
+emptyTvSubstEnv = emptyVarEnv
+
+composeTvSubst :: InScopeSet -> TvSubstEnv -> TvSubstEnv -> TvSubstEnv
+-- (compose env1 env2)(x) is env1(env2(x)); i.e. apply env2 then env1
+-- It assumes that both are idempotent
+-- Typically, env1 is the refinement to a base substitution env2
+composeTvSubst in_scope env1 env2
+ = env1 `plusVarEnv` mapVarEnv (substTy subst1) env2
+ -- First apply env1 to the range of env2
+ -- Then combine the two, making sure that env1 loses if
+ -- both bind the same variable; that's why env1 is the
+ -- *left* argument to plusVarEnv, because the right arg wins
+ where
+ subst1 = TvSubst in_scope env1
+
+emptyTvSubst = TvSubst emptyInScopeSet emptyVarEnv
+
+isEmptyTvSubst :: TvSubst -> Bool
+isEmptyTvSubst (TvSubst _ env) = isEmptyVarEnv env
+
+mkTvSubst :: InScopeSet -> TvSubstEnv -> TvSubst
+mkTvSubst = TvSubst
+
+getTvSubstEnv :: TvSubst -> TvSubstEnv
+getTvSubstEnv (TvSubst _ env) = env
+
+getTvInScope :: TvSubst -> InScopeSet
+getTvInScope (TvSubst in_scope _) = in_scope
+
+isInScope :: Var -> TvSubst -> Bool
+isInScope v (TvSubst in_scope _) = v `elemInScopeSet` in_scope
+
+notElemTvSubst :: TyVar -> TvSubst -> Bool
+notElemTvSubst tv (TvSubst _ env) = not (tv `elemVarEnv` env)
+
+setTvSubstEnv :: TvSubst -> TvSubstEnv -> TvSubst
+setTvSubstEnv (TvSubst in_scope _) env = TvSubst in_scope env
+
+extendTvInScope :: TvSubst -> [Var] -> TvSubst
+extendTvInScope (TvSubst in_scope env) vars = TvSubst (extendInScopeSetList in_scope vars) env
+
+extendTvSubst :: TvSubst -> TyVar -> Type -> TvSubst
+extendTvSubst (TvSubst in_scope env) tv ty = TvSubst in_scope (extendVarEnv env tv ty)
+
+extendTvSubstList :: TvSubst -> [TyVar] -> [Type] -> TvSubst
+extendTvSubstList (TvSubst in_scope env) tvs tys
+ = TvSubst in_scope (extendVarEnvList env (tvs `zip` tys))
+
+-- mkOpenTvSubst and zipOpenTvSubst generate the in-scope set from
+-- the types given; but it's just a thunk so with a bit of luck
+-- it'll never be evaluated
+
+mkOpenTvSubst :: TvSubstEnv -> TvSubst
+mkOpenTvSubst env = TvSubst (mkInScopeSet (tyVarsOfTypes (varEnvElts env))) env
+
+zipOpenTvSubst :: [TyVar] -> [Type] -> TvSubst
+zipOpenTvSubst tyvars tys
+#ifdef DEBUG
+ | length tyvars /= length tys
+ = pprTrace "zipOpenTvSubst" (ppr tyvars $$ ppr tys) emptyTvSubst
+ | otherwise
+#endif
+ = TvSubst (mkInScopeSet (tyVarsOfTypes tys)) (zipTyEnv tyvars tys)
+
+-- mkTopTvSubst is called when doing top-level substitutions.
+-- Here we expect that the free vars of the range of the
+-- substitution will be empty.
+mkTopTvSubst :: [(TyVar, Type)] -> TvSubst
+mkTopTvSubst prs = TvSubst emptyInScopeSet (mkVarEnv prs)
+
+zipTopTvSubst :: [TyVar] -> [Type] -> TvSubst
+zipTopTvSubst tyvars tys
+#ifdef DEBUG
+ | length tyvars /= length tys
+ = pprTrace "zipOpenTvSubst" (ppr tyvars $$ ppr tys) emptyTvSubst
+ | otherwise
+#endif
+ = TvSubst emptyInScopeSet (zipTyEnv tyvars tys)
+
+zipTyEnv :: [TyVar] -> [Type] -> TvSubstEnv
+zipTyEnv tyvars tys
+#ifdef DEBUG
+ | length tyvars /= length tys
+ = pprTrace "mkTopTvSubst" (ppr tyvars $$ ppr tys) emptyVarEnv
+ | otherwise
+#endif
+ = zip_ty_env tyvars tys emptyVarEnv
+
+-- Later substitutions in the list over-ride earlier ones,
+-- but there should be no loops
+zip_ty_env [] [] env = env
+zip_ty_env (tv:tvs) (ty:tys) env = zip_ty_env tvs tys (extendVarEnv env tv ty)
+ -- There used to be a special case for when
+ -- ty == TyVarTy tv
+ -- (a not-uncommon case) in which case the substitution was dropped.
+ -- But the type-tidier changes the print-name of a type variable without
+ -- changing the unique, and that led to a bug. Why? Pre-tidying, we had
+ -- a type {Foo t}, where Foo is a one-method class. So Foo is really a newtype.
+ -- And it happened that t was the type variable of the class. Post-tiding,
+ -- it got turned into {Foo t2}. The ext-core printer expanded this using
+ -- sourceTypeRep, but that said "Oh, t == t2" because they have the same unique,
+ -- and so generated a rep type mentioning t not t2.
+ --
+ -- Simplest fix is to nuke the "optimisation"
+zip_ty_env tvs tys env = pprTrace "Var/Type length mismatch: " (ppr tvs $$ ppr tys) env
+-- zip_ty_env _ _ env = env
+
+instance Outputable TvSubst where
+ ppr (TvSubst ins env)
+ = sep[ ptext SLIT("<TvSubst"),
+ nest 2 (ptext SLIT("In scope:") <+> ppr ins),
+ nest 2 (ptext SLIT("Env:") <+> ppr env) ]
\end{code}
-Types are ordered so we can sort on types in the renamer etc. DNT: Since
-this class is also used in CoreLint and other such places, we DO expand out
-Fun/Syn/Dict types (if necessary).
+%************************************************************************
+%* *
+ Performing type substitutions
+%* *
+%************************************************************************
\begin{code}
-eqTy :: Type -> Type -> Bool
-
-eqTy t1 t2 =
- eq nullTyVarEnv nullUVarEnv t1 t2
- where
- eq tve uve (TyVarTy tv1) (TyVarTy tv2) =
- tv1 == tv2 ||
- case (lookupTyVarEnv tve tv1) of
- Just tv -> tv == tv2
- Nothing -> False
- eq tve uve (AppTy f1 a1) (AppTy f2 a2) =
- eq tve uve f1 f2 && eq tve uve a1 a2
- eq tve uve (TyConTy tc1 u1) (TyConTy tc2 u2) =
- tc1 == tc2 -- ToDo: LATER: && eqUsage uve u1 u2
-
- eq tve uve (FunTy f1 a1 u1) (FunTy f2 a2 u2) =
- eq tve uve f1 f2 && eq tve uve a1 a2 && eqUsage uve u1 u2
- eq tve uve (FunTy f1 a1 u1) t2 =
- -- Expand t1 just in case t2 matches that version
- eq tve uve (AppTy (AppTy (TyConTy mkFunTyCon u1) f1) a1) t2
- eq tve uve t1 (FunTy f2 a2 u2) =
- -- Expand t2 just in case t1 matches that version
- eq tve uve t1 (AppTy (AppTy (TyConTy mkFunTyCon u2) f2) a2)
-
- eq tve uve (DictTy c1 t1 u1) (DictTy c2 t2 u2)
- | c1 == c2
- = eq tve uve t1 t2 && eqUsage uve u1 u2
- -- NB we use a guard for c1==c2 so that if they aren't equal we
- -- fall through into expanding the type. Why? Because brain-dead
- -- people might write
- -- class Foo a => Baz a where {}
- -- and that means that a Foo dictionary and a Baz dictionary are identical
- -- Sigh. Let's hope we don't spend too much time in here!
-
- eq tve uve t1@(DictTy _ _ _) t2 =
- eq tve uve (expandTy t1) t2 -- Expand the dictionary and try again
- eq tve uve t1 t2@(DictTy _ _ _) =
- eq tve uve t1 (expandTy t2) -- Expand the dictionary and try again
-
- eq tve uve (SynTy tc1 ts1 t1) (SynTy tc2 ts2 t2) =
- (tc1 == tc2 && and (zipWith (eq tve uve) ts1 ts2) && length ts1 == length ts2)
- || eq tve uve t1 t2
- eq tve uve (SynTy _ _ t1) t2 =
- eq tve uve t1 t2 -- Expand the abbrevation and try again
- eq tve uve t1 (SynTy _ _ t2) =
- eq tve uve t1 t2 -- Expand the abbrevation and try again
-
- eq tve uve (ForAllTy tv1 t1) (ForAllTy tv2 t2) =
- eq (addOneToTyVarEnv tve tv1 tv2) uve t1 t2
- eq tve uve (ForAllUsageTy u1 b1 t1) (ForAllUsageTy u2 b2 t2) =
- eqBounds uve b1 b2 && eq tve (addOneToUVarEnv uve u1 u2) t1 t2
-
- eq _ _ _ _ = False
-
- eqBounds uve [] [] = True
- eqBounds uve (u1:b1) (u2:b2) = eqUVar uve u1 u2 && eqBounds uve b1 b2
- eqBounds uve _ _ = False
+substTyWith :: [TyVar] -> [Type] -> Type -> Type
+substTyWith tvs tys = ASSERT( length tvs == length tys )
+ substTy (zipOpenTvSubst tvs tys)
+
+substTy :: TvSubst -> Type -> Type
+substTy subst ty | isEmptyTvSubst subst = ty
+ | otherwise = subst_ty subst ty
+
+substTys :: TvSubst -> [Type] -> [Type]
+substTys subst tys | isEmptyTvSubst subst = tys
+ | otherwise = map (subst_ty subst) tys
+
+substTheta :: TvSubst -> ThetaType -> ThetaType
+substTheta subst theta
+ | isEmptyTvSubst subst = theta
+ | otherwise = map (substPred subst) theta
+
+substPred :: TvSubst -> PredType -> PredType
+substPred subst (IParam n ty) = IParam n (subst_ty subst ty)
+substPred subst (ClassP clas tys) = ClassP clas (map (subst_ty subst) tys)
+
+deShadowTy :: TyVarSet -> Type -> Type -- Remove any nested binders mentioning tvs
+deShadowTy tvs ty
+ = subst_ty (mkTvSubst in_scope emptyTvSubstEnv) ty
+ where
+ in_scope = mkInScopeSet tvs
+
+-- Note that the in_scope set is poked only if we hit a forall
+-- so it may often never be fully computed
+subst_ty subst ty
+ = go ty
+ where
+ go (TyVarTy tv) = substTyVar subst tv
+ go (TyConApp tc tys) = let args = map go tys
+ in args `seqList` TyConApp tc args
+
+ go (PredTy p) = PredTy $! (substPred subst p)
+
+ 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)
+ -- The mkAppTy smart constructor is important
+ -- we might be replacing (a Int), represented with App
+ -- by [Int], represented with TyConApp
+ go (ForAllTy tv ty) = case substTyVarBndr subst tv of
+ (subst', tv') -> ForAllTy tv' $! (subst_ty subst' ty)
+
+substTyVar :: TvSubst -> TyVar -> Type
+substTyVar subst tv
+ = case lookupTyVar subst tv of
+ Nothing -> TyVarTy tv
+ Just ty' -> ty' -- See Note [Apply Once]
+
+lookupTyVar :: TvSubst -> TyVar -> Maybe Type
+lookupTyVar (TvSubst in_scope env) tv = lookupVarEnv env tv
+
+substTyVarBndr :: TvSubst -> TyVar -> (TvSubst, TyVar)
+substTyVarBndr subst@(TvSubst in_scope env) old_var
+ | old_var == new_var -- No need to clone
+ -- But we *must* zap any current substitution for the variable.
+ -- For example:
+ -- (\x.e) with id_subst = [x |-> e']
+ -- Here we must simply zap the substitution for x
+ --
+ -- The new_id isn't cloned, but it may have a different type
+ -- etc, so we must return it, not the old id
+ = (TvSubst (in_scope `extendInScopeSet` new_var)
+ (delVarEnv env old_var),
+ new_var)
+
+ | otherwise -- The new binder 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
+ = (TvSubst (in_scope `extendInScopeSet` new_var)
+ (extendVarEnv env old_var (TyVarTy new_var)),
+ new_var)
+ where
+ new_var = uniqAway in_scope old_var
+ -- The uniqAway part makes sure the new variable is not already in scope
\end{code}