-%
+]%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[HsTypes]{Abstract syntax: user-defined types}
\begin{code}
module HsTypes (
- HsType(..), HsTyVarBndr(..),
+ HsType(..), HsTyVarBndr(..),
, HsContext, HsPred(..)
- , HsTupCon(..), hsTupParens, mkHsTupCon,
- , hsUsOnce, hsUsMany
, mkHsForAllTy, mkHsDictTy, mkHsIParamTy
, hsTyVarName, hsTyVarNames, replaceTyVarName
- , getHsInstHead
+ , splitHsInstDeclTy
-- Type place holder
, PostTcType, placeHolderType,
+ -- Name place holder
+ , SyntaxName, placeHolderName,
+
-- Printing
, pprParendHsType, pprHsForAll, pprHsContext, ppr_hs_context, pprHsTyVarBndr
-
- -- Equality over Hs things
- , EqHsEnv, emptyEqHsEnv, extendEqHsEnv,
- , eqWithHsTyVars, eq_hsVar, eq_hsVars, eq_hsTyVars, eq_hsType, eq_hsContext, eqListBy
-
- -- Converting from Type to HsType
- , toHsType, toHsTyVar, toHsTyVars, toHsContext, toHsFDs
) where
#include "HsVersions.h"
-import Class ( FunDep )
-import TcType ( Type, Kind, ThetaType, SourceType(..),
- tcSplitSigmaTy, liftedTypeKind, eqKind, tcEqType
- )
-import TypeRep ( Type(..), TyNote(..) ) -- toHsType sees the representation
-import TyCon ( isTupleTyCon, tupleTyConBoxity, tyConArity, isNewTyCon, getSynTyConDefn )
-import RdrName ( RdrName, mkUnqual )
-import Name ( Name, getName )
-import OccName ( NameSpace, tvName )
-import Var ( TyVar, tyVarKind )
-import Subst ( substTyWith )
-import PprType ( {- instance Outputable Kind -}, pprParendKind )
-import BasicTypes ( Boxity(..), Arity, IPName, tupleParens )
-import PrelNames ( mkTupConRdrName, listTyConKey, usOnceTyConKey, usManyTyConKey, hasKey,
- usOnceTyConName, usManyTyConName
- )
-import FiniteMap
-import Util ( eqListBy, lengthIs )
+import TcType ( Type, Kind, liftedTypeKind, eqKind )
+import TypeRep ( Type )
+import Name ( Name, mkInternalName )
+import OccName ( mkVarOcc )
+import PprType ( {- instance Outputable Kind -}, pprParendKind, pprKind )
+import BasicTypes ( IPName, Boxity, tupleParens )
+import PrelNames ( unboundKey )
+import SrcLoc ( noSrcLoc )
import Outputable
\end{code}
placeHolderType :: PostTcType -- Used before typechecking
placeHolderType = panic "Evaluated the place holder for a PostTcType"
+
+
+type SyntaxName = Name -- These names are filled in by the renamer
+ -- Before then they are a placeHolderName (so that
+ -- we can still print the HsSyn)
+ -- They correspond to "rebindable syntax";
+ -- See RnEnv.lookupSyntaxName
+
+placeHolderName :: SyntaxName
+placeHolderName = mkInternalName unboundKey
+ (mkVarOcc FSLIT("syntaxPlaceHolder"))
+ noSrcLoc
\end{code}
| HsAppTy (HsType name)
(HsType name)
- | HsFunTy (HsType name) -- function type
+ | HsFunTy (HsType name) -- function type
(HsType name)
| HsListTy (HsType name) -- Element type
- | HsTupleTy (HsTupCon name)
- [HsType name] -- Element types (length gives arity)
- -- Generics
- | HsOpTy (HsType name) name (HsType name)
- | HsNumTy Integer
+ | HsPArrTy (HsType name) -- Elem. type of parallel array: [:t:]
- -- these next two are only used in interfaces
- | HsPredTy (HsPred name)
+ | HsTupleTy Boxity
+ [HsType name] -- Element types (length gives arity)
+ | HsOpTy (HsType name) name (HsType name)
------------------------
-hsUsOnce, hsUsMany :: HsType RdrName
-hsUsOnce = HsTyVar (mkUnqual tvName SLIT(".")) -- deep magic
-hsUsMany = HsTyVar (mkUnqual tvName SLIT("!")) -- deep magic
+ | HsParTy (HsType name)
+ -- Parenthesis preserved for the precedence re-arrangement in RnTypes
+ -- It's important that a * (b + c) doesn't get rearranged to (a*b) + c!
+ --
+ -- However, NB that toHsType doesn't add HsParTys (in an effort to keep
+ -- interface files smaller), so when printing a HsType we may need to
+ -- add parens.
-hsUsOnce_Name, hsUsMany_Name :: HsType Name
-hsUsOnce_Name = HsTyVar usOnceTyConName
-hsUsMany_Name = HsTyVar usManyTyConName
+ | HsNumTy Integer -- Generics only
------------------------
-data HsTupCon name = HsTupCon name Boxity Arity
+ -- these next two are only used in interfaces
+ | HsPredTy (HsPred name)
-instance Eq name => Eq (HsTupCon name) where
- (HsTupCon _ b1 a1) == (HsTupCon _ b2 a2) = b1==b2 && a1==a2
-
-mkHsTupCon :: NameSpace -> Boxity -> [a] -> HsTupCon RdrName
-mkHsTupCon space boxity args = HsTupCon (mkTupConRdrName space boxity arity) boxity arity
- where
- arity = length args
+ | HsKindSig (HsType name) -- (ty :: kind)
+ Kind -- A type with a kind signature
-hsTupParens :: HsTupCon name -> SDoc -> SDoc
-hsTupParens (HsTupCon _ b _) p = tupleParens b p
-----------------------
-- Combine adjacent for-alls.
--
-- A valid type must have one for-all at the top of the type, or of the fn arg types
-mkHsForAllTy (Just []) [] ty = ty -- Explicit for-all with no tyvars
-mkHsForAllTy mtvs1 [] (HsForAllTy mtvs2 ctxt ty) = mkHsForAllTy (mtvs1 `plus` mtvs2) ctxt ty
- where
- mtvs1 `plus` Nothing = mtvs1
- Nothing `plus` mtvs2 = mtvs2
- (Just tvs1) `plus` (Just tvs2) = Just (tvs1 ++ tvs2)
-mkHsForAllTy tvs ctxt ty = HsForAllTy tvs ctxt ty
+mkHsForAllTy mtvs [] ty = mk_forall_ty mtvs ty
+mkHsForAllTy mtvs ctxt ty = HsForAllTy mtvs ctxt ty
+
+-- mk_forall_ty makes a pure for-all type (no context)
+mk_forall_ty (Just []) ty = ty -- Explicit for-all with no tyvars
+mk_forall_ty mtvs1 (HsParTy ty) = mk_forall_ty mtvs1 ty
+mk_forall_ty mtvs1 (HsForAllTy mtvs2 ctxt ty) = mkHsForAllTy (mtvs1 `plus` mtvs2) ctxt ty
+mk_forall_ty mtvs1 ty = HsForAllTy mtvs1 [] ty
+
+mtvs1 `plus` Nothing = mtvs1
+Nothing `plus` mtvs2 = mtvs2
+(Just tvs1) `plus` (Just tvs2) = Just (tvs1 ++ tvs2)
mkHsDictTy cls tys = HsPredTy (HsClassP cls tys)
mkHsIParamTy v ty = HsPredTy (HsIParam v ty)
data HsTyVarBndr name
= UserTyVar name
- | IfaceTyVar name Kind
+ | KindedTyVar name Kind
-- *** NOTA BENE *** A "monotype" in a pragma can have
-- for-alls in it, (mostly to do with dictionaries). These
-- must be explicitly Kinded.
-hsTyVarName (UserTyVar n) = n
-hsTyVarName (IfaceTyVar n _) = n
+hsTyVarName (UserTyVar n) = n
+hsTyVarName (KindedTyVar n _) = n
hsTyVarNames tvs = map hsTyVarName tvs
replaceTyVarName :: HsTyVarBndr name1 -> name2 -> HsTyVarBndr name2
-replaceTyVarName (UserTyVar n) n' = UserTyVar n'
-replaceTyVarName (IfaceTyVar n k) n' = IfaceTyVar n' k
+replaceTyVarName (UserTyVar n) n' = UserTyVar n'
+replaceTyVarName (KindedTyVar n k) n' = KindedTyVar n' k
\end{code}
\begin{code}
-getHsInstHead :: HsType name -> ([HsTyVarBndr name], (name, [HsType name]))
- -- Split up an instance decl type, returning the 'head' part
-
--- In interface fiels, the type of the decl is held like this:
--- forall a. Foo a -> Baz (T a)
--- so we have to strip off function argument types,
--- as well as the bit before the '=>' (which is always
--- empty in interface files)
---
--- The parser ensures the type will have the right shape.
+splitHsInstDeclTy
+ :: Outputable name
+ => HsType name
+ -> ([HsTyVarBndr name], HsContext name, name, [HsType name])
+ -- Split up an instance decl type, returning the pieces
+
+-- In interface files, the instance declaration head is created
+-- by HsTypes.toHsType, which does not guarantee to produce a
+-- HsForAllTy. For example, if we had the weird decl
+-- instance Foo T => Foo [T]
+-- then we'd get the instance type
+-- Foo T -> Foo [T]
+-- So when colleting the instance context, to be on the safe side
+-- we gather predicate arguments
+--
+-- For source code, the parser ensures the type will have the right shape.
-- (e.g. see ParseUtil.checkInstType)
-getHsInstHead (HsForAllTy (Just tvs) _ tau) = (tvs, get_head1 tau)
-getHsInstHead tau = ([], get_head1 tau)
+splitHsInstDeclTy inst_ty
+ = case inst_ty of
+ HsForAllTy (Just tvs) cxt1 tau
+ -> (tvs, cxt1++cxt2, cls, tys)
+ where
+ (cxt2, cls, tys) = split_tau tau
-get_head1 (HsFunTy _ ty) = get_head1 ty
-get_head1 (HsPredTy (HsClassP cls tys)) = (cls,tys)
+ other -> ([], cxt2, cls, tys)
+ where
+ (cxt2, cls, tys) = split_tau inst_ty
+
+ where
+ split_tau (HsFunTy (HsPredTy p) ty) = (p:ps, cls, tys)
+ where
+ (ps, cls, tys) = split_tau ty
+ split_tau (HsPredTy (HsClassP cls tys)) = ([], cls,tys)
+ split_tau other = pprPanic "splitHsInstDeclTy" (ppr inst_ty)
\end{code}
ppr ty = pprHsType ty
instance (Outputable name) => Outputable (HsTyVarBndr name) where
- ppr (UserTyVar name) = ppr name
- ppr (IfaceTyVar name kind) = pprHsTyVarBndr name kind
+ ppr (UserTyVar name) = ppr name
+ ppr (KindedTyVar name kind) = pprHsTyVarBndr name kind
instance Outputable name => Outputable (HsPred name) where
ppr (HsClassP clas tys) = ppr clas <+> hsep (map pprParendHsType tys)
\begin{code}
pREC_TOP = (0 :: Int) -- type in ParseIface.y
pREC_FUN = (1 :: Int) -- btype in ParseIface.y
-pREC_CON = (2 :: Int) -- atype in ParseIface.y
-
-maybeParen :: Bool -> SDoc -> SDoc
-maybeParen True p = parens p
-maybeParen False p = p
+ -- Used for LH arg of (->)
+pREC_OP = (2 :: Int) -- Used for arg of any infix operator
+ -- (we don't keep their fixities around)
+pREC_CON = (3 :: Int) -- Used for arg of type applicn:
+ -- always parenthesise unless atomic
+
+maybeParen :: Int -- Precedence of context
+ -> Int -- Precedence of top-level operator
+ -> SDoc -> SDoc -- Wrap in parens if (ctxt >= op)
+maybeParen ctxt_prec op_prec p | ctxt_prec >= op_prec = parens p
+ | otherwise = p
-- printing works more-or-less as for Types
pprHsType, pprParendHsType :: (Outputable name) => HsType name -> SDoc
-pprHsType ty = ppr_mono_ty pREC_TOP ty
+pprHsType ty = ppr_mono_ty pREC_TOP (de_paren ty)
pprParendHsType ty = ppr_mono_ty pREC_CON ty
+-- Remove outermost HsParTy parens before printing a type
+de_paren (HsParTy ty) = de_paren ty
+de_paren ty = ty
+
ppr_mono_ty ctxt_prec (HsForAllTy maybe_tvs ctxt ty)
- = maybeParen (ctxt_prec >= pREC_FUN) $
+ = maybeParen ctxt_prec pREC_FUN $
sep [pp_header, pprHsType ty]
where
pp_header = case maybe_tvs of
Just tvs -> pprHsForAll tvs ctxt
Nothing -> pprHsContext ctxt
-ppr_mono_ty ctxt_prec (HsTyVar name)
- = ppr name
-
-ppr_mono_ty ctxt_prec (HsFunTy ty1 ty2)
- = let p1 = ppr_mono_ty pREC_FUN ty1
- p2 = ppr_mono_ty pREC_TOP ty2
- in
- maybeParen (ctxt_prec >= pREC_FUN)
- (sep [p1, (<>) (ptext SLIT("-> ")) p2])
-
-ppr_mono_ty ctxt_prec (HsTupleTy con tys) = hsTupParens con (interpp'SP tys)
+ppr_mono_ty ctxt_prec (HsTyVar name) = ppr name
+ppr_mono_ty ctxt_prec (HsFunTy ty1 ty2) = ppr_fun_ty ctxt_prec ty1 ty2
+ppr_mono_ty ctxt_prec (HsTupleTy con tys) = tupleParens con (interpp'SP tys)
+ppr_mono_ty ctxt_prec (HsKindSig ty kind) = parens (ppr_mono_ty pREC_TOP ty <+> dcolon <+> pprKind kind)
ppr_mono_ty ctxt_prec (HsListTy ty) = brackets (ppr_mono_ty pREC_TOP ty)
+ppr_mono_ty ctxt_prec (HsPArrTy ty) = pabrackets (ppr_mono_ty pREC_TOP ty)
+ppr_mono_ty ctxt_prec (HsPredTy pred) = braces (ppr pred)
+ppr_mono_ty ctxt_prec (HsNumTy n) = integer n -- generics only
ppr_mono_ty ctxt_prec (HsAppTy fun_ty arg_ty)
- = maybeParen (ctxt_prec >= pREC_CON)
- (hsep [ppr_mono_ty pREC_FUN fun_ty, ppr_mono_ty pREC_CON arg_ty])
-
-ppr_mono_ty ctxt_prec (HsPredTy pred)
- = braces (ppr pred)
-
--- Generics
-ppr_mono_ty ctxt_prec (HsNumTy n) = integer n
-ppr_mono_ty ctxt_prec (HsOpTy ty1 op ty2) = ppr ty1 <+> ppr op <+> ppr ty2
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Converting from Type to HsType}
-%* *
-%************************************************************************
-
-@toHsType@ converts from a Type to a HsType, making the latter look as
-user-friendly as possible. Notably, it uses synonyms where possible, and
-expresses overloaded functions using the '=>' context part of a HsForAllTy.
+ = maybeParen ctxt_prec pREC_CON $
+ hsep [ppr_mono_ty pREC_FUN fun_ty, ppr_mono_ty pREC_CON arg_ty]
-\begin{code}
-toHsTyVar :: TyVar -> HsTyVarBndr Name
-toHsTyVar tv = IfaceTyVar (getName tv) (tyVarKind tv)
-
-toHsTyVars tvs = map toHsTyVar tvs
-
-toHsType :: Type -> HsType Name
--- This function knows the representation of types
-toHsType (TyVarTy tv) = HsTyVar (getName tv)
-toHsType (FunTy arg res) = HsFunTy (toHsType arg) (toHsType res)
-toHsType (AppTy fun arg) = HsAppTy (toHsType fun) (toHsType arg)
-
-toHsType (NoteTy (SynNote ty@(TyConApp tycon tyargs)) real_ty)
- | isNewTyCon tycon = toHsType ty
- | syn_matches = toHsType ty -- Use synonyms if possible!!
- | otherwise =
-#ifdef DEBUG
- pprTrace "WARNING: synonym info lost in .hi file for " (ppr syn_ty) $
-#endif
- toHsType real_ty -- but drop it if not.
- where
- syn_matches = ty_from_syn `tcEqType` real_ty
- (tyvars,syn_ty) = getSynTyConDefn tycon
- ty_from_syn = substTyWith tyvars tyargs syn_ty
-
- -- We only use the type synonym in the file if this doesn't cause
- -- us to lose important information. This matters for usage
- -- annotations. It's an issue if some of the args to the synonym
- -- have arrows in them, or if the synonym's RHS has an arrow; for
- -- example, with nofib/real/ebnf2ps/ in Parsers.using.
-
- -- **! It would be nice if when this test fails we could still
- -- write the synonym in as a Note, so we don't lose the info for
- -- error messages, but it's too much work for right now.
- -- KSW 2000-07.
-
-toHsType (NoteTy _ ty) = toHsType ty
-
-toHsType (SourceTy (NType tc tys)) = foldl HsAppTy (HsTyVar (getName tc)) (map toHsType tys)
-toHsType (SourceTy pred) = HsPredTy (toHsPred pred)
-
-toHsType ty@(TyConApp tc tys) -- Must be saturated because toHsType's arg is of kind *
- | not saturated = generic_case
- | isTupleTyCon tc = HsTupleTy (HsTupCon (getName tc) (tupleTyConBoxity tc) (tyConArity tc)) tys'
- | tc `hasKey` listTyConKey = HsListTy (head tys')
- | tc `hasKey` usOnceTyConKey = hsUsOnce_Name -- must print !, . unqualified
- | tc `hasKey` usManyTyConKey = hsUsMany_Name -- must print !, . unqualified
- | otherwise = generic_case
- where
- generic_case = foldl HsAppTy (HsTyVar (getName tc)) tys'
- tys' = map toHsType tys
- saturated = tys `lengthIs` tyConArity tc
-
-toHsType ty@(ForAllTy _ _) = case tcSplitSigmaTy ty of
- (tvs, preds, tau) -> HsForAllTy (Just (map toHsTyVar tvs))
- (map toHsPred preds)
- (toHsType tau)
-
-toHsPred (ClassP cls tys) = HsClassP (getName cls) (map toHsType tys)
-toHsPred (IParam n ty) = HsIParam n (toHsType ty)
-
-toHsContext :: ThetaType -> HsContext Name
-toHsContext theta = map toHsPred theta
-
-toHsFDs :: [FunDep TyVar] -> [FunDep Name]
-toHsFDs fds = [(map getName ns, map getName ms) | (ns,ms) <- fds]
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Comparison}
-%* *
-%************************************************************************
-
-\begin{code}
-instance Ord a => Eq (HsType a) where
- -- The Ord is needed because we keep a
- -- finite map of variables to variables
- (==) a b = eq_hsType emptyEqHsEnv a b
-
-instance Ord a => Eq (HsPred a) where
- (==) a b = eq_hsPred emptyEqHsEnv a b
-
-eqWithHsTyVars :: Ord name =>
- [HsTyVarBndr name] -> [HsTyVarBndr name]
- -> (EqHsEnv name -> Bool) -> Bool
-eqWithHsTyVars = eq_hsTyVars emptyEqHsEnv
-\end{code}
-
-\begin{code}
-type EqHsEnv n = FiniteMap n n
--- Tracks the mapping from L-variables to R-variables
-
-eq_hsVar :: Ord n => EqHsEnv n -> n -> n -> Bool
-eq_hsVar env n1 n2 = case lookupFM env n1 of
- Just n1 -> n1 == n2
- Nothing -> n1 == n2
+ppr_mono_ty ctxt_prec (HsOpTy ty1 op ty2)
+ = maybeParen ctxt_prec pREC_OP $
+ ppr_mono_ty pREC_OP ty1 <+> ppr op <+> ppr_mono_ty pREC_OP ty2
-extendEqHsEnv env n1 n2
- | n1 == n2 = env
- | otherwise = addToFM env n1 n2
+ppr_mono_ty ctxt_prec (HsParTy ty)
+ = parens (ppr_mono_ty pREC_TOP ty)
+ -- Put the parens in where the user did
+ -- But we still use the precedence stuff to add parens because
+ -- toHsType doesn't put in any HsParTys, so we may still need them
-emptyEqHsEnv :: EqHsEnv n
-emptyEqHsEnv = emptyFM
-\end{code}
-
-We do define a specialised equality for these \tr{*Type} types; used
-in checking interfaces.
+--------------------------
+ppr_fun_ty ctxt_prec ty1 ty2
+ = let p1 = ppr_mono_ty pREC_FUN ty1
+ p2 = ppr_mono_ty pREC_TOP ty2
+ in
+ maybeParen ctxt_prec pREC_FUN $
+ sep [p1, ptext SLIT("->") <+> p2]
-\begin{code}
--------------------
-eq_hsTyVars env [] [] k = k env
-eq_hsTyVars env (tv1:tvs1) (tv2:tvs2) k = eq_hsTyVar env tv1 tv2 $ \ env ->
- eq_hsTyVars env tvs1 tvs2 k
-eq_hsTyVars env _ _ _ = False
-
-eq_hsTyVar env (UserTyVar v1) (UserTyVar v2) k = k (extendEqHsEnv env v1 v2)
-eq_hsTyVar env (IfaceTyVar v1 k1) (IfaceTyVar v2 k2) k = k1 `eqKind` k2 && k (extendEqHsEnv env v1 v2)
-eq_hsTyVar env _ _ _ = False
-
-eq_hsVars env [] [] k = k env
-eq_hsVars env (v1:bs1) (v2:bs2) k = eq_hsVars (extendEqHsEnv env v1 v2) bs1 bs2 k
-eq_hsVars env _ _ _ = False
+--------------------------
+pabrackets p = ptext SLIT("[:") <> p <> ptext SLIT(":]")
\end{code}
-\begin{code}
--------------------
-eq_hsTypes env = eqListBy (eq_hsType env)
-
--------------------
-eq_hsType env (HsForAllTy tvs1 c1 t1) (HsForAllTy tvs2 c2 t2)
- = eq_tvs tvs1 tvs2 $ \env ->
- eq_hsContext env c1 c2 &&
- eq_hsType env t1 t2
- where
- eq_tvs Nothing (Just _) k = False
- eq_tvs Nothing Nothing k = k env
- eq_tvs (Just _) Nothing k = False
- eq_tvs (Just tvs1) (Just tvs2) k = eq_hsTyVars env tvs1 tvs2 k
-
-eq_hsType env (HsTyVar n1) (HsTyVar n2)
- = eq_hsVar env n1 n2
-
-eq_hsType env (HsTupleTy c1 tys1) (HsTupleTy c2 tys2)
- = (c1 == c2) && eq_hsTypes env tys1 tys2
-eq_hsType env (HsListTy ty1) (HsListTy ty2)
- = eq_hsType env ty1 ty2
-
-eq_hsType env (HsAppTy fun_ty1 arg_ty1) (HsAppTy fun_ty2 arg_ty2)
- = eq_hsType env fun_ty1 fun_ty2 && eq_hsType env arg_ty1 arg_ty2
-
-eq_hsType env (HsFunTy a1 b1) (HsFunTy a2 b2)
- = eq_hsType env a1 a2 && eq_hsType env b1 b2
-
-eq_hsType env (HsPredTy p1) (HsPredTy p2)
- = eq_hsPred env p1 p2
-
-eq_hsType env (HsOpTy lty1 op1 rty1) (HsOpTy lty2 op2 rty2)
- = eq_hsVar env op1 op2 && eq_hsType env lty1 lty2 && eq_hsType env rty1 rty2
-
-eq_hsType env ty1 ty2 = False
-
-
--------------------
-eq_hsContext env a b = eqListBy (eq_hsPred env) a b
-
--------------------
-eq_hsPred env (HsClassP c1 tys1) (HsClassP c2 tys2)
- = c1 == c2 && eq_hsTypes env tys1 tys2
-eq_hsPred env (HsIParam n1 ty1) (HsIParam n2 ty2)
- = n1 == n2 && eq_hsType env ty1 ty2
-eq_hsPred env _ _ = False
-\end{code}