-%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+]%
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[HsTypes]{Abstract syntax: user-defined types}
-If compiled without \tr{#define COMPILING_GHC}, you get
-(part of) a Haskell-abstract-syntax library. With it,
-you get part of GHC.
-
\begin{code}
-#include "HsVersions.h"
-
module HsTypes (
- HsType(..), HsTyVar(..),
- SYN_IE(Context), SYN_IE(ClassAssertion)
-
- , mkHsForAllTy
- , getTyVarName, replaceTyVarName
- , pprParendHsType
- , pprContext
- , cmpHsType, cmpContext
+ HsType(..), HsTyVarBndr(..),
+ , HsContext, HsPred(..)
+
+ , mkHsForAllTy, mkHsDictTy, mkHsIParamTy
+ , hsTyVarName, hsTyVarNames, replaceTyVarName
+ , splitHsInstDeclTy
+
+ -- Type place holder
+ , PostTcType, placeHolderType,
+
+ -- Name place holder
+ , SyntaxName, placeHolderName,
+
+ -- Printing
+ , pprParendHsType, pprHsForAll, pprHsContext, ppr_hs_context, pprHsTyVarBndr
) where
-IMP_Ubiq()
+#include "HsVersions.h"
+
+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}
+
+
+%************************************************************************
+%* *
+\subsection{Annotating the syntax}
+%* *
+%************************************************************************
+
+\begin{code}
+type PostTcType = Type -- Used for slots in the abstract syntax
+ -- where we want to keep slot for a type
+ -- to be added by the type checker...but
+ -- before typechecking it's just bogus
+
+placeHolderType :: PostTcType -- Used before typechecking
+placeHolderType = panic "Evaluated the place holder for a PostTcType"
+
-import Outputable ( interppSP, ifnotPprForUser )
-import Kind ( Kind {- instance Outputable -} )
-import Name ( nameOccName )
-import Pretty
-import PprStyle ( PprStyle(..) )
-import Util ( thenCmp, cmpList, isIn, panic# )
+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}
+
+%************************************************************************
+%* *
+\subsection{Data types}
+%* *
+%************************************************************************
+
This is the syntax for types as seen in type signatures.
\begin{code}
-type Context name = [ClassAssertion name]
+type HsContext name = [HsPred name]
-type ClassAssertion name = (name, HsType name)
- -- The type is usually a type variable, but it
- -- doesn't have to be when reading interface files
+data HsPred name = HsClassP name [HsType name]
+ | HsIParam (IPName name) (HsType name)
data HsType name
- = HsPreForAllTy (Context name)
- (HsType name)
+ = HsForAllTy (Maybe [HsTyVarBndr name]) -- Nothing for implicitly quantified signatures
+ (HsContext name)
+ (HsType name)
- -- The renamer turns HsPreForAllTys into HsForAllTys when they
- -- occur in signatures, to make the binding of variables
- -- explicit. This distinction is made visible for
- -- non-COMPILING_GHC code, because you probably want to do the
- -- same thing.
+ | HsTyVar name -- Type variable or type constructor
- | HsForAllTy [HsTyVar name]
- (Context name)
+ | HsAppTy (HsType name)
(HsType name)
- | MonoTyVar name -- Type variable
-
- | MonoTyApp (HsType name)
+ | HsFunTy (HsType name) -- function type
(HsType name)
- | MonoFunTy (HsType name) -- function type
- (HsType name)
+ | HsListTy (HsType name) -- Element type
- | MonoListTy name -- The list TyCon name
- (HsType name) -- Element type
+ | HsPArrTy (HsType name) -- Elem. type of parallel array: [:t:]
- | MonoTupleTy name -- The tuple TyCon name
+ | HsTupleTy Boxity
[HsType name] -- Element types (length gives arity)
- -- these next two are only used in unfoldings in interfaces
- | MonoDictTy name -- Class
- (HsType name)
-
-mkHsForAllTy [] [] ty = ty
-mkHsForAllTy tvs ctxt ty = HsForAllTy tvs ctxt ty
-
-data HsTyVar name
- = UserTyVar name
- | IfaceTyVar 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.
+ | HsOpTy (HsType name) name (HsType name)
-getTyVarName (UserTyVar n) = n
-getTyVarName (IfaceTyVar n _) = n
+ | 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.
-replaceTyVarName :: HsTyVar name1 -> name2 -> HsTyVar name2
-replaceTyVarName (UserTyVar n) n' = UserTyVar n'
-replaceTyVarName (IfaceTyVar n k) n' = IfaceTyVar n' k
-\end{code}
+ | HsNumTy Integer -- Generics only
+ -- these next two are only used in interfaces
+ | HsPredTy (HsPred name)
-%************************************************************************
-%* *
-\subsection{Pretty printing}
-%* *
-%************************************************************************
+ | HsKindSig (HsType name) -- (ty :: kind)
+ Kind -- A type with a kind signature
-\begin{code}
-instance (Outputable name) => Outputable (HsType name) where
- ppr = pprHsType
-
-instance (Outputable name) => Outputable (HsTyVar name) where
- ppr sty (UserTyVar name) = ppr_hs_tyname sty name
- ppr sty (IfaceTyVar name kind) = ppCat [ppr_hs_tyname sty name, ppStr "::", ppr sty kind]
-
-
--- Here comes a rather gross hack.
--- We want to print data and class decls in interface files, from the original source
--- When we do, we want the type variables to come out with their original names, not
--- some new unique (or else interfaces wobble too much). So when we come to one of
--- these type variables we sneakily change the style to PprForUser!
-ppr_hs_tyname PprInterface tv_name = ppr PprForUser tv_name
-ppr_hs_tyname other_sty tv_name = ppr other_sty tv_name
-
-ppr_forall sty ctxt_prec [] [] ty
- = ppr_mono_ty sty ctxt_prec ty
-ppr_forall sty ctxt_prec tvs ctxt ty
- = ppSep [ppStr "_forall_", ppBracket (interppSP sty tvs),
- pprContext sty ctxt, ppStr "=>",
- pprHsType sty ty]
-
-pprContext :: (Outputable name) => PprStyle -> (Context name) -> Pretty
-pprContext sty [] = ppNil
-pprContext sty context
- = ppCat [ppCurlies (ppIntersperse pp'SP (map ppr_assert context))]
- where
- ppr_assert (clas, ty) = ppCat [ppr sty clas, ppr sty ty]
-\end{code}
+-----------------------
+-- Combine adjacent for-alls.
+-- The following awkward situation can happen otherwise:
+-- f :: forall a. ((Num a) => Int)
+-- might generate HsForAll (Just [a]) [] (HsForAll Nothing [Num a] t)
+-- Then a isn't discovered as ambiguous, and we abstract the AbsBinds wrt []
+-- but the export list abstracts f wrt [a]. Disaster.
+--
+-- A valid type must have one for-all at the top of the type, or of the fn arg types
-\begin{code}
-pREC_TOP = (0 :: Int)
-pREC_FUN = (1 :: Int)
-pREC_CON = (2 :: Int)
+mkHsForAllTy mtvs [] ty = mk_forall_ty mtvs ty
+mkHsForAllTy mtvs ctxt ty = HsForAllTy mtvs ctxt ty
-maybeParen :: Bool -> Pretty -> Pretty
-maybeParen True p = ppParens p
-maybeParen False p = p
-
--- printing works more-or-less as for Types
+-- 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
-pprHsType, pprParendHsType :: (Outputable name) => PprStyle -> HsType name -> Pretty
+mtvs1 `plus` Nothing = mtvs1
+Nothing `plus` mtvs2 = mtvs2
+(Just tvs1) `plus` (Just tvs2) = Just (tvs1 ++ tvs2)
-pprHsType sty ty = ppr_mono_ty sty pREC_TOP ty
-pprParendHsType sty ty = ppr_mono_ty sty pREC_CON ty
+mkHsDictTy cls tys = HsPredTy (HsClassP cls tys)
+mkHsIParamTy v ty = HsPredTy (HsIParam v ty)
-ppr_mono_ty sty ctxt_prec (HsPreForAllTy ctxt ty) = ppr_forall sty ctxt_prec [] ctxt ty
-ppr_mono_ty sty ctxt_prec (HsForAllTy tvs ctxt ty) = ppr_forall sty ctxt_prec tvs ctxt ty
+data HsTyVarBndr name
+ = UserTyVar name
+ | 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.
-ppr_mono_ty sty ctxt_prec (MonoTyVar name) = ppr_hs_tyname sty name
+hsTyVarName (UserTyVar n) = n
+hsTyVarName (KindedTyVar n _) = n
-ppr_mono_ty sty ctxt_prec (MonoFunTy ty1 ty2)
- = let p1 = ppr_mono_ty sty pREC_FUN ty1
- p2 = ppr_mono_ty sty pREC_TOP ty2
- in
- maybeParen (ctxt_prec >= pREC_FUN)
- (ppSep [p1, ppBeside (ppStr "-> ") p2])
+hsTyVarNames tvs = map hsTyVarName tvs
-ppr_mono_ty sty ctxt_prec (MonoTupleTy _ tys)
- = ppParens (ppInterleave ppComma (map (ppr sty) tys))
+replaceTyVarName :: HsTyVarBndr name1 -> name2 -> HsTyVarBndr name2
+replaceTyVarName (UserTyVar n) n' = UserTyVar n'
+replaceTyVarName (KindedTyVar n k) n' = KindedTyVar n' k
+\end{code}
-ppr_mono_ty sty ctxt_prec (MonoListTy _ ty)
- = ppBesides [ppLbrack, ppr_mono_ty sty pREC_TOP ty, ppRbrack]
-ppr_mono_ty sty ctxt_prec (MonoTyApp fun_ty arg_ty)
- = maybeParen (ctxt_prec >= pREC_CON)
- (ppCat [ppr_mono_ty sty pREC_FUN fun_ty, ppr_mono_ty sty pREC_CON arg_ty])
+\begin{code}
+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)
+
+splitHsInstDeclTy inst_ty
+ = case inst_ty of
+ HsForAllTy (Just tvs) cxt1 tau
+ -> (tvs, cxt1++cxt2, cls, tys)
+ where
+ (cxt2, cls, tys) = split_tau tau
+
+ other -> ([], cxt2, cls, tys)
+ where
+ (cxt2, cls, tys) = split_tau inst_ty
-ppr_mono_ty sty ctxt_prec (MonoDictTy clas ty)
- = ppCurlies (ppCat [ppr sty clas, ppr_mono_ty sty pREC_CON ty])
- -- Curlies are temporary
+ 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}
%************************************************************************
%* *
-\subsection{Comparison}
+\subsection{Pretty printing}
%* *
%************************************************************************
-We do define a specialised equality for these \tr{*Type} types; used
-in checking interfaces. Most any other use is likely to be {\em
-wrong}, so be careful!
+NB: these types get printed into interface files, so
+ don't change the printing format lightly
\begin{code}
-cmpHsTyVar :: (a -> a -> TAG_) -> HsTyVar a -> HsTyVar a -> TAG_
-cmpHsType :: (a -> a -> TAG_) -> HsType a -> HsType a -> TAG_
-cmpContext :: (a -> a -> TAG_) -> Context a -> Context a -> TAG_
+instance (Outputable name) => Outputable (HsType name) where
+ ppr ty = pprHsType ty
-cmpHsTyVar cmp (UserTyVar v1) (UserTyVar v2) = v1 `cmp` v2
-cmpHsTyVar cmp (IfaceTyVar v1 _) (IfaceTyVar v2 _) = v1 `cmp` v2
-cmpHsTyVar cmp (UserTyVar _) other = LT_
-cmpHsTyVar cmp other1 other2 = GT_
+instance (Outputable name) => Outputable (HsTyVarBndr name) where
+ 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)
+ ppr (HsIParam n ty) = hsep [ppr n, dcolon, ppr ty]
--- We assume that HsPreForAllTys have been smashed by now.
-# ifdef DEBUG
-cmpHsType _ (HsPreForAllTy _ _) _ = panic# "cmpHsType:HsPreForAllTy:1st arg"
-cmpHsType _ _ (HsPreForAllTy _ _) = panic# "cmpHsType:HsPreForAllTy:2nd arg"
-# endif
+pprHsTyVarBndr :: Outputable name => name -> Kind -> SDoc
+pprHsTyVarBndr name kind | kind `eqKind` liftedTypeKind = ppr name
+ | otherwise = hsep [ppr name, dcolon, pprParendKind kind]
-cmpHsType cmp (HsForAllTy tvs1 c1 t1) (HsForAllTy tvs2 c2 t2)
- = cmpList (cmpHsTyVar cmp) tvs1 tvs2 `thenCmp`
- cmpContext cmp c1 c2 `thenCmp`
- cmpHsType cmp t1 t2
+pprHsForAll [] [] = empty
+pprHsForAll tvs cxt = ptext SLIT("forall") <+> interppSP tvs <+> pprHsContext cxt
-cmpHsType cmp (MonoTyVar n1) (MonoTyVar n2)
- = cmp n1 n2
+pprHsContext :: (Outputable name) => HsContext name -> SDoc
+pprHsContext [] = empty
+pprHsContext cxt = ppr_hs_context cxt <+> ptext SLIT("=>")
+
+ppr_hs_context [] = empty
+ppr_hs_context cxt = parens (interpp'SP cxt)
+\end{code}
-cmpHsType cmp (MonoTupleTy _ tys1) (MonoTupleTy _ tys2)
- = cmpList (cmpHsType cmp) tys1 tys2
-cmpHsType cmp (MonoListTy _ ty1) (MonoListTy _ ty2)
- = cmpHsType cmp ty1 ty2
+\begin{code}
+pREC_TOP = (0 :: Int) -- type in ParseIface.y
+pREC_FUN = (1 :: Int) -- btype in ParseIface.y
+ -- 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
-cmpHsType cmp (MonoTyApp fun_ty1 arg_ty1) (MonoTyApp fun_ty2 arg_ty2)
- = cmpHsType cmp fun_ty1 fun_ty2 `thenCmp` cmpHsType cmp arg_ty1 arg_ty2
+pprHsType, pprParendHsType :: (Outputable name) => HsType name -> SDoc
-cmpHsType cmp (MonoFunTy a1 b1) (MonoFunTy a2 b2)
- = cmpHsType cmp a1 a2 `thenCmp` cmpHsType cmp b1 b2
+pprHsType ty = getPprStyle $ \sty -> ppr_mono_ty pREC_TOP (prepare sty ty)
+pprParendHsType ty = ppr_mono_ty pREC_CON ty
-cmpHsType cmp (MonoDictTy c1 ty1) (MonoDictTy c2 ty2)
- = cmp c1 c2 `thenCmp` cmpHsType cmp ty1 ty2
+-- Before printing a type
+-- (a) Remove outermost HsParTy parens
+-- (b) Drop top-level for-all type variables in user style
+-- since they are implicit in Haskell
+prepare sty (HsParTy ty) = prepare sty ty
+prepare sty (HsForAllTy _ cxt ty) | userStyle sty = (HsForAllTy Nothing cxt ty)
+prepare sty ty = ty
-cmpHsType cmp ty1 ty2 -- tags must be different
- = let tag1 = tag ty1
- tag2 = tag ty2
- in
- if tag1 _LT_ tag2 then LT_ else GT_
- where
- tag (MonoTyVar n1) = (ILIT(1) :: FAST_INT)
- tag (MonoTupleTy _ tys1) = ILIT(2)
- tag (MonoListTy _ ty1) = ILIT(3)
- tag (MonoTyApp tc1 tys1) = ILIT(4)
- tag (MonoFunTy a1 b1) = ILIT(5)
- tag (MonoDictTy c1 ty1) = ILIT(7)
- tag (HsForAllTy _ _ _) = ILIT(8)
- tag (HsPreForAllTy _ _) = ILIT(9)
-
--------------------
-cmpContext cmp a b
- = cmpList cmp_ctxt a b
+ppr_mono_ty ctxt_prec (HsForAllTy maybe_tvs ctxt ty)
+ = maybeParen ctxt_prec pREC_FUN $
+ sep [pp_header, ppr_mono_ty pREC_TOP ty]
where
- cmp_ctxt (c1, ty1) (c2, ty2)
- = cmp c1 c2 `thenCmp` cmpHsType cmp ty1 ty2
+ 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) = 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 (HsOpTy ty1 op ty2)
+ = maybeParen ctxt_prec pREC_OP $
+ ppr_mono_ty pREC_OP ty1 <+> ppr op <+> ppr_mono_ty pREC_OP ty2
+
+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
+
+--------------------------
+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]
+
+--------------------------
+pabrackets p = ptext SLIT("[:") <> p <> ptext SLIT(":]")
\end{code}
+
+
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