-]%
+%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[HsTypes]{Abstract syntax: user-defined types}
\begin{code}
module HsTypes (
- HsType(..), HsTyVarBndr(..),
- , HsContext, HsPred(..)
-
- , mkHsForAllTy, mkHsDictTy, mkHsIParamTy
- , hsTyVarName, hsTyVarNames, replaceTyVarName
- , splitHsInstDeclTy
+ HsType(..), LHsType,
+ HsTyVarBndr(..), LHsTyVarBndr,
+ HsExplicitForAll(..),
+ HsContext, LHsContext,
+ HsPred(..), LHsPred,
+
+ LBangType, BangType, HsBang(..),
+ getBangType, getBangStrictness,
+
+ mkExplicitHsForAllTy, mkImplicitHsForAllTy,
+ hsTyVarName, hsTyVarNames, replaceTyVarName,
+ hsLTyVarName, hsLTyVarNames, hsLTyVarLocName, hsLTyVarLocNames,
+ splitHsInstDeclTy, splitHsFunType,
-- Type place holder
- , PostTcType, placeHolderType,
-
- -- Name place holder
- , SyntaxName, placeHolderName,
+ PostTcType, placeHolderType,
-- Printing
- , pprParendHsType, pprHsForAll, pprHsContext, ppr_hs_context, pprHsTyVarBndr
+ pprParendHsType, pprHsForAll, pprHsContext, ppr_hs_context, pprHsTyVarBndr
) where
#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 {-# SOURCE #-} HsExpr ( HsSplice, pprSplice )
+
+import Type ( Type )
+import Kind ( {- instance Outputable Kind -}, Kind,
+ pprParendKind, pprKind, isLiftedTypeKind )
import BasicTypes ( IPName, Boxity, tupleParens )
-import PrelNames ( unboundKey )
-import SrcLoc ( noSrcLoc )
+import SrcLoc ( Located(..), unLoc, noSrcSpan )
+import StaticFlags ( opt_PprStyle_Debug )
import Outputable
\end{code}
placeHolderType :: PostTcType -- Used before typechecking
placeHolderType = panic "Evaluated the place holder for a PostTcType"
+\end{code}
+%************************************************************************
+%* *
+\subsection{Bang annotations}
+%* *
+%************************************************************************
-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
+\begin{code}
+type LBangType name = Located (BangType name)
+type BangType name = HsType name -- Bangs are in the HsType data type
+
+data HsBang = HsNoBang -- Only used as a return value for getBangStrictness,
+ -- never appears on a HsBangTy
+ | HsStrict -- !
+ | HsUnbox -- {-# UNPACK #-} ! (GHC extension, meaning "unbox")
+
+instance Outputable HsBang where
+ ppr (HsNoBang) = empty
+ ppr (HsStrict) = char '!'
+ ppr (HsUnbox) = ptext SLIT("!!")
+
+getBangType :: LHsType a -> LHsType a
+getBangType (L _ (HsBangTy _ ty)) = ty
+getBangType ty = ty
+
+getBangStrictness :: LHsType a -> HsBang
+getBangStrictness (L _ (HsBangTy s _)) = s
+getBangStrictness _ = HsNoBang
\end{code}
This is the syntax for types as seen in type signatures.
\begin{code}
-type HsContext name = [HsPred name]
+type LHsContext name = Located (HsContext name)
+
+type HsContext name = [LHsPred name]
+
+type LHsPred name = Located (HsPred name)
+
+data HsPred name = HsClassP name [LHsType name]
+ | HsIParam (IPName name) (LHsType name)
-data HsPred name = HsClassP name [HsType name]
- | HsIParam (IPName name) (HsType name)
+type LHsType name = Located (HsType name)
data HsType name
- = HsForAllTy (Maybe [HsTyVarBndr name]) -- Nothing for implicitly quantified signatures
- (HsContext name)
- (HsType name)
+ = HsForAllTy HsExplicitForAll -- Renamer leaves this flag unchanged, to record the way
+ -- the user wrote it originally, so that the printer can
+ -- print it as the user wrote it
+ [LHsTyVarBndr name] -- With ImplicitForAll, this is the empty list
+ -- until the renamer fills in the variables
+ (LHsContext name)
+ (LHsType name)
| HsTyVar name -- Type variable or type constructor
- | HsAppTy (HsType name)
- (HsType name)
+ | HsBangTy HsBang (LHsType name) -- Bang-style type annotations
- | HsFunTy (HsType name) -- function type
- (HsType name)
+ | HsAppTy (LHsType name)
+ (LHsType name)
- | HsListTy (HsType name) -- Element type
+ | HsFunTy (LHsType name) -- function type
+ (LHsType name)
- | HsPArrTy (HsType name) -- Elem. type of parallel array: [:t:]
+ | HsListTy (LHsType name) -- Element type
+
+ | HsPArrTy (LHsType name) -- Elem. type of parallel array: [:t:]
| HsTupleTy Boxity
- [HsType name] -- Element types (length gives arity)
+ [LHsType name] -- Element types (length gives arity)
- | HsOpTy (HsType name) name (HsType name)
+ | HsOpTy (LHsType name) (Located name) (LHsType name)
- | HsParTy (HsType name)
+ | HsParTy (LHsType 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!
--
| HsNumTy Integer -- Generics only
- -- these next two are only used in interfaces
- | HsPredTy (HsPred name)
+ | HsPredTy (HsPred name) -- Only used in the type of an instance
+ -- declaration, eg. Eq [a] -> Eq a
+ -- ^^^^
+ -- HsPredTy
+ -- Note no need for location info on the
+ -- enclosed HsPred; the one on the type will do
- | HsKindSig (HsType name) -- (ty :: kind)
+ | HsKindSig (LHsType name) -- (ty :: kind)
Kind -- A type with a kind signature
+ | HsSpliceTy (HsSplice name)
+
+data HsExplicitForAll = Explicit | Implicit
-----------------------
-- 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 mtvs [] ty = mk_forall_ty mtvs ty
-mkHsForAllTy mtvs ctxt ty = HsForAllTy mtvs ctxt ty
+mkImplicitHsForAllTy ctxt ty = mkHsForAllTy Implicit [] ctxt ty
+mkExplicitHsForAllTy tvs ctxt ty = mkHsForAllTy Explicit tvs ctxt ty
+
+mkHsForAllTy :: HsExplicitForAll -> [LHsTyVarBndr name] -> LHsContext name -> LHsType name -> HsType name
+-- Smart constructor for HsForAllTy
+mkHsForAllTy exp tvs (L _ []) ty = mk_forall_ty exp tvs ty
+mkHsForAllTy exp tvs ctxt ty = HsForAllTy exp tvs 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
+mk_forall_ty exp tvs (L _ (HsParTy ty)) = mk_forall_ty exp tvs ty
+mk_forall_ty exp1 tvs1 (L _ (HsForAllTy exp2 tvs2 ctxt ty)) = mkHsForAllTy (exp1 `plus` exp2) (tvs1 ++ tvs2) ctxt ty
+mk_forall_ty exp tvs ty = HsForAllTy exp tvs (L noSrcSpan []) ty
+ -- Even if tvs is empty, we still make a HsForAll!
+ -- In the Implicit case, this signals the place to do implicit quantification
+ -- In the Explicit case, it prevents implicit quantification
+ -- (see the sigtype production in Parser.y.pp)
+ -- so that (forall. ty) isn't implicitly quantified
-mtvs1 `plus` Nothing = mtvs1
-Nothing `plus` mtvs2 = mtvs2
-(Just tvs1) `plus` (Just tvs2) = Just (tvs1 ++ tvs2)
+Implicit `plus` Implicit = Implicit
+exp1 `plus` exp2 = Explicit
-mkHsDictTy cls tys = HsPredTy (HsClassP cls tys)
-mkHsIParamTy v ty = HsPredTy (HsIParam v ty)
+type LHsTyVarBndr name = Located (HsTyVarBndr name)
data HsTyVarBndr name
= UserTyVar name
| KindedTyVar name Kind
- -- *** NOTA BENE *** A "monotype" in a pragma can have
+ -- *** NOTA BENE *** A "monotype" in a pragma can have
-- for-alls in it, (mostly to do with dictionaries). These
-- must be explicitly Kinded.
+hsTyVarName :: HsTyVarBndr name -> name
hsTyVarName (UserTyVar n) = n
hsTyVarName (KindedTyVar n _) = n
+hsLTyVarName :: LHsTyVarBndr name -> name
+hsLTyVarName = hsTyVarName . unLoc
+
+hsTyVarNames :: [HsTyVarBndr name] -> [name]
hsTyVarNames tvs = map hsTyVarName tvs
+hsLTyVarNames :: [LHsTyVarBndr name] -> [name]
+hsLTyVarNames = map hsLTyVarName
+
+hsLTyVarLocName :: LHsTyVarBndr name -> Located name
+hsLTyVarLocName = fmap hsTyVarName
+
+hsLTyVarLocNames :: [LHsTyVarBndr name] -> [Located name]
+hsLTyVarLocNames = map hsLTyVarLocName
+
replaceTyVarName :: HsTyVarBndr name1 -> name2 -> HsTyVarBndr name2
replaceTyVarName (UserTyVar n) n' = UserTyVar n'
replaceTyVarName (KindedTyVar n k) n' = KindedTyVar n' k
\begin{code}
splitHsInstDeclTy
- :: Outputable name
+ :: OutputableBndr name
=> HsType name
- -> ([HsTyVarBndr name], HsContext name, name, [HsType name])
+ -> ([LHsTyVarBndr name], HsContext name, name, [LHsType 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
-
+ HsParTy (L _ ty) -> splitHsInstDeclTy ty
+ HsForAllTy _ tvs cxt (L _ ty) -> split_tau tvs (unLoc cxt) ty
+ other -> split_tau [] [] other
+ -- The type vars should have been computed by now, even if they were implicit
+ where
+ split_tau tvs cxt (HsPredTy (HsClassP cls tys)) = (tvs, cxt, cls, tys)
+ split_tau tvs cxt (HsParTy (L _ ty)) = split_tau tvs cxt ty
+
+-- Splits HsType into the (init, last) parts
+-- Breaks up any parens in the result type:
+-- splitHsFunType (a -> (b -> c)) = ([a,b], c)
+splitHsFunType :: LHsType name -> ([LHsType name], LHsType name)
+splitHsFunType (L l (HsFunTy x y)) = (x:args, res)
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)
+ (args, res) = splitHsFunType y
+splitHsFunType (L _ (HsParTy ty)) = splitHsFunType ty
+splitHsFunType other = ([], other)
\end{code}
don't change the printing format lightly
\begin{code}
-instance (Outputable name) => Outputable (HsType name) where
+instance (OutputableBndr name) => Outputable (HsType name) where
ppr ty = pprHsType ty
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)
+instance OutputableBndr name => Outputable (HsPred name) where
+ ppr (HsClassP clas tys) = ppr clas <+> hsep (map (pprParendHsType.unLoc) tys)
ppr (HsIParam n ty) = hsep [ppr n, dcolon, ppr ty]
pprHsTyVarBndr :: Outputable name => name -> Kind -> SDoc
-pprHsTyVarBndr name kind | kind `eqKind` liftedTypeKind = ppr name
- | otherwise = hsep [ppr name, dcolon, pprParendKind kind]
+pprHsTyVarBndr name kind | isLiftedTypeKind kind = ppr name
+ | otherwise = hsep [ppr name, dcolon, pprParendKind kind]
-pprHsForAll [] [] = empty
-pprHsForAll tvs cxt = ptext SLIT("forall") <+> interppSP tvs <+> pprHsContext cxt
+pprHsForAll exp tvs cxt
+ | show_forall = forall_part <+> pprHsContext (unLoc cxt)
+ | otherwise = pprHsContext (unLoc cxt)
+ where
+ show_forall = opt_PprStyle_Debug
+ || (not (null tvs) && is_explicit)
+ is_explicit = case exp of {Explicit -> True; Implicit -> False}
+ forall_part = ptext SLIT("forall") <+> interppSP tvs <> dot
-pprHsContext :: (Outputable name) => HsContext name -> SDoc
+pprHsContext :: (OutputableBndr name) => HsContext name -> SDoc
pprHsContext [] = empty
pprHsContext cxt = ppr_hs_context cxt <+> ptext SLIT("=>")
-- printing works more-or-less as for Types
-pprHsType, pprParendHsType :: (Outputable name) => HsType name -> SDoc
+pprHsType, pprParendHsType :: (OutputableBndr name) => HsType name -> SDoc
pprHsType ty = getPprStyle $ \sty -> ppr_mono_ty pREC_TOP (prepare sty ty)
pprParendHsType ty = ppr_mono_ty pREC_CON ty
-- (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 (HsParTy ty) = prepare sty (unLoc ty)
prepare sty ty = ty
-ppr_mono_ty ctxt_prec (HsForAllTy maybe_tvs ctxt ty)
+ppr_mono_lty ctxt_prec ty = ppr_mono_ty ctxt_prec (unLoc ty)
+
+ppr_mono_ty ctxt_prec (HsForAllTy exp tvs ctxt ty)
= maybeParen ctxt_prec pREC_FUN $
- sep [pp_header, ppr_mono_ty pREC_TOP ty]
- where
- pp_header = case maybe_tvs of
- Just tvs -> pprHsForAll tvs ctxt
- Nothing -> pprHsContext ctxt
+ sep [pprHsForAll exp tvs ctxt, ppr_mono_lty pREC_TOP ty]
+-- gaw 2004
+ppr_mono_ty ctxt_prec (HsBangTy b ty) = ppr b <> ppr ty
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 (HsKindSig ty kind) = parens (ppr_mono_lty pREC_TOP ty <+> dcolon <+> pprKind kind)
+ppr_mono_ty ctxt_prec (HsListTy ty) = brackets (ppr_mono_lty pREC_TOP ty)
+ppr_mono_ty ctxt_prec (HsPArrTy ty) = pabrackets (ppr_mono_lty 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 (HsSpliceTy s) = pprSplice s
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]
+ hsep [ppr_mono_lty pREC_FUN fun_ty, ppr_mono_lty 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_lty pREC_OP ty1 <+> ppr op <+> ppr_mono_lty pREC_OP ty2
ppr_mono_ty ctxt_prec (HsParTy ty)
- = parens (ppr_mono_ty pREC_TOP ty)
+ = parens (ppr_mono_lty 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
+ = let p1 = ppr_mono_lty pREC_FUN ty1
+ p2 = ppr_mono_lty pREC_TOP ty2
in
maybeParen ctxt_prec pREC_FUN $
sep [p1, ptext SLIT("->") <+> p2]
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