{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 HsTypes: Abstract syntax: user-defined types -} {-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE StandaloneDeriving #-} {-# LANGUAGE TypeSynonymInstances #-} {-# LANGUAGE UndecidableInstances #-} -- Note [Pass sensitive types] -- in module PlaceHolder {-# LANGUAGE ConstraintKinds #-} module HsTypes ( HsType(..), LHsType, HsKind, LHsKind, HsTyOp,LHsTyOp, HsTyVarBndr(..), LHsTyVarBndr, LHsTyVarBndrs(..), HsWithBndrs(..), HsTupleSort(..), HsExplicitFlag(..), HsContext, LHsContext, HsQuasiQuote(..), HsTyWrapper(..), HsTyLit(..), HsIPName(..), hsIPNameFS, LBangType, BangType, HsBang(..), HsSrcBang, HsImplBang, getBangType, getBangStrictness, ConDeclField(..), LConDeclField, pprConDeclFields, mkHsQTvs, hsQTvBndrs, isHsKindedTyVar, hsTvbAllKinded, mkExplicitHsForAllTy, mkImplicitHsForAllTy, mkQualifiedHsForAllTy, hsExplicitTvs, hsTyVarName, mkHsWithBndrs, hsLKiTyVarNames, hsLTyVarName, hsLTyVarNames, hsLTyVarLocName, hsLTyVarLocNames, splitLHsInstDeclTy_maybe, splitHsClassTy_maybe, splitLHsClassTy_maybe, splitHsFunType, splitHsAppTys, hsTyGetAppHead_maybe, mkHsAppTys, mkHsOpTy, isWildcardTy, isNamedWildcardTy, -- Printing pprParendHsType, pprHsForAll, pprHsForAllExtra, pprHsContext, pprHsContextNoArrow, pprHsContextMaybe ) where import {-# SOURCE #-} HsExpr ( HsSplice, pprUntypedSplice ) import PlaceHolder ( PostTc,PostRn,DataId,PlaceHolder(..) ) import Name( Name ) import RdrName( RdrName ) import DataCon( HsBang(..), HsSrcBang, HsImplBang ) import TysPrim( funTyConName ) import Type import HsDoc import BasicTypes import SrcLoc import StaticFlags import Outputable import FastString import Maybes( isJust ) import Data.Data hiding ( Fixity ) import Data.Maybe ( fromMaybe ) {- ************************************************************************ * * Quasi quotes; used in types and elsewhere * * ************************************************************************ -} data HsQuasiQuote id = HsQuasiQuote id -- The quasi-quoter SrcSpan -- The span of the enclosed string FastString -- The enclosed string deriving (Data, Typeable) instance OutputableBndr id => Outputable (HsQuasiQuote id) where ppr = ppr_qq ppr_qq :: OutputableBndr id => HsQuasiQuote id -> SDoc ppr_qq (HsQuasiQuote quoter _ quote) = char '[' <> ppr quoter <> ptext (sLit "|") <> ppr quote <> ptext (sLit "|]") {- ************************************************************************ * * \subsection{Bang annotations} * * ************************************************************************ -} type LBangType name = Located (BangType name) type BangType name = HsType name -- Bangs are in the HsType data type getBangType :: LHsType a -> LHsType a getBangType (L _ (HsBangTy _ ty)) = ty getBangType ty = ty getBangStrictness :: LHsType a -> HsSrcBang getBangStrictness (L _ (HsBangTy s _)) = s getBangStrictness _ = HsNoBang {- ************************************************************************ * * \subsection{Data types} * * ************************************************************************ This is the syntax for types as seen in type signatures. Note [HsBSig binder lists] ~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider a binder (or pattern) decoarated with a type or kind, \ (x :: a -> a). blah forall (a :: k -> *) (b :: k). blah Then we use a LHsBndrSig on the binder, so that the renamer can decorate it with the variables bound by the pattern ('a' in the first example, 'k' in the second), assuming that neither of them is in scope already See also Note [Kind and type-variable binders] in RnTypes -} type LHsContext name = Located (HsContext name) -- ^ 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnUnit' -- For details on above see note [Api annotations] in ApiAnnotation type HsContext name = [LHsType name] type LHsType name = Located (HsType name) -- ^ May have 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnComma' when -- in a list -- For details on above see note [Api annotations] in ApiAnnotation type HsKind name = HsType name type LHsKind name = Located (HsKind name) type LHsTyVarBndr name = Located (HsTyVarBndr name) data LHsTyVarBndrs name = HsQTvs { hsq_kvs :: [Name] -- Kind variables , hsq_tvs :: [LHsTyVarBndr name] -- Type variables -- See Note [HsForAllTy tyvar binders] } deriving( Typeable ) deriving instance (DataId name) => Data (LHsTyVarBndrs name) mkHsQTvs :: [LHsTyVarBndr RdrName] -> LHsTyVarBndrs RdrName -- Just at RdrName because in the Name variant we should know just -- what the kind-variable binders are; and we don't -- We put an empty list (rather than a panic) for the kind vars so -- that the pretty printer works ok on them. mkHsQTvs tvs = HsQTvs { hsq_kvs = [], hsq_tvs = tvs } emptyHsQTvs :: LHsTyVarBndrs name -- Use only when you know there are no kind binders emptyHsQTvs = HsQTvs { hsq_kvs = [], hsq_tvs = [] } hsQTvBndrs :: LHsTyVarBndrs name -> [LHsTyVarBndr name] hsQTvBndrs = hsq_tvs data HsWithBndrs name thing = HsWB { hswb_cts :: thing -- Main payload (type or list of types) , hswb_kvs :: PostRn name [Name] -- Kind vars , hswb_tvs :: PostRn name [Name] -- Type vars , hswb_wcs :: PostRn name [Name] -- Wildcards } deriving (Typeable) deriving instance (Data name, Data thing, Data (PostRn name [Name])) => Data (HsWithBndrs name thing) mkHsWithBndrs :: thing -> HsWithBndrs RdrName thing mkHsWithBndrs x = HsWB { hswb_cts = x, hswb_kvs = PlaceHolder , hswb_tvs = PlaceHolder , hswb_wcs = PlaceHolder } -- | These names are used early on to store the names of implicit -- parameters. They completely disappear after type-checking. newtype HsIPName = HsIPName FastString-- ?x deriving( Eq, Data, Typeable ) hsIPNameFS :: HsIPName -> FastString hsIPNameFS (HsIPName n) = n instance Outputable HsIPName where ppr (HsIPName n) = char '?' <> ftext n -- Ordinary implicit parameters instance OutputableBndr HsIPName where pprBndr _ n = ppr n -- Simple for now pprInfixOcc n = ppr n pprPrefixOcc n = ppr n data HsTyVarBndr name = UserTyVar -- no explicit kinding name | KindedTyVar (Located name) (LHsKind name) -- The user-supplied kind signature -- ^ -- - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen', -- 'ApiAnnotation.AnnDcolon', 'ApiAnnotation.AnnClose' -- For details on above see note [Api annotations] in ApiAnnotation deriving (Typeable) deriving instance (DataId name) => Data (HsTyVarBndr name) -- | Does this 'HsTyVarBndr' come with an explicit kind annotation? isHsKindedTyVar :: HsTyVarBndr name -> Bool isHsKindedTyVar (UserTyVar {}) = False isHsKindedTyVar (KindedTyVar {}) = True -- | Do all type variables in this 'LHsTyVarBndr' come with kind annotations? hsTvbAllKinded :: LHsTyVarBndrs name -> Bool hsTvbAllKinded = all (isHsKindedTyVar . unLoc) . hsQTvBndrs data HsType name = HsForAllTy HsExplicitFlag -- 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 (Maybe SrcSpan) -- Indicates whether extra constraints may be inferred. -- When Nothing, no, otherwise the location of the extra- -- constraints wildcard is stored. For instance, for the -- signature (Eq a, _) => a -> a -> Bool, this field would -- be something like (Just 1:8), with 1:8 being line 1, -- column 8. (LHsTyVarBndrs name) (LHsContext name) (LHsType name) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnForall', -- 'ApiAnnotation.AnnDot','ApiAnnotation.AnnDarrow' -- For details on above see note [Api annotations] in ApiAnnotation | HsTyVar name -- Type variable, type constructor, or data constructor -- see Note [Promotions (HsTyVar)] -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsAppTy (LHsType name) (LHsType name) -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsFunTy (LHsType name) -- function type (LHsType name) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnRarrow', -- For details on above see note [Api annotations] in ApiAnnotation | HsListTy (LHsType name) -- Element type -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'['@, -- 'ApiAnnotation.AnnClose' @']'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsPArrTy (LHsType name) -- Elem. type of parallel array: [:t:] -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'[:'@, -- 'ApiAnnotation.AnnClose' @':]'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsTupleTy HsTupleSort [LHsType name] -- Element types (length gives arity) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'(' or '(#'@, -- 'ApiAnnotation.AnnClose' @')' or '#)'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsOpTy (LHsType name) (LHsTyOp name) (LHsType name) -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsParTy (LHsType name) -- See Note [Parens in HsSyn] in HsExpr -- Parenthesis preserved for the precedence re-arrangement in RnTypes -- It's important that a * (b + c) doesn't get rearranged to (a*b) + c! -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'('@, -- 'ApiAnnotation.AnnClose' @')'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsIParamTy HsIPName -- (?x :: ty) (LHsType name) -- Implicit parameters as they occur in contexts -- ^ -- > (?x :: ty) -- -- - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnDcolon' -- For details on above see note [Api annotations] in ApiAnnotation | HsEqTy (LHsType name) -- ty1 ~ ty2 (LHsType name) -- Always allowed even without TypeOperators, and has special kinding rule -- ^ -- > ty1 ~ ty2 -- -- - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnTilde' -- For details on above see note [Api annotations] in ApiAnnotation | HsKindSig (LHsType name) -- (ty :: kind) (LHsKind name) -- A type with a kind signature -- ^ -- > (ty :: kind) -- -- - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'('@, -- 'ApiAnnotation.AnnDcolon','ApiAnnotation.AnnClose' @')'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsQuasiQuoteTy (HsQuasiQuote name) -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsSpliceTy (HsSplice name) (PostTc name Kind) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'$('@, -- 'ApiAnnotation.AnnClose' @')'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsDocTy (LHsType name) LHsDocString -- A documented type -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsBangTy HsSrcBang (LHsType name) -- Bang-style type annotations -- ^ - 'ApiAnnotation.AnnKeywordId' : -- 'ApiAnnotation.AnnOpen' @'{-\# UNPACK' or '{-\# NOUNPACK'@, -- 'ApiAnnotation.AnnClose' @'#-}'@ -- 'ApiAnnotation.AnnBang' @\'!\'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsRecTy [LConDeclField name] -- Only in data type declarations -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'{'@, -- 'ApiAnnotation.AnnClose' @'}'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsCoreTy Type -- An escape hatch for tunnelling a *closed* -- Core Type through HsSyn. -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsExplicitListTy -- A promoted explicit list (PostTc name Kind) -- See Note [Promoted lists and tuples] [LHsType name] -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @"'["@, -- 'ApiAnnotation.AnnClose' @']'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsExplicitTupleTy -- A promoted explicit tuple [PostTc name Kind] -- See Note [Promoted lists and tuples] [LHsType name] -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @"'("@, -- 'ApiAnnotation.AnnClose' @')'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsTyLit HsTyLit -- A promoted numeric literal. -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsWrapTy HsTyWrapper (HsType name) -- only in typechecker output -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsWildcardTy -- A type wildcard -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsNamedWildcardTy name -- A named wildcard -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation deriving (Typeable) deriving instance (DataId name) => Data (HsType name) -- Note [Literal source text] in BasicTypes for SourceText fields in -- the following data HsTyLit = HsNumTy SourceText Integer | HsStrTy SourceText FastString deriving (Data, Typeable) data HsTyWrapper = WpKiApps [Kind] -- kind instantiation: [] k1 k2 .. kn deriving (Data, Typeable) type LHsTyOp name = HsTyOp (Located name) type HsTyOp name = (HsTyWrapper, name) mkHsOpTy :: LHsType name -> Located name -> LHsType name -> HsType name mkHsOpTy ty1 op ty2 = HsOpTy ty1 (WpKiApps [], op) ty2 {- Note [HsForAllTy tyvar binders] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ After parsing: * Implicit => empty Explicit => the variables the user wrote After renaming * Implicit => the *type* variables free in the type Explicit => the variables the user wrote (renamed) Qualified currently behaves exactly as Implicit, but it is deprecated to use it for implicit quantification. In this case, GHC 7.10 gives a warning; see Note [Context quantification] and Trac #4426. In GHC 7.12, Qualified will no longer bind variables and this will become an error. The kind variables bound in the hsq_kvs field come both a) from the kind signatures on the kind vars (eg k1) b) from the scope of the forall (eg k2) Example: f :: forall (a::k1) b. T a (b::k2) Note [Unit tuples] ~~~~~~~~~~~~~~~~~~ Consider the type type instance F Int = () We want to parse that "()" as HsTupleTy HsBoxedOrConstraintTuple [], NOT as HsTyVar unitTyCon Why? Because F might have kind (* -> Constraint), so we when parsing we don't know if that tuple is going to be a constraint tuple or an ordinary unit tuple. The HsTupleSort flag is specifically designed to deal with that, but it has to work for unit tuples too. Note [Promotions (HsTyVar)] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ HsTyVar: A name in a type or kind. Here are the allowed namespaces for the name. In a type: Var: not allowed Data: promoted data constructor Tv: type variable TcCls before renamer: type constructor, class constructor, or promoted data constructor TcCls after renamer: type constructor or class constructor In a kind: Var, Data: not allowed Tv: kind variable TcCls: kind constructor or promoted type constructor Note [Promoted lists and tuples] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Notice the difference between HsListTy HsExplicitListTy HsTupleTy HsExplicitListTupleTy E.g. f :: [Int] HsListTy g3 :: T '[] All these use g2 :: T '[True] HsExplicitListTy g1 :: T '[True,False] g1a :: T [True,False] (can omit ' where unambiguous) kind of T :: [Bool] -> * This kind uses HsListTy! E.g. h :: (Int,Bool) HsTupleTy; f is a pair k :: S '(True,False) HsExplicitTypleTy; S is indexed by a type-level pair of booleans kind of S :: (Bool,Bool) -> * This kind uses HsExplicitTupleTy Note [Distinguishing tuple kinds] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Apart from promotion, tuples can have one of three different kinds: x :: (Int, Bool) -- Regular boxed tuples f :: Int# -> (# Int#, Int# #) -- Unboxed tuples g :: (Eq a, Ord a) => a -- Constraint tuples For convenience, internally we use a single constructor for all of these, namely HsTupleTy, but keep track of the tuple kind (in the first argument to HsTupleTy, a HsTupleSort). We can tell if a tuple is unboxed while parsing, because of the #. However, with -XConstraintKinds we can only distinguish between constraint and boxed tuples during type checking, in general. Hence the four constructors of HsTupleSort: HsUnboxedTuple -> Produced by the parser HsBoxedTuple -> Certainly a boxed tuple HsConstraintTuple -> Certainly a constraint tuple HsBoxedOrConstraintTuple -> Could be a boxed or a constraint tuple. Produced by the parser only, disappears after type checking -} data HsTupleSort = HsUnboxedTuple | HsBoxedTuple | HsConstraintTuple | HsBoxedOrConstraintTuple deriving (Data, Typeable) data HsExplicitFlag = Qualified | Implicit | Explicit deriving (Data, Typeable) type LConDeclField name = Located (ConDeclField name) -- ^ May have 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnComma' when -- in a list -- For details on above see note [Api annotations] in ApiAnnotation data ConDeclField name -- Record fields have Haddoc docs on them = ConDeclField { cd_fld_names :: [Located name], cd_fld_type :: LBangType name, cd_fld_doc :: Maybe LHsDocString } -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnDcolon' -- For details on above see note [Api annotations] in ApiAnnotation deriving (Typeable) deriving instance (DataId name) => Data (ConDeclField name) ----------------------- -- 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 mkImplicitHsForAllTy :: LHsContext RdrName -> LHsType RdrName -> HsType RdrName mkExplicitHsForAllTy :: [LHsTyVarBndr RdrName] -> LHsContext RdrName -> LHsType RdrName -> HsType RdrName mkQualifiedHsForAllTy :: LHsContext RdrName -> LHsType RdrName -> HsType RdrName mkImplicitHsForAllTy ctxt ty = mkHsForAllTy Implicit [] ctxt ty mkExplicitHsForAllTy tvs ctxt ty = mkHsForAllTy Explicit tvs ctxt ty mkQualifiedHsForAllTy ctxt ty = mkHsForAllTy Qualified [] ctxt ty mkHsForAllTy :: HsExplicitFlag -> [LHsTyVarBndr RdrName] -> LHsContext RdrName -> LHsType RdrName -> HsType RdrName -- Smart constructor for HsForAllTy mkHsForAllTy exp tvs (L _ []) ty = mk_forall_ty exp tvs ty mkHsForAllTy exp tvs ctxt ty = HsForAllTy exp extra (mkHsQTvs tvs) cleanCtxt ty where -- Separate the extra-constraints wildcard when present (cleanCtxt, extra) | (L l HsWildcardTy) <- ignoreParens (last (unLoc ctxt)) = (init `fmap` ctxt, Just l) | otherwise = (ctxt, Nothing) ignoreParens (L _ (HsParTy ty)) = ty ignoreParens ty = ty -- mk_forall_ty makes a pure for-all type (no context) mk_forall_ty :: HsExplicitFlag -> [LHsTyVarBndr RdrName] -> LHsType RdrName -> HsType RdrName mk_forall_ty exp1 tvs1 (L _ (HsForAllTy exp2 extra qtvs2 ctxt ty)) = addExtra $ mkHsForAllTy (exp1 `plus` exp2) (tvs1 ++ hsq_tvs qtvs2) ctxt ty where addExtra (HsForAllTy exp _ qtvs ctxt ty) = HsForAllTy exp extra qtvs ctxt ty addExtra ty = ty -- Impossible, as mkHsForAllTy always returns a HsForAllTy mk_forall_ty exp tvs (L _ (HsParTy ty)) = mk_forall_ty exp tvs ty mk_forall_ty exp tvs ty = HsForAllTy exp Nothing (mkHsQTvs tvs) (noLoc []) 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) -- so that (forall. ty) isn't implicitly quantified plus :: HsExplicitFlag -> HsExplicitFlag -> HsExplicitFlag Qualified `plus` Qualified = Qualified Explicit `plus` _ = Explicit _ `plus` Explicit = Explicit _ `plus` _ = Implicit hsExplicitTvs :: LHsType Name -> [Name] -- The explicitly-given forall'd type variables of a HsType hsExplicitTvs (L _ (HsForAllTy Explicit _ tvs _ _)) = hsLKiTyVarNames tvs hsExplicitTvs _ = [] --------------------- hsTyVarName :: HsTyVarBndr name -> name hsTyVarName (UserTyVar n) = n hsTyVarName (KindedTyVar (L _ n) _) = n hsLTyVarName :: LHsTyVarBndr name -> name hsLTyVarName = hsTyVarName . unLoc hsLTyVarNames :: LHsTyVarBndrs name -> [name] -- Type variables only hsLTyVarNames qtvs = map hsLTyVarName (hsQTvBndrs qtvs) hsLKiTyVarNames :: LHsTyVarBndrs Name -> [Name] -- Kind and type variables hsLKiTyVarNames (HsQTvs { hsq_kvs = kvs, hsq_tvs = tvs }) = kvs ++ map hsLTyVarName tvs hsLTyVarLocName :: LHsTyVarBndr name -> Located name hsLTyVarLocName = fmap hsTyVarName hsLTyVarLocNames :: LHsTyVarBndrs name -> [Located name] hsLTyVarLocNames qtvs = map hsLTyVarLocName (hsQTvBndrs qtvs) --------------------- isWildcardTy :: HsType a -> Bool isWildcardTy HsWildcardTy = True isWildcardTy _ = False isNamedWildcardTy :: HsType a -> Bool isNamedWildcardTy (HsNamedWildcardTy _) = True isNamedWildcardTy _ = False splitHsAppTys :: LHsType n -> [LHsType n] -> (LHsType n, [LHsType n]) splitHsAppTys (L _ (HsAppTy f a)) as = splitHsAppTys f (a:as) splitHsAppTys (L _ (HsParTy f)) as = splitHsAppTys f as splitHsAppTys f as = (f,as) -- retrieve the name of the "head" of a nested type application -- somewhat like splitHsAppTys, but a little more thorough -- used to examine the result of a GADT-like datacon, so it doesn't handle -- *all* cases (like lists, tuples, (~), etc.) hsTyGetAppHead_maybe :: LHsType n -> Maybe (n, [LHsType n]) hsTyGetAppHead_maybe = go [] where go tys (L _ (HsTyVar n)) = Just (n, tys) go tys (L _ (HsAppTy l r)) = go (r : tys) l go tys (L _ (HsOpTy l (_, L _ n) r)) = Just (n, l : r : tys) go tys (L _ (HsParTy t)) = go tys t go tys (L _ (HsKindSig t _)) = go tys t go _ _ = Nothing mkHsAppTys :: OutputableBndr n => LHsType n -> [LHsType n] -> HsType n mkHsAppTys fun_ty [] = pprPanic "mkHsAppTys" (ppr fun_ty) mkHsAppTys fun_ty (arg_ty:arg_tys) = foldl mk_app (HsAppTy fun_ty arg_ty) arg_tys where mk_app fun arg = HsAppTy (noLoc fun) arg -- Add noLocs for inner nodes of the application; -- they are never used splitLHsInstDeclTy_maybe :: LHsType name -> Maybe (LHsTyVarBndrs name, HsContext name, Located name, [LHsType name]) -- Split up an instance decl type, returning the pieces splitLHsInstDeclTy_maybe inst_ty = do let (tvs, cxt, ty) = splitLHsForAllTy inst_ty (cls, tys) <- splitLHsClassTy_maybe ty return (tvs, cxt, cls, tys) splitLHsForAllTy :: LHsType name -> (LHsTyVarBndrs name, HsContext name, LHsType name) splitLHsForAllTy poly_ty = case unLoc poly_ty of HsParTy ty -> splitLHsForAllTy ty HsForAllTy _ _ tvs cxt ty -> (tvs, unLoc cxt, ty) _ -> (emptyHsQTvs, [], poly_ty) -- The type vars should have been computed by now, even if they were implicit splitHsClassTy_maybe :: HsType name -> Maybe (name, [LHsType name]) splitHsClassTy_maybe ty = fmap (\(L _ n, tys) -> (n, tys)) $ splitLHsClassTy_maybe (noLoc ty) splitLHsClassTy_maybe :: LHsType name -> Maybe (Located name, [LHsType name]) --- Watch out.. in ...deriving( Show )... we use this on --- the list of partially applied predicates in the deriving, --- so there can be zero args. -- In TcDeriv we also use this to figure out what data type is being -- mentioned in a deriving (Generic (Foo bar baz)) declaration (i.e. "Foo"). splitLHsClassTy_maybe ty = checkl ty [] where checkl (L l ty) args = case ty of HsTyVar t -> Just (L l t, args) HsAppTy l r -> checkl l (r:args) HsOpTy l (_, tc) r -> checkl (fmap HsTyVar tc) (l:r:args) HsParTy t -> checkl t args HsKindSig ty _ -> checkl ty args _ -> Nothing -- splitHsFunType decomposes a type (t1 -> t2 ... -> tn) -- Breaks up any parens in the result type: -- splitHsFunType (a -> (b -> c)) = ([a,b], c) -- Also deals with (->) t1 t2; that is why it only works on LHsType Name -- (see Trac #9096) splitHsFunType :: LHsType Name -> ([LHsType Name], LHsType Name) splitHsFunType (L _ (HsParTy ty)) = splitHsFunType ty splitHsFunType (L _ (HsFunTy x y)) | (args, res) <- splitHsFunType y = (x:args, res) splitHsFunType orig_ty@(L _ (HsAppTy t1 t2)) = go t1 [t2] where -- Look for (->) t1 t2, possibly with parenthesisation go (L _ (HsTyVar fn)) tys | fn == funTyConName , [t1,t2] <- tys , (args, res) <- splitHsFunType t2 = (t1:args, res) go (L _ (HsAppTy t1 t2)) tys = go t1 (t2:tys) go (L _ (HsParTy ty)) tys = go ty tys go _ _ = ([], orig_ty) -- Failure to match splitHsFunType other = ([], other) {- ************************************************************************ * * \subsection{Pretty printing} * * ************************************************************************ -} instance (OutputableBndr name) => Outputable (HsType name) where ppr ty = pprHsType ty instance Outputable HsTyLit where ppr = ppr_tylit instance (OutputableBndr name) => Outputable (LHsTyVarBndrs name) where ppr (HsQTvs { hsq_kvs = kvs, hsq_tvs = tvs }) = sep [ ifPprDebug $ braces (interppSP kvs), interppSP tvs ] instance (OutputableBndr name) => Outputable (HsTyVarBndr name) where ppr (UserTyVar n) = ppr n ppr (KindedTyVar n k) = parens $ hsep [ppr n, dcolon, ppr k] instance (Outputable thing) => Outputable (HsWithBndrs name thing) where ppr (HsWB { hswb_cts = ty }) = ppr ty pprHsForAll :: OutputableBndr name => HsExplicitFlag -> LHsTyVarBndrs name -> LHsContext name -> SDoc pprHsForAll exp = pprHsForAllExtra exp Nothing -- | Version of 'pprHsForAll' that can also print an extra-constraints -- wildcard, e.g. @_ => a -> Bool@ or @(Show a, _) => a -> String@. This -- underscore will be printed when the 'Maybe SrcSpan' argument is a 'Just' -- containing the location of the extra-constraints wildcard. A special -- function for this is needed, as the extra-constraints wildcard is removed -- from the actual context and type, and stored in a separate field, thus just -- printing the type will not print the extra-constraints wildcard. pprHsForAllExtra :: OutputableBndr name => HsExplicitFlag -> Maybe SrcSpan -> LHsTyVarBndrs name -> LHsContext name -> SDoc pprHsForAllExtra exp extra qtvs cxt | show_forall = forall_part <+> pprHsContextExtra show_extra (unLoc cxt) | otherwise = pprHsContextExtra show_extra (unLoc cxt) where show_extra = isJust extra show_forall = opt_PprStyle_Debug || (not (null (hsQTvBndrs qtvs)) && is_explicit) is_explicit = case exp of {Explicit -> True; Implicit -> False; Qualified -> False} forall_part = forAllLit <+> ppr qtvs <> dot pprHsContext :: (OutputableBndr name) => HsContext name -> SDoc pprHsContext = maybe empty (<+> darrow) . pprHsContextMaybe pprHsContextNoArrow :: (OutputableBndr name) => HsContext name -> SDoc pprHsContextNoArrow = fromMaybe empty . pprHsContextMaybe pprHsContextMaybe :: (OutputableBndr name) => HsContext name -> Maybe SDoc pprHsContextMaybe [] = Nothing pprHsContextMaybe [L _ pred] = Just $ ppr_mono_ty FunPrec pred pprHsContextMaybe cxt = Just $ parens (interpp'SP cxt) -- True <=> print an extra-constraints wildcard, e.g. @(Show a, _) =>@ pprHsContextExtra :: (OutputableBndr name) => Bool -> HsContext name -> SDoc pprHsContextExtra False = pprHsContext pprHsContextExtra True = \ctxt -> case ctxt of [] -> char '_' <+> darrow _ -> parens (sep (punctuate comma ctxt')) <+> darrow where ctxt' = map ppr ctxt ++ [char '_'] pprConDeclFields :: OutputableBndr name => [LConDeclField name] -> SDoc pprConDeclFields fields = braces (sep (punctuate comma (map ppr_fld fields))) where ppr_fld (L _ (ConDeclField { cd_fld_names = ns, cd_fld_type = ty, cd_fld_doc = doc })) = ppr_names ns <+> dcolon <+> ppr ty <+> ppr_mbDoc doc ppr_names [n] = ppr n ppr_names ns = sep (punctuate comma (map ppr ns)) {- Note [Printing KindedTyVars] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Trac #3830 reminded me that we should really only print the kind signature on a KindedTyVar if the kind signature was put there by the programmer. During kind inference GHC now adds a PostTcKind to UserTyVars, rather than converting to KindedTyVars as before. (As it happens, the message in #3830 comes out a different way now, and the problem doesn't show up; but having the flag on a KindedTyVar seems like the Right Thing anyway.) -} -- Printing works more-or-less as for Types pprHsType, pprParendHsType :: (OutputableBndr name) => HsType name -> SDoc pprHsType ty = getPprStyle $ \sty -> ppr_mono_ty TopPrec (prepare sty ty) pprParendHsType ty = ppr_mono_ty TyConPrec ty -- 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 :: PprStyle -> HsType name -> HsType name prepare sty (HsParTy ty) = prepare sty (unLoc ty) prepare _ ty = ty ppr_mono_lty :: (OutputableBndr name) => TyPrec -> LHsType name -> SDoc ppr_mono_lty ctxt_prec ty = ppr_mono_ty ctxt_prec (unLoc ty) ppr_mono_ty :: (OutputableBndr name) => TyPrec -> HsType name -> SDoc ppr_mono_ty ctxt_prec (HsForAllTy exp extra tvs ctxt ty) = maybeParen ctxt_prec FunPrec $ sep [pprHsForAllExtra exp extra tvs ctxt, ppr_mono_lty TopPrec ty] ppr_mono_ty _ (HsBangTy b ty) = ppr b <> ppr_mono_lty TyConPrec ty ppr_mono_ty _ (HsQuasiQuoteTy qq) = ppr qq ppr_mono_ty _ (HsRecTy flds) = pprConDeclFields flds ppr_mono_ty _ (HsTyVar name) = pprPrefixOcc name ppr_mono_ty prec (HsFunTy ty1 ty2) = ppr_fun_ty prec ty1 ty2 ppr_mono_ty _ (HsTupleTy con tys) = tupleParens std_con (interpp'SP tys) where std_con = case con of HsUnboxedTuple -> UnboxedTuple _ -> BoxedTuple ppr_mono_ty _ (HsKindSig ty kind) = parens (ppr_mono_lty TopPrec ty <+> dcolon <+> ppr kind) ppr_mono_ty _ (HsListTy ty) = brackets (ppr_mono_lty TopPrec ty) ppr_mono_ty _ (HsPArrTy ty) = paBrackets (ppr_mono_lty TopPrec ty) ppr_mono_ty prec (HsIParamTy n ty) = maybeParen prec FunPrec (ppr n <+> dcolon <+> ppr_mono_lty TopPrec ty) ppr_mono_ty _ (HsSpliceTy s _) = pprUntypedSplice s ppr_mono_ty _ (HsCoreTy ty) = ppr ty ppr_mono_ty _ (HsExplicitListTy _ tys) = quote $ brackets (interpp'SP tys) ppr_mono_ty _ (HsExplicitTupleTy _ tys) = quote $ parens (interpp'SP tys) ppr_mono_ty _ (HsTyLit t) = ppr_tylit t ppr_mono_ty _ HsWildcardTy = char '_' ppr_mono_ty _ (HsNamedWildcardTy name) = ppr name ppr_mono_ty ctxt_prec (HsWrapTy (WpKiApps _kis) ty) = ppr_mono_ty ctxt_prec ty -- We are not printing kind applications. If we wanted to do so, we should do -- something like this: {- = go ctxt_prec kis ty where go ctxt_prec [] ty = ppr_mono_ty ctxt_prec ty go ctxt_prec (ki:kis) ty = maybeParen ctxt_prec TyConPrec $ hsep [ go FunPrec kis ty , ptext (sLit "@") <> pprParendKind ki ] -} ppr_mono_ty ctxt_prec (HsEqTy ty1 ty2) = maybeParen ctxt_prec TyOpPrec $ ppr_mono_lty TyOpPrec ty1 <+> char '~' <+> ppr_mono_lty TyOpPrec ty2 ppr_mono_ty ctxt_prec (HsAppTy fun_ty arg_ty) = maybeParen ctxt_prec TyConPrec $ hsep [ppr_mono_lty FunPrec fun_ty, ppr_mono_lty TyConPrec arg_ty] ppr_mono_ty ctxt_prec (HsOpTy ty1 (_wrapper, L _ op) ty2) = maybeParen ctxt_prec TyOpPrec $ sep [ ppr_mono_lty TyOpPrec ty1 , sep [pprInfixOcc op, ppr_mono_lty TyOpPrec ty2 ] ] -- Don't print the wrapper (= kind applications) -- c.f. HsWrapTy ppr_mono_ty _ (HsParTy ty) = parens (ppr_mono_lty TopPrec 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_mono_ty ctxt_prec (HsDocTy ty doc) = maybeParen ctxt_prec TyOpPrec $ ppr_mono_lty TyOpPrec ty <+> ppr (unLoc doc) -- we pretty print Haddock comments on types as if they were -- postfix operators -------------------------- ppr_fun_ty :: (OutputableBndr name) => TyPrec -> LHsType name -> LHsType name -> SDoc ppr_fun_ty ctxt_prec ty1 ty2 = let p1 = ppr_mono_lty FunPrec ty1 p2 = ppr_mono_lty TopPrec ty2 in maybeParen ctxt_prec FunPrec $ sep [p1, ptext (sLit "->") <+> p2] -------------------------- ppr_tylit :: HsTyLit -> SDoc ppr_tylit (HsNumTy _ i) = integer i ppr_tylit (HsStrTy _ s) = text (show s)