{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 GHC.Hs.Types: Abstract syntax: user-defined types -} {-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE StandaloneDeriving #-} {-# LANGUAGE TypeSynonymInstances #-} {-# LANGUAGE UndecidableInstances #-} -- Note [Pass sensitive types] -- in module GHC.Hs.PlaceHolder {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE CPP #-} {-# LANGUAGE TypeFamilies #-} module GHC.Hs.Types ( HsType(..), NewHsTypeX(..), LHsType, HsKind, LHsKind, HsTyVarBndr(..), LHsTyVarBndr, ForallVisFlag(..), LHsQTyVars(..), HsImplicitBndrs(..), HsWildCardBndrs(..), LHsSigType, LHsSigWcType, LHsWcType, HsTupleSort(..), HsContext, LHsContext, noLHsContext, HsTyLit(..), HsIPName(..), hsIPNameFS, HsArg(..), numVisibleArgs, LHsTypeArg, LBangType, BangType, HsSrcBang(..), HsImplBang(..), SrcStrictness(..), SrcUnpackedness(..), getBangType, getBangStrictness, ConDeclField(..), LConDeclField, pprConDeclFields, HsConDetails(..), FieldOcc(..), LFieldOcc, mkFieldOcc, AmbiguousFieldOcc(..), mkAmbiguousFieldOcc, rdrNameAmbiguousFieldOcc, selectorAmbiguousFieldOcc, unambiguousFieldOcc, ambiguousFieldOcc, mkAnonWildCardTy, pprAnonWildCard, mkHsImplicitBndrs, mkHsWildCardBndrs, hsImplicitBody, mkEmptyImplicitBndrs, mkEmptyWildCardBndrs, mkHsQTvs, hsQTvExplicit, emptyLHsQTvs, isEmptyLHsQTvs, isHsKindedTyVar, hsTvbAllKinded, isLHsForAllTy, hsScopedTvs, hsWcScopedTvs, dropWildCards, hsTyVarName, hsAllLTyVarNames, hsLTyVarLocNames, hsLTyVarName, hsLTyVarNames, hsLTyVarLocName, hsExplicitLTyVarNames, splitLHsInstDeclTy, getLHsInstDeclHead, getLHsInstDeclClass_maybe, splitLHsPatSynTy, splitLHsForAllTyInvis, splitLHsQualTy, splitLHsSigmaTyInvis, splitHsFunType, hsTyGetAppHead_maybe, mkHsOpTy, mkHsAppTy, mkHsAppTys, mkHsAppKindTy, ignoreParens, hsSigType, hsSigWcType, hsLTyVarBndrToType, hsLTyVarBndrsToTypes, hsTyKindSig, hsConDetailsArgs, -- Printing pprHsType, pprHsForAll, pprHsForAllExtra, pprHsExplicitForAll, pprLHsContext, hsTypeNeedsParens, parenthesizeHsType, parenthesizeHsContext ) where #include "HsVersions.h" import GhcPrelude import {-# SOURCE #-} GHC.Hs.Expr ( HsSplice, pprSplice ) import GHC.Hs.Extension import Id ( Id ) import Name( Name, NamedThing(getName) ) import RdrName ( RdrName ) import DataCon( HsSrcBang(..), HsImplBang(..), SrcStrictness(..), SrcUnpackedness(..) ) import TysPrim( funTyConName ) import TysWiredIn( mkTupleStr ) import Type import GHC.Hs.Doc import BasicTypes import SrcLoc import Outputable import FastString import Maybes( isJust ) import Util ( count, debugIsOn ) import Data.Data hiding ( Fixity, Prefix, Infix ) {- ************************************************************************ * * \subsection{Bang annotations} * * ************************************************************************ -} -- | Located Bang Type type LBangType pass = Located (BangType pass) -- | Bang Type -- -- In the parser, strictness and packedness annotations bind more tightly -- than docstrings. This means that when consuming a 'BangType' (and looking -- for 'HsBangTy') we must be ready to peer behind a potential layer of -- 'HsDocTy'. See #15206 for motivation and 'getBangType' for an example. type BangType pass = HsType pass -- Bangs are in the HsType data type getBangType :: LHsType a -> LHsType a getBangType (L _ (HsBangTy _ _ lty)) = lty getBangType (L _ (HsDocTy x (L _ (HsBangTy _ _ lty)) lds)) = addCLoc lty lds (HsDocTy x lty lds) getBangType lty = lty getBangStrictness :: LHsType a -> HsSrcBang getBangStrictness (L _ (HsBangTy _ s _)) = s getBangStrictness (L _ (HsDocTy _ (L _ (HsBangTy _ s _)) _)) = s getBangStrictness _ = (HsSrcBang NoSourceText NoSrcUnpack NoSrcStrict) {- ************************************************************************ * * \subsection{Data types} * * ************************************************************************ This is the syntax for types as seen in type signatures. Note [HsBSig binder lists] ~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider a binder (or pattern) decorated 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 Note [HsType binders] ~~~~~~~~~~~~~~~~~~~~~ The system for recording type and kind-variable binders in HsTypes is a bit complicated. Here's how it works. * In a HsType, HsForAllTy represents an /explicit, user-written/ 'forall' e.g. forall a b. {...} or forall a b -> {...} HsQualTy represents an /explicit, user-written/ context e.g. (Eq a, Show a) => ... The context can be empty if that's what the user wrote These constructors represent what the user wrote, no more and no less. * The ForallVisFlag field of HsForAllTy represents whether a forall is invisible (e.g., forall a b. {...}, with a dot) or visible (e.g., forall a b -> {...}, with an arrow). * HsTyVarBndr describes a quantified type variable written by the user. For example f :: forall a (b :: *). blah here 'a' and '(b::*)' are each a HsTyVarBndr. A HsForAllTy has a list of LHsTyVarBndrs. * HsImplicitBndrs is a wrapper that gives the implicitly-quantified kind and type variables of the wrapped thing. It is filled in by the renamer. For example, if the user writes f :: a -> a the HsImplicitBinders binds the 'a' (not a HsForAllTy!). NB: this implicit quantification is purely lexical: we bind any type or kind variables that are not in scope. The type checker may subsequently quantify over further kind variables. * HsWildCardBndrs is a wrapper that binds the wildcard variables of the wrapped thing. It is filled in by the renamer f :: _a -> _ The enclosing HsWildCardBndrs binds the wildcards _a and _. * The explicit presence of these wrappers specifies, in the HsSyn, exactly where implicit quantification is allowed, and where wildcards are allowed. * LHsQTyVars is used in data/class declarations, where the user gives explicit *type* variable bindings, but we need to implicitly bind *kind* variables. For example class C (a :: k -> *) where ... The 'k' is implicitly bound in the hsq_tvs field of LHsQTyVars Note [The wildcard story for types] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Types can have wildcards in them, to support partial type signatures, like f :: Int -> (_ , _a) -> _a A wildcard in a type can be * An anonymous wildcard, written '_' In HsType this is represented by HsWildCardTy. The renamer leaves it untouched, and it is later given fresh meta tyvars in the typechecker. * A named wildcard, written '_a', '_foo', etc In HsType this is represented by (HsTyVar "_a") i.e. a perfectly ordinary type variable that happens to start with an underscore Note carefully: * When NamedWildCards is off, type variables that start with an underscore really /are/ ordinary type variables. And indeed, even when NamedWildCards is on you can bind _a explicitly as an ordinary type variable: data T _a _b = MkT _b _a Or even: f :: forall _a. _a -> _b Here _a is an ordinary forall'd binder, but (With NamedWildCards) _b is a named wildcard. (See the comments in #10982) * Named wildcards are bound by the HsWildCardBndrs construct, which wraps types that are allowed to have wildcards. Unnamed wildcards however are left unchanged until typechecking, where we give them fresh wild tyavrs and determine whether or not to emit hole constraints on each wildcard (we don't if it's a visible type/kind argument or a type family pattern). See related notes Note [Wildcards in visible kind application] and Note [Wildcards in visible type application] in TcHsType.hs * After type checking is done, we report what types the wildcards got unified with. Note [Ordering of implicit variables] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Since the advent of -XTypeApplications, GHC makes promises about the ordering of implicit variable quantification. Specifically, we offer that implicitly quantified variables (such as those in const :: a -> b -> a, without a `forall`) will occur in left-to-right order of first occurrence. Here are a few examples: const :: a -> b -> a -- forall a b. ... f :: Eq a => b -> a -> a -- forall a b. ... contexts are included type a <-< b = b -> a g :: a <-< b -- forall a b. ... type synonyms matter class Functor f where fmap :: (a -> b) -> f a -> f b -- forall f a b. ... -- The f is quantified by the class, so only a and b are considered in fmap This simple story is complicated by the possibility of dependency: all variables must come after any variables mentioned in their kinds. typeRep :: Typeable a => TypeRep (a :: k) -- forall k a. ... The k comes first because a depends on k, even though the k appears later than the a in the code. Thus, GHC does a *stable topological sort* on the variables. By "stable", we mean that any two variables who do not depend on each other preserve their existing left-to-right ordering. Implicitly bound variables are collected by the extract- family of functions (extractHsTysRdrTyVars, extractHsTyVarBndrsKVs, etc.) in RnTypes. These functions thus promise to keep left-to-right ordering. Look for pointers to this note to see the places where the action happens. Note that we also maintain this ordering in kind signatures. Even though there's no visible kind application (yet), having implicit variables be quantified in left-to-right order in kind signatures is nice since: * It's consistent with the treatment for type signatures. * It can affect how types are displayed with -fprint-explicit-kinds (see #15568 for an example), which is a situation where knowing the order in which implicit variables are quantified can be useful. * In the event that visible kind application is implemented, the order in which we would expect implicit variables to be ordered in kinds will have already been established. -} -- | Located Haskell Context type LHsContext pass = Located (HsContext pass) -- ^ 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnUnit' -- For details on above see note [Api annotations] in ApiAnnotation noLHsContext :: LHsContext pass -- Use this when there is no context in the original program -- It would really be more kosher to use a Maybe, to distinguish -- class () => C a where ... -- from -- class C a where ... noLHsContext = noLoc [] -- | Haskell Context type HsContext pass = [LHsType pass] -- | Located Haskell Type type LHsType pass = Located (HsType pass) -- ^ May have 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnComma' when -- in a list -- For details on above see note [Api annotations] in ApiAnnotation -- | Haskell Kind type HsKind pass = HsType pass -- | Located Haskell Kind type LHsKind pass = Located (HsKind pass) -- ^ 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnDcolon' -- For details on above see note [Api annotations] in ApiAnnotation -------------------------------------------------- -- LHsQTyVars -- The explicitly-quantified binders in a data/type declaration -- | Located Haskell Type Variable Binder type LHsTyVarBndr pass = Located (HsTyVarBndr pass) -- See Note [HsType binders] -- | Located Haskell Quantified Type Variables data LHsQTyVars pass -- See Note [HsType binders] = HsQTvs { hsq_ext :: XHsQTvs pass , hsq_explicit :: [LHsTyVarBndr pass] -- Explicit variables, written by the user -- See Note [HsForAllTy tyvar binders] } | XLHsQTyVars (XXLHsQTyVars pass) type HsQTvsRn = [Name] -- Implicit variables -- For example, in data T (a :: k1 -> k2) = ... -- the 'a' is explicit while 'k1', 'k2' are implicit type instance XHsQTvs GhcPs = NoExtField type instance XHsQTvs GhcRn = HsQTvsRn type instance XHsQTvs GhcTc = HsQTvsRn type instance XXLHsQTyVars (GhcPass _) = NoExtCon mkHsQTvs :: [LHsTyVarBndr GhcPs] -> LHsQTyVars GhcPs mkHsQTvs tvs = HsQTvs { hsq_ext = noExtField, hsq_explicit = tvs } hsQTvExplicit :: LHsQTyVars pass -> [LHsTyVarBndr pass] hsQTvExplicit = hsq_explicit emptyLHsQTvs :: LHsQTyVars GhcRn emptyLHsQTvs = HsQTvs { hsq_ext = [], hsq_explicit = [] } isEmptyLHsQTvs :: LHsQTyVars GhcRn -> Bool isEmptyLHsQTvs (HsQTvs { hsq_ext = imp, hsq_explicit = exp }) = null imp && null exp isEmptyLHsQTvs _ = False ------------------------------------------------ -- HsImplicitBndrs -- Used to quantify the implicit binders of a type -- * Implicit binders of a type signature (LHsSigType/LHsSigWcType) -- * Patterns in a type/data family instance (HsTyPats) -- | Haskell Implicit Binders data HsImplicitBndrs pass thing -- See Note [HsType binders] = HsIB { hsib_ext :: XHsIB pass thing -- after renamer: [Name] -- Implicitly-bound kind & type vars -- Order is important; see -- Note [Ordering of implicit variables] -- in RnTypes , hsib_body :: thing -- Main payload (type or list of types) } | XHsImplicitBndrs (XXHsImplicitBndrs pass thing) type instance XHsIB GhcPs _ = NoExtField type instance XHsIB GhcRn _ = [Name] type instance XHsIB GhcTc _ = [Name] type instance XXHsImplicitBndrs (GhcPass _) _ = NoExtCon -- | Haskell Wildcard Binders data HsWildCardBndrs pass thing -- See Note [HsType binders] -- See Note [The wildcard story for types] = HsWC { hswc_ext :: XHsWC pass thing -- after the renamer -- Wild cards, only named -- See Note [Wildcards in visible kind application] , hswc_body :: thing -- Main payload (type or list of types) -- If there is an extra-constraints wildcard, -- it's still there in the hsc_body. } | XHsWildCardBndrs (XXHsWildCardBndrs pass thing) type instance XHsWC GhcPs b = NoExtField type instance XHsWC GhcRn b = [Name] type instance XHsWC GhcTc b = [Name] type instance XXHsWildCardBndrs (GhcPass _) b = NoExtCon -- | Located Haskell Signature Type type LHsSigType pass = HsImplicitBndrs pass (LHsType pass) -- Implicit only -- | Located Haskell Wildcard Type type LHsWcType pass = HsWildCardBndrs pass (LHsType pass) -- Wildcard only -- | Located Haskell Signature Wildcard Type type LHsSigWcType pass = HsWildCardBndrs pass (LHsSigType pass) -- Both -- See Note [Representing type signatures] hsImplicitBody :: HsImplicitBndrs (GhcPass p) thing -> thing hsImplicitBody (HsIB { hsib_body = body }) = body hsImplicitBody (XHsImplicitBndrs nec) = noExtCon nec hsSigType :: LHsSigType (GhcPass p) -> LHsType (GhcPass p) hsSigType = hsImplicitBody hsSigWcType :: LHsSigWcType pass -> LHsType pass hsSigWcType sig_ty = hsib_body (hswc_body sig_ty) dropWildCards :: LHsSigWcType pass -> LHsSigType pass -- Drop the wildcard part of a LHsSigWcType dropWildCards sig_ty = hswc_body sig_ty {- Note [Representing type signatures] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HsSigType is used to represent an explicit user type signature such as f :: a -> a or g (x :: a -> a) = x A HsSigType is just a HsImplicitBndrs wrapping a LHsType. * The HsImplicitBndrs binds the /implicitly/ quantified tyvars * The LHsType binds the /explicitly/ quantified tyvars E.g. For a signature like f :: forall (a::k). blah we get HsIB { hsib_vars = [k] , hsib_body = HsForAllTy { hst_bndrs = [(a::*)] , hst_body = blah } The implicit kind variable 'k' is bound by the HsIB; the explicitly forall'd tyvar 'a' is bound by the HsForAllTy -} mkHsImplicitBndrs :: thing -> HsImplicitBndrs GhcPs thing mkHsImplicitBndrs x = HsIB { hsib_ext = noExtField , hsib_body = x } mkHsWildCardBndrs :: thing -> HsWildCardBndrs GhcPs thing mkHsWildCardBndrs x = HsWC { hswc_body = x , hswc_ext = noExtField } -- Add empty binders. This is a bit suspicious; what if -- the wrapped thing had free type variables? mkEmptyImplicitBndrs :: thing -> HsImplicitBndrs GhcRn thing mkEmptyImplicitBndrs x = HsIB { hsib_ext = [] , hsib_body = x } mkEmptyWildCardBndrs :: thing -> HsWildCardBndrs GhcRn thing mkEmptyWildCardBndrs x = HsWC { hswc_body = x , hswc_ext = [] } -------------------------------------------------- -- | These names are used early on to store the names of implicit -- parameters. They completely disappear after type-checking. newtype HsIPName = HsIPName FastString deriving( Eq, Data ) 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 -------------------------------------------------- -- | Haskell Type Variable Binder data HsTyVarBndr pass = UserTyVar -- no explicit kinding (XUserTyVar pass) (Located (IdP pass)) -- See Note [Located RdrNames] in GHC.Hs.Expr | KindedTyVar (XKindedTyVar pass) (Located (IdP pass)) (LHsKind pass) -- The user-supplied kind signature -- ^ -- - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen', -- 'ApiAnnotation.AnnDcolon', 'ApiAnnotation.AnnClose' -- For details on above see note [Api annotations] in ApiAnnotation | XTyVarBndr (XXTyVarBndr pass) type instance XUserTyVar (GhcPass _) = NoExtField type instance XKindedTyVar (GhcPass _) = NoExtField type instance XXTyVarBndr (GhcPass _) = NoExtCon -- | Does this 'HsTyVarBndr' come with an explicit kind annotation? isHsKindedTyVar :: HsTyVarBndr pass -> Bool isHsKindedTyVar (UserTyVar {}) = False isHsKindedTyVar (KindedTyVar {}) = True isHsKindedTyVar (XTyVarBndr {}) = False -- | Do all type variables in this 'LHsQTyVars' come with kind annotations? hsTvbAllKinded :: LHsQTyVars pass -> Bool hsTvbAllKinded = all (isHsKindedTyVar . unLoc) . hsQTvExplicit instance NamedThing (HsTyVarBndr GhcRn) where getName (UserTyVar _ v) = unLoc v getName (KindedTyVar _ v _) = unLoc v getName (XTyVarBndr nec) = noExtCon nec -- | Haskell Type data HsType pass = HsForAllTy -- See Note [HsType binders] { hst_xforall :: XForAllTy pass , hst_fvf :: ForallVisFlag -- Is this `forall a -> {...}` or -- `forall a. {...}`? , hst_bndrs :: [LHsTyVarBndr pass] -- Explicit, user-supplied 'forall a b c' , hst_body :: LHsType pass -- body type } -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnForall', -- 'ApiAnnotation.AnnDot','ApiAnnotation.AnnDarrow' -- For details on above see note [Api annotations] in ApiAnnotation | HsQualTy -- See Note [HsType binders] { hst_xqual :: XQualTy pass , hst_ctxt :: LHsContext pass -- Context C => blah , hst_body :: LHsType pass } | HsTyVar (XTyVar pass) PromotionFlag -- Whether explicitly promoted, -- for the pretty printer (Located (IdP pass)) -- Type variable, type constructor, or data constructor -- see Note [Promotions (HsTyVar)] -- See Note [Located RdrNames] in GHC.Hs.Expr -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsAppTy (XAppTy pass) (LHsType pass) (LHsType pass) -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsAppKindTy (XAppKindTy pass) -- type level type app (LHsType pass) (LHsKind pass) | HsFunTy (XFunTy pass) (LHsType pass) -- function type (LHsType pass) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnRarrow', -- For details on above see note [Api annotations] in ApiAnnotation | HsListTy (XListTy pass) (LHsType pass) -- Element type -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'['@, -- 'ApiAnnotation.AnnClose' @']'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsTupleTy (XTupleTy pass) HsTupleSort [LHsType pass] -- Element types (length gives arity) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'(' or '(#'@, -- 'ApiAnnotation.AnnClose' @')' or '#)'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsSumTy (XSumTy pass) [LHsType pass] -- Element types (length gives arity) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'(#'@, -- 'ApiAnnotation.AnnClose' '#)'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsOpTy (XOpTy pass) (LHsType pass) (Located (IdP pass)) (LHsType pass) -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsParTy (XParTy pass) (LHsType pass) -- See Note [Parens in HsSyn] in GHC.Hs.Expr -- 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 (XIParamTy pass) (Located HsIPName) -- (?x :: ty) (LHsType pass) -- Implicit parameters as they occur in -- contexts -- ^ -- > (?x :: ty) -- -- - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnDcolon' -- For details on above see note [Api annotations] in ApiAnnotation | HsStarTy (XStarTy pass) Bool -- Is this the Unicode variant? -- Note [HsStarTy] -- ^ - 'ApiAnnotation.AnnKeywordId' : None | HsKindSig (XKindSig pass) (LHsType pass) -- (ty :: kind) (LHsKind pass) -- 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 | HsSpliceTy (XSpliceTy pass) (HsSplice pass) -- Includes quasi-quotes -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'$('@, -- 'ApiAnnotation.AnnClose' @')'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsDocTy (XDocTy pass) (LHsType pass) LHsDocString -- A documented type -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsBangTy (XBangTy pass) HsSrcBang (LHsType pass) -- 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 (XRecTy pass) [LConDeclField pass] -- Only in data type declarations -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'{'@, -- 'ApiAnnotation.AnnClose' @'}'@ -- For details on above see note [Api annotations] in ApiAnnotation -- | HsCoreTy (XCoreTy pass) 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 (XExplicitListTy pass) PromotionFlag -- whether explcitly promoted, for pretty printer [LHsType pass] -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @"'["@, -- 'ApiAnnotation.AnnClose' @']'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsExplicitTupleTy -- A promoted explicit tuple (XExplicitTupleTy pass) [LHsType pass] -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @"'("@, -- 'ApiAnnotation.AnnClose' @')'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsTyLit (XTyLit pass) HsTyLit -- A promoted numeric literal. -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsWildCardTy (XWildCardTy pass) -- A type wildcard -- See Note [The wildcard story for types] -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation -- For adding new constructors via Trees that Grow | XHsType (XXType pass) data NewHsTypeX = NHsCoreTy Type -- An escape hatch for tunnelling a *closed* -- Core Type through HsSyn. deriving Data -- ^ - 'ApiAnnotation.AnnKeywordId' : None instance Outputable NewHsTypeX where ppr (NHsCoreTy ty) = ppr ty type instance XForAllTy (GhcPass _) = NoExtField type instance XQualTy (GhcPass _) = NoExtField type instance XTyVar (GhcPass _) = NoExtField type instance XAppTy (GhcPass _) = NoExtField type instance XFunTy (GhcPass _) = NoExtField type instance XListTy (GhcPass _) = NoExtField type instance XTupleTy (GhcPass _) = NoExtField type instance XSumTy (GhcPass _) = NoExtField type instance XOpTy (GhcPass _) = NoExtField type instance XParTy (GhcPass _) = NoExtField type instance XIParamTy (GhcPass _) = NoExtField type instance XStarTy (GhcPass _) = NoExtField type instance XKindSig (GhcPass _) = NoExtField type instance XAppKindTy (GhcPass _) = SrcSpan -- Where the `@` lives type instance XSpliceTy GhcPs = NoExtField type instance XSpliceTy GhcRn = NoExtField type instance XSpliceTy GhcTc = Kind type instance XDocTy (GhcPass _) = NoExtField type instance XBangTy (GhcPass _) = NoExtField type instance XRecTy (GhcPass _) = NoExtField type instance XExplicitListTy GhcPs = NoExtField type instance XExplicitListTy GhcRn = NoExtField type instance XExplicitListTy GhcTc = Kind type instance XExplicitTupleTy GhcPs = NoExtField type instance XExplicitTupleTy GhcRn = NoExtField type instance XExplicitTupleTy GhcTc = [Kind] type instance XTyLit (GhcPass _) = NoExtField type instance XWildCardTy (GhcPass _) = NoExtField type instance XXType (GhcPass _) = NewHsTypeX -- Note [Literal source text] in BasicTypes for SourceText fields in -- the following -- | Haskell Type Literal data HsTyLit = HsNumTy SourceText Integer | HsStrTy SourceText FastString deriving Data {- 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] in RnTypes, and #4426. In GHC 8.0, Qualified will no longer bind variables and this will become an error. The kind variables bound in the hsq_implicit 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 The 'Promoted' field in an HsTyVar captures whether the type was promoted in the source code by prefixing an apostrophe. Note [HsStarTy] ~~~~~~~~~~~~~~~ When the StarIsType extension is enabled, we want to treat '*' and its Unicode variant identically to 'Data.Kind.Type'. Unfortunately, doing so in the parser would mean that when we pretty-print it back, we don't know whether the user wrote '*' or 'Type', and lose the parse/ppr roundtrip property. As a workaround, we parse '*' as HsStarTy (if it stands for 'Data.Kind.Type') and then desugar it to 'Data.Kind.Type' in the typechecker (see tc_hs_type). When '*' is a regular type operator (StarIsType is disabled), HsStarTy is not involved. 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 -} -- | Haskell Tuple Sort data HsTupleSort = HsUnboxedTuple | HsBoxedTuple | HsConstraintTuple | HsBoxedOrConstraintTuple deriving Data -- | Located Constructor Declaration Field type LConDeclField pass = Located (ConDeclField pass) -- ^ May have 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnComma' when -- in a list -- For details on above see note [Api annotations] in ApiAnnotation -- | Constructor Declaration Field data ConDeclField pass -- Record fields have Haddoc docs on them = ConDeclField { cd_fld_ext :: XConDeclField pass, cd_fld_names :: [LFieldOcc pass], -- ^ See Note [ConDeclField passs] cd_fld_type :: LBangType pass, cd_fld_doc :: Maybe LHsDocString } -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnDcolon' -- For details on above see note [Api annotations] in ApiAnnotation | XConDeclField (XXConDeclField pass) type instance XConDeclField (GhcPass _) = NoExtField type instance XXConDeclField (GhcPass _) = NoExtCon instance OutputableBndrId p => Outputable (ConDeclField (GhcPass p)) where ppr (ConDeclField _ fld_n fld_ty _) = ppr fld_n <+> dcolon <+> ppr fld_ty ppr (XConDeclField x) = ppr x -- HsConDetails is used for patterns/expressions *and* for data type -- declarations -- | Haskell Constructor Details data HsConDetails arg rec = PrefixCon [arg] -- C p1 p2 p3 | RecCon rec -- C { x = p1, y = p2 } | InfixCon arg arg -- p1 `C` p2 deriving Data instance (Outputable arg, Outputable rec) => Outputable (HsConDetails arg rec) where ppr (PrefixCon args) = text "PrefixCon" <+> ppr args ppr (RecCon rec) = text "RecCon:" <+> ppr rec ppr (InfixCon l r) = text "InfixCon:" <+> ppr [l, r] hsConDetailsArgs :: HsConDetails (LHsType a) (Located [LConDeclField a]) -> [LHsType a] hsConDetailsArgs details = case details of InfixCon a b -> [a,b] PrefixCon xs -> xs RecCon r -> map (cd_fld_type . unLoc) (unLoc r) {- Note [ConDeclField passs] ~~~~~~~~~~~~~~~~~~~~~~~~~ A ConDeclField contains a list of field occurrences: these always include the field label as the user wrote it. After the renamer, it will additionally contain the identity of the selector function in the second component. Due to DuplicateRecordFields, the OccName of the selector function may have been mangled, which is why we keep the original field label separately. For example, when DuplicateRecordFields is enabled data T = MkT { x :: Int } gives ConDeclField { cd_fld_names = [L _ (FieldOcc "x" $sel:x:MkT)], ... }. -} ----------------------- -- A valid type must have a for-all at the top of the type, or of the fn arg -- types --------------------- hsWcScopedTvs :: LHsSigWcType GhcRn -> [Name] -- Get the lexically-scoped type variables of a HsSigType -- - the explicitly-given forall'd type variables -- - the named wildcars; see Note [Scoping of named wildcards] -- because they scope in the same way hsWcScopedTvs sig_ty | HsWC { hswc_ext = nwcs, hswc_body = sig_ty1 } <- sig_ty , HsIB { hsib_ext = vars , hsib_body = sig_ty2 } <- sig_ty1 = case sig_ty2 of L _ (HsForAllTy { hst_fvf = vis_flag , hst_bndrs = tvs }) -> ASSERT( vis_flag == ForallInvis ) -- See Note [hsScopedTvs vis_flag] vars ++ nwcs ++ hsLTyVarNames tvs _ -> nwcs hsWcScopedTvs (HsWC _ (XHsImplicitBndrs nec)) = noExtCon nec hsWcScopedTvs (XHsWildCardBndrs nec) = noExtCon nec hsScopedTvs :: LHsSigType GhcRn -> [Name] -- Same as hsWcScopedTvs, but for a LHsSigType hsScopedTvs sig_ty | HsIB { hsib_ext = vars , hsib_body = sig_ty2 } <- sig_ty , L _ (HsForAllTy { hst_fvf = vis_flag , hst_bndrs = tvs }) <- sig_ty2 = ASSERT( vis_flag == ForallInvis ) -- See Note [hsScopedTvs vis_flag] vars ++ hsLTyVarNames tvs | otherwise = [] {- Note [Scoping of named wildcards] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider f :: _a -> _a f x = let g :: _a -> _a g = ... in ... Currently, for better or worse, the "_a" variables are all the same. So although there is no explicit forall, the "_a" scopes over the definition. I don't know if this is a good idea, but there it is. -} {- Note [hsScopedTvs vis_flag] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -XScopedTypeVariables can be defined in terms of a desugaring to -XTypeAbstractions (GHC Proposal #50): fn :: forall a b c. tau(a,b,c) fn :: forall a b c. tau(a,b,c) fn = defn(a,b,c) ==> fn @x @y @z = defn(x,y,z) That is, for every type variable of the leading 'forall' in the type signature, we add an invisible binder at term level. This model does not extend to visible forall, as discussed here: * https://gitlab.haskell.org/ghc/ghc/issues/16734#note_203412 * https://github.com/ghc-proposals/ghc-proposals/pull/238 The conclusion of these discussions can be summarized as follows: > Assuming support for visible 'forall' in terms, consider this example: > > vfn :: forall x y -> tau(x,y) > vfn = \a b -> ... > > The user has written their own binders 'a' and 'b' to stand for 'x' and > 'y', and we definitely should not desugar this into: > > vfn :: forall x y -> tau(x,y) > vfn x y = \a b -> ... -- bad! At the moment, GHC does not support visible 'forall' in terms, so we simply cement our assumptions with an assert: hsScopedTvs (HsForAllTy { hst_fvf = vis_flag, ... }) = ASSERT( vis_flag == ForallInvis ) ... In the future, this assert can be safely turned into a pattern match to support visible forall in terms: hsScopedTvs (HsForAllTy { hst_fvf = ForallInvis, ... }) = ... -} --------------------- hsTyVarName :: HsTyVarBndr (GhcPass p) -> IdP (GhcPass p) hsTyVarName (UserTyVar _ (L _ n)) = n hsTyVarName (KindedTyVar _ (L _ n) _) = n hsTyVarName (XTyVarBndr nec) = noExtCon nec hsLTyVarName :: LHsTyVarBndr (GhcPass p) -> IdP (GhcPass p) hsLTyVarName = hsTyVarName . unLoc hsLTyVarNames :: [LHsTyVarBndr (GhcPass p)] -> [IdP (GhcPass p)] hsLTyVarNames = map hsLTyVarName hsExplicitLTyVarNames :: LHsQTyVars (GhcPass p) -> [IdP (GhcPass p)] -- Explicit variables only hsExplicitLTyVarNames qtvs = map hsLTyVarName (hsQTvExplicit qtvs) hsAllLTyVarNames :: LHsQTyVars GhcRn -> [Name] -- All variables hsAllLTyVarNames (HsQTvs { hsq_ext = kvs , hsq_explicit = tvs }) = kvs ++ hsLTyVarNames tvs hsAllLTyVarNames (XLHsQTyVars nec) = noExtCon nec hsLTyVarLocName :: LHsTyVarBndr (GhcPass p) -> Located (IdP (GhcPass p)) hsLTyVarLocName = onHasSrcSpan hsTyVarName hsLTyVarLocNames :: LHsQTyVars (GhcPass p) -> [Located (IdP (GhcPass p))] hsLTyVarLocNames qtvs = map hsLTyVarLocName (hsQTvExplicit qtvs) -- | Convert a LHsTyVarBndr to an equivalent LHsType. hsLTyVarBndrToType :: LHsTyVarBndr (GhcPass p) -> LHsType (GhcPass p) hsLTyVarBndrToType = onHasSrcSpan cvt where cvt (UserTyVar _ n) = HsTyVar noExtField NotPromoted n cvt (KindedTyVar _ (L name_loc n) kind) = HsKindSig noExtField (L name_loc (HsTyVar noExtField NotPromoted (L name_loc n))) kind cvt (XTyVarBndr nec) = noExtCon nec -- | Convert a LHsTyVarBndrs to a list of types. -- Works on *type* variable only, no kind vars. hsLTyVarBndrsToTypes :: LHsQTyVars (GhcPass p) -> [LHsType (GhcPass p)] hsLTyVarBndrsToTypes (HsQTvs { hsq_explicit = tvbs }) = map hsLTyVarBndrToType tvbs hsLTyVarBndrsToTypes (XLHsQTyVars nec) = noExtCon nec -- | Get the kind signature of a type, ignoring parentheses: -- -- hsTyKindSig `Maybe ` = Nothing -- hsTyKindSig `Maybe :: Type -> Type ` = Just `Type -> Type` -- hsTyKindSig `Maybe :: ((Type -> Type))` = Just `Type -> Type` -- -- This is used to extract the result kind of type synonyms with a CUSK: -- -- type S = (F :: res_kind) -- ^^^^^^^^ -- hsTyKindSig :: LHsType pass -> Maybe (LHsKind pass) hsTyKindSig lty = case unLoc lty of HsParTy _ lty' -> hsTyKindSig lty' HsKindSig _ _ k -> Just k _ -> Nothing --------------------- ignoreParens :: LHsType pass -> LHsType pass ignoreParens (L _ (HsParTy _ ty)) = ignoreParens ty ignoreParens ty = ty isLHsForAllTy :: LHsType p -> Bool isLHsForAllTy (L _ (HsForAllTy {})) = True isLHsForAllTy _ = False {- ************************************************************************ * * Building types * * ************************************************************************ -} mkAnonWildCardTy :: HsType GhcPs mkAnonWildCardTy = HsWildCardTy noExtField mkHsOpTy :: LHsType (GhcPass p) -> Located (IdP (GhcPass p)) -> LHsType (GhcPass p) -> HsType (GhcPass p) mkHsOpTy ty1 op ty2 = HsOpTy noExtField ty1 op ty2 mkHsAppTy :: LHsType (GhcPass p) -> LHsType (GhcPass p) -> LHsType (GhcPass p) mkHsAppTy t1 t2 = addCLoc t1 t2 (HsAppTy noExtField t1 (parenthesizeHsType appPrec t2)) mkHsAppTys :: LHsType (GhcPass p) -> [LHsType (GhcPass p)] -> LHsType (GhcPass p) mkHsAppTys = foldl' mkHsAppTy mkHsAppKindTy :: XAppKindTy (GhcPass p) -> LHsType (GhcPass p) -> LHsType (GhcPass p) -> LHsType (GhcPass p) mkHsAppKindTy ext ty k = addCLoc ty k (HsAppKindTy ext ty k) {- ************************************************************************ * * Decomposing HsTypes * * ************************************************************************ -} --------------------------------- -- 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 #9096) splitHsFunType :: LHsType GhcRn -> ([LHsType GhcRn], LHsType GhcRn) splitHsFunType (L _ (HsParTy _ ty)) = splitHsFunType ty splitHsFunType (L _ (HsFunTy _ x y)) | (args, res) <- splitHsFunType y = (x:args, res) {- This is not so correct, because it won't work with visible kind app, in case someone wants to write '(->) @k1 @k2 t1 t2'. Fixing this would require changing ConDeclGADT abstract syntax -} splitHsFunType orig_ty@(L _ (HsAppTy _ t1 t2)) = go t1 [t2] where -- Look for (->) t1 t2, possibly with parenthesisation go (L _ (HsTyVar _ _ (L _ 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) -- 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 (GhcPass p) -> Maybe (Located (IdP (GhcPass p))) hsTyGetAppHead_maybe = go where go (L _ (HsTyVar _ _ ln)) = Just ln go (L _ (HsAppTy _ l _)) = go l go (L _ (HsAppKindTy _ t _)) = go t go (L _ (HsOpTy _ _ (L loc n) _)) = Just (L loc n) go (L _ (HsParTy _ t)) = go t go (L _ (HsKindSig _ t _)) = go t go _ = Nothing ------------------------------------------------------------ -- Arguments in an expression/type after splitting data HsArg tm ty = HsValArg tm -- Argument is an ordinary expression (f arg) | HsTypeArg SrcSpan ty -- Argument is a visible type application (f @ty) -- SrcSpan is location of the `@` | HsArgPar SrcSpan -- See Note [HsArgPar] numVisibleArgs :: [HsArg tm ty] -> Arity numVisibleArgs = count is_vis where is_vis (HsValArg _) = True is_vis _ = False -- type level equivalent type LHsTypeArg p = HsArg (LHsType p) (LHsKind p) instance (Outputable tm, Outputable ty) => Outputable (HsArg tm ty) where ppr (HsValArg tm) = ppr tm ppr (HsTypeArg _ ty) = char '@' <> ppr ty ppr (HsArgPar sp) = text "HsArgPar" <+> ppr sp {- Note [HsArgPar] A HsArgPar indicates that everything to the left of this in the argument list is enclosed in parentheses together with the function itself. It is necessary so that we can recreate the parenthesis structure in the original source after typechecking the arguments. The SrcSpan is the span of the original HsPar ((f arg1) arg2 arg3) results in an input argument list of [HsValArg arg1, HsArgPar span1, HsValArg arg2, HsValArg arg3, HsArgPar span2] -} -------------------------------- -- | Decompose a pattern synonym type signature into its constituent parts. -- -- Note that this function looks through parentheses, so it will work on types -- such as @(forall a. <...>)@. The downside to this is that it is not -- generally possible to take the returned types and reconstruct the original -- type (parentheses and all) from them. splitLHsPatSynTy :: LHsType pass -> ( [LHsTyVarBndr pass] -- universals , LHsContext pass -- required constraints , [LHsTyVarBndr pass] -- existentials , LHsContext pass -- provided constraints , LHsType pass) -- body type splitLHsPatSynTy ty = (univs, reqs, exis, provs, ty4) where (univs, ty1) = splitLHsForAllTyInvis ty (reqs, ty2) = splitLHsQualTy ty1 (exis, ty3) = splitLHsForAllTyInvis ty2 (provs, ty4) = splitLHsQualTy ty3 -- | Decompose a sigma type (of the form @forall <tvs>. context => body@) -- into its constituent parts. Note that only /invisible/ @forall@s -- (i.e., @forall a.@, with a dot) are split apart; /visible/ @forall@s -- (i.e., @forall a ->@, with an arrow) are left untouched. -- -- This function is used to split apart certain types, such as instance -- declaration types, which disallow visible @forall@s. For instance, if GHC -- split apart the @forall@ in @instance forall a -> Show (Blah a)@, then that -- declaration would mistakenly be accepted! -- -- Note that this function looks through parentheses, so it will work on types -- such as @(forall a. <...>)@. The downside to this is that it is not -- generally possible to take the returned types and reconstruct the original -- type (parentheses and all) from them. splitLHsSigmaTyInvis :: LHsType pass -> ([LHsTyVarBndr pass], LHsContext pass, LHsType pass) splitLHsSigmaTyInvis ty | (tvs, ty1) <- splitLHsForAllTyInvis ty , (ctxt, ty2) <- splitLHsQualTy ty1 = (tvs, ctxt, ty2) -- | Decompose a type of the form @forall <tvs>. body@ into its constituent -- parts. Note that only /invisible/ @forall@s -- (i.e., @forall a.@, with a dot) are split apart; /visible/ @forall@s -- (i.e., @forall a ->@, with an arrow) are left untouched. -- -- This function is used to split apart certain types, such as instance -- declaration types, which disallow visible @forall@s. For instance, if GHC -- split apart the @forall@ in @instance forall a -> Show (Blah a)@, then that -- declaration would mistakenly be accepted! -- -- Note that this function looks through parentheses, so it will work on types -- such as @(forall a. <...>)@. The downside to this is that it is not -- generally possible to take the returned types and reconstruct the original -- type (parentheses and all) from them. splitLHsForAllTyInvis :: LHsType pass -> ([LHsTyVarBndr pass], LHsType pass) splitLHsForAllTyInvis lty@(L _ ty) = case ty of HsParTy _ ty' -> splitLHsForAllTyInvis ty' HsForAllTy { hst_fvf = fvf', hst_bndrs = tvs', hst_body = body' } | fvf' == ForallInvis -> (tvs', body') _ -> ([], lty) -- | Decompose a type of the form @context => body@ into its constituent parts. -- -- Note that this function looks through parentheses, so it will work on types -- such as @(context => <...>)@. The downside to this is that it is not -- generally possible to take the returned types and reconstruct the original -- type (parentheses and all) from them. splitLHsQualTy :: LHsType pass -> (LHsContext pass, LHsType pass) splitLHsQualTy (L _ (HsParTy _ ty)) = splitLHsQualTy ty splitLHsQualTy (L _ (HsQualTy { hst_ctxt = ctxt, hst_body = body })) = (ctxt, body) splitLHsQualTy body = (noLHsContext, body) -- | Decompose a type class instance type (of the form -- @forall <tvs>. context => instance_head@) into its constituent parts. -- -- Note that this function looks through parentheses, so it will work on types -- such as @(forall <tvs>. <...>)@. The downside to this is that it is not -- generally possible to take the returned types and reconstruct the original -- type (parentheses and all) from them. splitLHsInstDeclTy :: LHsSigType GhcRn -> ([Name], LHsContext GhcRn, LHsType GhcRn) -- Split up an instance decl type, returning the pieces splitLHsInstDeclTy (HsIB { hsib_ext = itkvs , hsib_body = inst_ty }) | (tvs, cxt, body_ty) <- splitLHsSigmaTyInvis inst_ty = (itkvs ++ hsLTyVarNames tvs, cxt, body_ty) -- Return implicitly bound type and kind vars -- For an instance decl, all of them are in scope splitLHsInstDeclTy (XHsImplicitBndrs nec) = noExtCon nec getLHsInstDeclHead :: LHsSigType (GhcPass p) -> LHsType (GhcPass p) getLHsInstDeclHead inst_ty | (_tvs, _cxt, body_ty) <- splitLHsSigmaTyInvis (hsSigType inst_ty) = body_ty getLHsInstDeclClass_maybe :: LHsSigType (GhcPass p) -> Maybe (Located (IdP (GhcPass p))) -- Works on (HsSigType RdrName) getLHsInstDeclClass_maybe inst_ty = do { let head_ty = getLHsInstDeclHead inst_ty ; cls <- hsTyGetAppHead_maybe head_ty ; return cls } {- ************************************************************************ * * FieldOcc * * ************************************************************************ -} -- | Located Field Occurrence type LFieldOcc pass = Located (FieldOcc pass) -- | Field Occurrence -- -- Represents an *occurrence* of an unambiguous field. We store -- both the 'RdrName' the user originally wrote, and after the -- renamer, the selector function. data FieldOcc pass = FieldOcc { extFieldOcc :: XCFieldOcc pass , rdrNameFieldOcc :: Located RdrName -- ^ See Note [Located RdrNames] in GHC.Hs.Expr } | XFieldOcc (XXFieldOcc pass) deriving instance Eq (XCFieldOcc (GhcPass p)) => Eq (FieldOcc (GhcPass p)) deriving instance Ord (XCFieldOcc (GhcPass p)) => Ord (FieldOcc (GhcPass p)) type instance XCFieldOcc GhcPs = NoExtField type instance XCFieldOcc GhcRn = Name type instance XCFieldOcc GhcTc = Id type instance XXFieldOcc (GhcPass _) = NoExtCon instance Outputable (FieldOcc pass) where ppr = ppr . rdrNameFieldOcc mkFieldOcc :: Located RdrName -> FieldOcc GhcPs mkFieldOcc rdr = FieldOcc noExtField rdr -- | Ambiguous Field Occurrence -- -- Represents an *occurrence* of a field that is potentially -- ambiguous after the renamer, with the ambiguity resolved by the -- typechecker. We always store the 'RdrName' that the user -- originally wrote, and store the selector function after the renamer -- (for unambiguous occurrences) or the typechecker (for ambiguous -- occurrences). -- -- See Note [HsRecField and HsRecUpdField] in GHC.Hs.Pat and -- Note [Disambiguating record fields] in TcExpr. -- See Note [Located RdrNames] in GHC.Hs.Expr data AmbiguousFieldOcc pass = Unambiguous (XUnambiguous pass) (Located RdrName) | Ambiguous (XAmbiguous pass) (Located RdrName) | XAmbiguousFieldOcc (XXAmbiguousFieldOcc pass) type instance XUnambiguous GhcPs = NoExtField type instance XUnambiguous GhcRn = Name type instance XUnambiguous GhcTc = Id type instance XAmbiguous GhcPs = NoExtField type instance XAmbiguous GhcRn = NoExtField type instance XAmbiguous GhcTc = Id type instance XXAmbiguousFieldOcc (GhcPass _) = NoExtCon instance Outputable (AmbiguousFieldOcc (GhcPass p)) where ppr = ppr . rdrNameAmbiguousFieldOcc instance OutputableBndr (AmbiguousFieldOcc (GhcPass p)) where pprInfixOcc = pprInfixOcc . rdrNameAmbiguousFieldOcc pprPrefixOcc = pprPrefixOcc . rdrNameAmbiguousFieldOcc mkAmbiguousFieldOcc :: Located RdrName -> AmbiguousFieldOcc GhcPs mkAmbiguousFieldOcc rdr = Unambiguous noExtField rdr rdrNameAmbiguousFieldOcc :: AmbiguousFieldOcc (GhcPass p) -> RdrName rdrNameAmbiguousFieldOcc (Unambiguous _ (L _ rdr)) = rdr rdrNameAmbiguousFieldOcc (Ambiguous _ (L _ rdr)) = rdr rdrNameAmbiguousFieldOcc (XAmbiguousFieldOcc nec) = noExtCon nec selectorAmbiguousFieldOcc :: AmbiguousFieldOcc GhcTc -> Id selectorAmbiguousFieldOcc (Unambiguous sel _) = sel selectorAmbiguousFieldOcc (Ambiguous sel _) = sel selectorAmbiguousFieldOcc (XAmbiguousFieldOcc nec) = noExtCon nec unambiguousFieldOcc :: AmbiguousFieldOcc GhcTc -> FieldOcc GhcTc unambiguousFieldOcc (Unambiguous rdr sel) = FieldOcc rdr sel unambiguousFieldOcc (Ambiguous rdr sel) = FieldOcc rdr sel unambiguousFieldOcc (XAmbiguousFieldOcc nec) = noExtCon nec ambiguousFieldOcc :: FieldOcc GhcTc -> AmbiguousFieldOcc GhcTc ambiguousFieldOcc (FieldOcc sel rdr) = Unambiguous sel rdr ambiguousFieldOcc (XFieldOcc nec) = noExtCon nec {- ************************************************************************ * * \subsection{Pretty printing} * * ************************************************************************ -} instance OutputableBndrId p => Outputable (HsType (GhcPass p)) where ppr ty = pprHsType ty instance Outputable HsTyLit where ppr = ppr_tylit instance OutputableBndrId p => Outputable (LHsQTyVars (GhcPass p)) where ppr (HsQTvs { hsq_explicit = tvs }) = interppSP tvs ppr (XLHsQTyVars x) = ppr x instance OutputableBndrId p => Outputable (HsTyVarBndr (GhcPass p)) where ppr (UserTyVar _ n) = ppr n ppr (KindedTyVar _ n k) = parens $ hsep [ppr n, dcolon, ppr k] ppr (XTyVarBndr nec) = noExtCon nec instance Outputable thing => Outputable (HsImplicitBndrs (GhcPass p) thing) where ppr (HsIB { hsib_body = ty }) = ppr ty ppr (XHsImplicitBndrs x) = ppr x instance Outputable thing => Outputable (HsWildCardBndrs (GhcPass p) thing) where ppr (HsWC { hswc_body = ty }) = ppr ty ppr (XHsWildCardBndrs x) = ppr x pprAnonWildCard :: SDoc pprAnonWildCard = char '_' -- | Prints a forall; When passed an empty list, prints @forall .@/@forall ->@ -- only when @-dppr-debug@ is enabled. pprHsForAll :: (OutputableBndrId p) => ForallVisFlag -> [LHsTyVarBndr (GhcPass p)] -> LHsContext (GhcPass p) -> SDoc pprHsForAll = pprHsForAllExtra 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 :: (OutputableBndrId p) => Maybe SrcSpan -> ForallVisFlag -> [LHsTyVarBndr (GhcPass p)] -> LHsContext (GhcPass p) -> SDoc pprHsForAllExtra extra fvf qtvs cxt = pp_forall <+> pprLHsContextExtra (isJust extra) cxt where pp_forall | null qtvs = whenPprDebug (forAllLit <> separator) | otherwise = forAllLit <+> interppSP qtvs <> separator separator = ppr_forall_separator fvf -- | Version of 'pprHsForAll' or 'pprHsForAllExtra' that will always print -- @forall.@ when passed @Just []@. Prints nothing if passed 'Nothing' pprHsExplicitForAll :: (OutputableBndrId p) => ForallVisFlag -> Maybe [LHsTyVarBndr (GhcPass p)] -> SDoc pprHsExplicitForAll fvf (Just qtvs) = forAllLit <+> interppSP qtvs <> ppr_forall_separator fvf pprHsExplicitForAll _ Nothing = empty -- | Prints an arrow for visible @forall@s (e.g., @forall a ->@) and a dot for -- invisible @forall@s (e.g., @forall a.@). ppr_forall_separator :: ForallVisFlag -> SDoc ppr_forall_separator ForallVis = space <> arrow ppr_forall_separator ForallInvis = dot pprLHsContext :: (OutputableBndrId p) => LHsContext (GhcPass p) -> SDoc pprLHsContext lctxt | null (unLoc lctxt) = empty | otherwise = pprLHsContextAlways lctxt -- For use in a HsQualTy, which always gets printed if it exists. pprLHsContextAlways :: (OutputableBndrId p) => LHsContext (GhcPass p) -> SDoc pprLHsContextAlways (L _ ctxt) = case ctxt of [] -> parens empty <+> darrow [L _ ty] -> ppr_mono_ty ty <+> darrow _ -> parens (interpp'SP ctxt) <+> darrow -- True <=> print an extra-constraints wildcard, e.g. @(Show a, _) =>@ pprLHsContextExtra :: (OutputableBndrId p) => Bool -> LHsContext (GhcPass p) -> SDoc pprLHsContextExtra show_extra lctxt@(L _ ctxt) | not show_extra = pprLHsContext lctxt | null ctxt = char '_' <+> darrow | otherwise = parens (sep (punctuate comma ctxt')) <+> darrow where ctxt' = map ppr ctxt ++ [char '_'] pprConDeclFields :: (OutputableBndrId p) => [LConDeclField (GhcPass p)] -> 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_fld (L _ (XConDeclField x)) = ppr x ppr_names [n] = ppr n ppr_names ns = sep (punctuate comma (map ppr ns)) {- Note [Printing KindedTyVars] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #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 :: (OutputableBndrId p) => HsType (GhcPass p) -> SDoc pprHsType ty = ppr_mono_ty ty ppr_mono_lty :: (OutputableBndrId p) => LHsType (GhcPass p) -> SDoc ppr_mono_lty ty = ppr_mono_ty (unLoc ty) ppr_mono_ty :: (OutputableBndrId p) => HsType (GhcPass p) -> SDoc ppr_mono_ty (HsForAllTy { hst_fvf = fvf, hst_bndrs = tvs, hst_body = ty }) = sep [pprHsForAll fvf tvs noLHsContext, ppr_mono_lty ty] ppr_mono_ty (HsQualTy { hst_ctxt = ctxt, hst_body = ty }) = sep [pprLHsContextAlways ctxt, ppr_mono_lty ty] ppr_mono_ty (HsBangTy _ b ty) = ppr b <> ppr_mono_lty ty ppr_mono_ty (HsRecTy _ flds) = pprConDeclFields flds ppr_mono_ty (HsTyVar _ prom (L _ name)) | isPromoted prom = quote (pprPrefixOcc name) | otherwise = pprPrefixOcc name ppr_mono_ty (HsFunTy _ ty1 ty2) = ppr_fun_ty ty1 ty2 ppr_mono_ty (HsTupleTy _ con tys) -- Special-case unary boxed tuples so that they are pretty-printed as -- `Unit x`, not `(x)` | [ty] <- tys , BoxedTuple <- std_con = sep [text (mkTupleStr Boxed 1), ppr_mono_lty ty] | otherwise = tupleParens std_con (pprWithCommas ppr tys) where std_con = case con of HsUnboxedTuple -> UnboxedTuple _ -> BoxedTuple ppr_mono_ty (HsSumTy _ tys) = tupleParens UnboxedTuple (pprWithBars ppr tys) ppr_mono_ty (HsKindSig _ ty kind) = ppr_mono_lty ty <+> dcolon <+> ppr kind ppr_mono_ty (HsListTy _ ty) = brackets (ppr_mono_lty ty) ppr_mono_ty (HsIParamTy _ n ty) = (ppr n <+> dcolon <+> ppr_mono_lty ty) ppr_mono_ty (HsSpliceTy _ s) = pprSplice s ppr_mono_ty (HsExplicitListTy _ prom tys) | isPromoted prom = quote $ brackets (maybeAddSpace tys $ interpp'SP tys) | otherwise = brackets (interpp'SP tys) ppr_mono_ty (HsExplicitTupleTy _ tys) -- Special-case unary boxed tuples so that they are pretty-printed as -- `'Unit x`, not `'(x)` | [ty] <- tys = quote $ sep [text (mkTupleStr Boxed 1), ppr_mono_lty ty] | otherwise = quote $ parens (maybeAddSpace tys $ interpp'SP tys) ppr_mono_ty (HsTyLit _ t) = ppr_tylit t ppr_mono_ty (HsWildCardTy {}) = char '_' ppr_mono_ty (HsStarTy _ isUni) = char (if isUni then '★' else '*') ppr_mono_ty (HsAppTy _ fun_ty arg_ty) = hsep [ppr_mono_lty fun_ty, ppr_mono_lty arg_ty] ppr_mono_ty (HsAppKindTy _ ty k) = ppr_mono_lty ty <+> char '@' <> ppr_mono_lty k ppr_mono_ty (HsOpTy _ ty1 (L _ op) ty2) = sep [ ppr_mono_lty ty1 , sep [pprInfixOcc op, ppr_mono_lty ty2 ] ] ppr_mono_ty (HsParTy _ ty) = parens (ppr_mono_lty 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 (HsDocTy _ ty doc) -- AZ: Should we add parens? Should we introduce "-- ^"? = ppr_mono_lty ty <+> ppr (unLoc doc) -- we pretty print Haddock comments on types as if they were -- postfix operators ppr_mono_ty (XHsType t) = ppr t -------------------------- ppr_fun_ty :: (OutputableBndrId p) => LHsType (GhcPass p) -> LHsType (GhcPass p) -> SDoc ppr_fun_ty ty1 ty2 = let p1 = ppr_mono_lty ty1 p2 = ppr_mono_lty ty2 in sep [p1, arrow <+> p2] -------------------------- ppr_tylit :: HsTyLit -> SDoc ppr_tylit (HsNumTy _ i) = integer i ppr_tylit (HsStrTy _ s) = text (show s) -- | @'hsTypeNeedsParens' p t@ returns 'True' if the type @t@ needs parentheses -- under precedence @p@. hsTypeNeedsParens :: PprPrec -> HsType pass -> Bool hsTypeNeedsParens p = go where go (HsForAllTy{}) = p >= funPrec go (HsQualTy{}) = p >= funPrec go (HsBangTy{}) = p > topPrec go (HsRecTy{}) = False go (HsTyVar{}) = False go (HsFunTy{}) = p >= funPrec go (HsTupleTy{}) = False go (HsSumTy{}) = False go (HsKindSig{}) = p >= sigPrec go (HsListTy{}) = False go (HsIParamTy{}) = p > topPrec go (HsSpliceTy{}) = False go (HsExplicitListTy{}) = False go (HsExplicitTupleTy{}) = False go (HsTyLit{}) = False go (HsWildCardTy{}) = False go (HsStarTy{}) = False go (HsAppTy{}) = p >= appPrec go (HsAppKindTy{}) = p >= appPrec go (HsOpTy{}) = p >= opPrec go (HsParTy{}) = False go (HsDocTy _ (L _ t) _) = go t go (XHsType{}) = False maybeAddSpace :: [LHsType pass] -> SDoc -> SDoc -- See Note [Printing promoted type constructors] -- in IfaceType. This code implements the same -- logic for printing HsType maybeAddSpace tys doc | (ty : _) <- tys , lhsTypeHasLeadingPromotionQuote ty = space <> doc | otherwise = doc lhsTypeHasLeadingPromotionQuote :: LHsType pass -> Bool lhsTypeHasLeadingPromotionQuote ty = goL ty where goL (L _ ty) = go ty go (HsForAllTy{}) = False go (HsQualTy{ hst_ctxt = ctxt, hst_body = body}) | L _ (c:_) <- ctxt = goL c | otherwise = goL body go (HsBangTy{}) = False go (HsRecTy{}) = False go (HsTyVar _ p _) = isPromoted p go (HsFunTy _ arg _) = goL arg go (HsListTy{}) = False go (HsTupleTy{}) = False go (HsSumTy{}) = False go (HsOpTy _ t1 _ _) = goL t1 go (HsKindSig _ t _) = goL t go (HsIParamTy{}) = False go (HsSpliceTy{}) = False go (HsExplicitListTy _ p _) = isPromoted p go (HsExplicitTupleTy{}) = True go (HsTyLit{}) = False go (HsWildCardTy{}) = False go (HsStarTy{}) = False go (HsAppTy _ t _) = goL t go (HsAppKindTy _ t _) = goL t go (HsParTy{}) = False go (HsDocTy _ t _) = goL t go (XHsType{}) = False -- | @'parenthesizeHsType' p ty@ checks if @'hsTypeNeedsParens' p ty@ is -- true, and if so, surrounds @ty@ with an 'HsParTy'. Otherwise, it simply -- returns @ty@. parenthesizeHsType :: PprPrec -> LHsType (GhcPass p) -> LHsType (GhcPass p) parenthesizeHsType p lty@(L loc ty) | hsTypeNeedsParens p ty = L loc (HsParTy noExtField lty) | otherwise = lty -- | @'parenthesizeHsContext' p ctxt@ checks if @ctxt@ is a single constraint -- @c@ such that @'hsTypeNeedsParens' p c@ is true, and if so, surrounds @c@ -- with an 'HsParTy' to form a parenthesized @ctxt@. Otherwise, it simply -- returns @ctxt@ unchanged. parenthesizeHsContext :: PprPrec -> LHsContext (GhcPass p) -> LHsContext (GhcPass p) parenthesizeHsContext p lctxt@(L loc ctxt) = case ctxt of [c] -> L loc [parenthesizeHsType p c] _ -> lctxt -- Other contexts are already "parenthesized" by virtue of -- being tuples.