{- (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 #-} {-# LANGUAGE CPP #-} module HsTypes ( HsType(..), LHsType, HsKind, LHsKind, HsTyVarBndr(..), LHsTyVarBndr, LHsQTyVars(..), HsImplicitBndrs(..), HsWildCardBndrs(..), LHsSigType, LHsSigWcType, LHsWcType, HsTupleSort(..), Promoted(..), HsContext, LHsContext, HsTyLit(..), HsIPName(..), hsIPNameFS, HsAppType(..),LHsAppType, LBangType, BangType, HsSrcBang(..), HsImplBang(..), SrcStrictness(..), SrcUnpackedness(..), getBangType, getBangStrictness, ConDeclField(..), LConDeclField, pprConDeclFields, updateGadtResult, HsConDetails(..), FieldOcc(..), LFieldOcc, mkFieldOcc, AmbiguousFieldOcc(..), mkAmbiguousFieldOcc, rdrNameAmbiguousFieldOcc, selectorAmbiguousFieldOcc, unambiguousFieldOcc, ambiguousFieldOcc, HsWildCardInfo(..), mkAnonWildCardTy, wildCardName, sameWildCard, mkHsImplicitBndrs, mkHsWildCardBndrs, hsImplicitBody, mkEmptyImplicitBndrs, mkEmptyWildCardBndrs, mkHsQTvs, hsQTvExplicit, emptyLHsQTvs, isEmptyLHsQTvs, isHsKindedTyVar, hsTvbAllKinded, hsScopedTvs, hsWcScopedTvs, dropWildCards, hsTyVarName, hsAllLTyVarNames, hsLTyVarLocNames, hsLTyVarName, hsLTyVarLocName, hsExplicitLTyVarNames, splitLHsInstDeclTy, getLHsInstDeclHead, getLHsInstDeclClass_maybe, splitLHsPatSynTy, splitLHsForAllTy, splitLHsQualTy, splitLHsSigmaTy, splitHsFunType, splitHsAppsTy, splitHsAppTys, getAppsTyHead_maybe, hsTyGetAppHead_maybe, mkHsOpTy, mkHsAppTy, mkHsAppTys, ignoreParens, hsSigType, hsSigWcType, hsLTyVarBndrToType, hsLTyVarBndrsToTypes, -- Printing pprHsType, pprHsForAll, pprHsForAllTvs, pprHsForAllExtra, pprHsContext, pprHsContextNoArrow, pprHsContextMaybe, isCompoundHsType, parenthesizeCompoundHsType ) where import GhcPrelude import {-# SOURCE #-} HsExpr ( HsSplice, pprSplice ) import PlaceHolder ( PlaceHolder(..) ) import HsExtension import Id ( Id ) import Name( Name ) import RdrName ( RdrName ) import NameSet ( NameSet, emptyNameSet ) import DataCon( HsSrcBang(..), HsImplBang(..), SrcStrictness(..), SrcUnpackedness(..) ) import TysPrim( funTyConName ) import Type import HsDoc import BasicTypes import SrcLoc import Outputable import FastString import Maybes( isJust ) import Data.Data hiding ( Fixity, Prefix, Infix ) import Data.Maybe ( fromMaybe ) import Control.Monad ( unless ) {- ************************************************************************ * * \subsection{Bang annotations} * * ************************************************************************ -} -- | Located Bang Type type LBangType pass = Located (BangType pass) -- | Bang Type type BangType pass = HsType pass -- 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 _ = (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. ... 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. * 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. After the renamer, this contains a Name which uniquely identifies this particular occurrence. * 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 Trac #10982) * All wildcards, whether named or anonymous, are bound by the HsWildCardBndrs construct, which wraps types that are allowed to have wildcards. * After type checking is done, we report what types the wildcards got unified with. -} -- | Located Haskell Context type LHsContext pass = Located (HsContext pass) -- ^ 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnUnit' -- For details on above see note [Api annotations] in ApiAnnotation -- | 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_implicit :: PostRn pass [Name] -- Implicit (dependent) variables , hsq_explicit :: [LHsTyVarBndr pass] -- Explicit variables, written by the user -- See Note [HsForAllTy tyvar binders] , hsq_dependent :: PostRn pass NameSet -- Which members of hsq_explicit are dependent; that is, -- mentioned in the kind of a later hsq_explicit, -- or mentioned in a kind in the scope of this HsQTvs -- See Note [Dependent LHsQTyVars] in TcHsType } deriving instance (DataId pass) => Data (LHsQTyVars pass) mkHsQTvs :: [LHsTyVarBndr GhcPs] -> LHsQTyVars GhcPs mkHsQTvs tvs = HsQTvs { hsq_implicit = PlaceHolder, hsq_explicit = tvs , hsq_dependent = PlaceHolder } hsQTvExplicit :: LHsQTyVars pass -> [LHsTyVarBndr pass] hsQTvExplicit = hsq_explicit emptyLHsQTvs :: LHsQTyVars GhcRn emptyLHsQTvs = HsQTvs [] [] emptyNameSet isEmptyLHsQTvs :: LHsQTyVars GhcRn -> Bool isEmptyLHsQTvs (HsQTvs [] [] _) = True 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_vars :: PostRn pass [Name] -- Implicitly-bound kind & type vars , hsib_body :: thing -- Main payload (type or list of types) , hsib_closed :: PostRn pass Bool -- Taking the hsib_vars into account, -- is the payload closed? Used in -- TcHsType.decideKindGeneralisationPlan } deriving instance (DataId pass, Data thing) => Data (HsImplicitBndrs pass thing) -- | Haskell Wildcard Binders data HsWildCardBndrs pass thing -- See Note [HsType binders] -- See Note [The wildcard story for types] = HsWC { hswc_wcs :: PostRn pass [Name] -- Wild cards, both named and anonymous -- after the renamer , 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. } deriving instance (DataId pass, Data thing) => Data (HsWildCardBndrs pass thing) -- | 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 pass thing -> thing hsImplicitBody (HsIB { hsib_body = body }) = body hsSigType :: LHsSigType pass -> LHsType pass 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_body = x , hsib_vars = PlaceHolder , hsib_closed = PlaceHolder } mkHsWildCardBndrs :: thing -> HsWildCardBndrs GhcPs thing mkHsWildCardBndrs x = HsWC { hswc_body = x , hswc_wcs = PlaceHolder } -- 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_body = x , hsib_vars = [] , hsib_closed = False } mkEmptyWildCardBndrs :: thing -> HsWildCardBndrs GhcRn thing mkEmptyWildCardBndrs x = HsWC { hswc_body = x , hswc_wcs = [] } -------------------------------------------------- -- | 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 (Located (IdP pass)) -- See Note [Located RdrNames] in HsExpr | KindedTyVar (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 deriving instance (DataId pass) => Data (HsTyVarBndr pass) -- | Does this 'HsTyVarBndr' come with an explicit kind annotation? isHsKindedTyVar :: HsTyVarBndr pass -> Bool isHsKindedTyVar (UserTyVar {}) = False isHsKindedTyVar (KindedTyVar {}) = True -- | Do all type variables in this 'LHsQTyVars' come with kind annotations? hsTvbAllKinded :: LHsQTyVars pass -> Bool hsTvbAllKinded = all (isHsKindedTyVar . unLoc) . hsQTvExplicit -- | Haskell Type data HsType pass = HsForAllTy -- See Note [HsType binders] { 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_ctxt :: LHsContext pass -- Context C => blah , hst_body :: LHsType pass } | HsTyVar Promoted -- 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 HsExpr -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsAppsTy [LHsAppType pass] -- Used only before renaming, -- Note [HsAppsTy] -- ^ - 'ApiAnnotation.AnnKeywordId' : None | HsAppTy (LHsType pass) (LHsType pass) -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsFunTy (LHsType pass) -- function type (LHsType pass) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnRarrow', -- For details on above see note [Api annotations] in ApiAnnotation | HsListTy (LHsType pass) -- Element type -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'['@, -- 'ApiAnnotation.AnnClose' @']'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsPArrTy (LHsType pass) -- 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 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 [LHsType pass] -- Element types (length gives arity) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'(#'@, -- 'ApiAnnotation.AnnClose' '#)'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsOpTy (LHsType pass) (Located (IdP pass)) (LHsType pass) -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsParTy (LHsType pass) -- 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 (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 | HsEqTy (LHsType pass) -- ty1 ~ ty2 (LHsType pass) -- 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 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 (HsSplice pass) -- Includes quasi-quotes (PostTc pass Kind) -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @'$('@, -- 'ApiAnnotation.AnnClose' @')'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsDocTy (LHsType pass) LHsDocString -- A documented type -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation | HsBangTy 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 [LConDeclField pass] -- 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 Promoted -- whether explcitly promoted, for pretty printer (PostTc pass Kind) -- See Note [Promoted lists and tuples] [LHsType pass] -- ^ - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnOpen' @"'["@, -- 'ApiAnnotation.AnnClose' @']'@ -- For details on above see note [Api annotations] in ApiAnnotation | HsExplicitTupleTy -- A promoted explicit tuple [PostTc pass Kind] -- See Note [Promoted lists and tuples] [LHsType pass] -- ^ - '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 | HsWildCardTy (HsWildCardInfo pass) -- A type wildcard -- See Note [The wildcard story for types] -- ^ - 'ApiAnnotation.AnnKeywordId' : None -- For details on above see note [Api annotations] in ApiAnnotation deriving instance (DataId pass) => Data (HsType pass) -- 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 newtype HsWildCardInfo pass -- See Note [The wildcard story for types] = AnonWildCard (PostRn pass (Located Name)) -- A anonymous wild card ('_'). A fresh Name is generated for -- each individual anonymous wildcard during renaming deriving instance (DataId pass) => Data (HsWildCardInfo pass) -- | Located Haskell Application Type type LHsAppType pass = Located (HsAppType pass) -- ^ 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnSimpleQuote' -- | Haskell Application Type data HsAppType pass = HsAppInfix (Located (IdP pass)) -- either a symbol or an id in backticks | HsAppPrefix (LHsType pass) -- anything else, including things like (+) deriving instance (DataId pass) => Data (HsAppType pass) instance (SourceTextX pass, OutputableBndrId pass) => Outputable (HsAppType pass) where ppr = ppr_app_ty {- 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 Trac #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 [HsAppsTy] ~~~~~~~~~~~~~~~ How to parse Foo * Int ? Is it `(*) Foo Int` or `Foo GHC.Types.* Int`? There's no way to know until renaming. So we just take type expressions like this and put each component in a list, so be sorted out in the renamer. The sorting out is done by RnTypes.mkHsOpTyRn. This means that the parser should never produce HsAppTy or HsOpTy. 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 -- | Promoted data types. data Promoted = Promoted | NotPromoted deriving (Data, Eq, Show) -- | 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_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 deriving instance (DataId pass) => Data (ConDeclField pass) instance (SourceTextX pass, OutputableBndrId pass) => Outputable (ConDeclField pass) where ppr (ConDeclField fld_n fld_ty _) = ppr fld_n <+> dcolon <+> ppr fld_ty -- 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] -- Takes details and result type of a GADT data constructor as created by the -- parser and rejigs them using information about fixities from the renamer. -- See Note [Sorting out the result type] in RdrHsSyn updateGadtResult :: (Monad m) => (SDoc -> m ()) -> SDoc -> HsConDetails (LHsType GhcRn) (Located [LConDeclField GhcRn]) -- ^ Original details -> LHsType GhcRn -- ^ Original result type -> m (HsConDetails (LHsType GhcRn) (Located [LConDeclField GhcRn]), LHsType GhcRn) updateGadtResult failWith doc details ty = do { let (arg_tys, res_ty) = splitHsFunType ty badConSig = text "Malformed constructor signature" ; case details of InfixCon {} -> pprPanic "updateGadtResult" (ppr ty) RecCon {} -> do { unless (null arg_tys) (failWith (doc <+> badConSig)) ; return (details, res_ty) } PrefixCon {} -> return (PrefixCon arg_tys, res_ty)} {- 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 implicitly-bound kind variables -- - the named wildcars; see Note [Scoping of named wildcards] -- because they scope in the same way hsWcScopedTvs sig_ty | HsWC { hswc_wcs = nwcs, hswc_body = sig_ty1 } <- sig_ty , HsIB { hsib_vars = vars, hsib_body = sig_ty2 } <- sig_ty1 = case sig_ty2 of L _ (HsForAllTy { hst_bndrs = tvs }) -> vars ++ nwcs ++ map hsLTyVarName tvs -- include kind variables only if the type is headed by forall -- (this is consistent with GHC 7 behaviour) _ -> nwcs hsScopedTvs :: LHsSigType GhcRn -> [Name] -- Same as hsWcScopedTvs, but for a LHsSigType hsScopedTvs sig_ty | HsIB { hsib_vars = vars, hsib_body = sig_ty2 } <- sig_ty , L _ (HsForAllTy { hst_bndrs = tvs }) <- sig_ty2 = vars ++ map hsLTyVarName 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. -} --------------------- hsTyVarName :: HsTyVarBndr pass -> IdP pass hsTyVarName (UserTyVar (L _ n)) = n hsTyVarName (KindedTyVar (L _ n) _) = n hsLTyVarName :: LHsTyVarBndr pass -> IdP pass hsLTyVarName = hsTyVarName . unLoc hsExplicitLTyVarNames :: LHsQTyVars pass -> [IdP pass] -- Explicit variables only hsExplicitLTyVarNames qtvs = map hsLTyVarName (hsQTvExplicit qtvs) hsAllLTyVarNames :: LHsQTyVars GhcRn -> [Name] -- All variables hsAllLTyVarNames (HsQTvs { hsq_implicit = kvs, hsq_explicit = tvs }) = kvs ++ map hsLTyVarName tvs hsLTyVarLocName :: LHsTyVarBndr pass -> Located (IdP pass) hsLTyVarLocName = fmap hsTyVarName hsLTyVarLocNames :: LHsQTyVars pass -> [Located (IdP pass)] hsLTyVarLocNames qtvs = map hsLTyVarLocName (hsQTvExplicit qtvs) -- | Convert a LHsTyVarBndr to an equivalent LHsType. hsLTyVarBndrToType :: LHsTyVarBndr pass -> LHsType pass hsLTyVarBndrToType = fmap cvt where cvt (UserTyVar n) = HsTyVar NotPromoted n cvt (KindedTyVar (L name_loc n) kind) = HsKindSig (L name_loc (HsTyVar NotPromoted (L name_loc n))) kind -- | Convert a LHsTyVarBndrs to a list of types. -- Works on *type* variable only, no kind vars. hsLTyVarBndrsToTypes :: LHsQTyVars pass -> [LHsType pass] hsLTyVarBndrsToTypes (HsQTvs { hsq_explicit = tvbs }) = map hsLTyVarBndrToType tvbs --------------------- wildCardName :: HsWildCardInfo GhcRn -> Name wildCardName (AnonWildCard (L _ n)) = n -- Two wild cards are the same when they have the same location sameWildCard :: Located (HsWildCardInfo pass) -> Located (HsWildCardInfo pass) -> Bool sameWildCard (L l1 (AnonWildCard _)) (L l2 (AnonWildCard _)) = l1 == l2 ignoreParens :: LHsType pass -> LHsType pass ignoreParens (L _ (HsParTy ty)) = ignoreParens ty ignoreParens (L _ (HsAppsTy [L _ (HsAppPrefix ty)])) = ignoreParens ty ignoreParens ty = ty {- ************************************************************************ * * Building types * * ************************************************************************ -} mkAnonWildCardTy :: HsType GhcPs mkAnonWildCardTy = HsWildCardTy (AnonWildCard PlaceHolder) mkHsOpTy :: LHsType pass -> Located (IdP pass) -> LHsType pass -> HsType pass mkHsOpTy ty1 op ty2 = HsOpTy ty1 op ty2 mkHsAppTy :: LHsType pass -> LHsType pass -> LHsType pass mkHsAppTy t1 t2 = addCLoc t1 t2 (HsAppTy t1 (parenthesizeCompoundHsType t2)) mkHsAppTys :: LHsType pass -> [LHsType pass] -> LHsType pass mkHsAppTys = foldl mkHsAppTy {- ************************************************************************ * * 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 Trac #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) 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) -------------------------------- -- | Retrieves the head of an HsAppsTy, if this can be done unambiguously, -- without consulting fixities. getAppsTyHead_maybe :: [LHsAppType pass] -> Maybe (LHsType pass, [LHsType pass], LexicalFixity) getAppsTyHead_maybe tys = case splitHsAppsTy tys of ([app1:apps], []) -> -- no symbols, some normal types Just (mkHsAppTys app1 apps, [], Prefix) ([app1l:appsl, app1r:appsr], [L loc op]) -> -- one operator Just ( L loc (HsTyVar NotPromoted (L loc op)) , [mkHsAppTys app1l appsl, mkHsAppTys app1r appsr], Infix) _ -> -- can't figure it out Nothing -- | Splits a [HsAppType pass] (the payload of an HsAppsTy) into regions of -- prefix types (normal types) and infix operators. -- If @splitHsAppsTy tys = (non_syms, syms)@, then @tys@ starts with the first -- element of @non_syms@ followed by the first element of @syms@ followed by -- the next element of @non_syms@, etc. It is guaranteed that the non_syms list -- has one more element than the syms list. splitHsAppsTy :: [LHsAppType pass] -> ([[LHsType pass]], [Located (IdP pass)]) splitHsAppsTy = go [] [] [] where go acc acc_non acc_sym [] = (reverse (reverse acc : acc_non), reverse acc_sym) go acc acc_non acc_sym (L _ (HsAppPrefix ty) : rest) = go (ty : acc) acc_non acc_sym rest go acc acc_non acc_sym (L _ (HsAppInfix op) : rest) = go [] (reverse acc : acc_non) (op : acc_sym) rest -- 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 pass -> Maybe (Located (IdP pass), [LHsType pass]) hsTyGetAppHead_maybe = go [] where go tys (L _ (HsTyVar _ ln)) = Just (ln, tys) go tys (L _ (HsAppsTy apps)) | Just (head, args, _) <- getAppsTyHead_maybe apps = go (args ++ tys) head go tys (L _ (HsAppTy l r)) = go (r : tys) l go tys (L _ (HsOpTy l (L loc n) r)) = Just (L loc n, l : r : tys) go tys (L _ (HsParTy t)) = go tys t go tys (L _ (HsKindSig t _)) = go tys t go _ _ = Nothing splitHsAppTys :: LHsType GhcRn -> [LHsType GhcRn] -> (LHsType GhcRn, [LHsType GhcRn]) -- no need to worry about HsAppsTy here splitHsAppTys (L _ (HsAppTy f a)) as = splitHsAppTys f (a:as) splitHsAppTys (L _ (HsParTy f)) as = splitHsAppTys f as splitHsAppTys f as = (f,as) -------------------------------- 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) = splitLHsForAllTy ty (reqs, ty2) = splitLHsQualTy ty1 (exis, ty3) = splitLHsForAllTy ty2 (provs, ty4) = splitLHsQualTy ty3 splitLHsSigmaTy :: LHsType pass -> ([LHsTyVarBndr pass], LHsContext pass, LHsType pass) splitLHsSigmaTy ty | (tvs, ty1) <- splitLHsForAllTy ty , (ctxt, ty2) <- splitLHsQualTy ty1 = (tvs, ctxt, ty2) splitLHsForAllTy :: LHsType pass -> ([LHsTyVarBndr pass], LHsType pass) splitLHsForAllTy (L _ (HsForAllTy { hst_bndrs = tvs, hst_body = body })) = (tvs, body) splitLHsForAllTy (L _ (HsParTy t)) = splitLHsForAllTy t splitLHsForAllTy body = ([], body) splitLHsQualTy :: LHsType pass -> (LHsContext pass, LHsType pass) splitLHsQualTy (L _ (HsQualTy { hst_ctxt = ctxt, hst_body = body })) = (ctxt, body) splitLHsQualTy (L _ (HsParTy t)) = splitLHsQualTy t splitLHsQualTy body = (noLoc [], body) splitLHsInstDeclTy :: LHsSigType GhcRn -> ([Name], LHsContext GhcRn, LHsType GhcRn) -- Split up an instance decl type, returning the pieces splitLHsInstDeclTy (HsIB { hsib_vars = itkvs , hsib_body = inst_ty }) | (tvs, cxt, body_ty) <- splitLHsSigmaTy inst_ty = (itkvs ++ map hsLTyVarName tvs, cxt, body_ty) -- Return implicitly bound type and kind vars -- For an instance decl, all of them are in scope getLHsInstDeclHead :: LHsSigType pass -> LHsType pass getLHsInstDeclHead inst_ty | (_tvs, _cxt, body_ty) <- splitLHsSigmaTy (hsSigType inst_ty) = body_ty getLHsInstDeclClass_maybe :: LHsSigType pass -> Maybe (Located (IdP pass)) -- 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 { rdrNameFieldOcc :: Located RdrName -- ^ See Note [Located RdrNames] in HsExpr , selectorFieldOcc :: PostRn pass (IdP pass) } deriving instance Eq (PostRn pass (IdP pass)) => Eq (FieldOcc pass) deriving instance Ord (PostRn pass (IdP pass)) => Ord (FieldOcc pass) deriving instance (DataId pass) => Data (FieldOcc pass) instance Outputable (FieldOcc pass) where ppr = ppr . rdrNameFieldOcc mkFieldOcc :: Located RdrName -> FieldOcc GhcPs mkFieldOcc rdr = FieldOcc rdr PlaceHolder -- | 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 HsPat and -- Note [Disambiguating record fields] in TcExpr. -- See Note [Located RdrNames] in HsExpr data AmbiguousFieldOcc pass = Unambiguous (Located RdrName) (PostRn pass (IdP pass)) | Ambiguous (Located RdrName) (PostTc pass (IdP pass)) deriving instance DataId pass => Data (AmbiguousFieldOcc pass) instance Outputable (AmbiguousFieldOcc pass) where ppr = ppr . rdrNameAmbiguousFieldOcc instance OutputableBndr (AmbiguousFieldOcc pass) where pprInfixOcc = pprInfixOcc . rdrNameAmbiguousFieldOcc pprPrefixOcc = pprPrefixOcc . rdrNameAmbiguousFieldOcc mkAmbiguousFieldOcc :: Located RdrName -> AmbiguousFieldOcc GhcPs mkAmbiguousFieldOcc rdr = Unambiguous rdr PlaceHolder rdrNameAmbiguousFieldOcc :: AmbiguousFieldOcc pass -> RdrName rdrNameAmbiguousFieldOcc (Unambiguous (L _ rdr) _) = rdr rdrNameAmbiguousFieldOcc (Ambiguous (L _ rdr) _) = rdr selectorAmbiguousFieldOcc :: AmbiguousFieldOcc GhcTc -> Id selectorAmbiguousFieldOcc (Unambiguous _ sel) = sel selectorAmbiguousFieldOcc (Ambiguous _ sel) = sel unambiguousFieldOcc :: AmbiguousFieldOcc GhcTc -> FieldOcc GhcTc unambiguousFieldOcc (Unambiguous rdr sel) = FieldOcc rdr sel unambiguousFieldOcc (Ambiguous rdr sel) = FieldOcc rdr sel ambiguousFieldOcc :: FieldOcc pass -> AmbiguousFieldOcc pass ambiguousFieldOcc (FieldOcc rdr sel) = Unambiguous rdr sel {- ************************************************************************ * * \subsection{Pretty printing} * * ************************************************************************ -} instance (SourceTextX pass, OutputableBndrId pass) => Outputable (HsType pass) where ppr ty = pprHsType ty instance Outputable HsTyLit where ppr = ppr_tylit instance (SourceTextX pass, OutputableBndrId pass) => Outputable (LHsQTyVars pass) where ppr (HsQTvs { hsq_explicit = tvs }) = interppSP tvs instance (SourceTextX pass, OutputableBndrId pass) => Outputable (HsTyVarBndr pass) where ppr (UserTyVar n) = ppr n ppr (KindedTyVar n k) = parens $ hsep [ppr n, dcolon, ppr k] instance (Outputable thing) => Outputable (HsImplicitBndrs pass thing) where ppr (HsIB { hsib_body = ty }) = ppr ty instance (Outputable thing) => Outputable (HsWildCardBndrs pass thing) where ppr (HsWC { hswc_body = ty }) = ppr ty instance Outputable (HsWildCardInfo pass) where ppr (AnonWildCard _) = char '_' pprHsForAll :: (SourceTextX pass, OutputableBndrId pass) => [LHsTyVarBndr pass] -> LHsContext pass -> 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 :: (SourceTextX pass, OutputableBndrId pass) => Maybe SrcSpan -> [LHsTyVarBndr pass] -> LHsContext pass -> SDoc pprHsForAllExtra extra qtvs cxt = pprHsForAllTvs qtvs <+> pprHsContextExtra show_extra (unLoc cxt) where show_extra = isJust extra pprHsForAllTvs :: (SourceTextX pass, OutputableBndrId pass) => [LHsTyVarBndr pass] -> SDoc pprHsForAllTvs qtvs | null qtvs = whenPprDebug (forAllLit <+> dot) | otherwise = forAllLit <+> interppSP qtvs <> dot pprHsContext :: (SourceTextX pass, OutputableBndrId pass) => HsContext pass -> SDoc pprHsContext = maybe empty (<+> darrow) . pprHsContextMaybe pprHsContextNoArrow :: (SourceTextX pass, OutputableBndrId pass) => HsContext pass -> SDoc pprHsContextNoArrow = fromMaybe empty . pprHsContextMaybe pprHsContextMaybe :: (SourceTextX pass, OutputableBndrId pass) => HsContext pass -> Maybe SDoc pprHsContextMaybe [] = Nothing pprHsContextMaybe [L _ pred] = Just $ ppr_mono_ty pred pprHsContextMaybe cxt = Just $ parens (interpp'SP cxt) -- For use in a HsQualTy, which always gets printed if it exists. pprHsContextAlways :: (SourceTextX pass, OutputableBndrId pass) => HsContext pass -> SDoc pprHsContextAlways [] = parens empty <+> darrow pprHsContextAlways [L _ ty] = ppr_mono_ty ty <+> darrow pprHsContextAlways cxt = parens (interpp'SP cxt) <+> darrow -- True <=> print an extra-constraints wildcard, e.g. @(Show a, _) =>@ pprHsContextExtra :: (SourceTextX pass, OutputableBndrId pass) => Bool -> HsContext pass -> SDoc pprHsContextExtra show_extra ctxt | not show_extra = pprHsContext ctxt | null ctxt = char '_' <+> darrow | otherwise = parens (sep (punctuate comma ctxt')) <+> darrow where ctxt' = map ppr ctxt ++ [char '_'] pprConDeclFields :: (SourceTextX pass, OutputableBndrId pass) => [LConDeclField pass] -> 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 :: (SourceTextX pass, OutputableBndrId pass) => HsType pass -> SDoc pprHsType ty = ppr_mono_ty ty ppr_mono_lty :: (SourceTextX pass, OutputableBndrId pass) => LHsType pass -> SDoc ppr_mono_lty ty = ppr_mono_ty (unLoc ty) ppr_mono_ty :: (SourceTextX pass, OutputableBndrId pass) => HsType pass -> SDoc ppr_mono_ty (HsForAllTy { hst_bndrs = tvs, hst_body = ty }) = sep [pprHsForAllTvs tvs, ppr_mono_lty ty] ppr_mono_ty (HsQualTy { hst_ctxt = L _ ctxt, hst_body = ty }) = sep [pprHsContextAlways 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 NotPromoted (L _ name))= pprPrefixOcc name ppr_mono_ty (HsTyVar Promoted (L _ name)) = space <> quote (pprPrefixOcc name) -- We need a space before the ' above, so the parser -- does not attach it to the previous symbol ppr_mono_ty (HsFunTy ty1 ty2) = ppr_fun_ty ty1 ty2 ppr_mono_ty (HsTupleTy con tys) = 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) = parens (ppr_mono_lty ty <+> dcolon <+> ppr kind) ppr_mono_ty (HsListTy ty) = brackets (ppr_mono_lty ty) ppr_mono_ty (HsPArrTy ty) = paBrackets (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 (HsCoreTy ty) = ppr ty ppr_mono_ty (HsExplicitListTy Promoted _ tys) = quote $ brackets (interpp'SP tys) ppr_mono_ty (HsExplicitListTy NotPromoted _ tys) = 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 (HsEqTy ty1 ty2) = ppr_mono_lty ty1 <+> char '~' <+> ppr_mono_lty ty2 ppr_mono_ty (HsAppsTy tys) = hsep (map (ppr_app_ty . unLoc) tys) ppr_mono_ty (HsAppTy fun_ty arg_ty) = hsep [ppr_mono_lty fun_ty, ppr_mono_lty arg_ty] 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_fun_ty :: (SourceTextX pass, OutputableBndrId pass) => LHsType pass -> LHsType pass -> SDoc ppr_fun_ty ty1 ty2 = let p1 = ppr_mono_lty ty1 p2 = ppr_mono_lty ty2 in sep [p1, text "->" <+> p2] -------------------------- ppr_app_ty :: (SourceTextX pass, OutputableBndrId pass) => HsAppType pass -> SDoc ppr_app_ty (HsAppInfix (L _ n)) = pprInfixOcc n ppr_app_ty (HsAppPrefix (L _ (HsTyVar NotPromoted (L _ n)))) = pprPrefixOcc n ppr_app_ty (HsAppPrefix (L _ (HsTyVar Promoted (L _ n)))) = space <> quote (pprPrefixOcc n) -- We need a space before the ' above, so -- the parser does not attach it to the -- previous symbol ppr_app_ty (HsAppPrefix ty) = ppr_mono_lty ty -------------------------- ppr_tylit :: HsTyLit -> SDoc ppr_tylit (HsNumTy _ i) = integer i ppr_tylit (HsStrTy _ s) = text (show s) -- | Return 'True' for compound types that will need parentheses when used in -- an argument position. isCompoundHsType :: LHsType pass -> Bool isCompoundHsType (L _ HsAppTy{} ) = True isCompoundHsType (L _ HsAppsTy{}) = True isCompoundHsType (L _ HsEqTy{} ) = True isCompoundHsType (L _ HsFunTy{} ) = True isCompoundHsType (L _ HsOpTy{} ) = True isCompoundHsType _ = False -- | @'parenthesizeCompoundHsType' ty@ checks if @'isCompoundHsType' ty@ is -- true, and if so, surrounds @ty@ with an 'HsParTy'. Otherwise, it simply -- returns @ty@. parenthesizeCompoundHsType :: LHsType pass -> LHsType pass parenthesizeCompoundHsType ty@(L loc _) | isCompoundHsType ty = L loc (HsParTy ty) | otherwise = ty