{-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE DeriveFunctor #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE LambdaCase #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow] -- in module Language.Haskell.Syntax.Extension {-# LANGUAGE ViewPatterns #-} {- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 \section[HsBinds]{Abstract syntax: top-level bindings and signatures} Datatype for: @BindGroup@, @Bind@, @Sig@, @Bind@. -} -- See Note [Language.Haskell.Syntax.* Hierarchy] for why not GHC.Hs.* module Language.Haskell.Syntax.Binds where import GHC.Prelude import {-# SOURCE #-} Language.Haskell.Syntax.Expr ( LHsExpr , MatchGroup , GRHSs ) import {-# SOURCE #-} Language.Haskell.Syntax.Pat ( LPat ) import Language.Haskell.Syntax.Extension import Language.Haskell.Syntax.Type import GHC.Tc.Types.Evidence import GHC.Core.Type import GHC.Types.Basic import GHC.Types.SourceText import GHC.Types.SrcLoc as SrcLoc import GHC.Types.Tickish import GHC.Types.Var import GHC.Types.Fixity import GHC.Data.Bag import GHC.Data.BooleanFormula (LBooleanFormula) import GHC.Utils.Outputable import Data.Data hiding ( Fixity ) import Data.Void {- ************************************************************************ * * \subsection{Bindings: @BindGroup@} * * ************************************************************************ Global bindings (where clauses) -} -- During renaming, we need bindings where the left-hand sides -- have been renamed but the right-hand sides have not. -- Other than during renaming, these will be the same. -- | Haskell Local Bindings type HsLocalBinds id = HsLocalBindsLR id id -- | Located Haskell local bindings type LHsLocalBinds id = XRec id (HsLocalBinds id) -- | Haskell Local Bindings with separate Left and Right identifier types -- -- Bindings in a 'let' expression -- or a 'where' clause data HsLocalBindsLR idL idR = HsValBinds (XHsValBinds idL idR) (HsValBindsLR idL idR) -- ^ Haskell Value Bindings -- There should be no pattern synonyms in the HsValBindsLR -- These are *local* (not top level) bindings -- The parser accepts them, however, leaving the -- renamer to report them | HsIPBinds (XHsIPBinds idL idR) (HsIPBinds idR) -- ^ Haskell Implicit Parameter Bindings | EmptyLocalBinds (XEmptyLocalBinds idL idR) -- ^ Empty Local Bindings | XHsLocalBindsLR !(XXHsLocalBindsLR idL idR) type LHsLocalBindsLR idL idR = XRec idL (HsLocalBindsLR idL idR) -- | Haskell Value Bindings type HsValBinds id = HsValBindsLR id id -- | Haskell Value bindings with separate Left and Right identifier types -- (not implicit parameters) -- Used for both top level and nested bindings -- May contain pattern synonym bindings data HsValBindsLR idL idR = -- | Value Bindings In -- -- Before renaming RHS; idR is always RdrName -- Not dependency analysed -- Recursive by default ValBinds (XValBinds idL idR) (LHsBindsLR idL idR) [LSig idR] -- | Value Bindings Out -- -- After renaming RHS; idR can be Name or Id Dependency analysed, -- later bindings in the list may depend on earlier ones. | XValBindsLR !(XXValBindsLR idL idR) -- --------------------------------------------------------------------- -- | Located Haskell Binding type LHsBind id = LHsBindLR id id -- | Located Haskell Bindings type LHsBinds id = LHsBindsLR id id -- | Haskell Binding type HsBind id = HsBindLR id id -- | Located Haskell Bindings with separate Left and Right identifier types type LHsBindsLR idL idR = Bag (LHsBindLR idL idR) -- | Located Haskell Binding with separate Left and Right identifier types type LHsBindLR idL idR = XRec idL (HsBindLR idL idR) {- Note [FunBind vs PatBind] ~~~~~~~~~~~~~~~~~~~~~~~~~ The distinction between FunBind and PatBind is a bit subtle. FunBind covers patterns which resemble function bindings and simple variable bindings. f x = e f !x = e f = e !x = e -- FunRhs has SrcStrict x `f` y = e -- FunRhs has Infix The actual patterns and RHSs of a FunBind are encoding in fun_matches. The m_ctxt field of each Match in fun_matches will be FunRhs and carries two bits of information about the match, * The mc_fixity field on each Match describes the fixity of the function binder in that match. E.g. this is legal: f True False = e1 True `f` True = e2 * The mc_strictness field is used /only/ for nullary FunBinds: ones with one Match, which has no pats. For these, it describes whether the match is decorated with a bang (e.g. `!x = e`). By contrast, PatBind represents data constructor patterns, as well as a few other interesting cases. Namely, Just x = e (x) = e x :: Ty = e -} -- | Haskell Binding with separate Left and Right id's data HsBindLR idL idR = -- | Function-like Binding -- -- FunBind is used for both functions @f x = e@ -- and variables @f = \x -> e@ -- and strict variables @!x = x + 1@ -- -- Reason 1: Special case for type inference: see 'GHC.Tc.Gen.Bind.tcMonoBinds'. -- -- Reason 2: Instance decls can only have FunBinds, which is convenient. -- If you change this, you'll need to change e.g. rnMethodBinds -- -- But note that the form @f :: a->a = ...@ -- parses as a pattern binding, just like -- @(f :: a -> a) = ... @ -- -- Strict bindings have their strictness recorded in the 'SrcStrictness' of their -- 'MatchContext'. See Note [FunBind vs PatBind] for -- details about the relationship between FunBind and PatBind. -- -- 'GHC.Parser.Annotation.AnnKeywordId's -- -- - 'GHC.Parser.Annotation.AnnFunId', attached to each element of fun_matches -- -- - 'GHC.Parser.Annotation.AnnEqual','GHC.Parser.Annotation.AnnWhere', -- 'GHC.Parser.Annotation.AnnOpen','GHC.Parser.Annotation.AnnClose', -- For details on above see note [exact print annotations] in GHC.Parser.Annotation FunBind { fun_ext :: XFunBind idL idR, -- ^ After the renamer (but before the type-checker), this contains the -- locally-bound free variables of this defn. See Note [Bind free vars] -- -- After the type-checker, this contains a coercion from the type of -- the MatchGroup to the type of the Id. Example: -- -- @ -- f :: Int -> forall a. a -> a -- f x y = y -- @ -- -- Then the MatchGroup will have type (Int -> a' -> a') -- (with a free type variable a'). The coercion will take -- a CoreExpr of this type and convert it to a CoreExpr of -- type Int -> forall a'. a' -> a' -- Notice that the coercion captures the free a'. fun_id :: LIdP idL, -- Note [fun_id in Match] in GHC.Hs.Expr fun_matches :: MatchGroup idR (LHsExpr idR), -- ^ The payload fun_tick :: [CoreTickish] -- ^ Ticks to put on the rhs, if any } -- | Pattern Binding -- -- The pattern is never a simple variable; -- That case is done by FunBind. -- See Note [FunBind vs PatBind] for details about the -- relationship between FunBind and PatBind. -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnBang', -- 'GHC.Parser.Annotation.AnnEqual','GHC.Parser.Annotation.AnnWhere', -- 'GHC.Parser.Annotation.AnnOpen','GHC.Parser.Annotation.AnnClose', -- For details on above see note [exact print annotations] in GHC.Parser.Annotation | PatBind { pat_ext :: XPatBind idL idR, -- ^ See Note [Bind free vars] pat_lhs :: LPat idL, pat_rhs :: GRHSs idR (LHsExpr idR), pat_ticks :: ([CoreTickish], [[CoreTickish]]) -- ^ Ticks to put on the rhs, if any, and ticks to put on -- the bound variables. } -- | Variable Binding -- -- Dictionary binding and suchlike. -- All VarBinds are introduced by the type checker | VarBind { var_ext :: XVarBind idL idR, var_id :: IdP idL, var_rhs :: LHsExpr idR -- ^ Located only for consistency } -- | Abstraction Bindings | AbsBinds { -- Binds abstraction; TRANSLATION abs_ext :: XAbsBinds idL idR, abs_tvs :: [TyVar], abs_ev_vars :: [EvVar], -- ^ Includes equality constraints -- | AbsBinds only gets used when idL = idR after renaming, -- but these need to be idL's for the collect... code in HsUtil -- to have the right type abs_exports :: [ABExport idL], -- | Evidence bindings -- Why a list? See "GHC.Tc.TyCl.Instance" -- Note [Typechecking plan for instance declarations] abs_ev_binds :: [TcEvBinds], -- | Typechecked user bindings abs_binds :: LHsBinds idL, abs_sig :: Bool -- See Note [The abs_sig field of AbsBinds] } -- | Patterns Synonym Binding | PatSynBind (XPatSynBind idL idR) (PatSynBind idL idR) -- ^ - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnPattern', -- 'GHC.Parser.Annotation.AnnLarrow','GHC.Parser.Annotation.AnnEqual', -- 'GHC.Parser.Annotation.AnnWhere' -- 'GHC.Parser.Annotation.AnnOpen' @'{'@,'GHC.Parser.Annotation.AnnClose' @'}'@ -- For details on above see note [exact print annotations] in GHC.Parser.Annotation | XHsBindsLR !(XXHsBindsLR idL idR) -- Consider (AbsBinds tvs ds [(ftvs, poly_f, mono_f) binds] -- -- Creates bindings for (polymorphic, overloaded) poly_f -- in terms of monomorphic, non-overloaded mono_f -- -- Invariants: -- 1. 'binds' binds mono_f -- 2. ftvs is a subset of tvs -- 3. ftvs includes all tyvars free in ds -- -- See Note [AbsBinds] -- | Abstraction Bindings Export data ABExport p = ABE { abe_ext :: XABE p , abe_poly :: IdP p -- ^ Any INLINE pragma is attached to this Id , abe_mono :: IdP p , abe_wrap :: HsWrapper -- ^ See Note [ABExport wrapper] -- Shape: (forall abs_tvs. abs_ev_vars => abe_mono) ~ abe_poly , abe_prags :: TcSpecPrags -- ^ SPECIALISE pragmas } | XABExport !(XXABExport p) -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnPattern', -- 'GHC.Parser.Annotation.AnnEqual','GHC.Parser.Annotation.AnnLarrow', -- 'GHC.Parser.Annotation.AnnWhere','GHC.Parser.Annotation.AnnOpen' @'{'@, -- 'GHC.Parser.Annotation.AnnClose' @'}'@, -- For details on above see note [exact print annotations] in GHC.Parser.Annotation -- | Pattern Synonym binding data PatSynBind idL idR = PSB { psb_ext :: XPSB idL idR, -- ^ Post renaming, FVs. -- See Note [Bind free vars] psb_id :: LIdP idL, -- ^ Name of the pattern synonym psb_args :: HsPatSynDetails idR, -- ^ Formal parameter names psb_def :: LPat idR, -- ^ Right-hand side psb_dir :: HsPatSynDir idR -- ^ Directionality } | XPatSynBind !(XXPatSynBind idL idR) {- Note [AbsBinds] ~~~~~~~~~~~~~~~ The AbsBinds constructor is used in the output of the type checker, to record *typechecked* and *generalised* bindings. Specifically AbsBinds { abs_tvs = tvs , abs_ev_vars = [d1,d2] , abs_exports = [ABE { abe_poly = fp, abe_mono = fm , abe_wrap = fwrap } ABE { slly for g } ] , abs_ev_binds = DBINDS , abs_binds = BIND[fm,gm] } where 'BIND' binds the monomorphic Ids 'fm' and 'gm', means fp = fwrap [/\ tvs. \d1 d2. letrec { DBINDS ] [ ; BIND[fm,gm] } ] [ in fm ] gp = ...same again, with gm instead of fm The 'fwrap' is an impedance-matcher that typically does nothing; see Note [ABExport wrapper]. This is a pretty bad translation, because it duplicates all the bindings. So the desugarer tries to do a better job: fp = /\ [a,b] -> \ [d1,d2] -> case tp [a,b] [d1,d2] of (fm,gm) -> fm ..ditto for gp.. tp = /\ [a,b] -> \ [d1,d2] -> letrec { DBINDS; BIND } in (fm,gm) In general: * abs_tvs are the type variables over which the binding group is generalised * abs_ev_var are the evidence variables (usually dictionaries) over which the binding group is generalised * abs_binds are the monomorphic bindings * abs_ex_binds are the evidence bindings that wrap the abs_binds * abs_exports connects the monomorphic Ids bound by abs_binds with the polymorphic Ids bound by the AbsBinds itself. For example, consider a module M, with this top-level binding, where there is no type signature for M.reverse, M.reverse [] = [] M.reverse (x:xs) = M.reverse xs ++ [x] In Hindley-Milner, a recursive binding is typechecked with the *recursive* uses being *monomorphic*. So after typechecking *and* desugaring we will get something like this M.reverse :: forall a. [a] -> [a] = /\a. letrec reverse :: [a] -> [a] = \xs -> case xs of [] -> [] (x:xs) -> reverse xs ++ [x] in reverse Notice that 'M.reverse' is polymorphic as expected, but there is a local definition for plain 'reverse' which is *monomorphic*. The type variable 'a' scopes over the entire letrec. That's after desugaring. What about after type checking but before desugaring? That's where AbsBinds comes in. It looks like this: AbsBinds { abs_tvs = [a] , abs_ev_vars = [] , abs_exports = [ABE { abe_poly = M.reverse :: forall a. [a] -> [a], , abe_mono = reverse :: [a] -> [a]}] , abs_ev_binds = {} , abs_binds = { reverse :: [a] -> [a] = \xs -> case xs of [] -> [] (x:xs) -> reverse xs ++ [x] } } Here, * abs_tvs says what type variables are abstracted over the binding group, just 'a' in this case. * abs_binds is the *monomorphic* bindings of the group * abs_exports describes how to get the polymorphic Id 'M.reverse' from the monomorphic one 'reverse' Notice that the *original* function (the polymorphic one you thought you were defining) appears in the abe_poly field of the abs_exports. The bindings in abs_binds are for fresh, local, Ids with a *monomorphic* Id. If there is a group of mutually recursive (see Note [Polymorphic recursion]) functions without type signatures, we get one AbsBinds with the monomorphic versions of the bindings in abs_binds, and one element of abe_exports for each variable bound in the mutually recursive group. This is true even for pattern bindings. Example: (f,g) = (\x -> x, f) After type checking we get AbsBinds { abs_tvs = [a] , abs_exports = [ ABE { abe_poly = M.f :: forall a. a -> a , abe_mono = f :: a -> a } , ABE { abe_poly = M.g :: forall a. a -> a , abe_mono = g :: a -> a }] , abs_binds = { (f,g) = (\x -> x, f) } Note [Polymorphic recursion] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider Rec { f x = ...(g ef)... ; g :: forall a. [a] -> [a] ; g y = ...(f eg)... } These bindings /are/ mutually recursive (f calls g, and g calls f). But we can use the type signature for g to break the recursion, like this: 1. Add g :: forall a. [a] -> [a] to the type environment 2. Typecheck the definition of f, all by itself, including generalising it to find its most general type, say f :: forall b. b -> b -> [b] 3. Extend the type environment with that type for f 4. Typecheck the definition of g, all by itself, checking that it has the type claimed by its signature Steps 2 and 4 each generate a separate AbsBinds, so we end up with Rec { AbsBinds { ...for f ... } ; AbsBinds { ...for g ... } } This approach allows both f and to call each other polymorphically, even though only g has a signature. We get an AbsBinds that encompasses multiple source-program bindings only when * Each binding in the group has at least one binder that lacks a user type signature * The group forms a strongly connected component Note [The abs_sig field of AbsBinds] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The abs_sig field supports a couple of special cases for bindings. Consider x :: Num a => (# a, a #) x = (# 3, 4 #) The general desugaring for AbsBinds would give x = /\a. \ ($dNum :: Num a) -> letrec xm = (# fromInteger $dNum 3, fromInteger $dNum 4 #) in xm But that has an illegal let-binding for an unboxed tuple. In this case we'd prefer to generate the (more direct) x = /\ a. \ ($dNum :: Num a) -> (# fromInteger $dNum 3, fromInteger $dNum 4 #) A similar thing happens with representation-polymorphic defns (#11405): undef :: forall (r :: RuntimeRep) (a :: TYPE r). HasCallStack => a undef = error "undef" Again, the vanilla desugaring gives a local let-binding for a representation-polymorphic (undefm :: a), which is illegal. But again we can desugar without a let: undef = /\ a. \ (d:HasCallStack) -> error a d "undef" The abs_sig field supports this direct desugaring, with no local let-binding. When abs_sig = True * the abs_binds is single FunBind * the abs_exports is a singleton * we have a complete type sig for binder and hence the abs_binds is non-recursive (it binds the mono_id but refers to the poly_id These properties are exploited in GHC.HsToCore.Binds.dsAbsBinds to generate code without a let-binding. Note [ABExport wrapper] ~~~~~~~~~~~~~~~~~~~~~~~ Consider (f,g) = (\x.x, \y.y) This ultimately desugars to something like this: tup :: forall a b. (a->a, b->b) tup = /\a b. (\x:a.x, \y:b.y) f :: forall a. a -> a f = /\a. case tup a Any of (fm::a->a,gm:Any->Any) -> fm ...similarly for g... The abe_wrap field deals with impedance-matching between (/\a b. case tup a b of { (f,g) -> f }) and the thing we really want, which may have fewer type variables. The action happens in GHC.Tc.Gen.Bind.mkExport. Note [Bind free vars] ~~~~~~~~~~~~~~~~~~~~~ The bind_fvs field of FunBind and PatBind records the free variables of the definition. It is used for the following purposes a) Dependency analysis prior to type checking (see GHC.Tc.Gen.Bind.tc_group) b) Deciding whether we can do generalisation of the binding (see GHC.Tc.Gen.Bind.decideGeneralisationPlan) c) Deciding whether the binding can be used in static forms (see GHC.Tc.Gen.Expr.checkClosedInStaticForm for the HsStatic case and GHC.Tc.Gen.Bind.isClosedBndrGroup). Specifically, * bind_fvs includes all free vars that are defined in this module (including top-level things and lexically scoped type variables) * bind_fvs excludes imported vars; this is just to keep the set smaller * Before renaming, and after typechecking, the field is unused; it's just an error thunk -} {- ************************************************************************ * * Implicit parameter bindings * * ************************************************************************ -} -- | Haskell Implicit Parameter Bindings data HsIPBinds id = IPBinds (XIPBinds id) [LIPBind id] -- TcEvBinds -- Only in typechecker output; binds -- -- uses of the implicit parameters | XHsIPBinds !(XXHsIPBinds id) -- | Located Implicit Parameter Binding type LIPBind id = XRec id (IPBind id) -- ^ May have 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnSemi' when in a -- list -- For details on above see note [exact print annotations] in GHC.Parser.Annotation -- | Implicit parameter bindings. -- -- These bindings start off as (Left "x") in the parser and stay -- that way until after type-checking when they are replaced with -- (Right d), where "d" is the name of the dictionary holding the -- evidence for the implicit parameter. -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnEqual' -- For details on above see note [exact print annotations] in GHC.Parser.Annotation data IPBind id = IPBind (XCIPBind id) (Either (XRec id HsIPName) (IdP id)) (LHsExpr id) | XIPBind !(XXIPBind id) {- ************************************************************************ * * \subsection{@Sig@: type signatures and value-modifying user pragmas} * * ************************************************************************ It is convenient to lump ``value-modifying'' user-pragmas (e.g., ``specialise this function to these four types...'') in with type signatures. Then all the machinery to move them into place, etc., serves for both. -} -- | Located Signature type LSig pass = XRec pass (Sig pass) -- | Signatures and pragmas data Sig pass = -- | An ordinary type signature -- -- > f :: Num a => a -> a -- -- After renaming, this list of Names contains the named -- wildcards brought into scope by this signature. For a signature -- @_ -> _a -> Bool@, the renamer will leave the unnamed wildcard @_@ -- untouched, and the named wildcard @_a@ is then replaced with -- fresh meta vars in the type. Their names are stored in the type -- signature that brought them into scope, in this third field to be -- more specific. -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnDcolon', -- 'GHC.Parser.Annotation.AnnComma' -- For details on above see note [exact print annotations] in GHC.Parser.Annotation TypeSig (XTypeSig pass) [LIdP pass] -- LHS of the signature; e.g. f,g,h :: blah (LHsSigWcType pass) -- RHS of the signature; can have wildcards -- | A pattern synonym type signature -- -- > pattern Single :: () => (Show a) => a -> [a] -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnPattern', -- 'GHC.Parser.Annotation.AnnDcolon','GHC.Parser.Annotation.AnnForall' -- 'GHC.Parser.Annotation.AnnDot','GHC.Parser.Annotation.AnnDarrow' -- For details on above see note [exact print annotations] in GHC.Parser.Annotation | PatSynSig (XPatSynSig pass) [LIdP pass] (LHsSigType pass) -- P :: forall a b. Req => Prov => ty -- | A signature for a class method -- False: ordinary class-method signature -- True: generic-default class method signature -- e.g. class C a where -- op :: a -> a -- Ordinary -- default op :: Eq a => a -> a -- Generic default -- No wildcards allowed here -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnDefault', -- 'GHC.Parser.Annotation.AnnDcolon' | ClassOpSig (XClassOpSig pass) Bool [LIdP pass] (LHsSigType pass) -- | A type signature in generated code, notably the code -- generated for record selectors. We simply record -- the desired Id itself, replete with its name, type -- and IdDetails. Otherwise it's just like a type -- signature: there should be an accompanying binding | IdSig (XIdSig pass) Id -- | An ordinary fixity declaration -- -- > infixl 8 *** -- -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnInfix', -- 'GHC.Parser.Annotation.AnnVal' -- For details on above see note [exact print annotations] in GHC.Parser.Annotation | FixSig (XFixSig pass) (FixitySig pass) -- | An inline pragma -- -- > {#- INLINE f #-} -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : -- 'GHC.Parser.Annotation.AnnOpen' @'{-\# INLINE'@ and @'['@, -- 'GHC.Parser.Annotation.AnnClose','GHC.Parser.Annotation.AnnOpen', -- 'GHC.Parser.Annotation.AnnVal','GHC.Parser.Annotation.AnnTilde', -- 'GHC.Parser.Annotation.AnnClose' -- For details on above see note [exact print annotations] in GHC.Parser.Annotation | InlineSig (XInlineSig pass) (LIdP pass) -- Function name InlinePragma -- Never defaultInlinePragma -- | A specialisation pragma -- -- > {-# SPECIALISE f :: Int -> Int #-} -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen', -- 'GHC.Parser.Annotation.AnnOpen' @'{-\# SPECIALISE'@ and @'['@, -- 'GHC.Parser.Annotation.AnnTilde', -- 'GHC.Parser.Annotation.AnnVal', -- 'GHC.Parser.Annotation.AnnClose' @']'@ and @'\#-}'@, -- 'GHC.Parser.Annotation.AnnDcolon' -- For details on above see note [exact print annotations] in GHC.Parser.Annotation | SpecSig (XSpecSig pass) (LIdP pass) -- Specialise a function or datatype ... [LHsSigType pass] -- ... to these types InlinePragma -- The pragma on SPECIALISE_INLINE form. -- If it's just defaultInlinePragma, then we said -- SPECIALISE, not SPECIALISE_INLINE -- | A specialisation pragma for instance declarations only -- -- > {-# SPECIALISE instance Eq [Int] #-} -- -- (Class tys); should be a specialisation of the -- current instance declaration -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen', -- 'GHC.Parser.Annotation.AnnInstance','GHC.Parser.Annotation.AnnClose' -- For details on above see note [exact print annotations] in GHC.Parser.Annotation | SpecInstSig (XSpecInstSig pass) SourceText (LHsSigType pass) -- Note [Pragma source text] in GHC.Types.SourceText -- | A minimal complete definition pragma -- -- > {-# MINIMAL a | (b, c | (d | e)) #-} -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen', -- 'GHC.Parser.Annotation.AnnVbar','GHC.Parser.Annotation.AnnComma', -- 'GHC.Parser.Annotation.AnnClose' -- For details on above see note [exact print annotations] in GHC.Parser.Annotation | MinimalSig (XMinimalSig pass) SourceText (LBooleanFormula (LIdP pass)) -- Note [Pragma source text] in GHC.Types.SourceText -- | A "set cost centre" pragma for declarations -- -- > {-# SCC funName #-} -- -- or -- -- > {-# SCC funName "cost_centre_name" #-} | SCCFunSig (XSCCFunSig pass) SourceText -- Note [Pragma source text] in GHC.Types.SourceText (LIdP pass) -- Function name (Maybe (XRec pass StringLiteral)) -- | A complete match pragma -- -- > {-# COMPLETE C, D [:: T] #-} -- -- Used to inform the pattern match checker about additional -- complete matchings which, for example, arise from pattern -- synonym definitions. | CompleteMatchSig (XCompleteMatchSig pass) SourceText (XRec pass [LIdP pass]) (Maybe (LIdP pass)) | XSig !(XXSig pass) -- | Located Fixity Signature type LFixitySig pass = XRec pass (FixitySig pass) -- | Fixity Signature data FixitySig pass = FixitySig (XFixitySig pass) [LIdP pass] Fixity | XFixitySig !(XXFixitySig pass) -- | Type checker Specialisation Pragmas -- -- 'TcSpecPrags' conveys @SPECIALISE@ pragmas from the type checker to the desugarer data TcSpecPrags = IsDefaultMethod -- ^ Super-specialised: a default method should -- be macro-expanded at every call site | SpecPrags [LTcSpecPrag] deriving Data -- | Located Type checker Specification Pragmas type LTcSpecPrag = Located TcSpecPrag -- | Type checker Specification Pragma data TcSpecPrag = SpecPrag Id HsWrapper InlinePragma -- ^ The Id to be specialised, a wrapper that specialises the -- polymorphic function, and inlining spec for the specialised function deriving Data noSpecPrags :: TcSpecPrags noSpecPrags = SpecPrags [] hasSpecPrags :: TcSpecPrags -> Bool hasSpecPrags (SpecPrags ps) = not (null ps) hasSpecPrags IsDefaultMethod = False isDefaultMethod :: TcSpecPrags -> Bool isDefaultMethod IsDefaultMethod = True isDefaultMethod (SpecPrags {}) = False isFixityLSig :: forall p. UnXRec p => LSig p -> Bool isFixityLSig (unXRec @p -> FixSig {}) = True isFixityLSig _ = False isTypeLSig :: forall p. UnXRec p => LSig p -> Bool -- Type signatures isTypeLSig (unXRec @p -> TypeSig {}) = True isTypeLSig (unXRec @p -> ClassOpSig {}) = True isTypeLSig (unXRec @p -> IdSig {}) = True isTypeLSig _ = False isSpecLSig :: forall p. UnXRec p => LSig p -> Bool isSpecLSig (unXRec @p -> SpecSig {}) = True isSpecLSig _ = False isSpecInstLSig :: forall p. UnXRec p => LSig p -> Bool isSpecInstLSig (unXRec @p -> SpecInstSig {}) = True isSpecInstLSig _ = False isPragLSig :: forall p. UnXRec p => LSig p -> Bool -- Identifies pragmas isPragLSig (unXRec @p -> SpecSig {}) = True isPragLSig (unXRec @p -> InlineSig {}) = True isPragLSig (unXRec @p -> SCCFunSig {}) = True isPragLSig (unXRec @p -> CompleteMatchSig {}) = True isPragLSig _ = False isInlineLSig :: forall p. UnXRec p => LSig p -> Bool -- Identifies inline pragmas isInlineLSig (unXRec @p -> InlineSig {}) = True isInlineLSig _ = False isMinimalLSig :: forall p. UnXRec p => LSig p -> Bool isMinimalLSig (unXRec @p -> MinimalSig {}) = True isMinimalLSig _ = False isSCCFunSig :: forall p. UnXRec p => LSig p -> Bool isSCCFunSig (unXRec @p -> SCCFunSig {}) = True isSCCFunSig _ = False isCompleteMatchSig :: forall p. UnXRec p => LSig p -> Bool isCompleteMatchSig (unXRec @p -> CompleteMatchSig {} ) = True isCompleteMatchSig _ = False hsSigDoc :: Sig name -> SDoc hsSigDoc (TypeSig {}) = text "type signature" hsSigDoc (PatSynSig {}) = text "pattern synonym signature" hsSigDoc (ClassOpSig _ is_deflt _ _) | is_deflt = text "default type signature" | otherwise = text "class method signature" hsSigDoc (IdSig {}) = text "id signature" hsSigDoc (SpecSig _ _ _ inl) = ppr inl <+> text "pragma" hsSigDoc (InlineSig _ _ prag) = ppr (inlinePragmaSpec prag) <+> text "pragma" hsSigDoc (SpecInstSig _ src _) = pprWithSourceText src empty <+> text "instance pragma" hsSigDoc (FixSig {}) = text "fixity declaration" hsSigDoc (MinimalSig {}) = text "MINIMAL pragma" hsSigDoc (SCCFunSig {}) = text "SCC pragma" hsSigDoc (CompleteMatchSig {}) = text "COMPLETE pragma" hsSigDoc (XSig {}) = text "XSIG TTG extension" {- ************************************************************************ * * \subsection[PatSynBind]{A pattern synonym definition} * * ************************************************************************ -} -- | Haskell Pattern Synonym Details type HsPatSynDetails pass = HsConDetails Void (LIdP pass) [RecordPatSynField pass] -- See Note [Record PatSyn Fields] -- | Record Pattern Synonym Field data RecordPatSynField pass = RecordPatSynField { recordPatSynField :: FieldOcc pass -- ^ Field label visible in rest of the file , recordPatSynPatVar :: LIdP pass -- ^ Filled in by renamer, the name used internally by the pattern } {- Note [Record PatSyn Fields] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider the following two pattern synonyms. pattern P x y = ([x,True], [y,'v']) pattern Q{ x, y } =([x,True], [y,'v']) In P, we just have two local binders, x and y. In Q, we have local binders but also top-level record selectors x :: ([Bool], [Char]) -> Bool y :: ([Bool], [Char]) -> Char Both are recorded in the `RecordPatSynField`s for `x` and `y`: * recordPatSynField: the top-level record selector * recordPatSynPatVar: the local `x`, bound only in the RHS of the pattern synonym. It would make sense to support record-like syntax pattern Q{ x=x1, y=y1 } = ([x1,True], [y1,'v']) when we have a different name for the local and top-level binder, making the distinction between the two names clear. -} instance Outputable (RecordPatSynField a) where ppr (RecordPatSynField { recordPatSynField = v }) = ppr v -- | Haskell Pattern Synonym Direction data HsPatSynDir id = Unidirectional | ImplicitBidirectional | ExplicitBidirectional (MatchGroup id (LHsExpr id))