{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 -} {-# LANGUAGE CPP, DeriveDataTypeable, ScopedTypeVariables #-} {-# LANGUAGE StandaloneDeriving #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow] -- in module GHC.Hs.Extension {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE ExistentialQuantification #-} {-# LANGUAGE DeriveFunctor #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE ViewPatterns #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE TypeFamilyDependencies #-} {-# LANGUAGE LambdaCase #-} {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-} -- | Abstract Haskell syntax for expressions. module GHC.Hs.Expr where #include "HsVersions.h" -- friends: import GHC.Prelude import GHC.Hs.Decls import GHC.Hs.Pat import GHC.Hs.Lit import GHC.Hs.Extension import GHC.Hs.Type import GHC.Hs.Binds -- others: import GHC.Tc.Types.Evidence import GHC.Core import GHC.Types.Name import GHC.Types.Name.Set import GHC.Types.Basic import GHC.Core.ConLike import GHC.Types.SrcLoc import GHC.Unit.Module (ModuleName) import GHC.Utils.Misc import GHC.Utils.Outputable import GHC.Data.FastString import GHC.Core.Type import GHC.Builtin.Types (mkTupleStr) import GHC.Tc.Utils.TcType (TcType) import {-# SOURCE #-} GHC.Tc.Types (TcLclEnv) -- libraries: import Data.Data hiding (Fixity(..)) import qualified Data.Data as Data (Fixity(..)) import qualified Data.Kind import Data.Maybe (isJust) import GHCi.RemoteTypes ( ForeignRef ) import qualified Language.Haskell.TH as TH (Q) {- ************************************************************************ * * \subsection{Expressions proper} * * ************************************************************************ -} -- * Expressions proper -- | Located Haskell Expression type LHsExpr p = Located (HsExpr p) -- ^ May have 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnComma' when -- in a list -- For details on above see note [Api annotations] in GHC.Parser.Annotation ------------------------- -- | Post-Type checking Expression -- -- PostTcExpr is an evidence expression attached to the syntax tree by the -- type checker (c.f. postTcType). type PostTcExpr = HsExpr GhcTc -- | Post-Type checking Table -- -- We use a PostTcTable where there are a bunch of pieces of evidence, more -- than is convenient to keep individually. type PostTcTable = [(Name, PostTcExpr)] ------------------------- {- Note [NoSyntaxExpr] ~~~~~~~~~~~~~~~~~~~~~~ Syntax expressions can be missing (NoSyntaxExprRn or NoSyntaxExprTc) for several reasons: 1. As described in Note [Rebindable if] 2. In order to suppress "not in scope: xyz" messages when a bit of rebindable syntax does not apply. For example, when using an irrefutable pattern in a BindStmt, we don't need a `fail` operator. 3. Rebindable syntax might just not make sense. For example, a BodyStmt contains the syntax for `guard`, but that's used only in monad comprehensions. If we had more of a whiz-bang type system, we might be able to rule this case out statically. -} -- | Syntax Expression -- -- SyntaxExpr is represents the function used in interpreting rebindable -- syntax. In the parser, we have no information to supply; in the renamer, -- we have the name of the function (but see -- Note [Monad fail : Rebindable syntax, overloaded strings] for a wrinkle) -- and in the type-checker we have a more elaborate structure 'SyntaxExprTc'. -- -- In some contexts, rebindable syntax is not implemented, and so we have -- constructors to represent that possibility in both the renamer and -- typechecker instantiations. -- -- E.g. @(>>=)@ is filled in before the renamer by the appropriate 'Name' for -- @(>>=)@, and then instantiated by the type checker with its type args -- etc type family SyntaxExpr p -- Defining SyntaxExpr in two stages allows for better type inference, because -- we can declare SyntaxExprGhc to be injective (and closed). Without injectivity, -- noSyntaxExpr would be ambiguous. type instance SyntaxExpr (GhcPass p) = SyntaxExprGhc p type family SyntaxExprGhc (p :: Pass) = (r :: Data.Kind.Type) | r -> p where SyntaxExprGhc 'Parsed = NoExtField SyntaxExprGhc 'Renamed = SyntaxExprRn SyntaxExprGhc 'Typechecked = SyntaxExprTc -- | The function to use in rebindable syntax. See Note [NoSyntaxExpr]. data SyntaxExprRn = SyntaxExprRn (HsExpr GhcRn) -- Why is the payload not just a Name? -- See Note [Monad fail : Rebindable syntax, overloaded strings] in "GHC.Rename.Expr" | NoSyntaxExprRn -- | An expression with wrappers, used for rebindable syntax -- -- This should desugar to -- -- > syn_res_wrap $ syn_expr (syn_arg_wraps[0] arg0) -- > (syn_arg_wraps[1] arg1) ... -- -- where the actual arguments come from elsewhere in the AST. data SyntaxExprTc = SyntaxExprTc { syn_expr :: HsExpr GhcTc , syn_arg_wraps :: [HsWrapper] , syn_res_wrap :: HsWrapper } | NoSyntaxExprTc -- See Note [NoSyntaxExpr] -- | This is used for rebindable-syntax pieces that are too polymorphic -- for tcSyntaxOp (trS_fmap and the mzip in ParStmt) noExpr :: HsExpr (GhcPass p) noExpr = HsLit noExtField (HsString (SourceText "noExpr") (fsLit "noExpr")) noSyntaxExpr :: forall p. IsPass p => SyntaxExpr (GhcPass p) -- Before renaming, and sometimes after -- See Note [NoSyntaxExpr] noSyntaxExpr = case ghcPass @p of GhcPs -> noExtField GhcRn -> NoSyntaxExprRn GhcTc -> NoSyntaxExprTc -- | Make a 'SyntaxExpr GhcRn' from an expression -- Used only in getMonadFailOp. -- See Note [Monad fail : Rebindable syntax, overloaded strings] in "GHC.Rename.Expr" mkSyntaxExpr :: HsExpr GhcRn -> SyntaxExprRn mkSyntaxExpr = SyntaxExprRn -- | Make a 'SyntaxExpr' from a 'Name' (the "rn" is because this is used in the -- renamer). mkRnSyntaxExpr :: Name -> SyntaxExprRn mkRnSyntaxExpr name = SyntaxExprRn $ HsVar noExtField $ noLoc name instance Outputable SyntaxExprRn where ppr (SyntaxExprRn expr) = ppr expr ppr NoSyntaxExprRn = text "" instance Outputable SyntaxExprTc where ppr (SyntaxExprTc { syn_expr = expr , syn_arg_wraps = arg_wraps , syn_res_wrap = res_wrap }) = sdocOption sdocPrintExplicitCoercions $ \print_co -> getPprDebug $ \debug -> if debug || print_co then ppr expr <> braces (pprWithCommas ppr arg_wraps) <> braces (ppr res_wrap) else ppr expr ppr NoSyntaxExprTc = text "" -- | Command Syntax Table (for Arrow syntax) type CmdSyntaxTable p = [(Name, HsExpr p)] -- See Note [CmdSyntaxTable] {- Note [CmdSyntaxTable] ~~~~~~~~~~~~~~~~~~~~~ Used only for arrow-syntax stuff (HsCmdTop), the CmdSyntaxTable keeps track of the methods needed for a Cmd. * Before the renamer, this list is an empty list * After the renamer, it takes the form @[(std_name, HsVar actual_name)]@ For example, for the 'arr' method * normal case: (GHC.Control.Arrow.arr, HsVar GHC.Control.Arrow.arr) * with rebindable syntax: (GHC.Control.Arrow.arr, arr_22) where @arr_22@ is whatever 'arr' is in scope * After the type checker, it takes the form [(std_name, )] where is the evidence for the method. This evidence is instantiated with the class, but is still polymorphic in everything else. For example, in the case of 'arr', the evidence has type forall b c. (b->c) -> a b c where 'a' is the ambient type of the arrow. This polymorphism is important because the desugarer uses the same evidence at multiple different types. This is Less Cool than what we normally do for rebindable syntax, which is to make fully-instantiated piece of evidence at every use site. The Cmd way is Less Cool because * The renamer has to predict which methods are needed. See the tedious GHC.Rename.Expr.methodNamesCmd. * The desugarer has to know the polymorphic type of the instantiated method. This is checked by Inst.tcSyntaxName, but is less flexible than the rest of rebindable syntax, where the type is less pre-ordained. (And this flexibility is useful; for example we can typecheck do-notation with (>>=) :: m1 a -> (a -> m2 b) -> m2 b.) -} -- | A Haskell expression. data HsExpr p = HsVar (XVar p) (Located (IdP p)) -- ^ Variable -- See Note [Located RdrNames] | HsUnboundVar (XUnboundVar p) OccName -- ^ Unbound variable; also used for "holes" -- (_ or _x). -- Turned from HsVar to HsUnboundVar by the -- renamer, when it finds an out-of-scope -- variable or hole. -- Turned into HsVar by type checker, to support -- deferred type errors. | HsConLikeOut (XConLikeOut p) ConLike -- ^ After typechecker only; must be different -- HsVar for pretty printing | HsRecFld (XRecFld p) (AmbiguousFieldOcc p) -- ^ Variable pointing to record selector -- Not in use after typechecking | HsOverLabel (XOverLabel p) (Maybe (IdP p)) FastString -- ^ Overloaded label (Note [Overloaded labels] in GHC.OverloadedLabels) -- @Just id@ means @RebindableSyntax@ is in use, and gives the id of the -- in-scope 'fromLabel'. -- NB: Not in use after typechecking | HsIPVar (XIPVar p) HsIPName -- ^ Implicit parameter (not in use after typechecking) | HsOverLit (XOverLitE p) (HsOverLit p) -- ^ Overloaded literals | HsLit (XLitE p) (HsLit p) -- ^ Simple (non-overloaded) literals | HsLam (XLam p) (MatchGroup p (LHsExpr p)) -- ^ Lambda abstraction. Currently always a single match -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnLam', -- 'GHC.Parser.Annotation.AnnRarrow', -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsLamCase (XLamCase p) (MatchGroup p (LHsExpr p)) -- ^ Lambda-case -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnLam', -- 'GHC.Parser.Annotation.AnnCase','GHC.Parser.Annotation.AnnOpen', -- 'GHC.Parser.Annotation.AnnClose' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsApp (XApp p) (LHsExpr p) (LHsExpr p) -- ^ Application | HsAppType (XAppTypeE p) -- After typechecking: the type argument (LHsExpr p) (LHsWcType (NoGhcTc p)) -- ^ Visible type application -- -- Explicit type argument; e.g f @Int x y -- NB: Has wildcards, but no implicit quantification -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnAt', -- | Operator applications: -- NB Bracketed ops such as (+) come out as Vars. -- NB We need an expr for the operator in an OpApp/Section since -- the typechecker may need to apply the operator to a few types. | OpApp (XOpApp p) (LHsExpr p) -- left operand (LHsExpr p) -- operator (LHsExpr p) -- right operand -- | Negation operator. Contains the negated expression and the name -- of 'negate' -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnMinus' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | NegApp (XNegApp p) (LHsExpr p) (SyntaxExpr p) -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen' @'('@, -- 'GHC.Parser.Annotation.AnnClose' @')'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsPar (XPar p) (LHsExpr p) -- ^ Parenthesised expr; see Note [Parens in HsSyn] | SectionL (XSectionL p) (LHsExpr p) -- operand; see Note [Sections in HsSyn] (LHsExpr p) -- operator | SectionR (XSectionR p) (LHsExpr p) -- operator; see Note [Sections in HsSyn] (LHsExpr p) -- operand -- | Used for explicit tuples and sections thereof -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen', -- 'GHC.Parser.Annotation.AnnClose' -- For details on above see note [Api annotations] in GHC.Parser.Annotation -- Note [ExplicitTuple] | ExplicitTuple (XExplicitTuple p) [LHsTupArg p] Boxity -- | Used for unboxed sum types -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen' @'(#'@, -- 'GHC.Parser.Annotation.AnnVbar', 'GHC.Parser.Annotation.AnnClose' @'#)'@, -- -- There will be multiple 'GHC.Parser.Annotation.AnnVbar', (1 - alternative) before -- the expression, (arity - alternative) after it | ExplicitSum (XExplicitSum p) ConTag -- Alternative (one-based) Arity -- Sum arity (LHsExpr p) -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnCase', -- 'GHC.Parser.Annotation.AnnOf','GHC.Parser.Annotation.AnnOpen' @'{'@, -- 'GHC.Parser.Annotation.AnnClose' @'}'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsCase (XCase p) (LHsExpr p) (MatchGroup p (LHsExpr p)) -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnIf', -- 'GHC.Parser.Annotation.AnnSemi', -- 'GHC.Parser.Annotation.AnnThen','GHC.Parser.Annotation.AnnSemi', -- 'GHC.Parser.Annotation.AnnElse', -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsIf (XIf p) -- GhcPs: this is a Bool; False <=> do not use -- rebindable syntax (SyntaxExpr p) -- cond function -- NoSyntaxExpr => use the built-in 'if' -- See Note [Rebindable if] (LHsExpr p) -- predicate (LHsExpr p) -- then part (LHsExpr p) -- else part -- | Multi-way if -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnIf' -- 'GHC.Parser.Annotation.AnnOpen','GHC.Parser.Annotation.AnnClose', -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsMultiIf (XMultiIf p) [LGRHS p (LHsExpr p)] -- | let(rec) -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnLet', -- 'GHC.Parser.Annotation.AnnOpen' @'{'@, -- 'GHC.Parser.Annotation.AnnClose' @'}'@,'GHC.Parser.Annotation.AnnIn' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsLet (XLet p) (LHsLocalBinds p) (LHsExpr p) -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnDo', -- 'GHC.Parser.Annotation.AnnOpen', 'GHC.Parser.Annotation.AnnSemi', -- 'GHC.Parser.Annotation.AnnVbar', -- 'GHC.Parser.Annotation.AnnClose' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsDo (XDo p) -- Type of the whole expression (HsStmtContext GhcRn) -- The parameterisation is unimportant -- because in this context we never use -- the PatGuard or ParStmt variant (Located [ExprLStmt p]) -- "do":one or more stmts -- | Syntactic list: [a,b,c,...] -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen' @'['@, -- 'GHC.Parser.Annotation.AnnClose' @']'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation -- See Note [Empty lists] | ExplicitList (XExplicitList p) -- Gives type of components of list (Maybe (SyntaxExpr p)) -- For OverloadedLists, the fromListN witness [LHsExpr p] -- | Record construction -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen' @'{'@, -- 'GHC.Parser.Annotation.AnnDotdot','GHC.Parser.Annotation.AnnClose' @'}'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | RecordCon { rcon_ext :: XRecordCon p , rcon_con_name :: Located (IdP p) -- The constructor name; -- not used after type checking , rcon_flds :: HsRecordBinds p } -- The fields -- | Record update -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen' @'{'@, -- 'GHC.Parser.Annotation.AnnDotdot','GHC.Parser.Annotation.AnnClose' @'}'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | RecordUpd { rupd_ext :: XRecordUpd p , rupd_expr :: LHsExpr p , rupd_flds :: [LHsRecUpdField p] } -- For a type family, the arg types are of the *instance* tycon, -- not the family tycon -- | Expression with an explicit type signature. @e :: type@ -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnDcolon' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | ExprWithTySig (XExprWithTySig p) (LHsExpr p) (LHsSigWcType (NoGhcTc p)) -- | Arithmetic sequence -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen' @'['@, -- 'GHC.Parser.Annotation.AnnComma','GHC.Parser.Annotation.AnnDotdot', -- 'GHC.Parser.Annotation.AnnClose' @']'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | ArithSeq (XArithSeq p) (Maybe (SyntaxExpr p)) -- For OverloadedLists, the fromList witness (ArithSeqInfo p) -- For details on above see note [Api annotations] in GHC.Parser.Annotation ----------------------------------------------------------- -- MetaHaskell Extensions -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen', -- 'GHC.Parser.Annotation.AnnOpenE','GHC.Parser.Annotation.AnnOpenEQ', -- 'GHC.Parser.Annotation.AnnClose','GHC.Parser.Annotation.AnnCloseQ' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsBracket (XBracket p) (HsBracket p) -- See Note [Pending Splices] | HsRnBracketOut (XRnBracketOut p) (HsBracket GhcRn) -- Output of the renamer is the *original* renamed -- expression, plus [PendingRnSplice] -- _renamed_ splices to be type checked | HsTcBracketOut (XTcBracketOut p) (Maybe QuoteWrapper) -- The wrapper to apply type and dictionary argument -- to the quote. (HsBracket GhcRn) -- Output of the type checker is the *original* -- renamed expression, plus [PendingTcSplice] -- _typechecked_ splices to be -- pasted back in by the desugarer -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen', -- 'GHC.Parser.Annotation.AnnClose' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsSpliceE (XSpliceE p) (HsSplice p) ----------------------------------------------------------- -- Arrow notation extension -- | @proc@ notation for Arrows -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnProc', -- 'GHC.Parser.Annotation.AnnRarrow' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsProc (XProc p) (LPat p) -- arrow abstraction, proc (LHsCmdTop p) -- body of the abstraction -- always has an empty stack --------------------------------------- -- static pointers extension -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnStatic', -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsStatic (XStatic p) -- Free variables of the body (LHsExpr p) -- Body --------------------------------------- -- Haskell program coverage (Hpc) Support | HsTick (XTick p) (Tickish (IdP p)) (LHsExpr p) -- sub-expression | HsBinTick (XBinTick p) Int -- module-local tick number for True Int -- module-local tick number for False (LHsExpr p) -- sub-expression --------------------------------------- -- Expressions annotated with pragmas, written as {-# ... #-} | HsPragE (XPragE p) (HsPragE p) (LHsExpr p) | XExpr !(XXExpr p) -- Note [Trees that Grow] extension constructor -- | Extra data fields for a 'RecordCon', added by the type checker data RecordConTc = RecordConTc { rcon_con_like :: ConLike -- The data constructor or pattern synonym , rcon_con_expr :: PostTcExpr -- Instantiated constructor function } -- | Extra data fields for a 'RecordUpd', added by the type checker data RecordUpdTc = RecordUpdTc { rupd_cons :: [ConLike] -- Filled in by the type checker to the -- _non-empty_ list of DataCons that have -- all the upd'd fields , rupd_in_tys :: [Type] -- Argument types of *input* record type , rupd_out_tys :: [Type] -- and *output* record type -- The original type can be reconstructed -- with conLikeResTy , rupd_wrap :: HsWrapper -- See note [Record Update HsWrapper] } -- | HsWrap appears only in typechecker output -- Invariant: The contained Expr is *NOT* itself an HsWrap. -- See Note [Detecting forced eta expansion] in "GHC.HsToCore.Expr". -- This invariant is maintained by 'GHC.Hs.Utils.mkHsWrap'. -- hs_syn is something like HsExpr or HsCmd data HsWrap hs_syn = HsWrap HsWrapper -- the wrapper (hs_syn GhcTc) -- the thing that is wrapped deriving instance (Data (hs_syn GhcTc), Typeable hs_syn) => Data (HsWrap hs_syn) -- --------------------------------------------------------------------- type instance XVar (GhcPass _) = NoExtField type instance XUnboundVar (GhcPass _) = NoExtField type instance XConLikeOut (GhcPass _) = NoExtField type instance XRecFld (GhcPass _) = NoExtField type instance XOverLabel (GhcPass _) = NoExtField type instance XIPVar (GhcPass _) = NoExtField type instance XOverLitE (GhcPass _) = NoExtField type instance XLitE (GhcPass _) = NoExtField type instance XLam (GhcPass _) = NoExtField type instance XLamCase (GhcPass _) = NoExtField type instance XApp (GhcPass _) = NoExtField type instance XAppTypeE GhcPs = NoExtField type instance XAppTypeE GhcRn = NoExtField type instance XAppTypeE GhcTc = Type type instance XOpApp GhcPs = NoExtField type instance XOpApp GhcRn = Fixity type instance XOpApp GhcTc = Fixity type instance XNegApp (GhcPass _) = NoExtField type instance XPar (GhcPass _) = NoExtField type instance XSectionL (GhcPass _) = NoExtField type instance XSectionR (GhcPass _) = NoExtField type instance XExplicitTuple (GhcPass _) = NoExtField type instance XExplicitSum GhcPs = NoExtField type instance XExplicitSum GhcRn = NoExtField type instance XExplicitSum GhcTc = [Type] type instance XCase (GhcPass _) = NoExtField type instance XIf GhcPs = Bool -- True <=> might use rebindable syntax type instance XIf GhcRn = NoExtField type instance XIf GhcTc = NoExtField type instance XMultiIf GhcPs = NoExtField type instance XMultiIf GhcRn = NoExtField type instance XMultiIf GhcTc = Type type instance XLet (GhcPass _) = NoExtField type instance XDo GhcPs = NoExtField type instance XDo GhcRn = NoExtField type instance XDo GhcTc = Type type instance XExplicitList GhcPs = NoExtField type instance XExplicitList GhcRn = NoExtField type instance XExplicitList GhcTc = Type type instance XRecordCon GhcPs = NoExtField type instance XRecordCon GhcRn = NoExtField type instance XRecordCon GhcTc = RecordConTc type instance XRecordUpd GhcPs = NoExtField type instance XRecordUpd GhcRn = NoExtField type instance XRecordUpd GhcTc = RecordUpdTc type instance XExprWithTySig (GhcPass _) = NoExtField type instance XArithSeq GhcPs = NoExtField type instance XArithSeq GhcRn = NoExtField type instance XArithSeq GhcTc = PostTcExpr type instance XBracket (GhcPass _) = NoExtField type instance XRnBracketOut (GhcPass _) = NoExtField type instance XTcBracketOut (GhcPass _) = NoExtField type instance XSpliceE (GhcPass _) = NoExtField type instance XProc (GhcPass _) = NoExtField type instance XStatic GhcPs = NoExtField type instance XStatic GhcRn = NameSet type instance XStatic GhcTc = NameSet type instance XTick (GhcPass _) = NoExtField type instance XBinTick (GhcPass _) = NoExtField type instance XPragE (GhcPass _) = NoExtField type instance XXExpr GhcPs = NoExtCon type instance XXExpr GhcRn = NoExtCon type instance XXExpr GhcTc = HsWrap HsExpr -- --------------------------------------------------------------------- -- | A pragma, written as {-# ... #-}, that may appear within an expression. data HsPragE p = HsPragSCC (XSCC p) SourceText -- Note [Pragma source text] in GHC.Types.Basic StringLiteral -- "set cost centre" SCC pragma -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen' @'{-\# CORE'@, -- 'GHC.Parser.Annotation.AnnVal', 'GHC.Parser.Annotation.AnnClose' @'\#-}'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsPragCore (XCoreAnn p) SourceText -- Note [Pragma source text] in GHC.Types.Basic StringLiteral -- hdaume: core annotation -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen', -- 'GHC.Parser.Annotation.AnnOpen' @'{-\# GENERATED'@, -- 'GHC.Parser.Annotation.AnnVal','GHC.Parser.Annotation.AnnVal', -- 'GHC.Parser.Annotation.AnnColon','GHC.Parser.Annotation.AnnVal', -- 'GHC.Parser.Annotation.AnnMinus', -- 'GHC.Parser.Annotation.AnnVal','GHC.Parser.Annotation.AnnColon', -- 'GHC.Parser.Annotation.AnnVal', -- 'GHC.Parser.Annotation.AnnClose' @'\#-}'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsPragTick -- A pragma introduced tick (XTickPragma p) SourceText -- Note [Pragma source text] in GHC.Types.Basic (StringLiteral,(Int,Int),(Int,Int)) -- external span for this tick ((SourceText,SourceText),(SourceText,SourceText)) -- Source text for the four integers used in the span. -- See note [Pragma source text] in GHC.Types.Basic | XHsPragE !(XXPragE p) type instance XSCC (GhcPass _) = NoExtField type instance XCoreAnn (GhcPass _) = NoExtField type instance XTickPragma (GhcPass _) = NoExtField type instance XXPragE (GhcPass _) = NoExtCon -- | Located Haskell Tuple Argument -- -- 'HsTupArg' is used for tuple sections -- @(,a,)@ is represented by -- @ExplicitTuple [Missing ty1, Present a, Missing ty3]@ -- Which in turn stands for @(\x:ty1 \y:ty2. (x,a,y))@ type LHsTupArg id = Located (HsTupArg id) -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnComma' -- For details on above see note [Api annotations] in GHC.Parser.Annotation -- | Haskell Tuple Argument data HsTupArg id = Present (XPresent id) (LHsExpr id) -- ^ The argument | Missing (XMissing id) -- ^ The argument is missing, but this is its type | XTupArg !(XXTupArg id) -- ^ Note [Trees that Grow] extension point type instance XPresent (GhcPass _) = NoExtField type instance XMissing GhcPs = NoExtField type instance XMissing GhcRn = NoExtField type instance XMissing GhcTc = Scaled Type type instance XXTupArg (GhcPass _) = NoExtCon tupArgPresent :: LHsTupArg id -> Bool tupArgPresent (L _ (Present {})) = True tupArgPresent (L _ (Missing {})) = False tupArgPresent (L _ (XTupArg {})) = False {- Note [Parens in HsSyn] ~~~~~~~~~~~~~~~~~~~~~~ HsPar (and ParPat in patterns, HsParTy in types) is used as follows * HsPar is required; the pretty printer does not add parens. * HsPars are respected when rearranging operator fixities. So a * (b + c) means what it says (where the parens are an HsPar) * For ParPat and HsParTy the pretty printer does add parens but this should be a no-op for ParsedSource, based on the pretty printer round trip feature introduced in https://phabricator.haskell.org/rGHC499e43824bda967546ebf95ee33ec1f84a114a7c * ParPat and HsParTy are pretty printed as '( .. )' regardless of whether or not they are strictly necessary. This should be addressed when #13238 is completed, to be treated the same as HsPar. Note [Sections in HsSyn] ~~~~~~~~~~~~~~~~~~~~~~~~ Sections should always appear wrapped in an HsPar, thus HsPar (SectionR ...) The parser parses sections in a wider variety of situations (See Note [Parsing sections]), but the renamer checks for those parens. This invariant makes pretty-printing easier; we don't need a special case for adding the parens round sections. Note [Rebindable if] ~~~~~~~~~~~~~~~~~~~~ The rebindable syntax for 'if' is a bit special, because when rebindable syntax is *off* we do not want to treat (if c then t else e) as if it was an application (ifThenElse c t e). Why not? Because we allow an 'if' to return *unboxed* results, thus if blah then 3# else 4# whereas that would not be possible using a all to a polymorphic function (because you can't call a polymorphic function at an unboxed type). So we use NoSyntaxExpr to mean "use the old built-in typing rule". A further complication is that, in the `deriving` code, we never want to use rebindable syntax. So, even in GhcPs, we want to denote whether to use rebindable syntax or not. This is done via the type instance for XIf GhcPs. Note [Record Update HsWrapper] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ There is a wrapper in RecordUpd which is used for the *required* constraints for pattern synonyms. This wrapper is created in the typechecking and is then directly used in the desugaring without modification. For example, if we have the record pattern synonym P, pattern P :: (Show a) => a -> Maybe a pattern P{x} = Just x foo = (Just True) { x = False } then `foo` desugars to something like foo = case Just True of P x -> P False hence we need to provide the correct dictionaries to P's matcher on the RHS so that we can build the expression. Note [Located RdrNames] ~~~~~~~~~~~~~~~~~~~~~~~ A number of syntax elements have seemingly redundant locations attached to them. This is deliberate, to allow transformations making use of the API Annotations to easily correlate a Located Name in the RenamedSource with a Located RdrName in the ParsedSource. There are unfortunately enough differences between the ParsedSource and the RenamedSource that the API Annotations cannot be used directly with RenamedSource, so this allows a simple mapping to be used based on the location. Note [ExplicitTuple] ~~~~~~~~~~~~~~~~~~~~ An ExplicitTuple is never just a data constructor like (,,,). That is, the `[LHsTupArg p]` argument of `ExplicitTuple` has at least one `Present` member (and is thus never empty). A tuple data constructor like () or (,,,) is parsed as an `HsVar`, not an `ExplicitTuple`, and stays that way. This is important for two reasons: 1. We don't need -XTupleSections for (,,,) 2. The type variables in (,,,) can be instantiated with visible type application. That is, (,,) :: forall a b c. a -> b -> c -> (a,b,c) (True,,) :: forall {b} {c}. b -> c -> (Bool,b,c) Note that the tuple section has *inferred* arguments, while the data constructor has *specified* ones. (See Note [Required, Specified, and Inferred for types] in GHC.Tc.TyCl for background.) Sadly, the grammar for this is actually ambiguous, and it's only thanks to the preference of a shift in a shift/reduce conflict that the parser works as this Note details. Search for a reference to this Note in GHC.Parser for further explanation. Note [Empty lists] ~~~~~~~~~~~~~~~~~~ An empty list could be considered either a data constructor (stored with HsVar) or an ExplicitList. This Note describes how empty lists flow through the various phases and why. Parsing ------- An empty list is parsed by the sysdcon nonterminal. It thus comes to life via HsVar nilDataCon (defined in GHC.Builtin.Types). A freshly-parsed (HsExpr GhcPs) empty list is never a ExplicitList. Renaming -------- If -XOverloadedLists is enabled, we must type-check the empty list as if it were a call to fromListN. (This is true regardless of the setting of -XRebindableSyntax.) This is very easy if the empty list is an ExplicitList, but an annoying special case if it's an HsVar. So the renamer changes a HsVar nilDataCon to an ExplicitList [], but only if -XOverloadedLists is on. (Why not always? Read on, dear friend.) This happens in the HsVar case of rnExpr. Type-checking ------------- We want to accept an expression like [] @Int. To do this, we must infer that [] :: forall a. [a]. This is easy if [] is a HsVar with the right DataCon inside. However, the type-checking for explicit lists works differently: [x,y,z] is never polymorphic. Instead, we unify the types of x, y, and z together, and use the unified type as the argument to the cons and nil constructors. Thus, treating [] as an empty ExplicitList in the type-checker would prevent [] @Int from working. However, if -XOverloadedLists is on, then [] @Int really shouldn't be allowed: it's just like fromListN 0 [] @Int. Since fromListN :: forall list. IsList list => Int -> [Item list] -> list that expression really should be rejected. Thus, the renamer's behaviour is exactly what we want: treat [] as a datacon when -XNoOverloadedLists, and as an empty ExplicitList when -XOverloadedLists. See also #13680, which requested [] @Int to work. -} instance (OutputableBndrId p) => Outputable (HsExpr (GhcPass p)) where ppr expr = pprExpr expr ----------------------- -- pprExpr, pprLExpr, pprBinds call pprDeeper; -- the underscore versions do not pprLExpr :: (OutputableBndrId p) => LHsExpr (GhcPass p) -> SDoc pprLExpr (L _ e) = pprExpr e pprExpr :: (OutputableBndrId p) => HsExpr (GhcPass p) -> SDoc pprExpr e | isAtomicHsExpr e || isQuietHsExpr e = ppr_expr e | otherwise = pprDeeper (ppr_expr e) isQuietHsExpr :: HsExpr id -> Bool -- Parentheses do display something, but it gives little info and -- if we go deeper when we go inside them then we get ugly things -- like (...) isQuietHsExpr (HsPar {}) = True -- applications don't display anything themselves isQuietHsExpr (HsApp {}) = True isQuietHsExpr (HsAppType {}) = True isQuietHsExpr (OpApp {}) = True isQuietHsExpr _ = False pprBinds :: (OutputableBndrId idL, OutputableBndrId idR) => HsLocalBindsLR (GhcPass idL) (GhcPass idR) -> SDoc pprBinds b = pprDeeper (ppr b) ----------------------- ppr_lexpr :: (OutputableBndrId p) => LHsExpr (GhcPass p) -> SDoc ppr_lexpr e = ppr_expr (unLoc e) ppr_expr :: forall p. (OutputableBndrId p) => HsExpr (GhcPass p) -> SDoc ppr_expr (HsVar _ (L _ v)) = pprPrefixOcc v ppr_expr (HsUnboundVar _ uv)= pprPrefixOcc uv ppr_expr (HsConLikeOut _ c) = pprPrefixOcc c ppr_expr (HsIPVar _ v) = ppr v ppr_expr (HsOverLabel _ _ l)= char '#' <> ppr l ppr_expr (HsLit _ lit) = ppr lit ppr_expr (HsOverLit _ lit) = ppr lit ppr_expr (HsPar _ e) = parens (ppr_lexpr e) ppr_expr (HsPragE _ prag e) = sep [ppr prag, ppr_lexpr e] ppr_expr e@(HsApp {}) = ppr_apps e [] ppr_expr e@(HsAppType {}) = ppr_apps e [] ppr_expr (OpApp _ e1 op e2) | Just pp_op <- ppr_infix_expr (unLoc op) = pp_infixly pp_op | otherwise = pp_prefixly where pp_e1 = pprDebugParendExpr opPrec e1 -- In debug mode, add parens pp_e2 = pprDebugParendExpr opPrec e2 -- to make precedence clear pp_prefixly = hang (ppr op) 2 (sep [pp_e1, pp_e2]) pp_infixly pp_op = hang pp_e1 2 (sep [pp_op, nest 2 pp_e2]) ppr_expr (NegApp _ e _) = char '-' <+> pprDebugParendExpr appPrec e ppr_expr (SectionL _ expr op) | Just pp_op <- ppr_infix_expr (unLoc op) = pp_infixly pp_op | otherwise = pp_prefixly where pp_expr = pprDebugParendExpr opPrec expr pp_prefixly = hang (hsep [text " \\ x_ ->", ppr op]) 4 (hsep [pp_expr, text "x_ )"]) pp_infixly v = (sep [pp_expr, v]) ppr_expr (SectionR _ op expr) | Just pp_op <- ppr_infix_expr (unLoc op) = pp_infixly pp_op | otherwise = pp_prefixly where pp_expr = pprDebugParendExpr opPrec expr pp_prefixly = hang (hsep [text "( \\ x_ ->", ppr op, text "x_"]) 4 (pp_expr <> rparen) pp_infixly v = sep [v, pp_expr] ppr_expr (ExplicitTuple _ exprs boxity) -- Special-case unary boxed tuples so that they are pretty-printed as -- `Solo x`, not `(x)` | [L _ (Present _ expr)] <- exprs , Boxed <- boxity = hsep [text (mkTupleStr Boxed 1), ppr expr] | otherwise = tupleParens (boxityTupleSort boxity) (fcat (ppr_tup_args $ map unLoc exprs)) where ppr_tup_args [] = [] ppr_tup_args (Present _ e : es) = (ppr_lexpr e <> punc es) : ppr_tup_args es ppr_tup_args (Missing _ : es) = punc es : ppr_tup_args es punc (Present {} : _) = comma <> space punc (Missing {} : _) = comma punc (XTupArg {} : _) = comma <> space punc [] = empty ppr_expr (ExplicitSum _ alt arity expr) = text "(#" <+> ppr_bars (alt - 1) <+> ppr expr <+> ppr_bars (arity - alt) <+> text "#)" where ppr_bars n = hsep (replicate n (char '|')) ppr_expr (HsLam _ matches) = pprMatches matches ppr_expr (HsLamCase _ matches) = sep [ sep [text "\\case"], nest 2 (pprMatches matches) ] ppr_expr (HsCase _ expr matches@(MG { mg_alts = L _ [_] })) = sep [ sep [text "case", nest 4 (ppr expr), ptext (sLit "of {")], nest 2 (pprMatches matches) <+> char '}'] ppr_expr (HsCase _ expr matches) = sep [ sep [text "case", nest 4 (ppr expr), ptext (sLit "of")], nest 2 (pprMatches matches) ] ppr_expr (HsIf _ _ e1 e2 e3) = sep [hsep [text "if", nest 2 (ppr e1), ptext (sLit "then")], nest 4 (ppr e2), text "else", nest 4 (ppr e3)] ppr_expr (HsMultiIf _ alts) = hang (text "if") 3 (vcat (map ppr_alt alts)) where ppr_alt (L _ (GRHS _ guards expr)) = hang vbar 2 (ppr_one one_alt) where ppr_one [] = panic "ppr_exp HsMultiIf" ppr_one (h:t) = hang h 2 (sep t) one_alt = [ interpp'SP guards , text "->" <+> pprDeeper (ppr expr) ] ppr_alt (L _ (XGRHS x)) = ppr x -- special case: let ... in let ... ppr_expr (HsLet _ (L _ binds) expr@(L _ (HsLet _ _ _))) = sep [hang (text "let") 2 (hsep [pprBinds binds, ptext (sLit "in")]), ppr_lexpr expr] ppr_expr (HsLet _ (L _ binds) expr) = sep [hang (text "let") 2 (pprBinds binds), hang (text "in") 2 (ppr expr)] ppr_expr (HsDo _ do_or_list_comp (L _ stmts)) = pprDo do_or_list_comp stmts ppr_expr (ExplicitList _ _ exprs) = brackets (pprDeeperList fsep (punctuate comma (map ppr_lexpr exprs))) ppr_expr (RecordCon { rcon_con_name = con_id, rcon_flds = rbinds }) = hang (ppr con_id) 2 (ppr rbinds) ppr_expr (RecordUpd { rupd_expr = L _ aexp, rupd_flds = rbinds }) = hang (ppr aexp) 2 (braces (fsep (punctuate comma (map ppr rbinds)))) ppr_expr (ExprWithTySig _ expr sig) = hang (nest 2 (ppr_lexpr expr) <+> dcolon) 4 (ppr sig) ppr_expr (ArithSeq _ _ info) = brackets (ppr info) ppr_expr (HsSpliceE _ s) = pprSplice s ppr_expr (HsBracket _ b) = pprHsBracket b ppr_expr (HsRnBracketOut _ e []) = ppr e ppr_expr (HsRnBracketOut _ e ps) = ppr e $$ text "pending(rn)" <+> ppr ps ppr_expr (HsTcBracketOut _ _wrap e []) = ppr e ppr_expr (HsTcBracketOut _ _wrap e ps) = ppr e $$ text "pending(tc)" <+> pprIfTc @p (ppr ps) ppr_expr (HsProc _ pat (L _ (HsCmdTop _ cmd))) = hsep [text "proc", ppr pat, ptext (sLit "->"), ppr cmd] ppr_expr (HsStatic _ e) = hsep [text "static", ppr e] ppr_expr (HsTick _ tickish exp) = pprTicks (ppr exp) $ ppr tickish <+> ppr_lexpr exp ppr_expr (HsBinTick _ tickIdTrue tickIdFalse exp) = pprTicks (ppr exp) $ hcat [text "bintick<", ppr tickIdTrue, text ",", ppr tickIdFalse, text ">(", ppr exp, text ")"] ppr_expr (HsRecFld _ f) = ppr f ppr_expr (XExpr x) = case ghcPass @p of #if __GLASGOW_HASKELL__ < 811 GhcPs -> ppr x GhcRn -> ppr x #endif GhcTc -> case x of HsWrap co_fn e -> pprHsWrapper co_fn (\parens -> if parens then pprExpr e else pprExpr e) ppr_infix_expr :: forall p. (OutputableBndrId p) => HsExpr (GhcPass p) -> Maybe SDoc ppr_infix_expr (HsVar _ (L _ v)) = Just (pprInfixOcc v) ppr_infix_expr (HsConLikeOut _ c) = Just (pprInfixOcc (conLikeName c)) ppr_infix_expr (HsRecFld _ f) = Just (pprInfixOcc f) ppr_infix_expr (HsUnboundVar _ occ) = Just (pprInfixOcc occ) ppr_infix_expr (XExpr x) | GhcTc <- ghcPass @p , HsWrap _ e <- x = ppr_infix_expr e ppr_infix_expr _ = Nothing ppr_apps :: (OutputableBndrId p) => HsExpr (GhcPass p) -> [Either (LHsExpr (GhcPass p)) (LHsWcType (NoGhcTc (GhcPass p)))] -> SDoc ppr_apps (HsApp _ (L _ fun) arg) args = ppr_apps fun (Left arg : args) ppr_apps (HsAppType _ (L _ fun) arg) args = ppr_apps fun (Right arg : args) ppr_apps fun args = hang (ppr_expr fun) 2 (fsep (map pp args)) where pp (Left arg) = ppr arg -- pp (Right (LHsWcTypeX (HsWC { hswc_body = L _ arg }))) -- = char '@' <> pprHsType arg pp (Right arg) = text "@" <> ppr arg pprExternalSrcLoc :: (StringLiteral,(Int,Int),(Int,Int)) -> SDoc pprExternalSrcLoc (StringLiteral _ src,(n1,n2),(n3,n4)) = ppr (src,(n1,n2),(n3,n4)) {- HsSyn records exactly where the user put parens, with HsPar. So generally speaking we print without adding any parens. However, some code is internally generated, and in some places parens are absolutely required; so for these places we use pprParendLExpr (but don't print double parens of course). For operator applications we don't add parens, because the operator fixities should do the job, except in debug mode (-dppr-debug) so we can see the structure of the parse tree. -} pprDebugParendExpr :: (OutputableBndrId p) => PprPrec -> LHsExpr (GhcPass p) -> SDoc pprDebugParendExpr p expr = getPprDebug $ \case True -> pprParendLExpr p expr False -> pprLExpr expr pprParendLExpr :: (OutputableBndrId p) => PprPrec -> LHsExpr (GhcPass p) -> SDoc pprParendLExpr p (L _ e) = pprParendExpr p e pprParendExpr :: (OutputableBndrId p) => PprPrec -> HsExpr (GhcPass p) -> SDoc pprParendExpr p expr | hsExprNeedsParens p expr = parens (pprExpr expr) | otherwise = pprExpr expr -- Using pprLExpr makes sure that we go 'deeper' -- I think that is usually (always?) right -- | @'hsExprNeedsParens' p e@ returns 'True' if the expression @e@ needs -- parentheses under precedence @p@. hsExprNeedsParens :: forall p. IsPass p => PprPrec -> HsExpr (GhcPass p) -> Bool hsExprNeedsParens p = go where go (HsVar{}) = False go (HsUnboundVar{}) = False go (HsConLikeOut{}) = False go (HsIPVar{}) = False go (HsOverLabel{}) = False go (HsLit _ l) = hsLitNeedsParens p l go (HsOverLit _ ol) = hsOverLitNeedsParens p ol go (HsPar{}) = False go (HsApp{}) = p >= appPrec go (HsAppType {}) = p >= appPrec go (OpApp{}) = p >= opPrec go (NegApp{}) = p > topPrec go (SectionL{}) = True go (SectionR{}) = True go (ExplicitTuple{}) = False go (ExplicitSum{}) = False go (HsLam{}) = p > topPrec go (HsLamCase{}) = p > topPrec go (HsCase{}) = p > topPrec go (HsIf{}) = p > topPrec go (HsMultiIf{}) = p > topPrec go (HsLet{}) = p > topPrec go (HsDo _ sc _) | isComprehensionContext sc = False | otherwise = p > topPrec go (ExplicitList{}) = False go (RecordUpd{}) = False go (ExprWithTySig{}) = p >= sigPrec go (ArithSeq{}) = False go (HsPragE{}) = p >= appPrec go (HsSpliceE{}) = False go (HsBracket{}) = False go (HsRnBracketOut{}) = False go (HsTcBracketOut{}) = False go (HsProc{}) = p > topPrec go (HsStatic{}) = p >= appPrec go (HsTick _ _ (L _ e)) = go e go (HsBinTick _ _ _ (L _ e)) = go e go (RecordCon{}) = False go (HsRecFld{}) = False go (XExpr x) | GhcTc <- ghcPass @p , HsWrap _ e <- x = go e | otherwise = True -- | @'parenthesizeHsExpr' p e@ checks if @'hsExprNeedsParens' p e@ is true, -- and if so, surrounds @e@ with an 'HsPar'. Otherwise, it simply returns @e@. parenthesizeHsExpr :: IsPass p => PprPrec -> LHsExpr (GhcPass p) -> LHsExpr (GhcPass p) parenthesizeHsExpr p le@(L loc e) | hsExprNeedsParens p e = L loc (HsPar noExtField le) | otherwise = le stripParensLHsExpr :: LHsExpr (GhcPass p) -> LHsExpr (GhcPass p) stripParensLHsExpr (L _ (HsPar _ e)) = stripParensLHsExpr e stripParensLHsExpr e = e stripParensHsExpr :: HsExpr (GhcPass p) -> HsExpr (GhcPass p) stripParensHsExpr (HsPar _ (L _ e)) = stripParensHsExpr e stripParensHsExpr e = e isAtomicHsExpr :: forall p. IsPass p => HsExpr (GhcPass p) -> Bool -- True of a single token isAtomicHsExpr (HsVar {}) = True isAtomicHsExpr (HsConLikeOut {}) = True isAtomicHsExpr (HsLit {}) = True isAtomicHsExpr (HsOverLit {}) = True isAtomicHsExpr (HsIPVar {}) = True isAtomicHsExpr (HsOverLabel {}) = True isAtomicHsExpr (HsUnboundVar {}) = True isAtomicHsExpr (HsPar _ e) = isAtomicHsExpr (unLoc e) isAtomicHsExpr (HsRecFld{}) = True isAtomicHsExpr (XExpr x) | GhcTc <- ghcPass @p , HsWrap _ e <- x = isAtomicHsExpr e isAtomicHsExpr _ = False instance Outputable (HsPragE (GhcPass p)) where ppr (HsPragCore _ stc (StringLiteral sta s)) = pprWithSourceText stc (text "{-# CORE") <+> pprWithSourceText sta (doubleQuotes $ ftext s) <+> text "#-}" ppr (HsPragSCC _ st (StringLiteral stl lbl)) = pprWithSourceText st (text "{-# SCC") -- no doublequotes if stl empty, for the case where the SCC was written -- without quotes. <+> pprWithSourceText stl (ftext lbl) <+> text "#-}" ppr (HsPragTick _ st (StringLiteral sta s, (v1,v2), (v3,v4)) ((s1,s2),(s3,s4))) = pprWithSourceText st (text "{-# GENERATED") <+> pprWithSourceText sta (doubleQuotes $ ftext s) <+> pprWithSourceText s1 (ppr v1) <+> char ':' <+> pprWithSourceText s2 (ppr v2) <+> char '-' <+> pprWithSourceText s3 (ppr v3) <+> char ':' <+> pprWithSourceText s4 (ppr v4) <+> text "#-}" {- ************************************************************************ * * \subsection{Commands (in arrow abstractions)} * * ************************************************************************ We re-use HsExpr to represent these. -} -- | Located Haskell Command (for arrow syntax) type LHsCmd id = Located (HsCmd id) -- | Haskell Command (e.g. a "statement" in an Arrow proc block) data HsCmd id -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.Annlarrowtail', -- 'GHC.Parser.Annotation.Annrarrowtail','GHC.Parser.Annotation.AnnLarrowtail', -- 'GHC.Parser.Annotation.AnnRarrowtail' -- For details on above see note [Api annotations] in GHC.Parser.Annotation = HsCmdArrApp -- Arrow tail, or arrow application (f -< arg) (XCmdArrApp id) -- type of the arrow expressions f, -- of the form a t t', where arg :: t (LHsExpr id) -- arrow expression, f (LHsExpr id) -- input expression, arg HsArrAppType -- higher-order (-<<) or first-order (-<) Bool -- True => right-to-left (f -< arg) -- False => left-to-right (arg >- f) -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpenB' @'(|'@, -- 'GHC.Parser.Annotation.AnnCloseB' @'|)'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsCmdArrForm -- Command formation, (| e cmd1 .. cmdn |) (XCmdArrForm id) (LHsExpr id) -- The operator. -- After type-checking, a type abstraction to be -- applied to the type of the local environment tuple LexicalFixity -- Whether the operator appeared prefix or infix when -- parsed. (Maybe Fixity) -- fixity (filled in by the renamer), for forms that -- were converted from OpApp's by the renamer [LHsCmdTop id] -- argument commands | HsCmdApp (XCmdApp id) (LHsCmd id) (LHsExpr id) | HsCmdLam (XCmdLam id) (MatchGroup id (LHsCmd id)) -- kappa -- ^ - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnLam', -- 'GHC.Parser.Annotation.AnnRarrow', -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsCmdPar (XCmdPar id) (LHsCmd id) -- parenthesised command -- ^ - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnOpen' @'('@, -- 'GHC.Parser.Annotation.AnnClose' @')'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsCmdCase (XCmdCase id) (LHsExpr id) (MatchGroup id (LHsCmd id)) -- bodies are HsCmd's -- ^ - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnCase', -- 'GHC.Parser.Annotation.AnnOf','GHC.Parser.Annotation.AnnOpen' @'{'@, -- 'GHC.Parser.Annotation.AnnClose' @'}'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsCmdLamCase (XCmdLamCase id) (MatchGroup id (LHsCmd id)) -- bodies are HsCmd's -- ^ - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnLam', -- 'GHC.Parser.Annotation.AnnCase','GHC.Parser.Annotation.AnnOpen' @'{'@, -- 'GHC.Parser.Annotation.AnnClose' @'}'@ -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsCmdIf (XCmdIf id) (SyntaxExpr id) -- cond function (LHsExpr id) -- predicate (LHsCmd id) -- then part (LHsCmd id) -- else part -- ^ - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnIf', -- 'GHC.Parser.Annotation.AnnSemi', -- 'GHC.Parser.Annotation.AnnThen','GHC.Parser.Annotation.AnnSemi', -- 'GHC.Parser.Annotation.AnnElse', -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsCmdLet (XCmdLet id) (LHsLocalBinds id) -- let(rec) (LHsCmd id) -- ^ - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnLet', -- 'GHC.Parser.Annotation.AnnOpen' @'{'@, -- 'GHC.Parser.Annotation.AnnClose' @'}'@,'GHC.Parser.Annotation.AnnIn' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | HsCmdDo (XCmdDo id) -- Type of the whole expression (Located [CmdLStmt id]) -- ^ - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnDo', -- 'GHC.Parser.Annotation.AnnOpen', 'GHC.Parser.Annotation.AnnSemi', -- 'GHC.Parser.Annotation.AnnVbar', -- 'GHC.Parser.Annotation.AnnClose' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | XCmd !(XXCmd id) -- Note [Trees that Grow] extension point type instance XCmdArrApp GhcPs = NoExtField type instance XCmdArrApp GhcRn = NoExtField type instance XCmdArrApp GhcTc = Type type instance XCmdArrForm (GhcPass _) = NoExtField type instance XCmdApp (GhcPass _) = NoExtField type instance XCmdLam (GhcPass _) = NoExtField type instance XCmdPar (GhcPass _) = NoExtField type instance XCmdCase (GhcPass _) = NoExtField type instance XCmdLamCase (GhcPass _) = NoExtField type instance XCmdIf (GhcPass _) = NoExtField type instance XCmdLet (GhcPass _) = NoExtField type instance XCmdDo GhcPs = NoExtField type instance XCmdDo GhcRn = NoExtField type instance XCmdDo GhcTc = Type type instance XCmdWrap (GhcPass _) = NoExtField type instance XXCmd GhcPs = NoExtCon type instance XXCmd GhcRn = NoExtCon type instance XXCmd GhcTc = HsWrap HsCmd -- If cmd :: arg1 --> res -- wrap :: arg1 "->" arg2 -- Then (XCmd (HsWrap wrap cmd)) :: arg2 --> res -- | Haskell Array Application Type data HsArrAppType = HsHigherOrderApp | HsFirstOrderApp deriving Data {- | Top-level command, introducing a new arrow. This may occur inside a proc (where the stack is empty) or as an argument of a command-forming operator. -} -- | Located Haskell Top-level Command type LHsCmdTop p = Located (HsCmdTop p) -- | Haskell Top-level Command data HsCmdTop p = HsCmdTop (XCmdTop p) (LHsCmd p) | XCmdTop !(XXCmdTop p) -- Note [Trees that Grow] extension point data CmdTopTc = CmdTopTc Type -- Nested tuple of inputs on the command's stack Type -- return type of the command (CmdSyntaxTable GhcTc) -- See Note [CmdSyntaxTable] type instance XCmdTop GhcPs = NoExtField type instance XCmdTop GhcRn = CmdSyntaxTable GhcRn -- See Note [CmdSyntaxTable] type instance XCmdTop GhcTc = CmdTopTc type instance XXCmdTop (GhcPass _) = NoExtCon instance (OutputableBndrId p) => Outputable (HsCmd (GhcPass p)) where ppr cmd = pprCmd cmd ----------------------- -- pprCmd and pprLCmd call pprDeeper; -- the underscore versions do not pprLCmd :: (OutputableBndrId p) => LHsCmd (GhcPass p) -> SDoc pprLCmd (L _ c) = pprCmd c pprCmd :: (OutputableBndrId p) => HsCmd (GhcPass p) -> SDoc pprCmd c | isQuietHsCmd c = ppr_cmd c | otherwise = pprDeeper (ppr_cmd c) isQuietHsCmd :: HsCmd id -> Bool -- Parentheses do display something, but it gives little info and -- if we go deeper when we go inside them then we get ugly things -- like (...) isQuietHsCmd (HsCmdPar {}) = True -- applications don't display anything themselves isQuietHsCmd (HsCmdApp {}) = True isQuietHsCmd _ = False ----------------------- ppr_lcmd :: (OutputableBndrId p) => LHsCmd (GhcPass p) -> SDoc ppr_lcmd c = ppr_cmd (unLoc c) ppr_cmd :: forall p. (OutputableBndrId p) => HsCmd (GhcPass p) -> SDoc ppr_cmd (HsCmdPar _ c) = parens (ppr_lcmd c) ppr_cmd (HsCmdApp _ c e) = let (fun, args) = collect_args c [e] in hang (ppr_lcmd fun) 2 (sep (map ppr args)) where collect_args (L _ (HsCmdApp _ fun arg)) args = collect_args fun (arg:args) collect_args fun args = (fun, args) ppr_cmd (HsCmdLam _ matches) = pprMatches matches ppr_cmd (HsCmdCase _ expr matches) = sep [ sep [text "case", nest 4 (ppr expr), ptext (sLit "of")], nest 2 (pprMatches matches) ] ppr_cmd (HsCmdLamCase _ matches) = sep [ text "\\case", nest 2 (pprMatches matches) ] ppr_cmd (HsCmdIf _ _ e ct ce) = sep [hsep [text "if", nest 2 (ppr e), ptext (sLit "then")], nest 4 (ppr ct), text "else", nest 4 (ppr ce)] -- special case: let ... in let ... ppr_cmd (HsCmdLet _ (L _ binds) cmd@(L _ (HsCmdLet {}))) = sep [hang (text "let") 2 (hsep [pprBinds binds, ptext (sLit "in")]), ppr_lcmd cmd] ppr_cmd (HsCmdLet _ (L _ binds) cmd) = sep [hang (text "let") 2 (pprBinds binds), hang (text "in") 2 (ppr cmd)] ppr_cmd (HsCmdDo _ (L _ stmts)) = pprDo ArrowExpr stmts ppr_cmd (HsCmdArrApp _ arrow arg HsFirstOrderApp True) = hsep [ppr_lexpr arrow, larrowt, ppr_lexpr arg] ppr_cmd (HsCmdArrApp _ arrow arg HsFirstOrderApp False) = hsep [ppr_lexpr arg, arrowt, ppr_lexpr arrow] ppr_cmd (HsCmdArrApp _ arrow arg HsHigherOrderApp True) = hsep [ppr_lexpr arrow, larrowtt, ppr_lexpr arg] ppr_cmd (HsCmdArrApp _ arrow arg HsHigherOrderApp False) = hsep [ppr_lexpr arg, arrowtt, ppr_lexpr arrow] ppr_cmd (HsCmdArrForm _ (L _ (HsVar _ (L _ v))) _ (Just _) [arg1, arg2]) = hang (pprCmdArg (unLoc arg1)) 4 (sep [ pprInfixOcc v , pprCmdArg (unLoc arg2)]) ppr_cmd (HsCmdArrForm _ (L _ (HsVar _ (L _ v))) Infix _ [arg1, arg2]) = hang (pprCmdArg (unLoc arg1)) 4 (sep [ pprInfixOcc v , pprCmdArg (unLoc arg2)]) ppr_cmd (HsCmdArrForm _ (L _ (HsConLikeOut _ c)) _ (Just _) [arg1, arg2]) = hang (pprCmdArg (unLoc arg1)) 4 (sep [ pprInfixOcc (conLikeName c) , pprCmdArg (unLoc arg2)]) ppr_cmd (HsCmdArrForm _ (L _ (HsConLikeOut _ c)) Infix _ [arg1, arg2]) = hang (pprCmdArg (unLoc arg1)) 4 (sep [ pprInfixOcc (conLikeName c) , pprCmdArg (unLoc arg2)]) ppr_cmd (HsCmdArrForm _ op _ _ args) = hang (text "(|" <+> ppr_lexpr op) 4 (sep (map (pprCmdArg.unLoc) args) <+> text "|)") ppr_cmd (XCmd x) = case ghcPass @p of #if __GLASGOW_HASKELL__ < 811 GhcPs -> ppr x GhcRn -> ppr x #endif GhcTc -> case x of HsWrap w cmd -> pprHsWrapper w (\_ -> parens (ppr_cmd cmd)) pprCmdArg :: (OutputableBndrId p) => HsCmdTop (GhcPass p) -> SDoc pprCmdArg (HsCmdTop _ cmd) = ppr_lcmd cmd instance (OutputableBndrId p) => Outputable (HsCmdTop (GhcPass p)) where ppr = pprCmdArg {- ************************************************************************ * * \subsection{Record binds} * * ************************************************************************ -} -- | Haskell Record Bindings type HsRecordBinds p = HsRecFields p (LHsExpr p) {- ************************************************************************ * * \subsection{@Match@, @GRHSs@, and @GRHS@ datatypes} * * ************************************************************************ @Match@es are sets of pattern bindings and right hand sides for functions, patterns or case branches. For example, if a function @g@ is defined as: \begin{verbatim} g (x,y) = y g ((x:ys),y) = y+1, \end{verbatim} then \tr{g} has two @Match@es: @(x,y) = y@ and @((x:ys),y) = y+1@. It is always the case that each element of an @[Match]@ list has the same number of @pats@s inside it. This corresponds to saying that a function defined by pattern matching must have the same number of patterns in each equation. -} data MatchGroup p body = MG { mg_ext :: XMG p body -- Post-typechecker, types of args and result , mg_alts :: Located [LMatch p body] -- The alternatives , mg_origin :: Origin } -- The type is the type of the entire group -- t1 -> ... -> tn -> tr -- where there are n patterns | XMatchGroup !(XXMatchGroup p body) data MatchGroupTc = MatchGroupTc { mg_arg_tys :: [Scaled Type] -- Types of the arguments, t1..tn , mg_res_ty :: Type -- Type of the result, tr } deriving Data type instance XMG GhcPs b = NoExtField type instance XMG GhcRn b = NoExtField type instance XMG GhcTc b = MatchGroupTc type instance XXMatchGroup (GhcPass _) b = NoExtCon -- | Located Match type LMatch id body = Located (Match id body) -- ^ May have 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnSemi' when in a -- list -- For details on above see note [Api annotations] in GHC.Parser.Annotation data Match p body = Match { m_ext :: XCMatch p body, m_ctxt :: HsMatchContext (NoGhcTc p), -- See note [m_ctxt in Match] m_pats :: [LPat p], -- The patterns m_grhss :: (GRHSs p body) } | XMatch !(XXMatch p body) type instance XCMatch (GhcPass _) b = NoExtField type instance XXMatch (GhcPass _) b = NoExtCon instance (OutputableBndrId pr, Outputable body) => Outputable (Match (GhcPass pr) body) where ppr = pprMatch {- Note [m_ctxt in Match] ~~~~~~~~~~~~~~~~~~~~~~ A Match can occur in a number of contexts, such as a FunBind, HsCase, HsLam and so on. In order to simplify tooling processing and pretty print output, the provenance is captured in an HsMatchContext. This is particularly important for the API Annotations for a multi-equation FunBind. The parser initially creates a FunBind with a single Match in it for every function definition it sees. These are then grouped together by getMonoBind into a single FunBind, where all the Matches are combined. In the process, all the original FunBind fun_id's bar one are discarded, including the locations. This causes a problem for source to source conversions via API Annotations, so the original fun_ids and infix flags are preserved in the Match, when it originates from a FunBind. Example infix function definition requiring individual API Annotations (&&& ) [] [] = [] xs &&& [] = xs ( &&& ) [] ys = ys -} isInfixMatch :: Match id body -> Bool isInfixMatch match = case m_ctxt match of FunRhs {mc_fixity = Infix} -> True _ -> False isEmptyMatchGroup :: MatchGroup id body -> Bool isEmptyMatchGroup (MG { mg_alts = ms }) = null $ unLoc ms isEmptyMatchGroup (XMatchGroup {}) = False -- | Is there only one RHS in this list of matches? isSingletonMatchGroup :: [LMatch id body] -> Bool isSingletonMatchGroup matches | [L _ match] <- matches , Match { m_grhss = GRHSs { grhssGRHSs = [_] } } <- match = True | otherwise = False matchGroupArity :: MatchGroup (GhcPass id) body -> Arity -- Precondition: MatchGroup is non-empty -- This is called before type checking, when mg_arg_tys is not set matchGroupArity (MG { mg_alts = alts }) | L _ (alt1:_) <- alts = length (hsLMatchPats alt1) | otherwise = panic "matchGroupArity" hsLMatchPats :: LMatch (GhcPass id) body -> [LPat (GhcPass id)] hsLMatchPats (L _ (Match { m_pats = pats })) = pats -- | Guarded Right-Hand Sides -- -- GRHSs are used both for pattern bindings and for Matches -- -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnVbar', -- 'GHC.Parser.Annotation.AnnEqual','GHC.Parser.Annotation.AnnWhere', -- 'GHC.Parser.Annotation.AnnOpen','GHC.Parser.Annotation.AnnClose' -- 'GHC.Parser.Annotation.AnnRarrow','GHC.Parser.Annotation.AnnSemi' -- For details on above see note [Api annotations] in GHC.Parser.Annotation data GRHSs p body = GRHSs { grhssExt :: XCGRHSs p body, grhssGRHSs :: [LGRHS p body], -- ^ Guarded RHSs grhssLocalBinds :: LHsLocalBinds p -- ^ The where clause } | XGRHSs !(XXGRHSs p body) type instance XCGRHSs (GhcPass _) b = NoExtField type instance XXGRHSs (GhcPass _) b = NoExtCon -- | Located Guarded Right-Hand Side type LGRHS id body = Located (GRHS id body) -- | Guarded Right Hand Side. data GRHS p body = GRHS (XCGRHS p body) [GuardLStmt p] -- Guards body -- Right hand side | XGRHS !(XXGRHS p body) type instance XCGRHS (GhcPass _) b = NoExtField type instance XXGRHS (GhcPass _) b = NoExtCon -- We know the list must have at least one @Match@ in it. pprMatches :: (OutputableBndrId idR, Outputable body) => MatchGroup (GhcPass idR) body -> SDoc pprMatches MG { mg_alts = matches } = vcat (map pprMatch (map unLoc (unLoc matches))) -- Don't print the type; it's only a place-holder before typechecking -- Exported to GHC.Hs.Binds, which can't see the defn of HsMatchContext pprFunBind :: (OutputableBndrId idR, Outputable body) => MatchGroup (GhcPass idR) body -> SDoc pprFunBind matches = pprMatches matches -- Exported to GHC.Hs.Binds, which can't see the defn of HsMatchContext pprPatBind :: forall bndr p body. (OutputableBndrId bndr, OutputableBndrId p, Outputable body) => LPat (GhcPass bndr) -> GRHSs (GhcPass p) body -> SDoc pprPatBind pat (grhss) = sep [ppr pat, nest 2 (pprGRHSs (PatBindRhs :: HsMatchContext (GhcPass p)) grhss)] pprMatch :: (OutputableBndrId idR, Outputable body) => Match (GhcPass idR) body -> SDoc pprMatch (Match { m_pats = pats, m_ctxt = ctxt, m_grhss = grhss }) = sep [ sep (herald : map (nest 2 . pprParendLPat appPrec) other_pats) , nest 2 (pprGRHSs ctxt grhss) ] where (herald, other_pats) = case ctxt of FunRhs {mc_fun=L _ fun, mc_fixity=fixity, mc_strictness=strictness} | SrcStrict <- strictness -> ASSERT(null pats) -- A strict variable binding (char '!'<>pprPrefixOcc fun, pats) | Prefix <- fixity -> (pprPrefixOcc fun, pats) -- f x y z = e -- Not pprBndr; the AbsBinds will -- have printed the signature | otherwise -> case pats of (p1:p2:rest) | null rest -> (pp_infix, []) -- x &&& y = e | otherwise -> (parens pp_infix, rest) -- (x &&& y) z = e where pp_infix = pprParendLPat opPrec p1 <+> pprInfixOcc fun <+> pprParendLPat opPrec p2 _ -> pprPanic "pprMatch" (ppr ctxt $$ ppr pats) LambdaExpr -> (char '\\', pats) _ -> case pats of [] -> (empty, []) [pat] -> (ppr pat, []) -- No parens around the single pat in a case _ -> pprPanic "pprMatch" (ppr ctxt $$ ppr pats) pprGRHSs :: (OutputableBndrId idR, Outputable body) => HsMatchContext passL -> GRHSs (GhcPass idR) body -> SDoc pprGRHSs ctxt (GRHSs _ grhss (L _ binds)) = vcat (map (pprGRHS ctxt . unLoc) grhss) -- Print the "where" even if the contents of the binds is empty. Only -- EmptyLocalBinds means no "where" keyword $$ ppUnless (eqEmptyLocalBinds binds) (text "where" $$ nest 4 (pprBinds binds)) pprGRHS :: (OutputableBndrId idR, Outputable body) => HsMatchContext passL -> GRHS (GhcPass idR) body -> SDoc pprGRHS ctxt (GRHS _ [] body) = pp_rhs ctxt body pprGRHS ctxt (GRHS _ guards body) = sep [vbar <+> interpp'SP guards, pp_rhs ctxt body] pp_rhs :: Outputable body => HsMatchContext passL -> body -> SDoc pp_rhs ctxt rhs = matchSeparator ctxt <+> pprDeeper (ppr rhs) {- ************************************************************************ * * \subsection{Do stmts and list comprehensions} * * ************************************************************************ -} -- | Located @do@ block Statement type LStmt id body = Located (StmtLR id id body) -- | Located Statement with separate Left and Right id's type LStmtLR idL idR body = Located (StmtLR idL idR body) -- | @do@ block Statement type Stmt id body = StmtLR id id body -- | Command Located Statement type CmdLStmt id = LStmt id (LHsCmd id) -- | Command Statement type CmdStmt id = Stmt id (LHsCmd id) -- | Expression Located Statement type ExprLStmt id = LStmt id (LHsExpr id) -- | Expression Statement type ExprStmt id = Stmt id (LHsExpr id) -- | Guard Located Statement type GuardLStmt id = LStmt id (LHsExpr id) -- | Guard Statement type GuardStmt id = Stmt id (LHsExpr id) -- | Ghci Located Statement type GhciLStmt id = LStmt id (LHsExpr id) -- | Ghci Statement type GhciStmt id = Stmt id (LHsExpr id) -- The SyntaxExprs in here are used *only* for do-notation and monad -- comprehensions, which have rebindable syntax. Otherwise they are unused. -- | API Annotations when in qualifier lists or guards -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnVbar', -- 'GHC.Parser.Annotation.AnnComma','GHC.Parser.Annotation.AnnThen', -- 'GHC.Parser.Annotation.AnnBy','GHC.Parser.Annotation.AnnBy', -- 'GHC.Parser.Annotation.AnnGroup','GHC.Parser.Annotation.AnnUsing' -- For details on above see note [Api annotations] in GHC.Parser.Annotation data StmtLR idL idR body -- body should always be (LHs**** idR) = LastStmt -- Always the last Stmt in ListComp, MonadComp, -- and (after the renamer, see GHC.Rename.Expr.checkLastStmt) DoExpr, MDoExpr -- Not used for GhciStmtCtxt, PatGuard, which scope over other stuff (XLastStmt idL idR body) body (Maybe Bool) -- Whether return was stripped -- Just True <=> return with a dollar was stripped by ApplicativeDo -- Just False <=> return without a dollar was stripped by ApplicativeDo -- Nothing <=> Nothing was stripped (SyntaxExpr idR) -- The return operator -- The return operator is used only for MonadComp -- For ListComp we use the baked-in 'return' -- For DoExpr, MDoExpr, we don't apply a 'return' at all -- See Note [Monad Comprehensions] -- - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnLarrow' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | BindStmt (XBindStmt idL idR body) -- ^ Post renaming has optional fail and bind / (>>=) operator. -- Post typechecking, also has multiplicity of the argument -- and the result type of the function passed to bind; -- that is, (P, S) in (>>=) :: Q -> (R # P -> S) -> T -- See Note [The type of bind in Stmts] (LPat idL) body -- | 'ApplicativeStmt' represents an applicative expression built with -- '<$>' and '<*>'. It is generated by the renamer, and is desugared into the -- appropriate applicative expression by the desugarer, but it is intended -- to be invisible in error messages. -- -- For full details, see Note [ApplicativeDo] in "GHC.Rename.Expr" -- | ApplicativeStmt (XApplicativeStmt idL idR body) -- Post typecheck, Type of the body [ ( SyntaxExpr idR , ApplicativeArg idL) ] -- [(<$>, e1), (<*>, e2), ..., (<*>, en)] (Maybe (SyntaxExpr idR)) -- 'join', if necessary | BodyStmt (XBodyStmt idL idR body) -- Post typecheck, element type -- of the RHS (used for arrows) body -- See Note [BodyStmt] (SyntaxExpr idR) -- The (>>) operator (SyntaxExpr idR) -- The `guard` operator; used only in MonadComp -- See notes [Monad Comprehensions] -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnLet' -- 'GHC.Parser.Annotation.AnnOpen' @'{'@,'GHC.Parser.Annotation.AnnClose' @'}'@, -- For details on above see note [Api annotations] in GHC.Parser.Annotation | LetStmt (XLetStmt idL idR body) (LHsLocalBindsLR idL idR) -- ParStmts only occur in a list/monad comprehension | ParStmt (XParStmt idL idR body) -- Post typecheck, -- S in (>>=) :: Q -> (R -> S) -> T [ParStmtBlock idL idR] (HsExpr idR) -- Polymorphic `mzip` for monad comprehensions (SyntaxExpr idR) -- The `>>=` operator -- See notes [Monad Comprehensions] -- After renaming, the ids are the binders -- bound by the stmts and used after themp | TransStmt { trS_ext :: XTransStmt idL idR body, -- Post typecheck, -- R in (>>=) :: Q -> (R -> S) -> T trS_form :: TransForm, trS_stmts :: [ExprLStmt idL], -- Stmts to the *left* of the 'group' -- which generates the tuples to be grouped trS_bndrs :: [(IdP idR, IdP idR)], -- See Note [TransStmt binder map] trS_using :: LHsExpr idR, trS_by :: Maybe (LHsExpr idR), -- "by e" (optional) -- Invariant: if trS_form = GroupBy, then grp_by = Just e trS_ret :: SyntaxExpr idR, -- The monomorphic 'return' function for -- the inner monad comprehensions trS_bind :: SyntaxExpr idR, -- The '(>>=)' operator trS_fmap :: HsExpr idR -- The polymorphic 'fmap' function for desugaring -- Only for 'group' forms -- Just a simple HsExpr, because it's -- too polymorphic for tcSyntaxOp } -- See Note [Monad Comprehensions] -- Recursive statement (see Note [How RecStmt works] below) -- | - 'GHC.Parser.Annotation.AnnKeywordId' : 'GHC.Parser.Annotation.AnnRec' -- For details on above see note [Api annotations] in GHC.Parser.Annotation | RecStmt { recS_ext :: XRecStmt idL idR body , recS_stmts :: [LStmtLR idL idR body] -- The next two fields are only valid after renaming , recS_later_ids :: [IdP idR] -- The ids are a subset of the variables bound by the -- stmts that are used in stmts that follow the RecStmt , recS_rec_ids :: [IdP idR] -- Ditto, but these variables are the "recursive" ones, -- that are used before they are bound in the stmts of -- the RecStmt. -- An Id can be in both groups -- Both sets of Ids are (now) treated monomorphically -- See Note [How RecStmt works] for why they are separate -- Rebindable syntax , recS_bind_fn :: SyntaxExpr idR -- The bind function , recS_ret_fn :: SyntaxExpr idR -- The return function , recS_mfix_fn :: SyntaxExpr idR -- The mfix function } | XStmtLR !(XXStmtLR idL idR body) -- Extra fields available post typechecking for RecStmt. data RecStmtTc = RecStmtTc { recS_bind_ty :: Type -- S in (>>=) :: Q -> (R -> S) -> T , recS_later_rets :: [PostTcExpr] -- (only used in the arrow version) , recS_rec_rets :: [PostTcExpr] -- These expressions correspond 1-to-1 -- with recS_later_ids and recS_rec_ids, -- and are the expressions that should be -- returned by the recursion. -- They may not quite be the Ids themselves, -- because the Id may be *polymorphic*, but -- the returned thing has to be *monomorphic*, -- so they may be type applications , recS_ret_ty :: Type -- The type of -- do { stmts; return (a,b,c) } -- With rebindable syntax the type might not -- be quite as simple as (m (tya, tyb, tyc)). } type instance XLastStmt (GhcPass _) (GhcPass _) b = NoExtField type instance XBindStmt (GhcPass _) GhcPs b = NoExtField type instance XBindStmt (GhcPass _) GhcRn b = XBindStmtRn type instance XBindStmt (GhcPass _) GhcTc b = XBindStmtTc data XBindStmtRn = XBindStmtRn { xbsrn_bindOp :: SyntaxExpr GhcRn , xbsrn_failOp :: FailOperator GhcRn } data XBindStmtTc = XBindStmtTc { xbstc_bindOp :: SyntaxExpr GhcTc , xbstc_boundResultType :: Type -- If (>>=) :: Q -> (R -> S) -> T, this is S , xbstc_boundResultMult :: Mult -- If (>>=) :: Q -> (R -> S) -> T, this is S , xbstc_failOp :: FailOperator GhcTc } type instance XApplicativeStmt (GhcPass _) GhcPs b = NoExtField type instance XApplicativeStmt (GhcPass _) GhcRn b = NoExtField type instance XApplicativeStmt (GhcPass _) GhcTc b = Type type instance XBodyStmt (GhcPass _) GhcPs b = NoExtField type instance XBodyStmt (GhcPass _) GhcRn b = NoExtField type instance XBodyStmt (GhcPass _) GhcTc b = Type type instance XLetStmt (GhcPass _) (GhcPass _) b = NoExtField type instance XParStmt (GhcPass _) GhcPs b = NoExtField type instance XParStmt (GhcPass _) GhcRn b = NoExtField type instance XParStmt (GhcPass _) GhcTc b = Type type instance XTransStmt (GhcPass _) GhcPs b = NoExtField type instance XTransStmt (GhcPass _) GhcRn b = NoExtField type instance XTransStmt (GhcPass _) GhcTc b = Type type instance XRecStmt (GhcPass _) GhcPs b = NoExtField type instance XRecStmt (GhcPass _) GhcRn b = NoExtField type instance XRecStmt (GhcPass _) GhcTc b = RecStmtTc type instance XXStmtLR (GhcPass _) (GhcPass _) b = NoExtCon data TransForm -- The 'f' below is the 'using' function, 'e' is the by function = ThenForm -- then f or then f by e (depending on trS_by) | GroupForm -- then group using f or then group by e using f (depending on trS_by) deriving Data -- | Parenthesised Statement Block data ParStmtBlock idL idR = ParStmtBlock (XParStmtBlock idL idR) [ExprLStmt idL] [IdP idR] -- The variables to be returned (SyntaxExpr idR) -- The return operator | XParStmtBlock !(XXParStmtBlock idL idR) type instance XParStmtBlock (GhcPass pL) (GhcPass pR) = NoExtField type instance XXParStmtBlock (GhcPass pL) (GhcPass pR) = NoExtCon -- | The fail operator -- -- This is used for `.. <-` "bind statments" in do notation, including -- non-monadic "binds" in applicative. -- -- The fail operator is 'Just expr' if it potentially fail monadically. if the -- pattern match cannot fail, or shouldn't fail monadically (regular incomplete -- pattern exception), it is 'Nothing'. -- -- See Note [Monad fail : Rebindable syntax, overloaded strings] for the type of -- expression in the 'Just' case, and why it is so. -- -- See Note [Failing pattern matches in Stmts] for which contexts for -- '@BindStmt@'s should use the monadic fail and which shouldn't. type FailOperator id = Maybe (SyntaxExpr id) -- | Applicative Argument data ApplicativeArg idL = ApplicativeArgOne -- A single statement (BindStmt or BodyStmt) { xarg_app_arg_one :: XApplicativeArgOne idL -- ^ The fail operator, after renaming -- -- The fail operator is needed if this is a BindStmt -- where the pattern can fail. E.g.: -- (Just a) <- stmt -- The fail operator will be invoked if the pattern -- match fails. -- It is also used for guards in MonadComprehensions. -- The fail operator is Nothing -- if the pattern match can't fail , app_arg_pattern :: LPat idL -- WildPat if it was a BodyStmt (see below) , arg_expr :: LHsExpr idL , is_body_stmt :: Bool -- ^ True <=> was a BodyStmt, -- False <=> was a BindStmt. -- See Note [Applicative BodyStmt] } | ApplicativeArgMany -- do { stmts; return vars } { xarg_app_arg_many :: XApplicativeArgMany idL , app_stmts :: [ExprLStmt idL] -- stmts , final_expr :: HsExpr idL -- return (v1,..,vn), or just (v1,..,vn) , bv_pattern :: LPat idL -- (v1,...,vn) , stmt_context :: HsStmtContext GhcRn -- context of the do expression -- used in pprArg } | XApplicativeArg !(XXApplicativeArg idL) type instance XApplicativeArgOne GhcPs = NoExtField type instance XApplicativeArgOne GhcRn = FailOperator GhcRn type instance XApplicativeArgOne GhcTc = FailOperator GhcTc type instance XApplicativeArgMany (GhcPass _) = NoExtField type instance XXApplicativeArg (GhcPass _) = NoExtCon {- Note [The type of bind in Stmts] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Some Stmts, notably BindStmt, keep the (>>=) bind operator. We do NOT assume that it has type (>>=) :: m a -> (a -> m b) -> m b In some cases (see #303, #1537) it might have a more exotic type, such as (>>=) :: m i j a -> (a -> m j k b) -> m i k b So we must be careful not to make assumptions about the type. In particular, the monad may not be uniform throughout. Note [TransStmt binder map] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ The [(idR,idR)] in a TransStmt behaves as follows: * Before renaming: [] * After renaming: [ (x27,x27), ..., (z35,z35) ] These are the variables bound by the stmts to the left of the 'group' and used either in the 'by' clause, or in the stmts following the 'group' Each item is a pair of identical variables. * After typechecking: [ (x27:Int, x27:[Int]), ..., (z35:Bool, z35:[Bool]) ] Each pair has the same unique, but different *types*. Note [BodyStmt] ~~~~~~~~~~~~~~~ BodyStmts are a bit tricky, because what they mean depends on the context. Consider the following contexts: A do expression of type (m res_ty) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * BodyStmt E any_ty: do { ....; E; ... } E :: m any_ty Translation: E >> ... A list comprehensions of type [elt_ty] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * BodyStmt E Bool: [ .. | .... E ] [ .. | ..., E, ... ] [ .. | .... | ..., E | ... ] E :: Bool Translation: if E then fail else ... A guard list, guarding a RHS of type rhs_ty ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * BodyStmt E BooParStmtBlockl: f x | ..., E, ... = ...rhs... E :: Bool Translation: if E then fail else ... A monad comprehension of type (m res_ty) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * BodyStmt E Bool: [ .. | .... E ] E :: Bool Translation: guard E >> ... Array comprehensions are handled like list comprehensions. Note [How RecStmt works] ~~~~~~~~~~~~~~~~~~~~~~~~ Example: HsDo [ BindStmt x ex , RecStmt { recS_rec_ids = [a, c] , recS_stmts = [ BindStmt b (return (a,c)) , LetStmt a = ...b... , BindStmt c ec ] , recS_later_ids = [a, b] , return (a b) ] Here, the RecStmt binds a,b,c; but - Only a,b are used in the stmts *following* the RecStmt, - Only a,c are used in the stmts *inside* the RecStmt *before* their bindings Why do we need *both* rec_ids and later_ids? For monads they could be combined into a single set of variables, but not for arrows. That follows from the types of the respective feedback operators: mfix :: MonadFix m => (a -> m a) -> m a loop :: ArrowLoop a => a (b,d) (c,d) -> a b c * For mfix, the 'a' covers the union of the later_ids and the rec_ids * For 'loop', 'c' is the later_ids and 'd' is the rec_ids Note [Typing a RecStmt] ~~~~~~~~~~~~~~~~~~~~~~~ A (RecStmt stmts) types as if you had written (v1,..,vn, _, ..., _) <- mfix (\~(_, ..., _, r1, ..., rm) -> do { stmts ; return (v1,..vn, r1, ..., rm) }) where v1..vn are the later_ids r1..rm are the rec_ids Note [Monad Comprehensions] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Monad comprehensions require separate functions like 'return' and '>>=' for desugaring. These functions are stored in the statements used in monad comprehensions. For example, the 'return' of the 'LastStmt' expression is used to lift the body of the monad comprehension: [ body | stmts ] => stmts >>= \bndrs -> return body In transform and grouping statements ('then ..' and 'then group ..') the 'return' function is required for nested monad comprehensions, for example: [ body | stmts, then f, rest ] => f [ env | stmts ] >>= \bndrs -> [ body | rest ] BodyStmts require the 'Control.Monad.guard' function for boolean expressions: [ body | exp, stmts ] => guard exp >> [ body | stmts ] Parallel statements require the 'Control.Monad.Zip.mzip' function: [ body | stmts1 | stmts2 | .. ] => mzip stmts1 (mzip stmts2 (..)) >>= \(bndrs1, (bndrs2, ..)) -> return body In any other context than 'MonadComp', the fields for most of these 'SyntaxExpr's stay bottom. Note [Applicative BodyStmt] (#12143) For the purposes of ApplicativeDo, we treat any BodyStmt as if it was a BindStmt with a wildcard pattern. For example, do x <- A B return x is transformed as if it were do x <- A _ <- B return x so it transforms to (\(x,_) -> x) <$> A <*> B But we have to remember when we treat a BodyStmt like a BindStmt, because in error messages we want to emit the original syntax the user wrote, not our internal representation. So ApplicativeArgOne has a Bool flag that is True when the original statement was a BodyStmt, so that we can pretty-print it correctly. -} instance (Outputable (StmtLR idL idL (LHsExpr idL)), Outputable (XXParStmtBlock idL idR)) => Outputable (ParStmtBlock idL idR) where ppr (ParStmtBlock _ stmts _ _) = interpp'SP stmts ppr (XParStmtBlock x) = ppr x instance (OutputableBndrId pl, OutputableBndrId pr, Outputable body) => Outputable (StmtLR (GhcPass pl) (GhcPass pr) body) where ppr stmt = pprStmt stmt pprStmt :: forall idL idR body . (OutputableBndrId idL, OutputableBndrId idR, Outputable body) => (StmtLR (GhcPass idL) (GhcPass idR) body) -> SDoc pprStmt (LastStmt _ expr m_dollar_stripped _) = whenPprDebug (text "[last]") <+> (case m_dollar_stripped of Just True -> text "return $" Just False -> text "return" Nothing -> empty) <+> ppr expr pprStmt (BindStmt _ pat expr) = hsep [ppr pat, larrow, ppr expr] pprStmt (LetStmt _ (L _ binds)) = hsep [text "let", pprBinds binds] pprStmt (BodyStmt _ expr _ _) = ppr expr pprStmt (ParStmt _ stmtss _ _) = sep (punctuate (text " | ") (map ppr stmtss)) pprStmt (TransStmt { trS_stmts = stmts, trS_by = by , trS_using = using, trS_form = form }) = sep $ punctuate comma (map ppr stmts ++ [pprTransStmt by using form]) pprStmt (RecStmt { recS_stmts = segment, recS_rec_ids = rec_ids , recS_later_ids = later_ids }) = text "rec" <+> vcat [ ppr_do_stmts segment , whenPprDebug (vcat [ text "rec_ids=" <> ppr rec_ids , text "later_ids=" <> ppr later_ids])] pprStmt (ApplicativeStmt _ args mb_join) = getPprStyle $ \style -> if userStyle style then pp_for_user else pp_debug where -- make all the Applicative stuff invisible in error messages by -- flattening the whole ApplicativeStmt nest back to a sequence -- of statements. pp_for_user = vcat $ concatMap flattenArg args -- ppr directly rather than transforming here, because we need to -- inject a "return" which is hard when we're polymorphic in the id -- type. flattenStmt :: ExprLStmt (GhcPass idL) -> [SDoc] flattenStmt (L _ (ApplicativeStmt _ args _)) = concatMap flattenArg args flattenStmt stmt = [ppr stmt] flattenArg :: forall a . (a, ApplicativeArg (GhcPass idL)) -> [SDoc] flattenArg (_, ApplicativeArgOne _ pat expr isBody) | isBody = -- See Note [Applicative BodyStmt] [ppr (BodyStmt (panic "pprStmt") expr noSyntaxExpr noSyntaxExpr :: ExprStmt (GhcPass idL))] | otherwise = [ppr (BindStmt (panic "pprStmt") pat expr :: ExprStmt (GhcPass idL))] flattenArg (_, ApplicativeArgMany _ stmts _ _ _) = concatMap flattenStmt stmts pp_debug = let ap_expr = sep (punctuate (text " |") (map pp_arg args)) in whenPprDebug (if isJust mb_join then text "[join]" else empty) <+> (if lengthAtLeast args 2 then parens else id) ap_expr pp_arg :: (a, ApplicativeArg (GhcPass idL)) -> SDoc pp_arg (_, applicativeArg) = ppr applicativeArg instance (OutputableBndrId idL) => Outputable (ApplicativeArg (GhcPass idL)) where ppr = pprArg pprArg :: forall idL . (OutputableBndrId idL) => ApplicativeArg (GhcPass idL) -> SDoc pprArg (ApplicativeArgOne _ pat expr isBody) | isBody = -- See Note [Applicative BodyStmt] ppr (BodyStmt (panic "pprStmt") expr noSyntaxExpr noSyntaxExpr :: ExprStmt (GhcPass idL)) | otherwise = ppr (BindStmt (panic "pprStmt") pat expr :: ExprStmt (GhcPass idL)) pprArg (ApplicativeArgMany _ stmts return pat ctxt) = ppr pat <+> text "<-" <+> ppr (HsDo (panic "pprStmt") ctxt (noLoc (stmts ++ [noLoc (LastStmt noExtField (noLoc return) Nothing noSyntaxExpr)]))) pprTransformStmt :: (OutputableBndrId p) => [IdP (GhcPass p)] -> LHsExpr (GhcPass p) -> Maybe (LHsExpr (GhcPass p)) -> SDoc pprTransformStmt bndrs using by = sep [ text "then" <+> whenPprDebug (braces (ppr bndrs)) , nest 2 (ppr using) , nest 2 (pprBy by)] pprTransStmt :: Outputable body => Maybe body -> body -> TransForm -> SDoc pprTransStmt by using ThenForm = sep [ text "then", nest 2 (ppr using), nest 2 (pprBy by)] pprTransStmt by using GroupForm = sep [ text "then group", nest 2 (pprBy by), nest 2 (ptext (sLit "using") <+> ppr using)] pprBy :: Outputable body => Maybe body -> SDoc pprBy Nothing = empty pprBy (Just e) = text "by" <+> ppr e pprDo :: (OutputableBndrId p, Outputable body) => HsStmtContext any -> [LStmt (GhcPass p) body] -> SDoc pprDo (DoExpr m) stmts = ppr_module_name_prefix m <> text "do" <+> ppr_do_stmts stmts pprDo GhciStmtCtxt stmts = text "do" <+> ppr_do_stmts stmts pprDo ArrowExpr stmts = text "do" <+> ppr_do_stmts stmts pprDo (MDoExpr m) stmts = ppr_module_name_prefix m <> text "mdo" <+> ppr_do_stmts stmts pprDo ListComp stmts = brackets $ pprComp stmts pprDo MonadComp stmts = brackets $ pprComp stmts pprDo _ _ = panic "pprDo" -- PatGuard, ParStmtCxt ppr_module_name_prefix :: Maybe ModuleName -> SDoc ppr_module_name_prefix = \case Nothing -> empty Just module_name -> ppr module_name <> char '.' ppr_do_stmts :: (OutputableBndrId idL, OutputableBndrId idR, Outputable body) => [LStmtLR (GhcPass idL) (GhcPass idR) body] -> SDoc -- Print a bunch of do stmts ppr_do_stmts stmts = pprDeeperList vcat (map ppr stmts) pprComp :: (OutputableBndrId p, Outputable body) => [LStmt (GhcPass p) body] -> SDoc pprComp quals -- Prints: body | qual1, ..., qualn | Just (initStmts, L _ (LastStmt _ body _ _)) <- snocView quals = if null initStmts -- If there are no statements in a list comprehension besides the last -- one, we simply treat it like a normal list. This does arise -- occasionally in code that GHC generates, e.g., in implementations of -- 'range' for derived 'Ix' instances for product datatypes with exactly -- one constructor (e.g., see #12583). then ppr body else hang (ppr body <+> vbar) 2 (pprQuals initStmts) | otherwise = pprPanic "pprComp" (pprQuals quals) pprQuals :: (OutputableBndrId p, Outputable body) => [LStmt (GhcPass p) body] -> SDoc -- Show list comprehension qualifiers separated by commas pprQuals quals = interpp'SP quals {- ************************************************************************ * * Template Haskell quotation brackets * * ************************************************************************ -} -- | Haskell Splice data HsSplice id = HsTypedSplice -- $$z or $$(f 4) (XTypedSplice id) SpliceDecoration -- Whether $$( ) variant found, for pretty printing (IdP id) -- A unique name to identify this splice point (LHsExpr id) -- See Note [Pending Splices] | HsUntypedSplice -- $z or $(f 4) (XUntypedSplice id) SpliceDecoration -- Whether $( ) variant found, for pretty printing (IdP id) -- A unique name to identify this splice point (LHsExpr id) -- See Note [Pending Splices] | HsQuasiQuote -- See Note [Quasi-quote overview] in GHC.Tc.Gen.Splice (XQuasiQuote id) (IdP id) -- Splice point (IdP id) -- Quoter SrcSpan -- The span of the enclosed string FastString -- The enclosed string -- AZ:TODO: use XSplice instead of HsSpliced | HsSpliced -- See Note [Delaying modFinalizers in untyped splices] in -- GHC.Rename.Splice. -- This is the result of splicing a splice. It is produced by -- the renamer and consumed by the typechecker. It lives only -- between the two. (XSpliced id) ThModFinalizers -- TH finalizers produced by the splice. (HsSplicedThing id) -- The result of splicing | XSplice !(XXSplice id) -- Note [Trees that Grow] extension point newtype HsSplicedT = HsSplicedT DelayedSplice deriving (Data) type instance XTypedSplice (GhcPass _) = NoExtField type instance XUntypedSplice (GhcPass _) = NoExtField type instance XQuasiQuote (GhcPass _) = NoExtField type instance XSpliced (GhcPass _) = NoExtField type instance XXSplice GhcPs = NoExtCon type instance XXSplice GhcRn = NoExtCon type instance XXSplice GhcTc = HsSplicedT -- | A splice can appear with various decorations wrapped around it. This data -- type captures explicitly how it was originally written, for use in the pretty -- printer. data SpliceDecoration = DollarSplice -- ^ $splice or $$splice | BareSplice -- ^ bare splice deriving (Data, Eq, Show) instance Outputable SpliceDecoration where ppr x = text $ show x isTypedSplice :: HsSplice id -> Bool isTypedSplice (HsTypedSplice {}) = True isTypedSplice _ = False -- Quasi-quotes are untyped splices -- | Finalizers produced by a splice with -- 'Language.Haskell.TH.Syntax.addModFinalizer' -- -- See Note [Delaying modFinalizers in untyped splices] in GHC.Rename.Splice. For how -- this is used. -- newtype ThModFinalizers = ThModFinalizers [ForeignRef (TH.Q ())] -- A Data instance which ignores the argument of 'ThModFinalizers'. instance Data ThModFinalizers where gunfold _ z _ = z $ ThModFinalizers [] toConstr a = mkConstr (dataTypeOf a) "ThModFinalizers" [] Data.Prefix dataTypeOf a = mkDataType "HsExpr.ThModFinalizers" [toConstr a] -- See Note [Running typed splices in the zonker] -- These are the arguments that are passed to `GHC.Tc.Gen.Splice.runTopSplice` data DelayedSplice = DelayedSplice TcLclEnv -- The local environment to run the splice in (LHsExpr GhcRn) -- The original renamed expression TcType -- The result type of running the splice, unzonked (LHsExpr GhcTc) -- The typechecked expression to run and splice in the result -- A Data instance which ignores the argument of 'DelayedSplice'. instance Data DelayedSplice where gunfold _ _ _ = panic "DelayedSplice" toConstr a = mkConstr (dataTypeOf a) "DelayedSplice" [] Data.Prefix dataTypeOf a = mkDataType "HsExpr.DelayedSplice" [toConstr a] -- | Haskell Spliced Thing -- -- Values that can result from running a splice. data HsSplicedThing id = HsSplicedExpr (HsExpr id) -- ^ Haskell Spliced Expression | HsSplicedTy (HsType id) -- ^ Haskell Spliced Type | HsSplicedPat (Pat id) -- ^ Haskell Spliced Pattern -- See Note [Pending Splices] type SplicePointName = Name -- | Pending Renamer Splice data PendingRnSplice = PendingRnSplice UntypedSpliceFlavour SplicePointName (LHsExpr GhcRn) data UntypedSpliceFlavour = UntypedExpSplice | UntypedPatSplice | UntypedTypeSplice | UntypedDeclSplice deriving Data -- | Pending Type-checker Splice data PendingTcSplice = PendingTcSplice SplicePointName (LHsExpr GhcTc) {- Note [Pending Splices] ~~~~~~~~~~~~~~~~~~~~~~ When we rename an untyped bracket, we name and lift out all the nested splices, so that when the typechecker hits the bracket, it can typecheck those nested splices without having to walk over the untyped bracket code. So for example [| f $(g x) |] looks like HsBracket (HsApp (HsVar "f") (HsSpliceE _ (g x))) which the renamer rewrites to HsRnBracketOut (HsApp (HsVar f) (HsSpliceE sn (g x))) [PendingRnSplice UntypedExpSplice sn (g x)] * The 'sn' is the Name of the splice point, the SplicePointName * The PendingRnExpSplice gives the splice that splice-point name maps to; and the typechecker can now conveniently find these sub-expressions * The other copy of the splice, in the second argument of HsSpliceE in the renamed first arg of HsRnBracketOut is used only for pretty printing There are four varieties of pending splices generated by the renamer, distinguished by their UntypedSpliceFlavour * Pending expression splices (UntypedExpSplice), e.g., [|$(f x) + 2|] UntypedExpSplice is also used for * quasi-quotes, where the pending expression expands to $(quoter "...blah...") (see GHC.Rename.Splice.makePending, HsQuasiQuote case) * cross-stage lifting, where the pending expression expands to $(lift x) (see GHC.Rename.Splice.checkCrossStageLifting) * Pending pattern splices (UntypedPatSplice), e.g., [| \$(f x) -> x |] * Pending type splices (UntypedTypeSplice), e.g., [| f :: $(g x) |] * Pending declaration (UntypedDeclSplice), e.g., [| let $(f x) in ... |] There is a fifth variety of pending splice, which is generated by the type checker: * Pending *typed* expression splices, (PendingTcSplice), e.g., [||1 + $$(f 2)||] It would be possible to eliminate HsRnBracketOut and use HsBracketOut for the output of the renamer. However, when pretty printing the output of the renamer, e.g., in a type error message, we *do not* want to print out the pending splices. In contrast, when pretty printing the output of the type checker, we *do* want to print the pending splices. So splitting them up seems to make sense, although I hate to add another constructor to HsExpr. -} instance OutputableBndrId p => Outputable (HsSplicedThing (GhcPass p)) where ppr (HsSplicedExpr e) = ppr_expr e ppr (HsSplicedTy t) = ppr t ppr (HsSplicedPat p) = ppr p instance (OutputableBndrId p) => Outputable (HsSplice (GhcPass p)) where ppr s = pprSplice s pprPendingSplice :: (OutputableBndrId p) => SplicePointName -> LHsExpr (GhcPass p) -> SDoc pprPendingSplice n e = angleBrackets (ppr n <> comma <+> ppr (stripParensLHsExpr e)) pprSpliceDecl :: (OutputableBndrId p) => HsSplice (GhcPass p) -> SpliceExplicitFlag -> SDoc pprSpliceDecl e@HsQuasiQuote{} _ = pprSplice e pprSpliceDecl e ExplicitSplice = text "$" <> ppr_splice_decl e pprSpliceDecl e ImplicitSplice = ppr_splice_decl e ppr_splice_decl :: (OutputableBndrId p) => HsSplice (GhcPass p) -> SDoc ppr_splice_decl (HsUntypedSplice _ _ n e) = ppr_splice empty n e empty ppr_splice_decl e = pprSplice e pprSplice :: forall p. (OutputableBndrId p) => HsSplice (GhcPass p) -> SDoc pprSplice (HsTypedSplice _ DollarSplice n e) = ppr_splice (text "$$") n e empty pprSplice (HsTypedSplice _ BareSplice _ _ ) = panic "Bare typed splice" -- impossible pprSplice (HsUntypedSplice _ DollarSplice n e) = ppr_splice (text "$") n e empty pprSplice (HsUntypedSplice _ BareSplice n e) = ppr_splice empty n e empty pprSplice (HsQuasiQuote _ n q _ s) = ppr_quasi n q s pprSplice (HsSpliced _ _ thing) = ppr thing pprSplice (XSplice x) = case ghcPass @p of #if __GLASGOW_HASKELL__ < 811 GhcPs -> noExtCon x GhcRn -> noExtCon x #endif GhcTc -> case x of HsSplicedT _ -> text "Unevaluated typed splice" ppr_quasi :: OutputableBndr p => p -> p -> FastString -> SDoc ppr_quasi n quoter quote = whenPprDebug (brackets (ppr n)) <> char '[' <> ppr quoter <> vbar <> ppr quote <> text "|]" ppr_splice :: (OutputableBndrId p) => SDoc -> (IdP (GhcPass p)) -> LHsExpr (GhcPass p) -> SDoc -> SDoc ppr_splice herald n e trail = herald <> whenPprDebug (brackets (ppr n)) <> ppr e <> trail -- | Haskell Bracket data HsBracket p = ExpBr (XExpBr p) (LHsExpr p) -- [| expr |] | PatBr (XPatBr p) (LPat p) -- [p| pat |] | DecBrL (XDecBrL p) [LHsDecl p] -- [d| decls |]; result of parser | DecBrG (XDecBrG p) (HsGroup p) -- [d| decls |]; result of renamer | TypBr (XTypBr p) (LHsType p) -- [t| type |] | VarBr (XVarBr p) Bool (IdP p) -- True: 'x, False: ''T -- (The Bool flag is used only in pprHsBracket) | TExpBr (XTExpBr p) (LHsExpr p) -- [|| expr ||] | XBracket !(XXBracket p) -- Note [Trees that Grow] extension point type instance XExpBr (GhcPass _) = NoExtField type instance XPatBr (GhcPass _) = NoExtField type instance XDecBrL (GhcPass _) = NoExtField type instance XDecBrG (GhcPass _) = NoExtField type instance XTypBr (GhcPass _) = NoExtField type instance XVarBr (GhcPass _) = NoExtField type instance XTExpBr (GhcPass _) = NoExtField type instance XXBracket (GhcPass _) = NoExtCon isTypedBracket :: HsBracket id -> Bool isTypedBracket (TExpBr {}) = True isTypedBracket _ = False instance OutputableBndrId p => Outputable (HsBracket (GhcPass p)) where ppr = pprHsBracket pprHsBracket :: (OutputableBndrId p) => HsBracket (GhcPass p) -> SDoc pprHsBracket (ExpBr _ e) = thBrackets empty (ppr e) pprHsBracket (PatBr _ p) = thBrackets (char 'p') (ppr p) pprHsBracket (DecBrG _ gp) = thBrackets (char 'd') (ppr gp) pprHsBracket (DecBrL _ ds) = thBrackets (char 'd') (vcat (map ppr ds)) pprHsBracket (TypBr _ t) = thBrackets (char 't') (ppr t) pprHsBracket (VarBr _ True n) = char '\'' <> pprPrefixOcc n pprHsBracket (VarBr _ False n) = text "''" <> pprPrefixOcc n pprHsBracket (TExpBr _ e) = thTyBrackets (ppr e) thBrackets :: SDoc -> SDoc -> SDoc thBrackets pp_kind pp_body = char '[' <> pp_kind <> vbar <+> pp_body <+> text "|]" thTyBrackets :: SDoc -> SDoc thTyBrackets pp_body = text "[||" <+> pp_body <+> ptext (sLit "||]") instance Outputable PendingRnSplice where ppr (PendingRnSplice _ n e) = pprPendingSplice n e instance Outputable PendingTcSplice where ppr (PendingTcSplice n e) = pprPendingSplice n e {- ************************************************************************ * * \subsection{Enumerations and list comprehensions} * * ************************************************************************ -} -- | Arithmetic Sequence Information data ArithSeqInfo id = From (LHsExpr id) | FromThen (LHsExpr id) (LHsExpr id) | FromTo (LHsExpr id) (LHsExpr id) | FromThenTo (LHsExpr id) (LHsExpr id) (LHsExpr id) -- AZ: Should ArithSeqInfo have a TTG extension? instance OutputableBndrId p => Outputable (ArithSeqInfo (GhcPass p)) where ppr (From e1) = hcat [ppr e1, pp_dotdot] ppr (FromThen e1 e2) = hcat [ppr e1, comma, space, ppr e2, pp_dotdot] ppr (FromTo e1 e3) = hcat [ppr e1, pp_dotdot, ppr e3] ppr (FromThenTo e1 e2 e3) = hcat [ppr e1, comma, space, ppr e2, pp_dotdot, ppr e3] pp_dotdot :: SDoc pp_dotdot = text " .. " {- ************************************************************************ * * \subsection{HsMatchCtxt} * * ************************************************************************ -} -- | Haskell Match Context -- -- Context of a pattern match. This is more subtle than it would seem. See Note -- [Varieties of pattern matches]. data HsMatchContext p = FunRhs { mc_fun :: LIdP p -- ^ function binder of @f@ , mc_fixity :: LexicalFixity -- ^ fixing of @f@ , mc_strictness :: SrcStrictness -- ^ was @f@ banged? -- See Note [FunBind vs PatBind] } -- ^A pattern matching on an argument of a -- function binding | LambdaExpr -- ^Patterns of a lambda | CaseAlt -- ^Patterns and guards on a case alternative | IfAlt -- ^Guards of a multi-way if alternative | ProcExpr -- ^Patterns of a proc | PatBindRhs -- ^A pattern binding eg [y] <- e = e | PatBindGuards -- ^Guards of pattern bindings, e.g., -- (Just b) | Just _ <- x = e -- | otherwise = e' | RecUpd -- ^Record update [used only in GHC.HsToCore.Expr to -- tell matchWrapper what sort of -- runtime error message to generate] | StmtCtxt (HsStmtContext p) -- ^Pattern of a do-stmt, list comprehension, -- pattern guard, etc | ThPatSplice -- ^A Template Haskell pattern splice | ThPatQuote -- ^A Template Haskell pattern quotation [p| (a,b) |] | PatSyn -- ^A pattern synonym declaration instance OutputableBndrId p => Outputable (HsMatchContext (GhcPass p)) where ppr m@(FunRhs{}) = text "FunRhs" <+> ppr (mc_fun m) <+> ppr (mc_fixity m) ppr LambdaExpr = text "LambdaExpr" ppr CaseAlt = text "CaseAlt" ppr IfAlt = text "IfAlt" ppr ProcExpr = text "ProcExpr" ppr PatBindRhs = text "PatBindRhs" ppr PatBindGuards = text "PatBindGuards" ppr RecUpd = text "RecUpd" ppr (StmtCtxt _) = text "StmtCtxt _" ppr ThPatSplice = text "ThPatSplice" ppr ThPatQuote = text "ThPatQuote" ppr PatSyn = text "PatSyn" isPatSynCtxt :: HsMatchContext p -> Bool isPatSynCtxt ctxt = case ctxt of PatSyn -> True _ -> False -- | Haskell Statement Context. data HsStmtContext p = ListComp | MonadComp | DoExpr (Maybe ModuleName) -- ^[ModuleName.]do { ... } | MDoExpr (Maybe ModuleName) -- ^[ModuleName.]mdo { ... } ie recursive do-expression | ArrowExpr -- ^do-notation in an arrow-command context | GhciStmtCtxt -- ^A command-line Stmt in GHCi pat <- rhs | PatGuard (HsMatchContext p) -- ^Pattern guard for specified thing | ParStmtCtxt (HsStmtContext p) -- ^A branch of a parallel stmt | TransStmtCtxt (HsStmtContext p) -- ^A branch of a transform stmt qualifiedDoModuleName_maybe :: HsStmtContext p -> Maybe ModuleName qualifiedDoModuleName_maybe ctxt = case ctxt of DoExpr m -> m MDoExpr m -> m _ -> Nothing isComprehensionContext :: HsStmtContext id -> Bool -- Uses comprehension syntax [ e | quals ] isComprehensionContext ListComp = True isComprehensionContext MonadComp = True isComprehensionContext (ParStmtCtxt c) = isComprehensionContext c isComprehensionContext (TransStmtCtxt c) = isComprehensionContext c isComprehensionContext _ = False -- | Is this a monadic context? isMonadStmtContext :: HsStmtContext id -> Bool isMonadStmtContext MonadComp = True isMonadStmtContext DoExpr{} = True isMonadStmtContext MDoExpr{} = True isMonadStmtContext GhciStmtCtxt = True isMonadStmtContext (ParStmtCtxt ctxt) = isMonadStmtContext ctxt isMonadStmtContext (TransStmtCtxt ctxt) = isMonadStmtContext ctxt isMonadStmtContext _ = False -- ListComp, PatGuard, ArrowExpr isMonadCompContext :: HsStmtContext id -> Bool isMonadCompContext MonadComp = True isMonadCompContext _ = False matchSeparator :: HsMatchContext p -> SDoc matchSeparator (FunRhs {}) = text "=" matchSeparator CaseAlt = text "->" matchSeparator IfAlt = text "->" matchSeparator LambdaExpr = text "->" matchSeparator ProcExpr = text "->" matchSeparator PatBindRhs = text "=" matchSeparator PatBindGuards = text "=" matchSeparator (StmtCtxt _) = text "<-" matchSeparator RecUpd = text "=" -- This can be printed by the pattern -- match checker trace matchSeparator ThPatSplice = panic "unused" matchSeparator ThPatQuote = panic "unused" matchSeparator PatSyn = panic "unused" pprMatchContext :: Outputable (IdP p) => HsMatchContext p -> SDoc pprMatchContext ctxt | want_an ctxt = text "an" <+> pprMatchContextNoun ctxt | otherwise = text "a" <+> pprMatchContextNoun ctxt where want_an (FunRhs {}) = True -- Use "an" in front want_an ProcExpr = True want_an _ = False pprMatchContextNoun :: Outputable (IdP id) => HsMatchContext id -> SDoc pprMatchContextNoun (FunRhs {mc_fun=L _ fun}) = text "equation for" <+> quotes (ppr fun) pprMatchContextNoun CaseAlt = text "case alternative" pprMatchContextNoun IfAlt = text "multi-way if alternative" pprMatchContextNoun RecUpd = text "record-update construct" pprMatchContextNoun ThPatSplice = text "Template Haskell pattern splice" pprMatchContextNoun ThPatQuote = text "Template Haskell pattern quotation" pprMatchContextNoun PatBindRhs = text "pattern binding" pprMatchContextNoun PatBindGuards = text "pattern binding guards" pprMatchContextNoun LambdaExpr = text "lambda abstraction" pprMatchContextNoun ProcExpr = text "arrow abstraction" pprMatchContextNoun (StmtCtxt ctxt) = text "pattern binding in" $$ pprAStmtContext ctxt pprMatchContextNoun PatSyn = text "pattern synonym declaration" ----------------- pprAStmtContext, pprStmtContext :: Outputable (IdP id) => HsStmtContext id -> SDoc pprAStmtContext ctxt = article <+> pprStmtContext ctxt where pp_an = text "an" pp_a = text "a" article = case ctxt of MDoExpr Nothing -> pp_an GhciStmtCtxt -> pp_an _ -> pp_a ----------------- pprStmtContext GhciStmtCtxt = text "interactive GHCi command" pprStmtContext (DoExpr m) = prependQualified m (text "'do' block") pprStmtContext (MDoExpr m) = prependQualified m (text "'mdo' block") pprStmtContext ArrowExpr = text "'do' block in an arrow command" pprStmtContext ListComp = text "list comprehension" pprStmtContext MonadComp = text "monad comprehension" pprStmtContext (PatGuard ctxt) = text "pattern guard for" $$ pprMatchContext ctxt -- Drop the inner contexts when reporting errors, else we get -- Unexpected transform statement -- in a transformed branch of -- transformed branch of -- transformed branch of monad comprehension pprStmtContext (ParStmtCtxt c) = ifPprDebug (sep [text "parallel branch of", pprAStmtContext c]) (pprStmtContext c) pprStmtContext (TransStmtCtxt c) = ifPprDebug (sep [text "transformed branch of", pprAStmtContext c]) (pprStmtContext c) prependQualified :: Maybe ModuleName -> SDoc -> SDoc prependQualified Nothing t = t prependQualified (Just _) t = text "qualified" <+> t instance OutputableBndrId p => Outputable (HsStmtContext (GhcPass p)) where ppr = pprStmtContext -- Used to generate the string for a *runtime* error message matchContextErrString :: OutputableBndrId p => HsMatchContext (GhcPass p) -> SDoc matchContextErrString (FunRhs{mc_fun=L _ fun}) = text "function" <+> ppr fun matchContextErrString CaseAlt = text "case" matchContextErrString IfAlt = text "multi-way if" matchContextErrString PatBindRhs = text "pattern binding" matchContextErrString PatBindGuards = text "pattern binding guards" matchContextErrString RecUpd = text "record update" matchContextErrString LambdaExpr = text "lambda" matchContextErrString ProcExpr = text "proc" matchContextErrString ThPatSplice = panic "matchContextErrString" -- Not used at runtime matchContextErrString ThPatQuote = panic "matchContextErrString" -- Not used at runtime matchContextErrString PatSyn = panic "matchContextErrString" -- Not used at runtime matchContextErrString (StmtCtxt (ParStmtCtxt c)) = matchContextErrString (StmtCtxt c) matchContextErrString (StmtCtxt (TransStmtCtxt c)) = matchContextErrString (StmtCtxt c) matchContextErrString (StmtCtxt (PatGuard _)) = text "pattern guard" matchContextErrString (StmtCtxt GhciStmtCtxt) = text "interactive GHCi command" matchContextErrString (StmtCtxt (DoExpr m)) = prependQualified m (text "'do' block") matchContextErrString (StmtCtxt ArrowExpr) = text "'do' block" matchContextErrString (StmtCtxt (MDoExpr m)) = prependQualified m (text "'mdo' block") matchContextErrString (StmtCtxt ListComp) = text "list comprehension" matchContextErrString (StmtCtxt MonadComp) = text "monad comprehension" pprMatchInCtxt :: (OutputableBndrId idR, Outputable body) => Match (GhcPass idR) body -> SDoc pprMatchInCtxt match = hang (text "In" <+> pprMatchContext (m_ctxt match) <> colon) 4 (pprMatch match) pprStmtInCtxt :: (OutputableBndrId idL, OutputableBndrId idR, Outputable body) => HsStmtContext (GhcPass idL) -> StmtLR (GhcPass idL) (GhcPass idR) body -> SDoc pprStmtInCtxt ctxt (LastStmt _ e _ _) | isComprehensionContext ctxt -- For [ e | .. ], do not mutter about "stmts" = hang (text "In the expression:") 2 (ppr e) pprStmtInCtxt ctxt stmt = hang (text "In a stmt of" <+> pprAStmtContext ctxt <> colon) 2 (ppr_stmt stmt) where -- For Group and Transform Stmts, don't print the nested stmts! ppr_stmt (TransStmt { trS_by = by, trS_using = using , trS_form = form }) = pprTransStmt by using form ppr_stmt stmt = pprStmt stmt