ghc-9.12.3: GHC/Hs/Expr.hs
{-# LANGUAGE CPP #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TypeFamilyDependencies #-}
{-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow]
-- in module Language.Haskell.Syntax.Extension
{-# OPTIONS_GHC -Wno-orphans #-} -- Outputable
{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-}
-- | Abstract Haskell syntax for expressions.
module GHC.Hs.Expr
( module Language.Haskell.Syntax.Expr
, module GHC.Hs.Expr
) where
import Language.Haskell.Syntax.Expr
-- friends:
import GHC.Prelude
import GHC.Hs.Basic() -- import instances
import GHC.Hs.Decls() -- import instances
import GHC.Hs.Pat
import GHC.Hs.Lit
import Language.Haskell.Syntax.Extension
import Language.Haskell.Syntax.Basic (FieldLabelString(..))
import GHC.Hs.Extension
import GHC.Hs.Type
import GHC.Hs.Binds
import GHC.Parser.Annotation
-- others:
import GHC.Tc.Types.Evidence
import GHC.Types.Id.Info ( RecSelParent )
import GHC.Types.Name
import GHC.Types.Name.Reader
import GHC.Types.Name.Set
import GHC.Types.Basic
import GHC.Types.Fixity
import GHC.Types.SourceText
import GHC.Types.SrcLoc
import GHC.Types.Tickish (CoreTickish)
import GHC.Types.Unique.Set (UniqSet)
import GHC.Core.ConLike ( conLikeName, ConLike )
import GHC.Unit.Module (ModuleName)
import GHC.Utils.Misc
import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Data.FastString
import GHC.Core.Type
import GHC.Builtin.Types (mkTupleStr)
import GHC.Tc.Utils.TcType (TcType, TcTyVar)
import {-# SOURCE #-} GHC.Tc.Types.LclEnv (TcLclEnv)
import GHCi.RemoteTypes ( ForeignRef )
import qualified GHC.Boot.TH.Syntax as TH (Q)
-- libraries:
import Data.Data hiding (Fixity(..))
import qualified Data.Data as Data (Fixity(..))
import qualified Data.Kind
import Data.Maybe (isJust)
import Data.Foldable ( toList )
import Data.List.NonEmpty (NonEmpty)
import Data.Void (Void)
{- *********************************************************************
* *
Expressions proper
* *
********************************************************************* -}
-- | 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)]
-------------------------
-- 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 $ fsLit "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 $ noLocA name
instance Outputable SyntaxExprRn where
ppr (SyntaxExprRn expr) = ppr expr
ppr NoSyntaxExprRn = text "<no syntax expr>"
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 "<no syntax expr>"
-- | HsWrap appears only in typechecker output
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)
-- ---------------------------------------------------------------------
data HsBracketTc = HsBracketTc
{ hsb_quote :: HsQuote GhcRn -- See Note [The life cycle of a TH quotation]
, hsb_ty :: Type
, hsb_wrap :: Maybe QuoteWrapper -- The wrapper to apply type and dictionary argument to the quote.
, hsb_splices :: [PendingTcSplice] -- Output of the type checker is the *original*
-- renamed expression, plus
-- _typechecked_ splices to be
-- pasted back in by the desugarer
}
type instance XTypedBracket GhcPs = (BracketAnn (EpToken "[||") (EpToken "[e||"), EpToken "||]")
type instance XTypedBracket GhcRn = NoExtField
type instance XTypedBracket GhcTc = HsBracketTc
type instance XUntypedBracket GhcPs = NoExtField
type instance XUntypedBracket GhcRn = [PendingRnSplice] -- See Note [Pending Splices]
-- Output of the renamer is the *original* renamed expression,
-- plus _renamed_ splices to be type checked
type instance XUntypedBracket GhcTc = HsBracketTc
data BracketAnn noE hasE
= BracketNoE noE
| BracketHasE hasE
deriving Data
instance (NoAnn n, NoAnn h) => NoAnn (BracketAnn n h) where
noAnn = BracketNoE noAnn
-- ---------------------------------------------------------------------
-- API Annotations types
data EpAnnHsCase = EpAnnHsCase
{ hsCaseAnnCase :: EpToken "case"
, hsCaseAnnOf :: EpToken "of"
} deriving Data
instance NoAnn EpAnnHsCase where
noAnn = EpAnnHsCase noAnn noAnn
data EpAnnLam = EpAnnLam
{ epl_lambda :: EpToken "\\" -- ^ Location of '\' keyword
, epl_case :: Maybe EpaLocation -- ^ Location of 'case' or
-- 'cases' keyword, depending
-- on related 'HsLamVariant'.
} deriving Data
instance NoAnn EpAnnLam where
noAnn = EpAnnLam noAnn noAnn
data EpAnnUnboundVar = EpAnnUnboundVar
{ hsUnboundBackquotes :: (EpToken "`", EpToken "`")
, hsUnboundHole :: EpToken "_"
} deriving Data
-- Record selectors at parse time are HsVar; they convert to HsRecSel
-- on renaming.
type instance XRecSel GhcPs = DataConCantHappen
type instance XRecSel GhcRn = NoExtField
type instance XRecSel GhcTc = NoExtField
-- OverLabel not present in GhcTc pass; see GHC.Rename.Expr
-- Note [Handling overloaded and rebindable constructs]
type instance XOverLabel GhcPs = SourceText
type instance XOverLabel GhcRn = SourceText
type instance XOverLabel GhcTc = DataConCantHappen
-- ---------------------------------------------------------------------
type instance XVar (GhcPass _) = NoExtField
type instance XUnboundVar GhcPs = Maybe EpAnnUnboundVar
type instance XUnboundVar GhcRn = NoExtField
type instance XUnboundVar GhcTc = HoleExprRef
-- We really don't need the whole HoleExprRef; just the IORef EvTerm
-- would be enough. But then deriving a Data instance becomes impossible.
-- Much, much easier just to define HoleExprRef with a Data instance and
-- store the whole structure.
type instance XIPVar GhcPs = NoExtField
type instance XIPVar GhcRn = NoExtField
type instance XIPVar GhcTc = DataConCantHappen
type instance XOverLitE (GhcPass _) = NoExtField
type instance XLitE (GhcPass _) = NoExtField
type instance XLam (GhcPass _) = EpAnnLam
type instance XApp (GhcPass _) = NoExtField
type instance XAppTypeE GhcPs = EpToken "@"
type instance XAppTypeE GhcRn = NoExtField
type instance XAppTypeE GhcTc = Type
-- OpApp not present in GhcTc pass; see GHC.Rename.Expr
-- Note [Handling overloaded and rebindable constructs]
type instance XOpApp GhcPs = NoExtField
type instance XOpApp GhcRn = Fixity
type instance XOpApp GhcTc = DataConCantHappen
-- SectionL, SectionR not present in GhcTc pass; see GHC.Rename.Expr
-- Note [Handling overloaded and rebindable constructs]
type instance XSectionL GhcPs = NoExtField
type instance XSectionR GhcPs = NoExtField
type instance XSectionL GhcRn = NoExtField
type instance XSectionR GhcRn = NoExtField
type instance XSectionL GhcTc = DataConCantHappen
type instance XSectionR GhcTc = DataConCantHappen
type instance XNegApp GhcPs = EpToken "-"
type instance XNegApp GhcRn = NoExtField
type instance XNegApp GhcTc = NoExtField
type instance XPar GhcPs = (EpToken "(", EpToken ")")
type instance XPar GhcRn = NoExtField
type instance XPar GhcTc = NoExtField
type instance XExplicitTuple GhcPs = (EpaLocation, EpaLocation)
type instance XExplicitTuple GhcRn = NoExtField
type instance XExplicitTuple GhcTc = NoExtField
type instance XExplicitSum GhcPs = AnnExplicitSum
type instance XExplicitSum GhcRn = NoExtField
type instance XExplicitSum GhcTc = [Type]
type instance XCase GhcPs = EpAnnHsCase
type instance XCase GhcRn = HsMatchContextRn
type instance XCase GhcTc = HsMatchContextRn
type instance XIf GhcPs = AnnsIf
type instance XIf GhcRn = NoExtField
type instance XIf GhcTc = NoExtField
type instance XMultiIf GhcPs = (EpToken "if", EpToken "{", EpToken "}")
type instance XMultiIf GhcRn = NoExtField
type instance XMultiIf GhcTc = Type
type instance XLet GhcPs = (EpToken "let", EpToken "in")
type instance XLet GhcRn = NoExtField
type instance XLet GhcTc = NoExtField
type instance XDo GhcPs = AnnList EpaLocation
type instance XDo GhcRn = NoExtField
type instance XDo GhcTc = Type
type instance XExplicitList GhcPs = AnnList ()
type instance XExplicitList GhcRn = NoExtField
type instance XExplicitList GhcTc = Type
-- GhcPs: ExplicitList includes all source-level
-- list literals, including overloaded ones
-- GhcRn and GhcTc: ExplicitList used only for list literals
-- that denote Haskell's built-in lists. Overloaded lists
-- have been expanded away in the renamer
-- See Note [Handling overloaded and rebindable constructs]
-- in GHC.Rename.Expr
type instance XRecordCon GhcPs = (Maybe (EpToken "{"), Maybe (EpToken "}"))
type instance XRecordCon GhcRn = NoExtField
type instance XRecordCon GhcTc = PostTcExpr -- Instantiated constructor function
type instance XRecordUpd GhcPs = (Maybe (EpToken "{"), Maybe (EpToken "}"))
type instance XRecordUpd GhcRn = NoExtField
type instance XRecordUpd GhcTc = DataConCantHappen
-- We desugar record updates in the typechecker.
-- See [Handling overloaded and rebindable constructs],
-- and [Record Updates] in GHC.Tc.Gen.Expr.
-- | Information about the parent of a record update:
--
-- - the parent type constructor or pattern synonym,
-- - the relevant con-likes,
-- - the field labels.
data family HsRecUpdParent x
data instance HsRecUpdParent GhcPs
data instance HsRecUpdParent GhcRn
= RnRecUpdParent
{ rnRecUpdLabels :: NonEmpty FieldGlobalRdrElt
, rnRecUpdCons :: UniqSet ConLikeName }
data instance HsRecUpdParent GhcTc
= TcRecUpdParent
{ tcRecUpdParent :: RecSelParent
, tcRecUpdLabels :: NonEmpty FieldGlobalRdrElt
, tcRecUpdCons :: UniqSet ConLike }
type instance XLHsRecUpdLabels GhcPs = NoExtField
type instance XLHsRecUpdLabels GhcRn = NonEmpty (HsRecUpdParent GhcRn)
-- Possible parents for the record update.
type instance XLHsRecUpdLabels GhcTc = DataConCantHappen
type instance XLHsOLRecUpdLabels p = NoExtField
type instance XGetField GhcPs = NoExtField
type instance XGetField GhcRn = NoExtField
type instance XGetField GhcTc = DataConCantHappen
-- HsGetField is eliminated by the renamer. See [Handling overloaded
-- and rebindable constructs].
type instance XProjection GhcPs = AnnProjection
type instance XProjection GhcRn = NoExtField
type instance XProjection GhcTc = DataConCantHappen
-- HsProjection is eliminated by the renamer. See [Handling overloaded
-- and rebindable constructs].
type instance XExprWithTySig GhcPs = TokDcolon
type instance XExprWithTySig GhcRn = NoExtField
type instance XExprWithTySig GhcTc = NoExtField
type instance XArithSeq GhcPs = AnnArithSeq
type instance XArithSeq GhcRn = NoExtField
type instance XArithSeq GhcTc = PostTcExpr
type instance XProc (GhcPass _) = (EpToken "proc", TokRarrow)
type instance XStatic GhcPs = EpToken "static"
type instance XStatic GhcRn = NameSet
type instance XStatic GhcTc = (NameSet, Type)
-- Free variables and type of expression, this is stored for convenience as wiring in
-- StaticPtr is a bit tricky (see #20150)
type instance XEmbTy GhcPs = EpToken "type"
type instance XEmbTy GhcRn = NoExtField
type instance XEmbTy GhcTc = DataConCantHappen
-- A free-standing HsEmbTy is an error.
-- Valid usages are immediately desugared into Type.
type instance XForAll GhcPs = NoExtField
type instance XForAll GhcRn = NoExtField
type instance XForAll GhcTc = DataConCantHappen
type instance XQual GhcPs = NoExtField
type instance XQual GhcRn = NoExtField
type instance XQual GhcTc = DataConCantHappen
type instance XFunArr GhcPs = NoExtField
type instance XFunArr GhcRn = NoExtField
type instance XFunArr GhcTc = DataConCantHappen
type instance XPragE (GhcPass _) = NoExtField
type instance XFunRhs = AnnFunRhs
type instance Anno [LocatedA ((StmtLR (GhcPass pl) (GhcPass pr) (LocatedA (body (GhcPass pr)))))] = SrcSpanAnnLW
type instance Anno (StmtLR GhcRn GhcRn (LocatedA (body GhcRn))) = SrcSpanAnnA
arrowToHsExpr :: HsArrowOf (LocatedA (HsExpr GhcRn)) GhcRn -> LocatedA (HsExpr GhcRn)
arrowToHsExpr = expandHsArrow (HsVar noExtField)
data AnnExplicitSum
= AnnExplicitSum {
aesOpen :: EpaLocation,
aesBarsBefore :: [EpToken "|"],
aesBarsAfter :: [EpToken "|"],
aesClose :: EpaLocation
} deriving Data
instance NoAnn AnnExplicitSum where
noAnn = AnnExplicitSum noAnn noAnn noAnn noAnn
data AnnFieldLabel
= AnnFieldLabel {
afDot :: Maybe (EpToken ".")
} deriving Data
instance NoAnn AnnFieldLabel where
noAnn = AnnFieldLabel Nothing
data AnnProjection
= AnnProjection {
apOpen :: EpToken "(",
apClose :: EpToken ")"
} deriving Data
instance NoAnn AnnProjection where
noAnn = AnnProjection noAnn noAnn
data AnnArithSeq
= AnnArithSeq {
aas_open :: EpToken "[",
aas_comma :: Maybe (EpToken ","),
aas_dotdot :: EpToken "..",
aas_close :: EpToken "]"
} deriving Data
instance NoAnn AnnArithSeq where
noAnn = AnnArithSeq noAnn noAnn noAnn noAnn
data AnnsIf
= AnnsIf {
aiIf :: EpToken "if",
aiThen :: EpToken "then",
aiElse :: EpToken "else",
aiThenSemi :: Maybe (EpToken ";"),
aiElseSemi :: Maybe (EpToken ";")
} deriving Data
instance NoAnn AnnsIf where
noAnn = AnnsIf noAnn noAnn noAnn Nothing Nothing
data AnnFunRhs
= AnnFunRhs {
afr_strict :: EpToken "!",
afr_opens :: [EpToken "("],
afr_closes :: [EpToken ")"]
} deriving Data
instance NoAnn AnnFunRhs where
noAnn = AnnFunRhs noAnn noAnn noAnn
-- ---------------------------------------------------------------------
type instance XSCC (GhcPass _) = (AnnPragma, SourceText)
type instance XXPragE (GhcPass _) = DataConCantHappen
type instance XCDotFieldOcc (GhcPass _) = AnnFieldLabel
type instance XXDotFieldOcc (GhcPass _) = DataConCantHappen
type instance XPresent (GhcPass _) = NoExtField
type instance XMissing GhcPs = EpAnn Bool -- True for empty last comma
type instance XMissing GhcRn = NoExtField
type instance XMissing GhcTc = Scaled Type
type instance XXTupArg (GhcPass _) = DataConCantHappen
tupArgPresent :: HsTupArg (GhcPass p) -> Bool
tupArgPresent (Present {}) = True
tupArgPresent (Missing {}) = False
tupArgPresent_maybe :: HsTupArg (GhcPass p) -> Maybe (LHsExpr (GhcPass p))
tupArgPresent_maybe (Present _ e) = Just e
tupArgPresent_maybe (Missing {}) = Nothing
tupArgsPresent_maybe :: [HsTupArg (GhcPass p)] -> Maybe [LHsExpr (GhcPass p)]
tupArgsPresent_maybe = traverse tupArgPresent_maybe
{- *********************************************************************
* *
XXExpr: the extension constructor of HsExpr
* *
********************************************************************* -}
type instance XXExpr GhcPs = DataConCantHappen
type instance XXExpr GhcRn = XXExprGhcRn
type instance XXExpr GhcTc = XXExprGhcTc
-- XXExprGhcRn: see Note [Rebindable syntax and XXExprGhcRn] below
{- *********************************************************************
* *
Generating code for ExpandedThingRn
See Note [Handling overloaded and rebindable constructs]
* *
********************************************************************* -}
-- | The different source constructs that we use to instantiate the "original" field
-- in an `XXExprGhcRn original expansion`
data HsThingRn = OrigExpr (HsExpr GhcRn)
| OrigStmt (ExprLStmt GhcRn)
| OrigPat (LPat GhcRn)
isHsThingRnExpr, isHsThingRnStmt, isHsThingRnPat :: HsThingRn -> Bool
isHsThingRnExpr (OrigExpr{}) = True
isHsThingRnExpr _ = False
isHsThingRnStmt (OrigStmt{}) = True
isHsThingRnStmt _ = False
isHsThingRnPat (OrigPat{}) = True
isHsThingRnPat _ = False
data XXExprGhcRn
= ExpandedThingRn { xrn_orig :: HsThingRn -- The original source thing
, xrn_expanded :: HsExpr GhcRn } -- The compiler generated expanded thing
| PopErrCtxt -- A hint for typechecker to pop
{-# UNPACK #-} !(LHsExpr GhcRn) -- the top of the error context stack
-- Does not presist post renaming phase
-- See Part 3. of Note [Expanding HsDo with XXExprGhcRn]
-- in `GHC.Tc.Gen.Do`
| HsRecSelRn (FieldOcc GhcRn) -- ^ Variable pointing to record selector
-- See Note [Non-overloaded record field selectors] and
-- Note [Record selectors in the AST]
-- | Wrap a located expression with a `PopErrCtxt`
mkPopErrCtxtExpr :: LHsExpr GhcRn -> HsExpr GhcRn
mkPopErrCtxtExpr a = XExpr (PopErrCtxt a)
-- | Wrap a located expression with a PopSrcExpr with an appropriate location
mkPopErrCtxtExprAt :: SrcSpanAnnA -> LHsExpr GhcRn -> LHsExpr GhcRn
mkPopErrCtxtExprAt loc a = L loc $ mkPopErrCtxtExpr a
-- | Build an expression using the extension constructor `XExpr`,
-- and the two components of the expansion: original expression and
-- expanded expressions.
mkExpandedExpr
:: HsExpr GhcRn -- ^ source expression
-> HsExpr GhcRn -- ^ expanded expression
-> HsExpr GhcRn -- ^ suitably wrapped 'XXExprGhcRn'
mkExpandedExpr oExpr eExpr = XExpr (ExpandedThingRn (OrigExpr oExpr) eExpr)
-- | Build an expression using the extension constructor `XExpr`,
-- and the two components of the expansion: original do stmt and
-- expanded expression
mkExpandedStmt
:: ExprLStmt GhcRn -- ^ source statement
-> HsExpr GhcRn -- ^ expanded expression
-> HsExpr GhcRn -- ^ suitably wrapped 'XXExprGhcRn'
mkExpandedStmt oStmt eExpr = XExpr (ExpandedThingRn (OrigStmt oStmt) eExpr)
mkExpandedPatRn
:: LPat GhcRn -- ^ source pattern
-> HsExpr GhcRn -- ^ expanded expression
-> HsExpr GhcRn -- ^ suitably wrapped 'XXExprGhcRn'
mkExpandedPatRn oPat eExpr = XExpr (ExpandedThingRn (OrigPat oPat) eExpr)
-- | Build an expression using the extension constructor `XExpr`,
-- and the two components of the expansion: original do stmt and
-- expanded expression an associate with a provided location
mkExpandedStmtAt
:: SrcSpanAnnA -- ^ Location for the expansion expression
-> ExprLStmt GhcRn -- ^ source statement
-> HsExpr GhcRn -- ^ expanded expression
-> LHsExpr GhcRn -- ^ suitably wrapped located 'XXExprGhcRn'
mkExpandedStmtAt loc oStmt eExpr = L loc $ mkExpandedStmt oStmt eExpr
-- | Wrap the expanded version of the expression with a pop.
mkExpandedStmtPopAt
:: SrcSpanAnnA -- ^ Location for the expansion statement
-> ExprLStmt GhcRn -- ^ source statement
-> HsExpr GhcRn -- ^ expanded expression
-> LHsExpr GhcRn -- ^ suitably wrapped 'XXExprGhcRn'
mkExpandedStmtPopAt loc oStmt eExpr = mkPopErrCtxtExprAt loc $ mkExpandedStmtAt loc oStmt eExpr
data XXExprGhcTc
= WrapExpr -- Type and evidence application and abstractions
HsWrapper (HsExpr GhcTc)
| ExpandedThingTc -- See Note [Rebindable syntax and XXExprGhcRn]
-- See Note [Expanding HsDo with XXExprGhcRn] in `GHC.Tc.Gen.Do`
{ xtc_orig :: HsThingRn -- The original user written thing
, xtc_expanded :: HsExpr GhcTc } -- The expanded typechecked expression
| ConLikeTc -- Result of typechecking a data-con
-- See Note [Typechecking data constructors] in
-- GHC.Tc.Gen.Head
-- The two arguments describe how to eta-expand
-- the data constructor when desugaring
ConLike [TcTyVar] [Scaled TcType]
---------------------------------------
-- Haskell program coverage (Hpc) Support
| HsTick
CoreTickish
(LHsExpr GhcTc) -- sub-expression
| HsBinTick
Int -- module-local tick number for True
Int -- module-local tick number for False
(LHsExpr GhcTc) -- sub-expression
| HsRecSelTc (FieldOcc GhcTc) -- ^ Variable pointing to record selector
-- See Note [Non-overloaded record field selectors] and
-- Note [Record selectors in the AST]
-- | Build a 'XXExprGhcRn' out of an extension constructor,
-- and the two components of the expansion: original and
-- expanded typechecked expressions.
mkExpandedExprTc
:: HsExpr GhcRn -- ^ source expression
-> HsExpr GhcTc -- ^ expanded typechecked expression
-> HsExpr GhcTc -- ^ suitably wrapped 'XXExprGhcRn'
mkExpandedExprTc oExpr eExpr = XExpr (ExpandedThingTc (OrigExpr oExpr) eExpr)
-- | Build a 'XXExprGhcRn' out of an extension constructor.
-- The two components of the expansion are: original statement and
-- expanded typechecked expression.
mkExpandedStmtTc
:: ExprLStmt GhcRn -- ^ source do statement
-> HsExpr GhcTc -- ^ expanded typechecked expression
-> HsExpr GhcTc -- ^ suitably wrapped 'XXExprGhcRn'
mkExpandedStmtTc oStmt eExpr = XExpr (ExpandedThingTc (OrigStmt oStmt) eExpr)
{- *********************************************************************
* *
Pretty-printing expressions
* *
********************************************************************* -}
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 (HsIPVar _ v) = ppr v
ppr_expr (HsOverLabel s l) = case ghcPass @p of
GhcPs -> helper s
GhcRn -> helper s
GhcTc -> dataConCantHappen s
where helper s =
char '#' <> case s of
NoSourceText -> ppr l
SourceText src -> ftext src
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
-- `MkSolo x`, not `(x)`
| [Present _ expr] <- exprs
, Boxed <- boxity
= hsep [text (mkTupleStr Boxed dataName 1), ppr expr]
| otherwise
= tupleParens (boxityTupleSort boxity) (fcat (ppr_tup_args 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 _ lam_variant matches)
= case lam_variant of
LamSingle -> pprMatches matches
_ -> sep [ sep [lamCaseKeyword lam_variant]
, nest 2 (pprMatches matches) ]
ppr_expr (HsCase _ expr matches@(MG { mg_alts = L _ alts }))
= sep [ sep [text "case", nest 4 (ppr expr), text "of"],
pp_alts ]
where
pp_alts | null alts = text "{}"
| otherwise = nest 2 (pprMatches matches)
ppr_expr (HsIf _ e1 e2 e3)
= sep [hsep [text "if", nest 2 (ppr e1), text "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 _ binds expr@(L _ (HsLet _ _ _)))
= sep [hang (text "let") 2 (hsep [pprBinds binds, text "in"]),
ppr_lexpr expr]
ppr_expr (HsLet _ 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 = con, rcon_flds = rbinds })
= hang pp_con 2 (ppr rbinds)
where
-- con :: ConLikeP (GhcPass p)
-- so we need case analysis to know to print it
pp_con = case ghcPass @p of
GhcPs -> ppr con
GhcRn -> ppr con
GhcTc -> ppr con
ppr_expr (RecordUpd { rupd_expr = L _ aexp, rupd_flds = flds })
= case flds of
RegularRecUpdFields { recUpdFields= rbinds } ->
hang (ppr aexp) 2 (braces (fsep (punctuate comma (map ppr rbinds))))
OverloadedRecUpdFields { olRecUpdFields = pbinds } ->
hang (ppr aexp) 2 (braces (fsep (punctuate comma (map ppr pbinds))))
ppr_expr (HsGetField { gf_expr = L _ fexp, gf_field = field })
= ppr fexp <> dot <> ppr field
ppr_expr (HsProjection { proj_flds = flds }) = parens (hcat (dot : (punctuate dot (map ppr $ toList flds))))
ppr_expr (ExprWithTySig _ expr sig)
= hang (nest 2 (ppr_lexpr expr) <+> dcolon)
4 (ppr sig)
ppr_expr (ArithSeq _ _ info) = brackets (ppr info)
ppr_expr (HsTypedSplice ext e) =
case ghcPass @p of
GhcPs -> pprTypedSplice Nothing e
GhcRn -> pprTypedSplice (Just ext) e
GhcTc -> pprTypedSplice Nothing e
ppr_expr (HsUntypedSplice ext s) =
case ghcPass @p of
GhcPs -> pprUntypedSplice True Nothing s
GhcRn | HsUntypedSpliceNested n <- ext -> pprUntypedSplice True (Just n) s
GhcRn | HsUntypedSpliceTop _ e <- ext -> ppr e
GhcTc -> dataConCantHappen ext
ppr_expr (HsTypedBracket b e)
= case ghcPass @p of
GhcPs -> thTyBrackets (ppr e)
GhcRn -> thTyBrackets (ppr e)
GhcTc | HsBracketTc _ _ty _wrap ps <- b ->
thTyBrackets (ppr e) `ppr_with_pending_tc_splices` ps
ppr_expr (HsUntypedBracket b q)
= case ghcPass @p of
GhcPs -> ppr q
GhcRn -> case b of
[] -> ppr q
ps -> ppr q $$ text "pending(rn)" <+> ppr ps
GhcTc | HsBracketTc rnq _ty _wrap ps <- b ->
ppr rnq `ppr_with_pending_tc_splices` ps
ppr_expr (HsProc _ pat (L _ (HsCmdTop _ cmd)))
= hsep [text "proc", ppr pat, text "->", ppr cmd]
ppr_expr (HsStatic _ e)
= hsep [text "static", ppr e]
ppr_expr (HsEmbTy _ ty)
= hsep [text "type", ppr ty]
ppr_expr (HsQual _ ctxt ty)
= sep [ppr_context ctxt, ppr_lexpr ty]
where
ppr_context (L _ ctxt) =
case ctxt of
[] -> parens empty <+> darrow
[L _ ty] -> ppr_expr ty <+> darrow
_ -> parens (interpp'SP ctxt) <+> darrow
ppr_expr (HsForAll _ tele ty)
= sep [pprHsForAll tele Nothing, ppr_lexpr ty]
ppr_expr (HsFunArr _ arr arg res)
= sep [ppr_lexpr arg, pprHsArrow arr <+> ppr_lexpr res]
ppr_expr (XExpr x) = case ghcPass @p of
GhcRn -> ppr x
GhcTc -> ppr x
instance Outputable HsThingRn where
ppr thing
= case thing of
OrigExpr x -> ppr_builder "<OrigExpr>:" x
OrigStmt x -> ppr_builder "<OrigStmt>:" x
OrigPat x -> ppr_builder "<OrigPat>:" x
where ppr_builder prefix x = ifPprDebug (braces (text prefix <+> parens (ppr x))) (ppr x)
instance Outputable XXExprGhcRn where
ppr (ExpandedThingRn o e) = ifPprDebug (braces $ vcat [ppr o, ppr e]) (ppr o)
ppr (PopErrCtxt e) = ifPprDebug (braces (text "<PopErrCtxt>" <+> ppr e)) (ppr e)
ppr (HsRecSelRn f) = pprPrefixOcc f
instance Outputable XXExprGhcTc where
ppr (WrapExpr co_fn e)
= pprHsWrapper co_fn (\_parens -> pprExpr e)
ppr (ExpandedThingTc o e)
= ifPprDebug (braces $ vcat [ppr o, ppr e]) (ppr o)
-- e is the expanded expression, we print the original
-- expression (HsExpr GhcRn), not the
-- expanded typechecked one (HsExpr GhcTc),
-- unless we are in ppr's debug mode printed both
ppr (ConLikeTc con _ _) = pprPrefixOcc con
-- Used in error messages generated by
-- the pattern match overlap checker
ppr (HsTick tickish exp) =
pprTicks (ppr exp) $
ppr tickish <+> ppr_lexpr exp
ppr (HsBinTick tickIdTrue tickIdFalse exp) =
pprTicks (ppr exp) $
hcat [text "bintick<",
ppr tickIdTrue,
text ",",
ppr tickIdFalse,
text ">(",
ppr exp, text ")"]
ppr (HsRecSelTc f) = pprPrefixOcc f
ppr_infix_expr :: forall p. (OutputableBndrId p) => HsExpr (GhcPass p) -> Maybe SDoc
ppr_infix_expr (HsVar _ (L _ v)) = Just (pprInfixOcc v)
ppr_infix_expr (HsUnboundVar _ occ) = Just (pprInfixOcc occ)
ppr_infix_expr (XExpr x) = case ghcPass @p of
GhcRn -> ppr_infix_expr_rn x
GhcTc -> ppr_infix_expr_tc x
ppr_infix_expr _ = Nothing
ppr_infix_expr_rn :: XXExprGhcRn -> Maybe SDoc
ppr_infix_expr_rn (ExpandedThingRn thing _) = ppr_infix_hs_expansion thing
ppr_infix_expr_rn (PopErrCtxt (L _ a)) = ppr_infix_expr a
ppr_infix_expr_rn (HsRecSelRn f) = Just (pprInfixOcc f)
ppr_infix_expr_tc :: XXExprGhcTc -> Maybe SDoc
ppr_infix_expr_tc (WrapExpr _ e) = ppr_infix_expr e
ppr_infix_expr_tc (ExpandedThingTc thing _) = ppr_infix_hs_expansion thing
ppr_infix_expr_tc (ConLikeTc {}) = Nothing
ppr_infix_expr_tc (HsTick {}) = Nothing
ppr_infix_expr_tc (HsBinTick {}) = Nothing
ppr_infix_expr_tc (HsRecSelTc f) = Just (pprInfixOcc f)
ppr_infix_hs_expansion :: HsThingRn -> Maybe SDoc
ppr_infix_hs_expansion (OrigExpr e) = ppr_infix_expr e
ppr_infix_hs_expansion _ = 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
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 prec = go
where
go :: HsExpr (GhcPass p) -> Bool
go (HsVar{}) = False
go (HsUnboundVar{}) = False
go (HsIPVar{}) = False
go (HsOverLabel{}) = False
go (HsLit _ l) = hsLitNeedsParens prec l
go (HsOverLit _ ol) = hsOverLitNeedsParens prec ol
go (HsPar{}) = False
go (HsApp{}) = prec >= appPrec
go (HsAppType {}) = prec >= appPrec
go (OpApp{}) = prec >= opPrec
go (NegApp{}) = prec > topPrec
go (SectionL{}) = True
go (SectionR{}) = True
-- Special-case unary boxed tuple applications so that they are
-- parenthesized as `Identity (Solo x)`, not `Identity Solo x` (#18612)
-- See Note [One-tuples] in GHC.Builtin.Types
go (ExplicitTuple _ [Present{}] Boxed)
= prec >= appPrec
go (ExplicitTuple{}) = False
go (ExplicitSum{}) = False
go (HsLam{}) = prec > topPrec
go (HsCase{}) = prec > topPrec
go (HsIf{}) = prec > topPrec
go (HsMultiIf{}) = prec > topPrec
go (HsLet{}) = prec > topPrec
go (HsDo _ sc _)
| isDoComprehensionContext sc = False
| otherwise = prec > topPrec
go (ExplicitList{}) = False
go (RecordUpd{}) = False
go (ExprWithTySig{}) = prec >= sigPrec
go (ArithSeq{}) = False
go (HsPragE{}) = prec >= appPrec
go (HsTypedSplice{}) = False
go (HsUntypedSplice{}) = False
go (HsTypedBracket{}) = False
go (HsUntypedBracket{}) = False
go (HsProc{}) = prec > topPrec
go (HsStatic{}) = prec >= appPrec
go (RecordCon{}) = False
go (HsProjection{}) = True
go (HsGetField{}) = False
go (HsEmbTy{}) = prec > topPrec
go (HsForAll{}) = prec >= funPrec
go (HsQual{}) = prec >= funPrec
go (HsFunArr{}) = prec >= funPrec
go (XExpr x) = case ghcPass @p of
GhcTc -> go_x_tc x
GhcRn -> go_x_rn x
go_x_tc :: XXExprGhcTc -> Bool
go_x_tc (WrapExpr _ e) = hsExprNeedsParens prec e
go_x_tc (ExpandedThingTc thing _) = hsExpandedNeedsParens thing
go_x_tc (ConLikeTc {}) = False
go_x_tc (HsTick _ (L _ e)) = hsExprNeedsParens prec e
go_x_tc (HsBinTick _ _ (L _ e)) = hsExprNeedsParens prec e
go_x_tc (HsRecSelTc{}) = False
go_x_rn :: XXExprGhcRn -> Bool
go_x_rn (ExpandedThingRn thing _) = hsExpandedNeedsParens thing
go_x_rn (PopErrCtxt (L _ a)) = hsExprNeedsParens prec a
go_x_rn (HsRecSelRn{}) = False
hsExpandedNeedsParens :: HsThingRn -> Bool
hsExpandedNeedsParens (OrigExpr e) = hsExprNeedsParens prec e
hsExpandedNeedsParens _ = False
-- | Parenthesize an expression without token information
gHsPar :: forall p. IsPass p => LHsExpr (GhcPass p) -> HsExpr (GhcPass p)
gHsPar e = HsPar x e
where
x = case ghcPass @p of
GhcPs -> noAnn
GhcRn -> noExtField
GhcTc -> noExtField
-- | @'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 (gHsPar 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 (HsLit {}) = True
isAtomicHsExpr (HsOverLit {}) = True
isAtomicHsExpr (HsIPVar {}) = True
isAtomicHsExpr (HsOverLabel {}) = True
isAtomicHsExpr (HsUnboundVar {}) = True
isAtomicHsExpr (XExpr x)
| GhcTc <- ghcPass @p = go_x_tc x
| GhcRn <- ghcPass @p = go_x_rn x
where
go_x_tc :: XXExprGhcTc -> Bool
go_x_tc (WrapExpr _ e) = isAtomicHsExpr e
go_x_tc (ExpandedThingTc thing _) = isAtomicExpandedThingRn thing
go_x_tc (ConLikeTc {}) = True
go_x_tc (HsTick {}) = False
go_x_tc (HsBinTick {}) = False
go_x_tc (HsRecSelTc{}) = True
go_x_rn :: XXExprGhcRn -> Bool
go_x_rn (ExpandedThingRn thing _) = isAtomicExpandedThingRn thing
go_x_rn (PopErrCtxt (L _ a)) = isAtomicHsExpr a
go_x_rn (HsRecSelRn{}) = True
isAtomicExpandedThingRn :: HsThingRn -> Bool
isAtomicExpandedThingRn (OrigExpr e) = isAtomicHsExpr e
isAtomicExpandedThingRn _ = False
isAtomicHsExpr _ = False
instance Outputable (HsPragE (GhcPass p)) where
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 "#-}"
{- *********************************************************************
* *
XXExprGhcRn and rebindable syntax
* *
********************************************************************* -}
{- Note [Rebindable syntax and XXExprGhcRn]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We implement rebindable syntax (RS) support by performing a desugaring
in the renamer. We transform GhcPs expressions and patterns affected by
RS into the appropriate desugared form, but **annotated with the original
expression/pattern**.
Let us consider a piece of code like:
{-# LANGUAGE RebindableSyntax #-}
ifThenElse :: Char -> () -> () -> ()
ifThenElse _ _ _ = ()
x = if 'a' then () else True
The parsed AST for the RHS of x would look something like (slightly simplified):
L locif (HsIf (L loca 'a') (L loctrue ()) (L locfalse True))
Upon seeing such an AST with RS on, we could transform it into a
mere function call, as per the RS rules, equivalent to the
following function application:
ifThenElse 'a' () True
which doesn't typecheck. But GHC would report an error about
not being able to match the third argument's type (Bool) with the
expected type: (), in the expression _as desugared_, i.e in
the aforementioned function application. But the user never
wrote a function application! This would be pretty bad.
To remedy this, instead of transforming the original HsIf
node into mere applications of 'ifThenElse', we keep the
original 'if' expression around too, using the TTG
XExpr extension point to allow GHC to construct an
'XXExprGhcRn' value that will keep track of the original
expression in its first field, and the desugared one in the
second field. The resulting renamed AST would look like:
L locif (XExpr
(ExpandedThingRn
(HsIf (L loca 'a')
(L loctrue ())
(L locfalse True)
)
(App (L generatedSrcSpan
(App (L generatedSrcSpan
(App (L generatedSrcSpan (Var ifThenElse))
(L loca 'a')
)
)
(L loctrue ())
)
)
(L locfalse True)
)
)
)
When comes the time to typecheck the program, we end up calling
tcMonoExpr on the AST above. If this expression gives rise to
a type error, then it will appear in a context line and GHC
will pretty-print it using the 'Outputable (XXExprGhcRn a b)'
instance defined below, which *only prints the original
expression*. This is the gist of the idea, but is not quite
enough to recover the error messages that we had with the
SyntaxExpr-based, typechecking/desugaring-to-core time
implementation of rebindable syntax. The key idea is to decorate
some elements of the desugared expression so as to be able to
give them a special treatment when typechecking the desugared
expression, to print a different context line or skip one
altogether.
Whenever we 'setSrcSpan' a 'generatedSrcSpan', we update a field in
TcLclEnv called 'tcl_in_gen_code', setting it to True, which indicates that we
entered generated code, i.e code fabricated by the compiler when rebinding some
syntax. If someone tries to push some error context line while that field is set
to True, the pushing won't actually happen and the context line is just dropped.
Once we 'setSrcSpan' a real span (for an expression that was in the original
source code), we set 'tcl_in_gen_code' back to False, indicating that we
"emerged from the generated code tunnel", and that the expressions we will be
processing are relevant to report in context lines again.
You might wonder why TcLclEnv has both
tcl_loc :: RealSrcSpan
tcl_in_gen_code :: Bool
Could we not store a Maybe RealSrcSpan? The problem is that we still
generate constraints when processing generated code, and a CtLoc must
contain a RealSrcSpan -- otherwise, error messages might appear
without source locations. So tcl_loc keeps the RealSrcSpan of the last
location spotted that wasn't generated; it's as good as we're going to
get in generated code. Once we get to sub-trees that are not
generated, then we update the RealSrcSpan appropriately, and set the
tcl_in_gen_code Bool to False.
---
An overview of the constructs that are desugared in this way is laid out in
Note [Handling overloaded and rebindable constructs] in GHC.Rename.Expr.
A general recipe to follow this approach for new constructs could go as follows:
- Remove any GhcRn-time SyntaxExpr extensions to the relevant constructor for your
construct, in HsExpr or related syntax data types.
- At renaming-time:
- take your original node of interest (HsIf above)
- rename its subexpressions/subpatterns (condition and true/false
branches above)
- construct the suitable "rebound"-and-renamed result (ifThenElse call
above), where the 'SrcSpan' attached to any _fabricated node_ (the
HsVar/HsApp nodes, above) is set to 'generatedSrcSpan'
- take both the original node and that rebound-and-renamed result and wrap
them into an expansion construct:
for expressions, XExpr (ExpandedThingRn <original node> <desugared>)
for patterns, XPat (HsPatExpanded <original node> <desugared>)
- At typechecking-time:
- remove any logic that was previously dealing with your rebindable
construct, typically involving [tc]SyntaxOp, SyntaxExpr and friends.
- the XExpr (ExpandedThingRn ... ...) case in tcExpr already makes sure that we
typecheck the desugared expression while reporting the original one in
errors
-}
{- Note [Overview of record dot syntax]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is the note that explains all the moving parts for record dot
syntax.
The language extensions @OverloadedRecordDot@ and
@OverloadedRecordUpdate@ (providing "record dot syntax") are
implemented using the techniques of Note [Rebindable syntax and
XXExprGhcRn].
When OverloadedRecordDot is enabled:
- Field selection expressions
- e.g. foo.bar.baz
- Have abstract syntax HsGetField
- After renaming are XExpr (ExpandedThingRn (HsGetField ...) (getField @"..."...)) expressions
- Field selector expressions e.g. (.x.y)
- Have abstract syntax HsProjection
- After renaming are XExpr (ExpandedThingRn (HsProjection ...) ((getField @"...") . (getField @"...") . ...) expressions
When OverloadedRecordUpdate is enabled:
- Record update expressions
- e.g. a{foo.bar=1, quux="corge", baz}
- Have abstract syntax RecordUpd
- With rupd_flds containting a Right
- See Note [RecordDotSyntax field updates] (in Language.Haskell.Syntax.Expr)
- After renaming are XExpr (ExpandedThingRn (RecordUpd ...) (setField@"..." ...) expressions
- Note that this is true for all record updates even for those that do not involve '.'
When OverloadedRecordDot is enabled and RebindableSyntax is not
enabled the name 'getField' is resolved to GHC.Records.getField. When
OverloadedRecordDot is enabled and RebindableSyntax is enabled the
name 'getField' is whatever in-scope name that is.
When OverloadedRecordUpd is enabled and RebindableSyntax is not
enabled it is an error for now (temporary while we wait on native
setField support; see
https://gitlab.haskell.org/ghc/ghc/-/issues/16232). When
OverloadedRecordUpd is enabled and RebindableSyntax is enabled the
names 'getField' and 'setField' are whatever in-scope names they are.
-}
{-
************************************************************************
* *
\subsection{Commands (in arrow abstractions)}
* *
************************************************************************
-}
type instance XCmdArrApp GhcPs = (IsUnicodeSyntax, EpaLocation)
type instance XCmdArrApp GhcRn = NoExtField
type instance XCmdArrApp GhcTc = Type
type instance XCmdArrForm GhcPs = AnnList ()
-- | fixity (filled in by the renamer), for forms that were converted from
-- OpApp's by the renamer
type instance XCmdArrForm GhcRn = Maybe Fixity
type instance XCmdArrForm GhcTc = Maybe Fixity
type instance XCmdApp (GhcPass _) = NoExtField
type instance XCmdLam (GhcPass _) = NoExtField
type instance XCmdPar GhcPs = (EpToken "(", EpToken ")")
type instance XCmdPar GhcRn = NoExtField
type instance XCmdPar GhcTc = NoExtField
type instance XCmdCase GhcPs = EpAnnHsCase
type instance XCmdCase GhcRn = NoExtField
type instance XCmdCase GhcTc = NoExtField
type instance XCmdLamCase (GhcPass _) = EpAnnLam
type instance XCmdIf GhcPs = AnnsIf
type instance XCmdIf GhcRn = NoExtField
type instance XCmdIf GhcTc = NoExtField
type instance XCmdLet GhcPs = (EpToken "let", EpToken "in")
type instance XCmdLet GhcRn = NoExtField
type instance XCmdLet GhcTc = NoExtField
type instance XCmdDo GhcPs = AnnList EpaLocation
type instance XCmdDo GhcRn = NoExtField
type instance XCmdDo GhcTc = Type
type instance XCmdWrap (GhcPass _) = NoExtField
type instance XXCmd GhcPs = DataConCantHappen
type instance XXCmd GhcRn = DataConCantHappen
type instance XXCmd GhcTc = HsWrap HsCmd
-- If cmd :: arg1 --> res
-- wrap :: arg1 "->" arg2
-- Then (XCmd (HsWrap wrap cmd)) :: arg2 --> res
-- | 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, <expression>)]
where <expression> 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.)
-}
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 _) = DataConCantHappen
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 _ LamSingle matches)
= pprMatches matches
ppr_cmd (HsCmdLam _ lam_variant matches)
= sep [ lamCaseKeyword lam_variant, nest 2 (pprMatches matches) ]
ppr_cmd (HsCmdCase _ expr matches)
= sep [ sep [text "case", nest 4 (ppr expr), text "of"],
nest 2 (pprMatches matches) ]
ppr_cmd (HsCmdIf _ _ e ct ce)
= sep [hsep [text "if", nest 2 (ppr e), text "then"],
nest 4 (ppr ct),
text "else",
nest 4 (ppr ce)]
-- special case: let ... in let ...
ppr_cmd (HsCmdLet _ binds cmd@(L _ (HsCmdLet {})))
= sep [hang (text "let") 2 (hsep [pprBinds binds, text "in"]),
ppr_lcmd cmd]
ppr_cmd (HsCmdLet _ binds cmd)
= sep [hang (text "let") 2 (pprBinds binds),
hang (text "in") 2 (ppr cmd)]
ppr_cmd (HsCmdDo _ (L _ stmts)) = pprArrowExpr 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 rn_fix (L _ op) ps_fix args)
| HsVar _ (L _ v) <- op
= ppr_cmd_infix v
| GhcTc <- ghcPass @p
, XExpr (ConLikeTc c _ _) <- op
= ppr_cmd_infix (conLikeName c)
| otherwise
= fall_through
where
fall_through = hang (text "(|" <+> ppr_expr op)
4 (sep (map (pprCmdArg.unLoc) args) <+> text "|)")
ppr_cmd_infix :: OutputableBndr v => v -> SDoc
ppr_cmd_infix v
| [arg1, arg2] <- args
, case ghcPass @p of
GhcPs -> ps_fix == Infix
GhcRn -> isJust rn_fix || ps_fix == Infix
GhcTc -> isJust rn_fix || ps_fix == Infix
= hang (pprCmdArg (unLoc arg1))
4 (sep [ pprInfixOcc v, pprCmdArg (unLoc arg2)])
| otherwise
= fall_through
ppr_cmd (XCmd x) = case ghcPass @p of
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{@Match@, @GRHSs@, and @GRHS@ datatypes}
* *
************************************************************************
-}
type instance XMG GhcPs b = Origin
type instance XMG GhcRn b = Origin -- See Note [Generated code and pattern-match checking]
type instance XMG GhcTc b = MatchGroupTc
data MatchGroupTc
= MatchGroupTc
{ mg_arg_tys :: [Scaled Type] -- Types of the arguments, t1..tn
, mg_res_ty :: Type -- Type of the result, tr
, mg_origin :: Origin -- Origin (Generated vs FromSource)
} deriving Data
type instance XXMatchGroup (GhcPass _) b = DataConCantHappen
type instance XCMatch (GhcPass _) b = NoExtField
type instance XXMatch (GhcPass _) b = DataConCantHappen
instance (OutputableBndrId pr, Outputable body)
=> Outputable (Match (GhcPass pr) body) where
ppr = pprMatch
isEmptyMatchGroup :: MatchGroup (GhcPass p) body -> Bool
isEmptyMatchGroup (MG { mg_alts = ms }) = null $ unLoc ms
-- | Is there only one RHS in this list of matches?
isSingletonMatchGroup :: [LMatch (GhcPass p) 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 = count (isVisArgPat . unLoc) (hsLMatchPats alt1)
| otherwise = panic "matchGroupArity"
hsLMatchPats :: LMatch (GhcPass id) body -> [LPat (GhcPass id)]
hsLMatchPats (L _ (Match { m_pats = L _ pats })) = pats
-- We keep the type checker happy by providing EpAnnComments. They
-- can only be used if they follow a `where` keyword with no binds,
-- but in that case the comment is attached to the following parsed
-- item. So this can never be used in practice.
type instance XCGRHSs (GhcPass _) _ = EpAnnComments
type instance XXGRHSs (GhcPass _) _ = DataConCantHappen
data GrhsAnn
= GrhsAnn {
ga_vbar :: Maybe (EpToken "|"),
ga_sep :: Either (EpToken "=") TokRarrow -- ^ Match separator location, `=` or `->`
} deriving (Data)
instance NoAnn GrhsAnn where
noAnn = GrhsAnn Nothing noAnn
type instance XCGRHS (GhcPass _) _ = EpAnn GrhsAnn
-- Location of matchSeparator
-- TODO:AZ does this belong on the GRHS, or GRHSs?
type instance XXGRHS (GhcPass _) b = DataConCantHappen
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)
=> MatchGroup (GhcPass idR) (LHsExpr (GhcPass idR)) -> SDoc
pprFunBind matches = pprMatches matches
-- Exported to GHC.Hs.Binds, which can't see the defn of HsMatchContext
pprPatBind :: forall bndr p . (OutputableBndrId bndr,
OutputableBndrId p)
=> LPat (GhcPass bndr) -> GRHSs (GhcPass p) (LHsExpr (GhcPass p)) -> SDoc
pprPatBind pat grhss
= sep [ppr pat,
nest 2 (pprGRHSs (PatBindRhs :: HsMatchContext Void) grhss)]
pprMatch :: (OutputableBndrId idR, Outputable body)
=> Match (GhcPass idR) body -> SDoc
pprMatch (Match { m_pats = L _ pats, m_ctxt = ctxt, m_grhss = grhss })
= sep [ sep (herald : map (nest 2 . pprParendLPat appPrec) other_pats)
, nest 2 (pprGRHSs ctxt grhss) ]
where
-- lam_cases_result: we don't simply return (empty, pats) to avoid
-- introducing an additional `nest 2` via the empty herald
lam_cases_result = case pats of
[] -> (empty, [])
(p:ps) -> (pprParendLPat appPrec p, ps)
(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)
LamAlt LamSingle -> (char '\\', pats)
ArrowMatchCtxt (ArrowLamAlt LamSingle) -> (char '\\', pats)
LamAlt LamCases -> lam_cases_result
ArrowMatchCtxt (ArrowLamAlt LamCases) -> lam_cases_result
ArrowMatchCtxt ProcExpr -> (text "proc", pats)
_ -> case pats of
[] -> (empty, [])
[pat] -> (ppr pat, []) -- No parens around the single pat in a case
_ -> pprPanic "pprMatch" (ppr ctxt $$ ppr pats)
pprGRHSs :: (OutputableBndrId idR, Outputable body)
=> HsMatchContext fn -> GRHSs (GhcPass idR) body -> SDoc
pprGRHSs ctxt (GRHSs _ grhss binds)
= vcat (map (pprGRHS ctxt . unLoc) grhss)
-- Print the "where" even if the contents of the binds is empty. Only
-- EmptyLocalBinds means no "where" keyword
$$ ppUnless (eqEmptyLocalBinds binds)
(text "where" $$ nest 4 (pprBinds binds))
pprGRHS :: (OutputableBndrId idR, Outputable body)
=> HsMatchContext fn -> 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 fn -> body -> SDoc
pp_rhs ctxt rhs = matchSeparator ctxt <+> pprDeeper (ppr rhs)
matchSeparator :: HsMatchContext fn -> SDoc
matchSeparator FunRhs{} = text "="
matchSeparator CaseAlt = text "->"
matchSeparator LamAlt{} = text "->"
matchSeparator IfAlt = text "->"
matchSeparator ArrowMatchCtxt{} = text "->"
matchSeparator PatBindRhs = text "="
matchSeparator PatBindGuards = text "="
matchSeparator StmtCtxt{} = text "<-"
matchSeparator RecUpd = text "=" -- This can be printed by the pattern
matchSeparator PatSyn = text "<-" -- match checker trace
matchSeparator LazyPatCtx = panic "unused"
matchSeparator ThPatSplice = panic "unused"
matchSeparator ThPatQuote = panic "unused"
instance Outputable GrhsAnn where
ppr (GrhsAnn v s) = text "GrhsAnn" <+> ppr v <+> ppr s
{-
************************************************************************
* *
\subsection{Do stmts and list comprehensions}
* *
************************************************************************
-}
-- 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 = EpUniToken "<-" "←"
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 = NoExtField
type instance XApplicativeStmt (GhcPass _) GhcRn = NoExtField
type instance XApplicativeStmt (GhcPass _) GhcTc = 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 = EpToken "let"
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 = AnnTransStmt
type instance XTransStmt (GhcPass _) GhcRn b = NoExtField
type instance XTransStmt (GhcPass _) GhcTc b = Type
type instance XRecStmt (GhcPass _) GhcPs b = AnnList (EpToken "rec")
type instance XRecStmt (GhcPass _) GhcRn b = NoExtField
type instance XRecStmt (GhcPass _) GhcTc b = RecStmtTc
type instance XXStmtLR (GhcPass _) GhcPs b = DataConCantHappen
type instance XXStmtLR (GhcPass x) GhcRn b = ApplicativeStmt (GhcPass x) GhcRn
type instance XXStmtLR (GhcPass x) GhcTc b = ApplicativeStmt (GhcPass x) GhcTc
data AnnTransStmt
= AnnTransStmt {
ats_then :: EpToken "then",
ats_group :: Maybe (EpToken "group"),
ats_by :: Maybe (EpToken "by"),
ats_using :: Maybe (EpToken "using")
} deriving Data
instance NoAnn AnnTransStmt where
noAnn = AnnTransStmt noAnn noAnn noAnn noAnn
-- | '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"
--
data ApplicativeStmt idL idR
= ApplicativeStmt
(XApplicativeStmt idL idR) -- Post typecheck, Type of the body
[ ( SyntaxExpr idR
, ApplicativeArg idL) ]
-- [(<$>, e1), (<*>, e2), ..., (<*>, en)]
(Maybe (SyntaxExpr idR)) -- 'join', if necessary
-- | 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 :: HsDoFlavour
-- ^ context of the do expression, used in pprArg
}
| XApplicativeArg !(XXApplicativeArg idL)
type family XApplicativeStmt x x'
-- ApplicativeArg type families
type family XApplicativeArgOne x
type family XApplicativeArgMany x
type family XXApplicativeArg x
type instance XParStmtBlock (GhcPass pL) (GhcPass pR) = NoExtField
type instance XXParStmtBlock (GhcPass pL) (GhcPass pR) = DataConCantHappen
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 _) = DataConCantHappen
instance (Outputable (StmtLR (GhcPass idL) (GhcPass idL) (LHsExpr (GhcPass idL))),
Outputable (XXParStmtBlock (GhcPass idL) (GhcPass idR)))
=> Outputable (ParStmtBlock (GhcPass idL) (GhcPass idR)) where
ppr (ParStmtBlock _ stmts _ _) = interpp'SP stmts
instance (OutputableBndrId pl, OutputableBndrId pr,
Anno (StmtLR (GhcPass pl) (GhcPass pr) body) ~ SrcSpanAnnA,
Outputable body)
=> Outputable (StmtLR (GhcPass pl) (GhcPass pr) body) where
ppr stmt = pprStmt stmt
pprStmt :: forall idL idR body . (OutputableBndrId idL,
OutputableBndrId idR,
Anno (StmtLR (GhcPass idL) (GhcPass idR) body) ~ SrcSpanAnnA,
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) = pprBindStmt pat expr
pprStmt (LetStmt _ 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 (unLoc segment)
, whenPprDebug (vcat [ text "rec_ids=" <> ppr rec_ids
, text "later_ids=" <> ppr later_ids])]
pprStmt (XStmtLR x) = case ghcPass :: GhcPass idR of
GhcRn -> pprApplicativeStmt x
GhcTc -> pprApplicativeStmt x
where
pprApplicativeStmt :: (OutputableBndrId idL, OutputableBndrId idR) => ApplicativeStmt (GhcPass idL) (GhcPass idR) -> SDoc
pprApplicativeStmt (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 _ (XStmtLR x)) = case ghcPass :: GhcPass idL of
GhcRn | (ApplicativeStmt _ args _) <- x -> concatMap flattenArg args
GhcTc | (ApplicativeStmt _ args _) <- x -> concatMap flattenArg args
flattenStmt stmt = [ppr stmt]
flattenArg :: (a, ApplicativeArg (GhcPass idL)) -> [SDoc]
flattenArg (_, ApplicativeArgOne _ pat expr isBody)
| isBody = [ppr expr] -- See Note [Applicative BodyStmt]
| otherwise = [pprBindStmt pat expr]
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
pprBindStmt :: (Outputable pat, Outputable expr) => pat -> expr -> SDoc
pprBindStmt pat expr = hsep [ppr pat, larrow, ppr expr]
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 = ppr expr -- See Note [Applicative BodyStmt]
| otherwise = pprBindStmt pat expr
pprArg (ApplicativeArgMany _ stmts return pat ctxt) =
ppr pat <+>
text "<-" <+>
pprDo ctxt (stmts ++
[noLocA (LastStmt noExtField (noLocA 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 (text "using" <+> ppr using)]
pprBy :: Outputable body => Maybe body -> SDoc
pprBy Nothing = empty
pprBy (Just e) = text "by" <+> ppr e
pprDo :: (OutputableBndrId p, Outputable body,
Anno (StmtLR (GhcPass p) (GhcPass p) body) ~ SrcSpanAnnA
)
=> HsDoFlavour -> [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 (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
pprArrowExpr :: (OutputableBndrId p, Outputable body,
Anno (StmtLR (GhcPass p) (GhcPass p) body) ~ SrcSpanAnnA
)
=> [LStmt (GhcPass p) body] -> SDoc
pprArrowExpr stmts = text "do" <+> ppr_do_stmts stmts
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,
Anno (StmtLR (GhcPass idL) (GhcPass idR) body) ~ SrcSpanAnnA,
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,
Anno (StmtLR (GhcPass p) (GhcPass p) body) ~ SrcSpanAnnA)
=> [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,
Anno (StmtLR (GhcPass p) (GhcPass p) body) ~ SrcSpanAnnA)
=> [LStmt (GhcPass p) body] -> SDoc
-- Show list comprehension qualifiers separated by commas
pprQuals quals = interpp'SP quals
{-
************************************************************************
* *
Template Haskell quotation brackets
* *
************************************************************************
-}
-- | 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 [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.
data HsUntypedSpliceResult thing -- 'thing' can be HsExpr or HsType
= HsUntypedSpliceTop
{ utsplice_result_finalizers :: ThModFinalizers -- ^ TH finalizers produced by the splice.
, utsplice_result :: thing -- ^ The result of splicing; See Note [Lifecycle of a splice]
}
| HsUntypedSpliceNested SplicePointName -- A unique name to identify this splice point
type instance XTypedSplice GhcPs = EpToken "$$"
type instance XTypedSplice GhcRn = SplicePointName
type instance XTypedSplice GhcTc = DelayedSplice
type instance XUntypedSplice GhcPs = NoExtField
type instance XUntypedSplice GhcRn = HsUntypedSpliceResult (HsExpr GhcRn)
type instance XUntypedSplice GhcTc = DataConCantHappen
-- HsUntypedSplice
type instance XUntypedSpliceExpr GhcPs = EpToken "$"
type instance XUntypedSpliceExpr GhcRn = EpToken "$"
type instance XUntypedSpliceExpr GhcTc = DataConCantHappen
type instance XQuasiQuote p = NoExtField
type instance XXUntypedSplice p = DataConCantHappen
-- 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]
-- See Note [Pending Splices]
type SplicePointName = Name
data UntypedSpliceFlavour
= UntypedExpSplice
| UntypedPatSplice
| UntypedTypeSplice
| UntypedDeclSplice
deriving Data
-- | Pending Renamer Splice
data PendingRnSplice
= PendingRnSplice UntypedSpliceFlavour SplicePointName (LHsExpr GhcRn)
-- | Pending Type-checker Splice
data PendingTcSplice
= PendingTcSplice SplicePointName (LHsExpr GhcTc)
pprPendingSplice :: (OutputableBndrId p)
=> SplicePointName -> LHsExpr (GhcPass p) -> SDoc
pprPendingSplice n e = angleBrackets (ppr n <> comma <+> ppr (stripParensLHsExpr e))
pprTypedSplice :: (OutputableBndrId p) => Maybe SplicePointName -> LHsExpr (GhcPass p) -> SDoc
pprTypedSplice n e = ppr_splice (text "$$") n e
pprUntypedSplice :: forall p. (OutputableBndrId p)
=> Bool -- Whether to precede the splice with "$"
-> Maybe SplicePointName -- Used for pretty printing when exists
-> HsUntypedSplice (GhcPass p)
-> SDoc
pprUntypedSplice True n (HsUntypedSpliceExpr _ e) = ppr_splice (text "$") n e
pprUntypedSplice False n (HsUntypedSpliceExpr _ e) = ppr_splice empty n e
pprUntypedSplice _ _ (HsQuasiQuote _ q s) = ppr_quasi q (unLoc s)
ppr_quasi :: OutputableBndr p => p -> FastString -> SDoc
ppr_quasi quoter quote = char '[' <> ppr quoter <> vbar <>
ppr quote <> text "|]"
ppr_splice :: (OutputableBndrId p)
=> SDoc
-> Maybe SplicePointName
-> LHsExpr (GhcPass p)
-> SDoc
ppr_splice herald mn e
= herald
<> (case mn of
Nothing -> empty
Just splice_name -> whenPprDebug (brackets (ppr splice_name)))
<> ppr e
type instance XExpBr GhcPs = (BracketAnn (EpUniToken "[|" "⟦") (EpToken "[e|"), EpUniToken "|]" "⟧")
type instance XPatBr GhcPs = (EpToken "[p|", EpUniToken "|]" "⟧")
type instance XDecBrL GhcPs = (EpToken "[d|", EpUniToken "|]" "⟧", (EpToken "{", EpToken "}"))
type instance XDecBrG GhcPs = NoExtField
type instance XTypBr GhcPs = (EpToken "[t|", EpUniToken "|]" "⟧")
type instance XVarBr GhcPs = EpaLocation
type instance XXQuote GhcPs = DataConCantHappen
type instance XExpBr GhcRn = NoExtField
type instance XPatBr GhcRn = NoExtField
type instance XDecBrL GhcRn = NoExtField
type instance XDecBrG GhcRn = NoExtField
type instance XTypBr GhcRn = NoExtField
type instance XVarBr GhcRn = NoExtField
type instance XXQuote GhcRn = DataConCantHappen
-- See Note [The life cycle of a TH quotation]
type instance XExpBr GhcTc = DataConCantHappen
type instance XPatBr GhcTc = DataConCantHappen
type instance XDecBrL GhcTc = DataConCantHappen
type instance XDecBrG GhcTc = DataConCantHappen
type instance XTypBr GhcTc = DataConCantHappen
type instance XVarBr GhcTc = DataConCantHappen
type instance XXQuote GhcTc = NoExtField
instance OutputableBndrId p
=> Outputable (HsQuote (GhcPass p)) where
ppr = pprHsQuote
where
pprHsQuote :: forall p. (OutputableBndrId p)
=> HsQuote (GhcPass p) -> SDoc
pprHsQuote (ExpBr _ e) = thBrackets empty (ppr e)
pprHsQuote (PatBr _ p) = thBrackets (char 'p') (ppr p)
pprHsQuote (DecBrG _ gp) = thBrackets (char 'd') (ppr gp)
pprHsQuote (DecBrL _ ds) = thBrackets (char 'd') (vcat (map ppr ds))
pprHsQuote (TypBr _ t) = thBrackets (char 't') (ppr t)
pprHsQuote (VarBr _ True n)
= char '\'' <> pprPrefixOcc (unLoc n)
pprHsQuote (VarBr _ False n)
= text "''" <> pprPrefixOcc (unLoc n)
pprHsQuote (XQuote b) = case ghcPass @p of
GhcTc -> pprPanic "pprHsQuote: `HsQuote GhcTc` shouldn't exist" (ppr b)
-- See Note [The life cycle of a TH quotation]
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 <+> text "||]"
instance Outputable PendingRnSplice where
ppr (PendingRnSplice _ n e) = pprPendingSplice n e
instance Outputable PendingTcSplice where
ppr (PendingTcSplice n e) = pprPendingSplice n e
ppr_with_pending_tc_splices :: SDoc -> [PendingTcSplice] -> SDoc
ppr_with_pending_tc_splices x [] = x
ppr_with_pending_tc_splices x ps = x $$ text "pending(tc)" <+> ppr ps
{-
************************************************************************
* *
\subsection{Enumerations and list comprehensions}
* *
************************************************************************
-}
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}
* *
************************************************************************
-}
type HsMatchContextPs = HsMatchContext (LIdP GhcPs)
type HsMatchContextRn = HsMatchContext (LIdP GhcRn)
type HsStmtContextRn = HsStmtContext (LIdP GhcRn)
instance Outputable fn => Outputable (HsMatchContext fn) where
ppr m@(FunRhs{}) = text "FunRhs" <+> ppr (mc_fun m) <+> ppr (mc_fixity m)
ppr CaseAlt = text "CaseAlt"
ppr (LamAlt lam_variant) = text "LamAlt" <+> ppr lam_variant
ppr IfAlt = text "IfAlt"
ppr (ArrowMatchCtxt c) = text "ArrowMatchCtxt" <+> ppr c
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"
ppr LazyPatCtx = text "LazyPatCtx"
instance Outputable HsLamVariant where
ppr = text . \case
LamSingle -> "LamSingle"
LamCase -> "LamCase"
LamCases -> "LamCases"
lamCaseKeyword :: HsLamVariant -> SDoc
lamCaseKeyword LamSingle = text "lambda"
lamCaseKeyword LamCase = text "\\case"
lamCaseKeyword LamCases = text "\\cases"
pprExternalSrcLoc :: (StringLiteral,(Int,Int),(Int,Int)) -> SDoc
pprExternalSrcLoc (StringLiteral _ src _,(n1,n2),(n3,n4))
= ppr (src,(n1,n2),(n3,n4))
instance Outputable HsArrowMatchContext where
ppr ProcExpr = text "ProcExpr"
ppr ArrowCaseAlt = text "ArrowCaseAlt"
ppr (ArrowLamAlt lam_variant) = parens $ text "ArrowLamCaseAlt" <+> ppr lam_variant
pprHsArrType :: HsArrAppType -> SDoc
pprHsArrType HsHigherOrderApp = text "higher order arrow application"
pprHsArrType HsFirstOrderApp = text "first order arrow application"
-----------------
instance Outputable fn => Outputable (HsStmtContext fn) where
ppr = pprStmtContext
-- Used to generate the string for a *runtime* error message
matchContextErrString :: Outputable fn => HsMatchContext fn -> SDoc
matchContextErrString (FunRhs{mc_fun=fun}) = text "function" <+> ppr fun
matchContextErrString CaseAlt = text "case"
matchContextErrString (LamAlt lam_variant) = lamCaseKeyword lam_variant
matchContextErrString IfAlt = text "multi-way if"
matchContextErrString PatBindRhs = text "pattern binding"
matchContextErrString PatBindGuards = text "pattern binding guards"
matchContextErrString RecUpd = text "record update"
matchContextErrString (ArrowMatchCtxt c) = matchArrowContextErrString c
matchContextErrString ThPatSplice = panic "matchContextErrString" -- Not used at runtime
matchContextErrString ThPatQuote = panic "matchContextErrString" -- Not used at runtime
matchContextErrString PatSyn = text "pattern synonym"
matchContextErrString (StmtCtxt (ParStmtCtxt c)) = matchContextErrString (StmtCtxt c)
matchContextErrString (StmtCtxt (TransStmtCtxt c)) = matchContextErrString (StmtCtxt c)
matchContextErrString (StmtCtxt (PatGuard _)) = text "pattern guard"
matchContextErrString (StmtCtxt (ArrowExpr)) = text "'do' block"
matchContextErrString (StmtCtxt (HsDoStmt flavour)) = matchDoContextErrString flavour
matchContextErrString LazyPatCtx = text "irrefutable pattern"
matchArrowContextErrString :: HsArrowMatchContext -> SDoc
matchArrowContextErrString ProcExpr = text "proc"
matchArrowContextErrString ArrowCaseAlt = text "case"
matchArrowContextErrString (ArrowLamAlt LamSingle) = text "kappa"
matchArrowContextErrString (ArrowLamAlt lam_variant) = lamCaseKeyword lam_variant
matchDoContextErrString :: HsDoFlavour -> SDoc
matchDoContextErrString GhciStmtCtxt = text "interactive GHCi command"
matchDoContextErrString (DoExpr m) = prependQualified m (text "'do' block")
matchDoContextErrString (MDoExpr m) = prependQualified m (text "'mdo' block")
matchDoContextErrString ListComp = text "list comprehension"
matchDoContextErrString 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 fn,
Outputable body,
Anno (StmtLR (GhcPass idL) (GhcPass idR) body) ~ SrcSpanAnnA)
=> HsStmtContext fn
-> 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
pprMatchContext :: Outputable fn => HsMatchContext fn -> 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 (ArrowMatchCtxt ProcExpr) = True
want_an (ArrowMatchCtxt (ArrowLamAlt LamSingle)) = True
want_an LazyPatCtx = True
want_an _ = False
pprMatchContextNoun :: Outputable fn => HsMatchContext fn -> SDoc
pprMatchContextNoun (FunRhs {mc_fun=fun}) = text "equation for" <+> quotes (ppr fun)
pprMatchContextNoun CaseAlt = text "case alternative"
pprMatchContextNoun (LamAlt LamSingle) = text "lambda abstraction"
pprMatchContextNoun (LamAlt lam_variant) = lamCaseKeyword lam_variant
<+> text "alternative"
pprMatchContextNoun IfAlt = text "multi-way if alternative"
pprMatchContextNoun RecUpd = text "record update"
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 (ArrowMatchCtxt c) = pprArrowMatchContextNoun c
pprMatchContextNoun (StmtCtxt ctxt) = text "pattern binding in"
$$ pprAStmtContext ctxt
pprMatchContextNoun PatSyn = text "pattern synonym declaration"
pprMatchContextNoun LazyPatCtx = text "irrefutable pattern"
pprMatchContextNouns :: Outputable fn => HsMatchContext fn -> SDoc
pprMatchContextNouns (FunRhs {mc_fun=fun}) = text "equations for" <+> quotes (ppr fun)
pprMatchContextNouns PatBindGuards = text "pattern binding guards"
pprMatchContextNouns (ArrowMatchCtxt c) = pprArrowMatchContextNouns c
pprMatchContextNouns (StmtCtxt ctxt) = text "pattern bindings in"
$$ pprAStmtContext ctxt
pprMatchContextNouns ctxt = pprMatchContextNoun ctxt <> char 's'
pprArrowMatchContextNoun :: HsArrowMatchContext -> SDoc
pprArrowMatchContextNoun ProcExpr = text "arrow proc pattern"
pprArrowMatchContextNoun ArrowCaseAlt = text "case alternative within arrow notation"
pprArrowMatchContextNoun (ArrowLamAlt LamSingle) = text "arrow kappa abstraction"
pprArrowMatchContextNoun (ArrowLamAlt lam_variant) = lamCaseKeyword lam_variant
<+> text "alternative within arrow notation"
pprArrowMatchContextNouns :: HsArrowMatchContext -> SDoc
pprArrowMatchContextNouns ArrowCaseAlt = text "case alternatives within arrow notation"
pprArrowMatchContextNouns (ArrowLamAlt LamSingle) = text "arrow kappa abstractions"
pprArrowMatchContextNouns (ArrowLamAlt lam_variant) = lamCaseKeyword lam_variant
<+> text "alternatives within arrow notation"
pprArrowMatchContextNouns ctxt = pprArrowMatchContextNoun ctxt <> char 's'
-----------------
pprAStmtContext, pprStmtContext :: Outputable fn => HsStmtContext fn -> SDoc
pprAStmtContext (HsDoStmt flavour) = pprAHsDoFlavour flavour
pprAStmtContext ctxt = text "a" <+> pprStmtContext ctxt
-----------------
pprStmtContext (HsDoStmt flavour) = pprHsDoFlavour flavour
pprStmtContext (PatGuard ctxt) = text "pattern guard for" $$ pprMatchContext ctxt
pprStmtContext ArrowExpr = text "'do' block in an arrow command"
-- 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)
pprStmtCat :: forall p body . IsPass p => Stmt (GhcPass p) body -> SDoc
pprStmtCat (TransStmt {}) = text "transform"
pprStmtCat (LastStmt {}) = text "return expression"
pprStmtCat (BodyStmt {}) = text "body"
pprStmtCat (BindStmt {}) = text "binding"
pprStmtCat (LetStmt {}) = text "let"
pprStmtCat (RecStmt {}) = text "rec"
pprStmtCat (ParStmt {}) = text "parallel"
pprStmtCat (XStmtLR _) = text "applicative"
pprAHsDoFlavour, pprHsDoFlavour :: HsDoFlavour -> SDoc
pprAHsDoFlavour flavour = article <+> pprHsDoFlavour flavour
where
pp_an = text "an"
pp_a = text "a"
article = case flavour of
MDoExpr Nothing -> pp_an
GhciStmtCtxt -> pp_an
_ -> pp_a
pprHsDoFlavour (DoExpr m) = prependQualified m (text "'do' block")
pprHsDoFlavour (MDoExpr m) = prependQualified m (text "'mdo' block")
pprHsDoFlavour ListComp = text "list comprehension"
pprHsDoFlavour MonadComp = text "monad comprehension"
pprHsDoFlavour GhciStmtCtxt = text "interactive GHCi command"
prependQualified :: Maybe ModuleName -> SDoc -> SDoc
prependQualified Nothing t = t
prependQualified (Just _) t = text "qualified" <+> t
{-
************************************************************************
* *
FieldLabelStrings
* *
************************************************************************
-}
instance (UnXRec p, Outputable (XRec p FieldLabelString)) => Outputable (FieldLabelStrings p) where
ppr (FieldLabelStrings flds) =
hcat (punctuate dot (map (ppr . unXRec @p) flds))
instance (UnXRec p, Outputable (XRec p FieldLabelString)) => OutputableBndr (FieldLabelStrings p) where
pprInfixOcc = pprFieldLabelStrings
pprPrefixOcc = pprFieldLabelStrings
instance (UnXRec p, Outputable (XRec p FieldLabelString)) => OutputableBndr (Located (FieldLabelStrings p)) where
pprInfixOcc = pprInfixOcc . unLoc
pprPrefixOcc = pprInfixOcc . unLoc
pprFieldLabelStrings :: forall p. (UnXRec p, Outputable (XRec p FieldLabelString)) => FieldLabelStrings p -> SDoc
pprFieldLabelStrings (FieldLabelStrings flds) =
hcat (punctuate dot (map (ppr . unXRec @p) flds))
pprPrefixFastString :: FastString -> SDoc
pprPrefixFastString fs = pprPrefixOcc (mkVarUnqual fs)
instance UnXRec p => Outputable (DotFieldOcc p) where
ppr (DotFieldOcc _ s) = (pprPrefixFastString . field_label . unXRec @p) s
ppr XDotFieldOcc{} = text "XDotFieldOcc"
{-
************************************************************************
* *
\subsection{Anno instances}
* *
************************************************************************
-}
type instance Anno (HsExpr (GhcPass p)) = SrcSpanAnnA
type instance Anno [LocatedA (HsExpr (GhcPass p))] = SrcSpanAnnC
type instance Anno [LocatedA (StmtLR (GhcPass pl) (GhcPass pr) (LocatedA (HsExpr (GhcPass pr))))] = SrcSpanAnnLW
type instance Anno [LocatedA (StmtLR (GhcPass pl) (GhcPass pr) (LocatedA (HsCmd (GhcPass pr))))] = SrcSpanAnnLW
type instance Anno (HsCmd (GhcPass p)) = SrcSpanAnnA
type instance Anno (HsCmdTop (GhcPass p)) = EpAnnCO
type instance Anno [LocatedA (Match (GhcPass p) (LocatedA (HsExpr (GhcPass p))))] = SrcSpanAnnLW
type instance Anno [LocatedA (Match (GhcPass p) (LocatedA (HsCmd (GhcPass p))))] = SrcSpanAnnLW
type instance Anno (Match (GhcPass p) (LocatedA (HsExpr (GhcPass p)))) = SrcSpanAnnA
type instance Anno (Match (GhcPass p) (LocatedA (HsCmd (GhcPass p)))) = SrcSpanAnnA
type instance Anno [LocatedA (Pat (GhcPass p))] = EpaLocation
type instance Anno (GRHS (GhcPass p) (LocatedA (HsExpr (GhcPass p)))) = EpAnnCO
type instance Anno (GRHS (GhcPass p) (LocatedA (HsCmd (GhcPass p)))) = EpAnnCO
type instance Anno (StmtLR (GhcPass pl) (GhcPass pr) (LocatedA (body (GhcPass pr)))) = SrcSpanAnnA
type instance Anno (HsUntypedSplice (GhcPass p)) = SrcSpanAnnA
type instance Anno [LocatedA (StmtLR (GhcPass pl) (GhcPass pr) (LocatedA (body (GhcPass pr))))] = SrcSpanAnnLW
type instance Anno (FieldLabelStrings (GhcPass p)) = EpAnnCO
type instance Anno FieldLabelString = SrcSpanAnnN
type instance Anno FastString = EpAnnCO
-- Used in HsQuasiQuote and perhaps elsewhere
type instance Anno (DotFieldOcc (GhcPass p)) = EpAnnCO
instance (HasAnnotation (Anno a))
=> WrapXRec (GhcPass p) a where
wrapXRec = noLocA