{-# LANGUAGE CPP #-} {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE ExistentialQuantification #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE LambdaCase #-} {-# 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-incomplete-uni-patterns #-} {-# 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 #include "GhclibHsVersions.h" import Language.Haskell.Syntax.Expr -- friends: import GHC.Prelude import GHC.Hs.Decls import GHC.Hs.Pat import GHC.Hs.Lit import Language.Haskell.Syntax.Extension import GHC.Hs.Extension import GHC.Hs.Type import GHC.Hs.Binds -- others: import GHC.Tc.Types.Evidence import GHC.Types.Name import GHC.Types.Name.Set import GHC.Types.Basic import GHC.Types.Fixity import GHC.Types.SourceText import GHC.Types.SrcLoc import GHC.Core.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) 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 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 "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 "" -- | 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 -- For a data family, these are the type args of the -- /representation/ type constructor , 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 HsDoRn (GhcPass _) = GhcRn type instance HsBracketRn (GhcPass _) = GhcRn type instance PendingRnSplice' (GhcPass _) = PendingRnSplice type instance PendingTcSplice' (GhcPass _) = PendingTcSplice -- --------------------------------------------------------------------- {- Note [Constructor cannot occur] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Some data constructors can't occur in certain phases; e.g. the output of the type checker never has OverLabel. We signal this by setting the extension field to Void. For example: type instance XOverLabel GhcTc = Void dsExpr (HsOverLabel x _) = absurd x It would be better to omit the pattern match altogether, but we could only do that if the extension field was strict (#18764) -} type instance XVar (GhcPass _) = NoExtField type instance XConLikeOut (GhcPass _) = NoExtField type instance XRecFld (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 -- OverLabel not present in GhcTc pass; see GHC.Rename.Expr -- Note [Handling overloaded and rebindable constructs] type instance XOverLabel GhcPs = NoExtField type instance XOverLabel GhcRn = NoExtField type instance XOverLabel GhcTc = Void -- See Note [Constructor cannot occur] type instance XUnboundVar GhcPs = NoExtField 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 XAppTypeE GhcPs = NoExtField 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 = Void -- See Note [Constructor cannot occur] -- 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 = Void -- See Note [Constructor cannot occur] type instance XSectionR GhcTc = Void -- See Note [Constructor cannot occur] type instance XNegApp (GhcPass _) = NoExtField type instance XPar (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 (GhcPass _) = 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 -- 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 = NoExtField type instance XRecordCon GhcRn = NoExtField type instance XRecordCon GhcTc = PostTcExpr -- Instantiated constructor function 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 -- See Note [Rebindable syntax and HsExpansion] below type instance XXExpr GhcRn = HsExpansion (HsExpr GhcRn) (HsExpr GhcRn) type instance XXExpr GhcTc = XXExprGhcTc data XXExprGhcTc = WrapExpr {-# UNPACK #-} !(HsWrap HsExpr) | ExpansionExpr {-# UNPACK #-} !(HsExpansion (HsExpr GhcRn) (HsExpr GhcTc)) -- --------------------------------------------------------------------- type instance XSCC (GhcPass _) = NoExtField type instance XXPragE (GhcPass _) = NoExtCon 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 (GhcPass p) -> Bool tupArgPresent (L _ (Present {})) = True tupArgPresent (L _ (Missing {})) = False 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 (HsRecFld _ f) = pprPrefixOcc f 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 = 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 = 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 (XExpr x) = case ghcPass @p of #if __GLASGOW_HASKELL__ < 811 GhcPs -> ppr x #endif GhcRn -> ppr x GhcTc -> case x of WrapExpr (HsWrap co_fn e) -> pprHsWrapper co_fn (\parens -> if parens then pprExpr e else pprExpr e) ExpansionExpr e -> ppr e -- e is an HsExpansion, we print the original -- expression (LHsExpr GhcPs), not the -- desugared one (LHsExpr GhcT). 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) = case (ghcPass @p, x) of #if __GLASGOW_HASKELL__ <= 810 (GhcPs, _) -> Nothing #endif (GhcRn, HsExpanded a _) -> ppr_infix_expr a (GhcTc, WrapExpr (HsWrap _ e)) -> ppr_infix_expr e (GhcTc, ExpansionExpr (HsExpanded a _)) -> ppr_infix_expr a 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 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 -- 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 _ [L _ Present{}] Boxed) = p >= appPrec 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 = case x of WrapExpr (HsWrap _ e) -> go e ExpansionExpr (HsExpanded a _) -> hsExprNeedsParens p a | GhcRn <- ghcPass @p = case x of HsExpanded a _ -> hsExprNeedsParens p a #if __GLASGOW_HASKELL__ <= 900 | otherwise = True #endif -- | @'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 (HsRecFld{}) = True isAtomicHsExpr (XExpr x) | GhcTc <- ghcPass @p = case x of WrapExpr (HsWrap _ e) -> isAtomicHsExpr e ExpansionExpr (HsExpanded a _) -> isAtomicHsExpr a | GhcRn <- ghcPass @p = case x of HsExpanded a _ -> isAtomicHsExpr a 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 "#-}" {- ********************************************************************* * * HsExpansion and rebindable syntax * * ********************************************************************* -} {- Note [Rebindable syntax and HsExpansion] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We implement rebindable syntax (RS) support by performing a desugaring in the renamer. We transform GhcPs expressions affected by RS into the appropriate desugared form, but **annotated with the original expression**. 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 'HsExpansion' 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 (HsExpanded (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 (HsExpansion 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. --- 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 (condition, true branch, false branch 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 in an XExpr: XExpr (HsExpanded ) - At typechecking-time: - remove any logic that was previously dealing with your rebindable construct, typically involving [tc]SyntaxOp, SyntaxExpr and friends. - the XExpr (HsExpanded ... ...) case in tcExpr already makes sure that we typecheck the desugared expression while reporting the original one in errors -} -- See Note [Rebindable syntax and HsExpansion] just above. data HsExpansion a b = HsExpanded a b deriving Data -- | Just print the original expression (the @a@). instance (Outputable a, Outputable b) => Outputable (HsExpansion a b) where ppr (HsExpanded a b) = ifPprDebug (vcat [ppr a, ppr b]) (ppr a) {- ************************************************************************ * * \subsection{Commands (in arrow abstractions)} * * ************************************************************************ -} 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 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{@Match@, @GRHSs@, and @GRHS@ datatypes} * * ************************************************************************ -} type instance XMG GhcPs b = NoExtField type instance XMG GhcRn b = NoExtField type instance XMG GhcTc b = MatchGroupTc type instance XXMatchGroup (GhcPass _) b = NoExtCon 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 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 = length (hsLMatchPats alt1) | otherwise = panic "matchGroupArity" hsLMatchPats :: LMatch (GhcPass id) body -> [LPat (GhcPass id)] hsLMatchPats (L _ (Match { m_pats = pats })) = pats type instance XCGRHSs (GhcPass _) b = NoExtField type instance XXGRHSs (GhcPass _) b = NoExtCon type instance XCGRHS (GhcPass _) b = NoExtField type instance XXGRHS (GhcPass _) b = NoExtCon 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} * * ************************************************************************ -} -- 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 type instance XParStmtBlock (GhcPass pL) (GhcPass pR) = NoExtField type instance XXParStmtBlock (GhcPass pL) (GhcPass pR) = NoExtCon 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 type instance ApplicativeArgStmCtxPass _ = GhcRn 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, 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) = pprBindStmt pat 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 = [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 ++ [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 * * ************************************************************************ -} 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 -- 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] -- | Pending Renamer Splice data PendingRnSplice = PendingRnSplice UntypedSpliceFlavour SplicePointName (LHsExpr GhcRn) -- | 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 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 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} * * ************************************************************************ -} 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} * * ************************************************************************ -} 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" ----------------- 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