{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 This module converts Template Haskell syntax into HsSyn -} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE ViewPatterns #-} module Convert( convertToHsExpr, convertToPat, convertToHsDecls, convertToHsType, thRdrNameGuesses ) where import GhcPrelude import HsSyn as Hs import PrelNames import RdrName import qualified Name import Module import RdrHsSyn import OccName import SrcLoc import Type import qualified Coercion ( Role(..) ) import TysWiredIn import BasicTypes as Hs import ForeignCall import Unique import ErrUtils import Bag import Lexeme import Util import FastString import Outputable import MonadUtils ( foldrM ) import qualified Data.ByteString as BS import Control.Monad( unless, liftM, ap ) import Data.Maybe( catMaybes, isNothing ) import Language.Haskell.TH as TH hiding (sigP) import Language.Haskell.TH.Syntax as TH ------------------------------------------------------------------- -- The external interface convertToHsDecls :: SrcSpan -> [TH.Dec] -> Either MsgDoc [LHsDecl GhcPs] convertToHsDecls loc ds = initCvt loc (fmap catMaybes (mapM cvt_dec ds)) where cvt_dec d = wrapMsg "declaration" d (cvtDec d) convertToHsExpr :: SrcSpan -> TH.Exp -> Either MsgDoc (LHsExpr GhcPs) convertToHsExpr loc e = initCvt loc $ wrapMsg "expression" e $ cvtl e convertToPat :: SrcSpan -> TH.Pat -> Either MsgDoc (LPat GhcPs) convertToPat loc p = initCvt loc $ wrapMsg "pattern" p $ cvtPat p convertToHsType :: SrcSpan -> TH.Type -> Either MsgDoc (LHsType GhcPs) convertToHsType loc t = initCvt loc $ wrapMsg "type" t $ cvtType t ------------------------------------------------------------------- newtype CvtM a = CvtM { unCvtM :: SrcSpan -> Either MsgDoc (SrcSpan, a) } -- Push down the source location; -- Can fail, with a single error message -- NB: If the conversion succeeds with (Right x), there should -- be no exception values hiding in x -- Reason: so a (head []) in TH code doesn't subsequently -- make GHC crash when it tries to walk the generated tree -- Use the loc everywhere, for lack of anything better -- In particular, we want it on binding locations, so that variables bound in -- the spliced-in declarations get a location that at least relates to the splice point instance Functor CvtM where fmap = liftM instance Applicative CvtM where pure x = CvtM $ \loc -> Right (loc,x) (<*>) = ap instance Monad CvtM where (CvtM m) >>= k = CvtM $ \loc -> case m loc of Left err -> Left err Right (loc',v) -> unCvtM (k v) loc' initCvt :: SrcSpan -> CvtM a -> Either MsgDoc a initCvt loc (CvtM m) = fmap snd (m loc) force :: a -> CvtM () force a = a `seq` return () failWith :: MsgDoc -> CvtM a failWith m = CvtM (\_ -> Left m) getL :: CvtM SrcSpan getL = CvtM (\loc -> Right (loc,loc)) setL :: SrcSpan -> CvtM () setL loc = CvtM (\_ -> Right (loc, ())) returnL :: HasSrcSpan a => SrcSpanLess a -> CvtM a returnL x = CvtM (\loc -> Right (loc, cL loc x)) returnJustL :: HasSrcSpan a => SrcSpanLess a -> CvtM (Maybe a) returnJustL = fmap Just . returnL wrapParL :: HasSrcSpan a => (a -> SrcSpanLess a) -> SrcSpanLess a -> CvtM (SrcSpanLess a) wrapParL add_par x = CvtM (\loc -> Right (loc, add_par (cL loc x))) wrapMsg :: (Show a, TH.Ppr a) => String -> a -> CvtM b -> CvtM b -- E.g wrapMsg "declaration" dec thing wrapMsg what item (CvtM m) = CvtM (\loc -> case m loc of Left err -> Left (err $$ getPprStyle msg) Right v -> Right v) where -- Show the item in pretty syntax normally, -- but with all its constructors if you say -dppr-debug msg sty = hang (text "When splicing a TH" <+> text what <> colon) 2 (if debugStyle sty then text (show item) else text (pprint item)) wrapL :: HasSrcSpan a => CvtM (SrcSpanLess a) -> CvtM a wrapL (CvtM m) = CvtM (\loc -> case m loc of Left err -> Left err Right (loc',v) -> Right (loc',cL loc v)) ------------------------------------------------------------------- cvtDecs :: [TH.Dec] -> CvtM [LHsDecl GhcPs] cvtDecs = fmap catMaybes . mapM cvtDec cvtDec :: TH.Dec -> CvtM (Maybe (LHsDecl GhcPs)) cvtDec (TH.ValD pat body ds) | TH.VarP s <- pat = do { s' <- vNameL s ; cl' <- cvtClause (mkPrefixFunRhs s') (Clause [] body ds) ; returnJustL $ Hs.ValD noExt $ mkFunBind s' [cl'] } | otherwise = do { pat' <- cvtPat pat ; body' <- cvtGuard body ; ds' <- cvtLocalDecs (text "a where clause") ds ; returnJustL $ Hs.ValD noExt $ PatBind { pat_lhs = pat' , pat_rhs = GRHSs noExt body' (noLoc ds') , pat_ext = noExt , pat_ticks = ([],[]) } } cvtDec (TH.FunD nm cls) | null cls = failWith (text "Function binding for" <+> quotes (text (TH.pprint nm)) <+> text "has no equations") | otherwise = do { nm' <- vNameL nm ; cls' <- mapM (cvtClause (mkPrefixFunRhs nm')) cls ; returnJustL $ Hs.ValD noExt $ mkFunBind nm' cls' } cvtDec (TH.SigD nm typ) = do { nm' <- vNameL nm ; ty' <- cvtType typ ; returnJustL $ Hs.SigD noExt (TypeSig noExt [nm'] (mkLHsSigWcType ty')) } cvtDec (TH.InfixD fx nm) -- Fixity signatures are allowed for variables, constructors, and types -- the renamer automatically looks for types during renaming, even when -- the RdrName says it's a variable or a constructor. So, just assume -- it's a variable or constructor and proceed. = do { nm' <- vcNameL nm ; returnJustL (Hs.SigD noExt (FixSig noExt (FixitySig noExt [nm'] (cvtFixity fx)))) } cvtDec (PragmaD prag) = cvtPragmaD prag cvtDec (TySynD tc tvs rhs) = do { (_, tc', tvs') <- cvt_tycl_hdr [] tc tvs ; rhs' <- cvtType rhs ; returnJustL $ TyClD noExt $ SynDecl { tcdSExt = noExt, tcdLName = tc', tcdTyVars = tvs' , tcdFixity = Prefix , tcdRhs = rhs' } } cvtDec (DataD ctxt tc tvs ksig constrs derivs) = do { let isGadtCon (GadtC _ _ _) = True isGadtCon (RecGadtC _ _ _) = True isGadtCon (ForallC _ _ c) = isGadtCon c isGadtCon _ = False isGadtDecl = all isGadtCon constrs isH98Decl = all (not . isGadtCon) constrs ; unless (isGadtDecl || isH98Decl) (failWith (text "Cannot mix GADT constructors with Haskell 98" <+> text "constructors")) ; unless (isNothing ksig || isGadtDecl) (failWith (text "Kind signatures are only allowed on GADTs")) ; (ctxt', tc', tvs') <- cvt_tycl_hdr ctxt tc tvs ; ksig' <- cvtKind `traverse` ksig ; cons' <- mapM cvtConstr constrs ; derivs' <- cvtDerivs derivs ; let defn = HsDataDefn { dd_ext = noExt , dd_ND = DataType, dd_cType = Nothing , dd_ctxt = ctxt' , dd_kindSig = ksig' , dd_cons = cons', dd_derivs = derivs' } ; returnJustL $ TyClD noExt (DataDecl { tcdDExt = noExt , tcdLName = tc', tcdTyVars = tvs' , tcdFixity = Prefix , tcdDataDefn = defn }) } cvtDec (NewtypeD ctxt tc tvs ksig constr derivs) = do { (ctxt', tc', tvs') <- cvt_tycl_hdr ctxt tc tvs ; ksig' <- cvtKind `traverse` ksig ; con' <- cvtConstr constr ; derivs' <- cvtDerivs derivs ; let defn = HsDataDefn { dd_ext = noExt , dd_ND = NewType, dd_cType = Nothing , dd_ctxt = ctxt' , dd_kindSig = ksig' , dd_cons = [con'] , dd_derivs = derivs' } ; returnJustL $ TyClD noExt (DataDecl { tcdDExt = noExt , tcdLName = tc', tcdTyVars = tvs' , tcdFixity = Prefix , tcdDataDefn = defn }) } cvtDec (ClassD ctxt cl tvs fds decs) = do { (cxt', tc', tvs') <- cvt_tycl_hdr ctxt cl tvs ; fds' <- mapM cvt_fundep fds ; (binds', sigs', fams', ats', adts') <- cvt_ci_decs (text "a class declaration") decs ; unless (null adts') (failWith $ (text "Default data instance declarations" <+> text "are not allowed:") $$ (Outputable.ppr adts')) ; at_defs <- mapM cvt_at_def ats' ; returnJustL $ TyClD noExt $ ClassDecl { tcdCExt = noExt , tcdCtxt = cxt', tcdLName = tc', tcdTyVars = tvs' , tcdFixity = Prefix , tcdFDs = fds', tcdSigs = Hs.mkClassOpSigs sigs' , tcdMeths = binds' , tcdATs = fams', tcdATDefs = at_defs, tcdDocs = [] } -- no docs in TH ^^ } where cvt_at_def :: LTyFamInstDecl GhcPs -> CvtM (LTyFamDefltEqn GhcPs) -- Very similar to what happens in RdrHsSyn.mkClassDecl cvt_at_def decl = case RdrHsSyn.mkATDefault decl of Right (def, _) -> return def Left (_, msg) -> failWith msg cvtDec (InstanceD o ctxt ty decs) = do { let doc = text "an instance declaration" ; (binds', sigs', fams', ats', adts') <- cvt_ci_decs doc decs ; unless (null fams') (failWith (mkBadDecMsg doc fams')) ; ctxt' <- cvtContext ctxt ; (dL->L loc ty') <- cvtType ty ; let inst_ty' = mkHsQualTy ctxt loc ctxt' $ cL loc ty' ; returnJustL $ InstD noExt $ ClsInstD noExt $ ClsInstDecl { cid_ext = noExt, cid_poly_ty = mkLHsSigType inst_ty' , cid_binds = binds' , cid_sigs = Hs.mkClassOpSigs sigs' , cid_tyfam_insts = ats', cid_datafam_insts = adts' , cid_overlap_mode = fmap (cL loc . overlap) o } } where overlap pragma = case pragma of TH.Overlaps -> Hs.Overlaps (SourceText "OVERLAPS") TH.Overlappable -> Hs.Overlappable (SourceText "OVERLAPPABLE") TH.Overlapping -> Hs.Overlapping (SourceText "OVERLAPPING") TH.Incoherent -> Hs.Incoherent (SourceText "INCOHERENT") cvtDec (ForeignD ford) = do { ford' <- cvtForD ford ; returnJustL $ ForD noExt ford' } cvtDec (DataFamilyD tc tvs kind) = do { (_, tc', tvs') <- cvt_tycl_hdr [] tc tvs ; result <- cvtMaybeKindToFamilyResultSig kind ; returnJustL $ TyClD noExt $ FamDecl noExt $ FamilyDecl noExt DataFamily tc' tvs' Prefix result Nothing } cvtDec (DataInstD ctxt bndrs tys ksig constrs derivs) = do { (ctxt', tc', bndrs', typats') <- cvt_datainst_hdr ctxt bndrs tys ; ksig' <- cvtKind `traverse` ksig ; cons' <- mapM cvtConstr constrs ; derivs' <- cvtDerivs derivs ; let defn = HsDataDefn { dd_ext = noExt , dd_ND = DataType, dd_cType = Nothing , dd_ctxt = ctxt' , dd_kindSig = ksig' , dd_cons = cons', dd_derivs = derivs' } ; returnJustL $ InstD noExt $ DataFamInstD { dfid_ext = noExt , dfid_inst = DataFamInstDecl { dfid_eqn = mkHsImplicitBndrs $ FamEqn { feqn_ext = noExt , feqn_tycon = tc' , feqn_bndrs = bndrs' , feqn_pats = typats' , feqn_rhs = defn , feqn_fixity = Prefix } }}} cvtDec (NewtypeInstD ctxt bndrs tys ksig constr derivs) = do { (ctxt', tc', bndrs', typats') <- cvt_datainst_hdr ctxt bndrs tys ; ksig' <- cvtKind `traverse` ksig ; con' <- cvtConstr constr ; derivs' <- cvtDerivs derivs ; let defn = HsDataDefn { dd_ext = noExt , dd_ND = NewType, dd_cType = Nothing , dd_ctxt = ctxt' , dd_kindSig = ksig' , dd_cons = [con'], dd_derivs = derivs' } ; returnJustL $ InstD noExt $ DataFamInstD { dfid_ext = noExt , dfid_inst = DataFamInstDecl { dfid_eqn = mkHsImplicitBndrs $ FamEqn { feqn_ext = noExt , feqn_tycon = tc' , feqn_bndrs = bndrs' , feqn_pats = typats' , feqn_rhs = defn , feqn_fixity = Prefix } }}} cvtDec (TySynInstD eqn) = do { (dL->L _ eqn') <- cvtTySynEqn eqn ; returnJustL $ InstD noExt $ TyFamInstD { tfid_ext = noExt , tfid_inst = TyFamInstDecl { tfid_eqn = eqn' } } } cvtDec (OpenTypeFamilyD head) = do { (tc', tyvars', result', injectivity') <- cvt_tyfam_head head ; returnJustL $ TyClD noExt $ FamDecl noExt $ FamilyDecl noExt OpenTypeFamily tc' tyvars' Prefix result' injectivity' } cvtDec (ClosedTypeFamilyD head eqns) = do { (tc', tyvars', result', injectivity') <- cvt_tyfam_head head ; eqns' <- mapM cvtTySynEqn eqns ; returnJustL $ TyClD noExt $ FamDecl noExt $ FamilyDecl noExt (ClosedTypeFamily (Just eqns')) tc' tyvars' Prefix result' injectivity' } cvtDec (TH.RoleAnnotD tc roles) = do { tc' <- tconNameL tc ; let roles' = map (noLoc . cvtRole) roles ; returnJustL $ Hs.RoleAnnotD noExt (RoleAnnotDecl noExt tc' roles') } cvtDec (TH.StandaloneDerivD ds cxt ty) = do { cxt' <- cvtContext cxt ; ds' <- traverse cvtDerivStrategy ds ; (dL->L loc ty') <- cvtType ty ; let inst_ty' = mkHsQualTy cxt loc cxt' $ cL loc ty' ; returnJustL $ DerivD noExt $ DerivDecl { deriv_ext =noExt , deriv_strategy = ds' , deriv_type = mkLHsSigWcType inst_ty' , deriv_overlap_mode = Nothing } } cvtDec (TH.DefaultSigD nm typ) = do { nm' <- vNameL nm ; ty' <- cvtType typ ; returnJustL $ Hs.SigD noExt $ ClassOpSig noExt True [nm'] (mkLHsSigType ty')} cvtDec (TH.PatSynD nm args dir pat) = do { nm' <- cNameL nm ; args' <- cvtArgs args ; dir' <- cvtDir nm' dir ; pat' <- cvtPat pat ; returnJustL $ Hs.ValD noExt $ PatSynBind noExt $ PSB noExt nm' args' pat' dir' } where cvtArgs (TH.PrefixPatSyn args) = Hs.PrefixCon <$> mapM vNameL args cvtArgs (TH.InfixPatSyn a1 a2) = Hs.InfixCon <$> vNameL a1 <*> vNameL a2 cvtArgs (TH.RecordPatSyn sels) = do { sels' <- mapM vNameL sels ; vars' <- mapM (vNameL . mkNameS . nameBase) sels ; return $ Hs.RecCon $ zipWith RecordPatSynField sels' vars' } cvtDir _ Unidir = return Unidirectional cvtDir _ ImplBidir = return ImplicitBidirectional cvtDir n (ExplBidir cls) = do { ms <- mapM (cvtClause (mkPrefixFunRhs n)) cls ; return $ ExplicitBidirectional $ mkMatchGroup FromSource ms } cvtDec (TH.PatSynSigD nm ty) = do { nm' <- cNameL nm ; ty' <- cvtPatSynSigTy ty ; returnJustL $ Hs.SigD noExt $ PatSynSig noExt [nm'] (mkLHsSigType ty')} -- Implicit parameter bindings are handled in cvtLocalDecs and -- cvtImplicitParamBind. They are not allowed in any other scope, so -- reaching this case indicates an error. cvtDec (TH.ImplicitParamBindD _ _) = failWith (text "Implicit parameter binding only allowed in let or where") ---------------- cvtTySynEqn :: TySynEqn -> CvtM (LTyFamInstEqn GhcPs) cvtTySynEqn (TySynEqn mb_bndrs lhs rhs) = do { mb_bndrs' <- traverse (mapM cvt_tv) mb_bndrs ; (head_ty, args) <- split_ty_app lhs ; case head_ty of ConT nm -> do { nm' <- tconNameL nm ; rhs' <- cvtType rhs ; let args' = map wrap_tyarg args ; returnL $ mkHsImplicitBndrs $ FamEqn { feqn_ext = noExt , feqn_tycon = nm' , feqn_bndrs = mb_bndrs' , feqn_pats = args' , feqn_fixity = Prefix , feqn_rhs = rhs' } } InfixT t1 nm t2 -> do { nm' <- tconNameL nm ; args' <- mapM cvtType [t1,t2] ; rhs' <- cvtType rhs ; returnL $ mkHsImplicitBndrs $ FamEqn { feqn_ext = noExt , feqn_tycon = nm' , feqn_bndrs = mb_bndrs' , feqn_pats = (map HsValArg args') ++ args , feqn_fixity = Hs.Infix , feqn_rhs = rhs' } } _ -> failWith $ text "Invalid type family instance LHS:" <+> text (show lhs) } ---------------- cvt_ci_decs :: MsgDoc -> [TH.Dec] -> CvtM (LHsBinds GhcPs, [LSig GhcPs], [LFamilyDecl GhcPs], [LTyFamInstDecl GhcPs], [LDataFamInstDecl GhcPs]) -- Convert the declarations inside a class or instance decl -- ie signatures, bindings, and associated types cvt_ci_decs doc decs = do { decs' <- cvtDecs decs ; let (ats', bind_sig_decs') = partitionWith is_tyfam_inst decs' ; let (adts', no_ats') = partitionWith is_datafam_inst bind_sig_decs' ; let (sigs', prob_binds') = partitionWith is_sig no_ats' ; let (binds', prob_fams') = partitionWith is_bind prob_binds' ; let (fams', bads) = partitionWith is_fam_decl prob_fams' ; unless (null bads) (failWith (mkBadDecMsg doc bads)) --We use FromSource as the origin of the bind -- because the TH declaration is user-written ; return (listToBag binds', sigs', fams', ats', adts') } ---------------- cvt_tycl_hdr :: TH.Cxt -> TH.Name -> [TH.TyVarBndr] -> CvtM ( LHsContext GhcPs , Located RdrName , LHsQTyVars GhcPs) cvt_tycl_hdr cxt tc tvs = do { cxt' <- cvtContext cxt ; tc' <- tconNameL tc ; tvs' <- cvtTvs tvs ; return (cxt', tc', tvs') } cvt_datainst_hdr :: TH.Cxt -> Maybe [TH.TyVarBndr] -> TH.Type -> CvtM ( LHsContext GhcPs , Located RdrName , Maybe [LHsTyVarBndr GhcPs] , HsTyPats GhcPs) cvt_datainst_hdr cxt bndrs tys = do { cxt' <- cvtContext cxt ; bndrs' <- traverse (mapM cvt_tv) bndrs ; (head_ty, args) <- split_ty_app tys ; case head_ty of ConT nm -> do { nm' <- tconNameL nm ; let args' = map wrap_tyarg args ; return (cxt', nm', bndrs', args') } InfixT t1 nm t2 -> do { nm' <- tconNameL nm ; args' <- mapM cvtType [t1,t2] ; return (cxt', nm', bndrs', ((map HsValArg args') ++ args)) } _ -> failWith $ text "Invalid type instance header:" <+> text (show tys) } ---------------- cvt_tyfam_head :: TypeFamilyHead -> CvtM ( Located RdrName , LHsQTyVars GhcPs , Hs.LFamilyResultSig GhcPs , Maybe (Hs.LInjectivityAnn GhcPs)) cvt_tyfam_head (TypeFamilyHead tc tyvars result injectivity) = do {(_, tc', tyvars') <- cvt_tycl_hdr [] tc tyvars ; result' <- cvtFamilyResultSig result ; injectivity' <- traverse cvtInjectivityAnnotation injectivity ; return (tc', tyvars', result', injectivity') } ------------------------------------------------------------------- -- Partitioning declarations ------------------------------------------------------------------- is_fam_decl :: LHsDecl GhcPs -> Either (LFamilyDecl GhcPs) (LHsDecl GhcPs) is_fam_decl (dL->L loc (TyClD _ (FamDecl { tcdFam = d }))) = Left (cL loc d) is_fam_decl decl = Right decl is_tyfam_inst :: LHsDecl GhcPs -> Either (LTyFamInstDecl GhcPs) (LHsDecl GhcPs) is_tyfam_inst (dL->L loc (Hs.InstD _ (TyFamInstD { tfid_inst = d }))) = Left (cL loc d) is_tyfam_inst decl = Right decl is_datafam_inst :: LHsDecl GhcPs -> Either (LDataFamInstDecl GhcPs) (LHsDecl GhcPs) is_datafam_inst (dL->L loc (Hs.InstD _ (DataFamInstD { dfid_inst = d }))) = Left (cL loc d) is_datafam_inst decl = Right decl is_sig :: LHsDecl GhcPs -> Either (LSig GhcPs) (LHsDecl GhcPs) is_sig (dL->L loc (Hs.SigD _ sig)) = Left (cL loc sig) is_sig decl = Right decl is_bind :: LHsDecl GhcPs -> Either (LHsBind GhcPs) (LHsDecl GhcPs) is_bind (dL->L loc (Hs.ValD _ bind)) = Left (cL loc bind) is_bind decl = Right decl is_ip_bind :: TH.Dec -> Either (String, TH.Exp) TH.Dec is_ip_bind (TH.ImplicitParamBindD n e) = Left (n, e) is_ip_bind decl = Right decl mkBadDecMsg :: Outputable a => MsgDoc -> [a] -> MsgDoc mkBadDecMsg doc bads = sep [ text "Illegal declaration(s) in" <+> doc <> colon , nest 2 (vcat (map Outputable.ppr bads)) ] --------------------------------------------------- -- Data types --------------------------------------------------- cvtConstr :: TH.Con -> CvtM (LConDecl GhcPs) cvtConstr (NormalC c strtys) = do { c' <- cNameL c ; tys' <- mapM cvt_arg strtys ; returnL $ mkConDeclH98 c' Nothing Nothing (PrefixCon tys') } cvtConstr (RecC c varstrtys) = do { c' <- cNameL c ; args' <- mapM cvt_id_arg varstrtys ; returnL $ mkConDeclH98 c' Nothing Nothing (RecCon (noLoc args')) } cvtConstr (InfixC st1 c st2) = do { c' <- cNameL c ; st1' <- cvt_arg st1 ; st2' <- cvt_arg st2 ; returnL $ mkConDeclH98 c' Nothing Nothing (InfixCon st1' st2') } cvtConstr (ForallC tvs ctxt con) = do { tvs' <- cvtTvs tvs ; ctxt' <- cvtContext ctxt ; (dL->L _ con') <- cvtConstr con ; returnL $ add_forall tvs' ctxt' con' } where add_cxt lcxt Nothing = Just lcxt add_cxt (dL->L loc cxt1) (Just (dL->L _ cxt2)) = Just (cL loc (cxt1 ++ cxt2)) add_forall tvs' cxt' con@(ConDeclGADT { con_qvars = qvars, con_mb_cxt = cxt }) = con { con_forall = noLoc $ not (null all_tvs) , con_qvars = mkHsQTvs all_tvs , con_mb_cxt = add_cxt cxt' cxt } where all_tvs = hsQTvExplicit tvs' ++ hsQTvExplicit qvars add_forall tvs' cxt' con@(ConDeclH98 { con_ex_tvs = ex_tvs, con_mb_cxt = cxt }) = con { con_forall = noLoc $ not (null all_tvs) , con_ex_tvs = all_tvs , con_mb_cxt = add_cxt cxt' cxt } where all_tvs = hsQTvExplicit tvs' ++ ex_tvs add_forall _ _ (XConDecl _) = panic "cvtConstr" cvtConstr (GadtC c strtys ty) = do { c' <- mapM cNameL c ; args <- mapM cvt_arg strtys ; (dL->L _ ty') <- cvtType ty ; c_ty <- mk_arr_apps args ty' ; returnL $ fst $ mkGadtDecl c' c_ty} cvtConstr (RecGadtC c varstrtys ty) = do { c' <- mapM cNameL c ; ty' <- cvtType ty ; rec_flds <- mapM cvt_id_arg varstrtys ; let rec_ty = noLoc (HsFunTy noExt (noLoc $ HsRecTy noExt rec_flds) ty') ; returnL $ fst $ mkGadtDecl c' rec_ty } cvtSrcUnpackedness :: TH.SourceUnpackedness -> SrcUnpackedness cvtSrcUnpackedness NoSourceUnpackedness = NoSrcUnpack cvtSrcUnpackedness SourceNoUnpack = SrcNoUnpack cvtSrcUnpackedness SourceUnpack = SrcUnpack cvtSrcStrictness :: TH.SourceStrictness -> SrcStrictness cvtSrcStrictness NoSourceStrictness = NoSrcStrict cvtSrcStrictness SourceLazy = SrcLazy cvtSrcStrictness SourceStrict = SrcStrict cvt_arg :: (TH.Bang, TH.Type) -> CvtM (LHsType GhcPs) cvt_arg (Bang su ss, ty) = do { ty'' <- cvtType ty ; let ty' = parenthesizeHsType appPrec ty'' su' = cvtSrcUnpackedness su ss' = cvtSrcStrictness ss ; returnL $ HsBangTy noExt (HsSrcBang NoSourceText su' ss') ty' } cvt_id_arg :: (TH.Name, TH.Bang, TH.Type) -> CvtM (LConDeclField GhcPs) cvt_id_arg (i, str, ty) = do { (dL->L li i') <- vNameL i ; ty' <- cvt_arg (str,ty) ; return $ noLoc (ConDeclField { cd_fld_ext = noExt , cd_fld_names = [cL li $ FieldOcc noExt (cL li i')] , cd_fld_type = ty' , cd_fld_doc = Nothing}) } cvtDerivs :: [TH.DerivClause] -> CvtM (HsDeriving GhcPs) cvtDerivs cs = do { cs' <- mapM cvtDerivClause cs ; returnL cs' } cvt_fundep :: FunDep -> CvtM (LHsFunDep GhcPs) cvt_fundep (FunDep xs ys) = do { xs' <- mapM tNameL xs ; ys' <- mapM tNameL ys ; returnL (xs', ys') } ------------------------------------------ -- Foreign declarations ------------------------------------------ cvtForD :: Foreign -> CvtM (ForeignDecl GhcPs) cvtForD (ImportF callconv safety from nm ty) -- the prim and javascript calling conventions do not support headers -- and are inserted verbatim, analogous to mkImport in RdrHsSyn | callconv == TH.Prim || callconv == TH.JavaScript = mk_imp (CImport (noLoc (cvt_conv callconv)) (noLoc safety') Nothing (CFunction (StaticTarget (SourceText from) (mkFastString from) Nothing True)) (noLoc $ quotedSourceText from)) | Just impspec <- parseCImport (noLoc (cvt_conv callconv)) (noLoc safety') (mkFastString (TH.nameBase nm)) from (noLoc $ quotedSourceText from) = mk_imp impspec | otherwise = failWith $ text (show from) <+> text "is not a valid ccall impent" where mk_imp impspec = do { nm' <- vNameL nm ; ty' <- cvtType ty ; return (ForeignImport { fd_i_ext = noExt , fd_name = nm' , fd_sig_ty = mkLHsSigType ty' , fd_fi = impspec }) } safety' = case safety of Unsafe -> PlayRisky Safe -> PlaySafe Interruptible -> PlayInterruptible cvtForD (ExportF callconv as nm ty) = do { nm' <- vNameL nm ; ty' <- cvtType ty ; let e = CExport (noLoc (CExportStatic (SourceText as) (mkFastString as) (cvt_conv callconv))) (noLoc (SourceText as)) ; return $ ForeignExport { fd_e_ext = noExt , fd_name = nm' , fd_sig_ty = mkLHsSigType ty' , fd_fe = e } } cvt_conv :: TH.Callconv -> CCallConv cvt_conv TH.CCall = CCallConv cvt_conv TH.StdCall = StdCallConv cvt_conv TH.CApi = CApiConv cvt_conv TH.Prim = PrimCallConv cvt_conv TH.JavaScript = JavaScriptCallConv ------------------------------------------ -- Pragmas ------------------------------------------ cvtPragmaD :: Pragma -> CvtM (Maybe (LHsDecl GhcPs)) cvtPragmaD (InlineP nm inline rm phases) = do { nm' <- vNameL nm ; let dflt = dfltActivation inline ; let src TH.NoInline = "{-# NOINLINE" src TH.Inline = "{-# INLINE" src TH.Inlinable = "{-# INLINABLE" ; let ip = InlinePragma { inl_src = SourceText $ src inline , inl_inline = cvtInline inline , inl_rule = cvtRuleMatch rm , inl_act = cvtPhases phases dflt , inl_sat = Nothing } ; returnJustL $ Hs.SigD noExt $ InlineSig noExt nm' ip } cvtPragmaD (SpecialiseP nm ty inline phases) = do { nm' <- vNameL nm ; ty' <- cvtType ty ; let src TH.NoInline = "{-# SPECIALISE NOINLINE" src TH.Inline = "{-# SPECIALISE INLINE" src TH.Inlinable = "{-# SPECIALISE INLINE" ; let (inline', dflt,srcText) = case inline of Just inline1 -> (cvtInline inline1, dfltActivation inline1, src inline1) Nothing -> (NoUserInline, AlwaysActive, "{-# SPECIALISE") ; let ip = InlinePragma { inl_src = SourceText srcText , inl_inline = inline' , inl_rule = Hs.FunLike , inl_act = cvtPhases phases dflt , inl_sat = Nothing } ; returnJustL $ Hs.SigD noExt $ SpecSig noExt nm' [mkLHsSigType ty'] ip } cvtPragmaD (SpecialiseInstP ty) = do { ty' <- cvtType ty ; returnJustL $ Hs.SigD noExt $ SpecInstSig noExt (SourceText "{-# SPECIALISE") (mkLHsSigType ty') } cvtPragmaD (RuleP nm ty_bndrs tm_bndrs lhs rhs phases) = do { let nm' = mkFastString nm ; let act = cvtPhases phases AlwaysActive ; ty_bndrs' <- traverse (mapM cvt_tv) ty_bndrs ; tm_bndrs' <- mapM cvtRuleBndr tm_bndrs ; lhs' <- cvtl lhs ; rhs' <- cvtl rhs ; returnJustL $ Hs.RuleD noExt $ HsRules { rds_ext = noExt , rds_src = SourceText "{-# RULES" , rds_rules = [noLoc $ HsRule { rd_ext = noExt , rd_name = (noLoc (quotedSourceText nm,nm')) , rd_act = act , rd_tyvs = ty_bndrs' , rd_tmvs = tm_bndrs' , rd_lhs = lhs' , rd_rhs = rhs' }] } } cvtPragmaD (AnnP target exp) = do { exp' <- cvtl exp ; target' <- case target of ModuleAnnotation -> return ModuleAnnProvenance TypeAnnotation n -> do n' <- tconName n return (TypeAnnProvenance (noLoc n')) ValueAnnotation n -> do n' <- vcName n return (ValueAnnProvenance (noLoc n')) ; returnJustL $ Hs.AnnD noExt $ HsAnnotation noExt (SourceText "{-# ANN") target' exp' } cvtPragmaD (LineP line file) = do { setL (srcLocSpan (mkSrcLoc (fsLit file) line 1)) ; return Nothing } cvtPragmaD (CompleteP cls mty) = do { cls' <- noLoc <$> mapM cNameL cls ; mty' <- traverse tconNameL mty ; returnJustL $ Hs.SigD noExt $ CompleteMatchSig noExt NoSourceText cls' mty' } dfltActivation :: TH.Inline -> Activation dfltActivation TH.NoInline = NeverActive dfltActivation _ = AlwaysActive cvtInline :: TH.Inline -> Hs.InlineSpec cvtInline TH.NoInline = Hs.NoInline cvtInline TH.Inline = Hs.Inline cvtInline TH.Inlinable = Hs.Inlinable cvtRuleMatch :: TH.RuleMatch -> RuleMatchInfo cvtRuleMatch TH.ConLike = Hs.ConLike cvtRuleMatch TH.FunLike = Hs.FunLike cvtPhases :: TH.Phases -> Activation -> Activation cvtPhases AllPhases dflt = dflt cvtPhases (FromPhase i) _ = ActiveAfter NoSourceText i cvtPhases (BeforePhase i) _ = ActiveBefore NoSourceText i cvtRuleBndr :: TH.RuleBndr -> CvtM (Hs.LRuleBndr GhcPs) cvtRuleBndr (RuleVar n) = do { n' <- vNameL n ; return $ noLoc $ Hs.RuleBndr noExt n' } cvtRuleBndr (TypedRuleVar n ty) = do { n' <- vNameL n ; ty' <- cvtType ty ; return $ noLoc $ Hs.RuleBndrSig noExt n' $ mkLHsSigWcType ty' } --------------------------------------------------- -- Declarations --------------------------------------------------- cvtLocalDecs :: MsgDoc -> [TH.Dec] -> CvtM (HsLocalBinds GhcPs) cvtLocalDecs doc ds = case partitionWith is_ip_bind ds of ([], []) -> return (EmptyLocalBinds noExt) ([], _) -> do ds' <- cvtDecs ds let (binds, prob_sigs) = partitionWith is_bind ds' let (sigs, bads) = partitionWith is_sig prob_sigs unless (null bads) (failWith (mkBadDecMsg doc bads)) return (HsValBinds noExt (ValBinds noExt (listToBag binds) sigs)) (ip_binds, []) -> do binds <- mapM (uncurry cvtImplicitParamBind) ip_binds return (HsIPBinds noExt (IPBinds noExt binds)) ((_:_), (_:_)) -> failWith (text "Implicit parameters mixed with other bindings") cvtClause :: HsMatchContext RdrName -> TH.Clause -> CvtM (Hs.LMatch GhcPs (LHsExpr GhcPs)) cvtClause ctxt (Clause ps body wheres) = do { ps' <- cvtPats ps ; let pps = map (parenthesizePat appPrec) ps' ; g' <- cvtGuard body ; ds' <- cvtLocalDecs (text "a where clause") wheres ; returnL $ Hs.Match noExt ctxt pps (GRHSs noExt g' (noLoc ds')) } cvtImplicitParamBind :: String -> TH.Exp -> CvtM (LIPBind GhcPs) cvtImplicitParamBind n e = do n' <- wrapL (ipName n) e' <- cvtl e returnL (IPBind noExt (Left n') e') ------------------------------------------------------------------- -- Expressions ------------------------------------------------------------------- cvtl :: TH.Exp -> CvtM (LHsExpr GhcPs) cvtl e = wrapL (cvt e) where cvt (VarE s) = do { s' <- vName s; return $ HsVar noExt (noLoc s') } cvt (ConE s) = do { s' <- cName s; return $ HsVar noExt (noLoc s') } cvt (LitE l) | overloadedLit l = go cvtOverLit (HsOverLit noExt) (hsOverLitNeedsParens appPrec) | otherwise = go cvtLit (HsLit noExt) (hsLitNeedsParens appPrec) where go :: (Lit -> CvtM (l GhcPs)) -> (l GhcPs -> HsExpr GhcPs) -> (l GhcPs -> Bool) -> CvtM (HsExpr GhcPs) go cvt_lit mk_expr is_compound_lit = do l' <- cvt_lit l let e' = mk_expr l' return $ if is_compound_lit l' then HsPar noExt (noLoc e') else e' cvt (AppE x@(LamE _ _) y) = do { x' <- cvtl x; y' <- cvtl y ; return $ HsApp noExt (mkLHsPar x') (mkLHsPar y')} cvt (AppE x y) = do { x' <- cvtl x; y' <- cvtl y ; return $ HsApp noExt (mkLHsPar x') (mkLHsPar y')} cvt (AppTypeE e t) = do { e' <- cvtl e ; t' <- cvtType t ; let tp = parenthesizeHsType appPrec t' ; return $ HsAppType noExt e' $ mkHsWildCardBndrs tp } cvt (LamE [] e) = cvt e -- Degenerate case. We convert the body as its -- own expression to avoid pretty-printing -- oddities that can result from zero-argument -- lambda expressions. See #13856. cvt (LamE ps e) = do { ps' <- cvtPats ps; e' <- cvtl e ; let pats = map (parenthesizePat appPrec) ps' ; return $ HsLam noExt (mkMatchGroup FromSource [mkSimpleMatch LambdaExpr pats e'])} cvt (LamCaseE ms) = do { ms' <- mapM (cvtMatch CaseAlt) ms ; return $ HsLamCase noExt (mkMatchGroup FromSource ms') } cvt (TupE [e]) = do { e' <- cvtl e; return $ HsPar noExt e' } -- Note [Dropping constructors] -- Singleton tuples treated like nothing (just parens) cvt (TupE es) = do { es' <- mapM cvtl es ; return $ ExplicitTuple noExt (map (noLoc . (Present noExt)) es') Boxed } cvt (UnboxedTupE es) = do { es' <- mapM cvtl es ; return $ ExplicitTuple noExt (map (noLoc . (Present noExt)) es') Unboxed } cvt (UnboxedSumE e alt arity) = do { e' <- cvtl e ; unboxedSumChecks alt arity ; return $ ExplicitSum noExt alt arity e'} cvt (CondE x y z) = do { x' <- cvtl x; y' <- cvtl y; z' <- cvtl z; ; return $ HsIf noExt (Just noSyntaxExpr) x' y' z' } cvt (MultiIfE alts) | null alts = failWith (text "Multi-way if-expression with no alternatives") | otherwise = do { alts' <- mapM cvtpair alts ; return $ HsMultiIf noExt alts' } cvt (LetE ds e) = do { ds' <- cvtLocalDecs (text "a let expression") ds ; e' <- cvtl e; return $ HsLet noExt (noLoc ds') e'} cvt (CaseE e ms) = do { e' <- cvtl e; ms' <- mapM (cvtMatch CaseAlt) ms ; return $ HsCase noExt e' (mkMatchGroup FromSource ms') } cvt (DoE ss) = cvtHsDo DoExpr ss cvt (MDoE ss) = cvtHsDo MDoExpr ss cvt (CompE ss) = cvtHsDo ListComp ss cvt (ArithSeqE dd) = do { dd' <- cvtDD dd ; return $ ArithSeq noExt Nothing dd' } cvt (ListE xs) | Just s <- allCharLs xs = do { l' <- cvtLit (StringL s) ; return (HsLit noExt l') } -- Note [Converting strings] | otherwise = do { xs' <- mapM cvtl xs ; return $ ExplicitList noExt Nothing xs' } -- Infix expressions cvt (InfixE (Just x) s (Just y)) = do { x' <- cvtl x ; s' <- cvtl s ; y' <- cvtl y ; let px = parenthesizeHsExpr opPrec x' py = parenthesizeHsExpr opPrec y' ; wrapParL (HsPar noExt) $ OpApp noExt px s' py } -- Parenthesise both arguments and result, -- to ensure this operator application does -- does not get re-associated -- See Note [Operator association] cvt (InfixE Nothing s (Just y)) = do { s' <- cvtl s; y' <- cvtl y ; wrapParL (HsPar noExt) $ SectionR noExt s' y' } -- See Note [Sections in HsSyn] in HsExpr cvt (InfixE (Just x) s Nothing ) = do { x' <- cvtl x; s' <- cvtl s ; wrapParL (HsPar noExt) $ SectionL noExt x' s' } cvt (InfixE Nothing s Nothing ) = do { s' <- cvtl s ; return $ HsPar noExt s' } -- Can I indicate this is an infix thing? -- Note [Dropping constructors] cvt (UInfixE x s y) = do { x' <- cvtl x ; let x'' = case unLoc x' of OpApp {} -> x' _ -> mkLHsPar x' ; cvtOpApp x'' s y } -- Note [Converting UInfix] cvt (ParensE e) = do { e' <- cvtl e; return $ HsPar noExt e' } cvt (SigE e t) = do { e' <- cvtl e; t' <- cvtType t ; let pe = parenthesizeHsExpr sigPrec e' ; return $ ExprWithTySig noExt pe (mkLHsSigWcType t') } cvt (RecConE c flds) = do { c' <- cNameL c ; flds' <- mapM (cvtFld (mkFieldOcc . noLoc)) flds ; return $ mkRdrRecordCon c' (HsRecFields flds' Nothing) } cvt (RecUpdE e flds) = do { e' <- cvtl e ; flds' <- mapM (cvtFld (mkAmbiguousFieldOcc . noLoc)) flds ; return $ mkRdrRecordUpd e' flds' } cvt (StaticE e) = fmap (HsStatic noExt) $ cvtl e cvt (UnboundVarE s) = do -- Use of 'vcName' here instead of 'vName' is -- important, because UnboundVarE may contain -- constructor names - see #14627. { s' <- vcName s ; return $ HsVar noExt (noLoc s') } cvt (LabelE s) = do { return $ HsOverLabel noExt Nothing (fsLit s) } cvt (ImplicitParamVarE n) = do { n' <- ipName n; return $ HsIPVar noExt n' } {- Note [Dropping constructors] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When we drop constructors from the input (for instance, when we encounter @TupE [e]@) we must insert parentheses around the argument. Otherwise, @UInfix@ constructors in @e@ could meet @UInfix@ constructors containing the @TupE [e]@. For example: UInfixE x * (TupE [UInfixE y + z]) If we drop the singleton tuple but don't insert parentheses, the @UInfixE@s would meet and the above expression would be reassociated to OpApp (OpApp x * y) + z which we don't want. -} cvtFld :: (RdrName -> t) -> (TH.Name, TH.Exp) -> CvtM (LHsRecField' t (LHsExpr GhcPs)) cvtFld f (v,e) = do { v' <- vNameL v; e' <- cvtl e ; return (noLoc $ HsRecField { hsRecFieldLbl = fmap f v' , hsRecFieldArg = e' , hsRecPun = False}) } cvtDD :: Range -> CvtM (ArithSeqInfo GhcPs) cvtDD (FromR x) = do { x' <- cvtl x; return $ From x' } cvtDD (FromThenR x y) = do { x' <- cvtl x; y' <- cvtl y; return $ FromThen x' y' } cvtDD (FromToR x y) = do { x' <- cvtl x; y' <- cvtl y; return $ FromTo x' y' } cvtDD (FromThenToR x y z) = do { x' <- cvtl x; y' <- cvtl y; z' <- cvtl z; return $ FromThenTo x' y' z' } {- Note [Operator assocation] We must be quite careful about adding parens: * Infix (UInfix ...) op arg Needs parens round the first arg * Infix (Infix ...) op arg Needs parens round the first arg * UInfix (UInfix ...) op arg No parens for first arg * UInfix (Infix ...) op arg Needs parens round first arg Note [Converting UInfix] ~~~~~~~~~~~~~~~~~~~~~~~~ When converting @UInfixE@, @UInfixP@, and @UInfixT@ values, we want to readjust the trees to reflect the fixities of the underlying operators: UInfixE x * (UInfixE y + z) ---> (x * y) + z This is done by the renamer (see @mkOppAppRn@, @mkConOppPatRn@, and @mkHsOpTyRn@ in RnTypes), which expects that the input will be completely right-biased for types and left-biased for everything else. So we left-bias the trees of @UInfixP@ and @UInfixE@ and right-bias the trees of @UInfixT@. Sample input: UInfixE (UInfixE x op1 y) op2 (UInfixE z op3 w) Sample output: OpApp (OpApp (OpApp x op1 y) op2 z) op3 w The functions @cvtOpApp@, @cvtOpAppP@, and @cvtOpAppT@ are responsible for this biasing. -} {- | @cvtOpApp x op y@ converts @op@ and @y@ and produces the operator application @x `op` y@. The produced tree of infix expressions will be left-biased, provided @x@ is. We can see that @cvtOpApp@ is correct as follows. The inductive hypothesis is that @cvtOpApp x op y@ is left-biased, provided @x@ is. It is clear that this holds for both branches (of @cvtOpApp@), provided we assume it holds for the recursive calls to @cvtOpApp@. When we call @cvtOpApp@ from @cvtl@, the first argument will always be left-biased since we have already run @cvtl@ on it. -} cvtOpApp :: LHsExpr GhcPs -> TH.Exp -> TH.Exp -> CvtM (HsExpr GhcPs) cvtOpApp x op1 (UInfixE y op2 z) = do { l <- wrapL $ cvtOpApp x op1 y ; cvtOpApp l op2 z } cvtOpApp x op y = do { op' <- cvtl op ; y' <- cvtl y ; return (OpApp noExt x op' y') } ------------------------------------- -- Do notation and statements ------------------------------------- cvtHsDo :: HsStmtContext Name.Name -> [TH.Stmt] -> CvtM (HsExpr GhcPs) cvtHsDo do_or_lc stmts | null stmts = failWith (text "Empty stmt list in do-block") | otherwise = do { stmts' <- cvtStmts stmts ; let Just (stmts'', last') = snocView stmts' ; last'' <- case last' of (dL->L loc (BodyStmt _ body _ _)) -> return (cL loc (mkLastStmt body)) _ -> failWith (bad_last last') ; return $ HsDo noExt do_or_lc (noLoc (stmts'' ++ [last''])) } where bad_last stmt = vcat [ text "Illegal last statement of" <+> pprAStmtContext do_or_lc <> colon , nest 2 $ Outputable.ppr stmt , text "(It should be an expression.)" ] cvtStmts :: [TH.Stmt] -> CvtM [Hs.LStmt GhcPs (LHsExpr GhcPs)] cvtStmts = mapM cvtStmt cvtStmt :: TH.Stmt -> CvtM (Hs.LStmt GhcPs (LHsExpr GhcPs)) cvtStmt (NoBindS e) = do { e' <- cvtl e; returnL $ mkBodyStmt e' } cvtStmt (TH.BindS p e) = do { p' <- cvtPat p; e' <- cvtl e; returnL $ mkBindStmt p' e' } cvtStmt (TH.LetS ds) = do { ds' <- cvtLocalDecs (text "a let binding") ds ; returnL $ LetStmt noExt (noLoc ds') } cvtStmt (TH.ParS dss) = do { dss' <- mapM cvt_one dss ; returnL $ ParStmt noExt dss' noExpr noSyntaxExpr } where cvt_one ds = do { ds' <- cvtStmts ds ; return (ParStmtBlock noExt ds' undefined noSyntaxExpr) } cvtStmt (TH.RecS ss) = do { ss' <- mapM cvtStmt ss; returnL (mkRecStmt ss') } cvtMatch :: HsMatchContext RdrName -> TH.Match -> CvtM (Hs.LMatch GhcPs (LHsExpr GhcPs)) cvtMatch ctxt (TH.Match p body decs) = do { p' <- cvtPat p ; let lp = case p' of (dL->L loc SigPat{}) -> cL loc (ParPat NoExt p') -- #14875 _ -> p' ; g' <- cvtGuard body ; decs' <- cvtLocalDecs (text "a where clause") decs ; returnL $ Hs.Match noExt ctxt [lp] (GRHSs noExt g' (noLoc decs')) } cvtGuard :: TH.Body -> CvtM [LGRHS GhcPs (LHsExpr GhcPs)] cvtGuard (GuardedB pairs) = mapM cvtpair pairs cvtGuard (NormalB e) = do { e' <- cvtl e ; g' <- returnL $ GRHS noExt [] e'; return [g'] } cvtpair :: (TH.Guard, TH.Exp) -> CvtM (LGRHS GhcPs (LHsExpr GhcPs)) cvtpair (NormalG ge,rhs) = do { ge' <- cvtl ge; rhs' <- cvtl rhs ; g' <- returnL $ mkBodyStmt ge' ; returnL $ GRHS noExt [g'] rhs' } cvtpair (PatG gs,rhs) = do { gs' <- cvtStmts gs; rhs' <- cvtl rhs ; returnL $ GRHS noExt gs' rhs' } cvtOverLit :: Lit -> CvtM (HsOverLit GhcPs) cvtOverLit (IntegerL i) = do { force i; return $ mkHsIntegral (mkIntegralLit i) } cvtOverLit (RationalL r) = do { force r; return $ mkHsFractional (mkFractionalLit r) } cvtOverLit (StringL s) = do { let { s' = mkFastString s } ; force s' ; return $ mkHsIsString (quotedSourceText s) s' } cvtOverLit _ = panic "Convert.cvtOverLit: Unexpected overloaded literal" -- An Integer is like an (overloaded) '3' in a Haskell source program -- Similarly 3.5 for fractionals {- Note [Converting strings] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If we get (ListE [CharL 'x', CharL 'y']) we'd like to convert to a string literal for "xy". Of course, we might hope to get (LitE (StringL "xy")), but not always, and allCharLs fails quickly if it isn't a literal string -} allCharLs :: [TH.Exp] -> Maybe String -- Note [Converting strings] -- NB: only fire up this setup for a non-empty list, else -- there's a danger of returning "" for [] :: [Int]! allCharLs xs = case xs of LitE (CharL c) : ys -> go [c] ys _ -> Nothing where go cs [] = Just (reverse cs) go cs (LitE (CharL c) : ys) = go (c:cs) ys go _ _ = Nothing cvtLit :: Lit -> CvtM (HsLit GhcPs) cvtLit (IntPrimL i) = do { force i; return $ HsIntPrim NoSourceText i } cvtLit (WordPrimL w) = do { force w; return $ HsWordPrim NoSourceText w } cvtLit (FloatPrimL f) = do { force f; return $ HsFloatPrim noExt (mkFractionalLit f) } cvtLit (DoublePrimL f) = do { force f; return $ HsDoublePrim noExt (mkFractionalLit f) } cvtLit (CharL c) = do { force c; return $ HsChar NoSourceText c } cvtLit (CharPrimL c) = do { force c; return $ HsCharPrim NoSourceText c } cvtLit (StringL s) = do { let { s' = mkFastString s } ; force s' ; return $ HsString (quotedSourceText s) s' } cvtLit (StringPrimL s) = do { let { s' = BS.pack s } ; force s' ; return $ HsStringPrim NoSourceText s' } cvtLit _ = panic "Convert.cvtLit: Unexpected literal" -- cvtLit should not be called on IntegerL, RationalL -- That precondition is established right here in -- Convert.hs, hence panic quotedSourceText :: String -> SourceText quotedSourceText s = SourceText $ "\"" ++ s ++ "\"" cvtPats :: [TH.Pat] -> CvtM [Hs.LPat GhcPs] cvtPats pats = mapM cvtPat pats cvtPat :: TH.Pat -> CvtM (Hs.LPat GhcPs) cvtPat pat = wrapL (cvtp pat) cvtp :: TH.Pat -> CvtM (Hs.Pat GhcPs) cvtp (TH.LitP l) | overloadedLit l = do { l' <- cvtOverLit l ; return (mkNPat (noLoc l') Nothing) } -- Not right for negative patterns; -- need to think about that! | otherwise = do { l' <- cvtLit l; return $ Hs.LitPat noExt l' } cvtp (TH.VarP s) = do { s' <- vName s ; return $ Hs.VarPat noExt (noLoc s') } cvtp (TupP [p]) = do { p' <- cvtPat p; return $ ParPat noExt p' } -- Note [Dropping constructors] cvtp (TupP ps) = do { ps' <- cvtPats ps ; return $ TuplePat noExt ps' Boxed } cvtp (UnboxedTupP ps) = do { ps' <- cvtPats ps ; return $ TuplePat noExt ps' Unboxed } cvtp (UnboxedSumP p alt arity) = do { p' <- cvtPat p ; unboxedSumChecks alt arity ; return $ SumPat noExt p' alt arity } cvtp (ConP s ps) = do { s' <- cNameL s; ps' <- cvtPats ps ; let pps = map (parenthesizePat appPrec) ps' ; return $ ConPatIn s' (PrefixCon pps) } cvtp (InfixP p1 s p2) = do { s' <- cNameL s; p1' <- cvtPat p1; p2' <- cvtPat p2 ; wrapParL (ParPat noExt) $ ConPatIn s' $ InfixCon (parenthesizePat opPrec p1') (parenthesizePat opPrec p2') } -- See Note [Operator association] cvtp (UInfixP p1 s p2) = do { p1' <- cvtPat p1; cvtOpAppP p1' s p2 } -- Note [Converting UInfix] cvtp (ParensP p) = do { p' <- cvtPat p; ; case unLoc p' of -- may be wrapped ConPatIn ParPat {} -> return $ unLoc p' _ -> return $ ParPat noExt p' } cvtp (TildeP p) = do { p' <- cvtPat p; return $ LazyPat noExt p' } cvtp (BangP p) = do { p' <- cvtPat p; return $ BangPat noExt p' } cvtp (TH.AsP s p) = do { s' <- vNameL s; p' <- cvtPat p ; return $ AsPat noExt s' p' } cvtp TH.WildP = return $ WildPat noExt cvtp (RecP c fs) = do { c' <- cNameL c; fs' <- mapM cvtPatFld fs ; return $ ConPatIn c' $ Hs.RecCon (HsRecFields fs' Nothing) } cvtp (ListP ps) = do { ps' <- cvtPats ps ; return $ ListPat noExt ps'} cvtp (SigP p t) = do { p' <- cvtPat p; t' <- cvtType t ; return $ SigPat noExt p' (mkLHsSigWcType t') } cvtp (ViewP e p) = do { e' <- cvtl e; p' <- cvtPat p ; return $ ViewPat noExt e' p'} cvtPatFld :: (TH.Name, TH.Pat) -> CvtM (LHsRecField GhcPs (LPat GhcPs)) cvtPatFld (s,p) = do { (dL->L ls s') <- vNameL s ; p' <- cvtPat p ; return (noLoc $ HsRecField { hsRecFieldLbl = cL ls $ mkFieldOcc (cL ls s') , hsRecFieldArg = p' , hsRecPun = False}) } {- | @cvtOpAppP x op y@ converts @op@ and @y@ and produces the operator application @x `op` y@. The produced tree of infix patterns will be left-biased, provided @x@ is. See the @cvtOpApp@ documentation for how this function works. -} cvtOpAppP :: Hs.LPat GhcPs -> TH.Name -> TH.Pat -> CvtM (Hs.Pat GhcPs) cvtOpAppP x op1 (UInfixP y op2 z) = do { l <- wrapL $ cvtOpAppP x op1 y ; cvtOpAppP l op2 z } cvtOpAppP x op y = do { op' <- cNameL op ; y' <- cvtPat y ; return (ConPatIn op' (InfixCon x y')) } ----------------------------------------------------------- -- Types and type variables cvtTvs :: [TH.TyVarBndr] -> CvtM (LHsQTyVars GhcPs) cvtTvs tvs = do { tvs' <- mapM cvt_tv tvs; return (mkHsQTvs tvs') } cvt_tv :: TH.TyVarBndr -> CvtM (LHsTyVarBndr GhcPs) cvt_tv (TH.PlainTV nm) = do { nm' <- tNameL nm ; returnL $ UserTyVar noExt nm' } cvt_tv (TH.KindedTV nm ki) = do { nm' <- tNameL nm ; ki' <- cvtKind ki ; returnL $ KindedTyVar noExt nm' ki' } cvtRole :: TH.Role -> Maybe Coercion.Role cvtRole TH.NominalR = Just Coercion.Nominal cvtRole TH.RepresentationalR = Just Coercion.Representational cvtRole TH.PhantomR = Just Coercion.Phantom cvtRole TH.InferR = Nothing cvtContext :: TH.Cxt -> CvtM (LHsContext GhcPs) cvtContext tys = do { preds' <- mapM cvtPred tys; returnL preds' } cvtPred :: TH.Pred -> CvtM (LHsType GhcPs) cvtPred = cvtType cvtDerivClause :: TH.DerivClause -> CvtM (LHsDerivingClause GhcPs) cvtDerivClause (TH.DerivClause ds ctxt) = do { ctxt' <- fmap (map mkLHsSigType) <$> cvtContext ctxt ; ds' <- traverse cvtDerivStrategy ds ; returnL $ HsDerivingClause noExt ds' ctxt' } cvtDerivStrategy :: TH.DerivStrategy -> CvtM (Hs.LDerivStrategy GhcPs) cvtDerivStrategy TH.StockStrategy = returnL Hs.StockStrategy cvtDerivStrategy TH.AnyclassStrategy = returnL Hs.AnyclassStrategy cvtDerivStrategy TH.NewtypeStrategy = returnL Hs.NewtypeStrategy cvtDerivStrategy (TH.ViaStrategy ty) = do ty' <- cvtType ty returnL $ Hs.ViaStrategy (mkLHsSigType ty') cvtType :: TH.Type -> CvtM (LHsType GhcPs) cvtType = cvtTypeKind "type" cvtTypeKind :: String -> TH.Type -> CvtM (LHsType GhcPs) cvtTypeKind ty_str ty = do { (head_ty, tys') <- split_ty_app ty ; let m_normals = mapM extract_normal tys' where extract_normal (HsValArg ty) = Just ty extract_normal _ = Nothing ; case head_ty of TupleT n | Just normals <- m_normals , normals `lengthIs` n -- Saturated -> if n==1 then return (head normals) -- Singleton tuples treated -- like nothing (ie just parens) else returnL (HsTupleTy noExt HsBoxedOrConstraintTuple normals) | n == 1 -> failWith (ptext (sLit ("Illegal 1-tuple " ++ ty_str ++ " constructor"))) | otherwise -> mk_apps (HsTyVar noExt NotPromoted (noLoc (getRdrName (tupleTyCon Boxed n)))) tys' UnboxedTupleT n | Just normals <- m_normals , normals `lengthIs` n -- Saturated -> returnL (HsTupleTy noExt HsUnboxedTuple normals) | otherwise -> mk_apps (HsTyVar noExt NotPromoted (noLoc (getRdrName (tupleTyCon Unboxed n)))) tys' UnboxedSumT n | n < 2 -> failWith $ vcat [ text "Illegal sum arity:" <+> text (show n) , nest 2 $ text "Sums must have an arity of at least 2" ] | Just normals <- m_normals , normals `lengthIs` n -- Saturated -> returnL (HsSumTy noExt normals) | otherwise -> mk_apps (HsTyVar noExt NotPromoted (noLoc (getRdrName (sumTyCon n)))) tys' ArrowT | Just normals <- m_normals , [x',y'] <- normals -> do x'' <- case unLoc x' of HsFunTy{} -> returnL (HsParTy noExt x') HsForAllTy{} -> returnL (HsParTy noExt x') -- #14646 HsQualTy{} -> returnL (HsParTy noExt x') -- #15324 _ -> return $ parenthesizeHsType sigPrec x' let y'' = parenthesizeHsType sigPrec y' returnL (HsFunTy noExt x'' y'') | otherwise -> mk_apps (HsTyVar noExt NotPromoted (noLoc (getRdrName funTyCon))) tys' ListT | Just normals <- m_normals , [x'] <- normals -> do returnL (HsListTy noExt x') | otherwise -> mk_apps (HsTyVar noExt NotPromoted (noLoc (getRdrName listTyCon))) tys' VarT nm -> do { nm' <- tNameL nm ; mk_apps (HsTyVar noExt NotPromoted nm') tys' } ConT nm -> do { nm' <- tconName nm ; -- ConT can contain both data constructor (i.e., -- promoted) names and other (i.e, unpromoted) -- names, as opposed to PromotedT, which can only -- contain data constructor names. See #15572. let prom = if isRdrDataCon nm' then IsPromoted else NotPromoted ; mk_apps (HsTyVar noExt prom (noLoc nm')) tys'} ForallT tvs cxt ty | null tys' -> do { tvs' <- cvtTvs tvs ; cxt' <- cvtContext cxt ; let pcxt = parenthesizeHsContext funPrec cxt' ; ty' <- cvtType ty ; loc <- getL ; let hs_ty = mkHsForAllTy tvs loc ForallInvis tvs' rho_ty rho_ty = mkHsQualTy cxt loc pcxt ty' ; return hs_ty } ForallVisT tvs ty | null tys' -> do { tvs' <- cvtTvs tvs ; ty' <- cvtType ty ; loc <- getL ; pure $ mkHsForAllTy tvs loc ForallVis tvs' ty' } SigT ty ki -> do { ty' <- cvtType ty ; ki' <- cvtKind ki ; mk_apps (HsKindSig noExt ty' ki') tys' } LitT lit -> mk_apps (HsTyLit noExt (cvtTyLit lit)) tys' WildCardT -> mk_apps mkAnonWildCardTy tys' InfixT t1 s t2 -> do { s' <- tconName s ; t1' <- cvtType t1 ; t2' <- cvtType t2 ; mk_apps (HsTyVar noExt NotPromoted (noLoc s')) ([HsValArg t1', HsValArg t2'] ++ tys') } UInfixT t1 s t2 -> do { t2' <- cvtType t2 ; t <- cvtOpAppT t1 s t2' ; mk_apps (unLoc t) tys' } -- Note [Converting UInfix] ParensT t -> do { t' <- cvtType t ; mk_apps (HsParTy noExt t') tys' } PromotedT nm -> do { nm' <- cName nm ; mk_apps (HsTyVar noExt IsPromoted (noLoc nm')) tys' } -- Promoted data constructor; hence cName PromotedTupleT n | n == 1 -> failWith (ptext (sLit ("Illegal promoted 1-tuple " ++ ty_str))) | Just normals <- m_normals , normals `lengthIs` n -- Saturated -> returnL (HsExplicitTupleTy noExt normals) | otherwise -> mk_apps (HsTyVar noExt IsPromoted (noLoc (getRdrName (tupleDataCon Boxed n)))) tys' PromotedNilT -> mk_apps (HsExplicitListTy noExt IsPromoted []) tys' PromotedConsT -- See Note [Representing concrete syntax in types] -- in Language.Haskell.TH.Syntax | Just normals <- m_normals , [ty1, dL->L _ (HsExplicitListTy _ ip tys2)] <- normals -> do returnL (HsExplicitListTy noExt ip (ty1:tys2)) | otherwise -> mk_apps (HsTyVar noExt IsPromoted (noLoc (getRdrName consDataCon))) tys' StarT -> mk_apps (HsTyVar noExt NotPromoted (noLoc (getRdrName liftedTypeKindTyCon))) tys' ConstraintT -> mk_apps (HsTyVar noExt NotPromoted (noLoc (getRdrName constraintKindTyCon))) tys' EqualityT | Just normals <- m_normals , [x',y'] <- normals -> let px = parenthesizeHsType opPrec x' py = parenthesizeHsType opPrec y' in returnL (HsOpTy noExt px (noLoc eqTyCon_RDR) py) -- The long-term goal is to remove the above case entirely and -- subsume it under the case for InfixT. See #15815, comment:6, -- for more details. | otherwise -> mk_apps (HsTyVar noExt NotPromoted (noLoc eqTyCon_RDR)) tys' ImplicitParamT n t -> do { n' <- wrapL $ ipName n ; t' <- cvtType t ; returnL (HsIParamTy noExt n' t') } _ -> failWith (ptext (sLit ("Malformed " ++ ty_str)) <+> text (show ty)) } -- | Constructs an application of a type to arguments passed in a list. mk_apps :: HsType GhcPs -> [LHsTypeArg GhcPs] -> CvtM (LHsType GhcPs) mk_apps head_ty type_args = do head_ty' <- returnL head_ty -- We must parenthesize the function type in case of an explicit -- signature. For instance, in `(Maybe :: Type -> Type) Int`, there -- _must_ be parentheses around `Maybe :: Type -> Type`. let phead_ty :: LHsType GhcPs phead_ty = parenthesizeHsType sigPrec head_ty' go :: [LHsTypeArg GhcPs] -> CvtM (LHsType GhcPs) go [] = pure head_ty' go (arg:args) = case arg of HsValArg ty -> do p_ty <- add_parens ty mk_apps (HsAppTy noExt phead_ty p_ty) args HsTypeArg l ki -> do p_ki <- add_parens ki mk_apps (HsAppKindTy l phead_ty p_ki) args HsArgPar _ -> mk_apps (HsParTy noExt phead_ty) args go type_args where -- See Note [Adding parens for splices] add_parens lt@(dL->L _ t) | hsTypeNeedsParens appPrec t = returnL (HsParTy noExt lt) | otherwise = return lt wrap_tyarg :: LHsTypeArg GhcPs -> LHsTypeArg GhcPs wrap_tyarg (HsValArg ty) = HsValArg $ parenthesizeHsType appPrec ty wrap_tyarg (HsTypeArg l ki) = HsTypeArg l $ parenthesizeHsType appPrec ki wrap_tyarg ta@(HsArgPar {}) = ta -- Already parenthesized -- --------------------------------------------------------------------- -- Note [Adding parens for splices] {- The hsSyn representation of parsed source explicitly contains all the original parens, as written in the source. When a Template Haskell (TH) splice is evaluated, the original splice is first renamed and type checked and then finally converted to core in DsMeta. This core is then run in the TH engine, and the result comes back as a TH AST. In the process, all parens are stripped out, as they are not needed. This Convert module then converts the TH AST back to hsSyn AST. In order to pretty-print this hsSyn AST, parens need to be adde back at certain points so that the code is readable with its original meaning. So scattered through Convert.hs are various points where parens are added. See (among other closed issued) https://ghc.haskell.org/trac/ghc/ticket/14289 -} -- --------------------------------------------------------------------- -- | Constructs an arrow type with a specified return type mk_arr_apps :: [LHsType GhcPs] -> HsType GhcPs -> CvtM (LHsType GhcPs) mk_arr_apps tys return_ty = foldrM go return_ty tys >>= returnL where go :: LHsType GhcPs -> HsType GhcPs -> CvtM (HsType GhcPs) go arg ret_ty = do { ret_ty_l <- returnL ret_ty ; return (HsFunTy noExt arg ret_ty_l) } split_ty_app :: TH.Type -> CvtM (TH.Type, [LHsTypeArg GhcPs]) split_ty_app ty = go ty [] where go (AppT f a) as' = do { a' <- cvtType a; go f (HsValArg a':as') } go (AppKindT ty ki) as' = do { ki' <- cvtKind ki ; go ty (HsTypeArg noSrcSpan ki':as') } go (ParensT t) as' = do { loc <- getL; go t (HsArgPar loc: as') } go f as = return (f,as) cvtTyLit :: TH.TyLit -> HsTyLit cvtTyLit (TH.NumTyLit i) = HsNumTy NoSourceText i cvtTyLit (TH.StrTyLit s) = HsStrTy NoSourceText (fsLit s) {- | @cvtOpAppT x op y@ converts @op@ and @y@ and produces the operator application @x `op` y@. The produced tree of infix types will be right-biased, provided @y@ is. See the @cvtOpApp@ documentation for how this function works. -} cvtOpAppT :: TH.Type -> TH.Name -> LHsType GhcPs -> CvtM (LHsType GhcPs) cvtOpAppT (UInfixT x op2 y) op1 z = do { l <- cvtOpAppT y op1 z ; cvtOpAppT x op2 l } cvtOpAppT x op y = do { op' <- tconNameL op ; x' <- cvtType x ; returnL (mkHsOpTy x' op' y) } cvtKind :: TH.Kind -> CvtM (LHsKind GhcPs) cvtKind = cvtTypeKind "kind" -- | Convert Maybe Kind to a type family result signature. Used with data -- families where naming of the result is not possible (thus only kind or no -- signature is possible). cvtMaybeKindToFamilyResultSig :: Maybe TH.Kind -> CvtM (LFamilyResultSig GhcPs) cvtMaybeKindToFamilyResultSig Nothing = returnL (Hs.NoSig noExt) cvtMaybeKindToFamilyResultSig (Just ki) = do { ki' <- cvtKind ki ; returnL (Hs.KindSig noExt ki') } -- | Convert type family result signature. Used with both open and closed type -- families. cvtFamilyResultSig :: TH.FamilyResultSig -> CvtM (Hs.LFamilyResultSig GhcPs) cvtFamilyResultSig TH.NoSig = returnL (Hs.NoSig noExt) cvtFamilyResultSig (TH.KindSig ki) = do { ki' <- cvtKind ki ; returnL (Hs.KindSig noExt ki') } cvtFamilyResultSig (TH.TyVarSig bndr) = do { tv <- cvt_tv bndr ; returnL (Hs.TyVarSig noExt tv) } -- | Convert injectivity annotation of a type family. cvtInjectivityAnnotation :: TH.InjectivityAnn -> CvtM (Hs.LInjectivityAnn GhcPs) cvtInjectivityAnnotation (TH.InjectivityAnn annLHS annRHS) = do { annLHS' <- tNameL annLHS ; annRHS' <- mapM tNameL annRHS ; returnL (Hs.InjectivityAnn annLHS' annRHS') } cvtPatSynSigTy :: TH.Type -> CvtM (LHsType GhcPs) -- pattern synonym types are of peculiar shapes, which is why we treat -- them separately from regular types; -- see Note [Pattern synonym type signatures and Template Haskell] cvtPatSynSigTy (ForallT univs reqs (ForallT exis provs ty)) | null exis, null provs = cvtType (ForallT univs reqs ty) | null univs, null reqs = do { l <- getL ; ty' <- cvtType (ForallT exis provs ty) ; return $ cL l (HsQualTy { hst_ctxt = cL l [] , hst_xqual = noExt , hst_body = ty' }) } | null reqs = do { l <- getL ; univs' <- hsQTvExplicit <$> cvtTvs univs ; ty' <- cvtType (ForallT exis provs ty) ; let forTy = HsForAllTy { hst_fvf = ForallInvis , hst_bndrs = univs' , hst_xforall = noExt , hst_body = cL l cxtTy } cxtTy = HsQualTy { hst_ctxt = cL l [] , hst_xqual = noExt , hst_body = ty' } ; return $ cL l forTy } | otherwise = cvtType (ForallT univs reqs (ForallT exis provs ty)) cvtPatSynSigTy ty = cvtType ty ----------------------------------------------------------- cvtFixity :: TH.Fixity -> Hs.Fixity cvtFixity (TH.Fixity prec dir) = Hs.Fixity NoSourceText prec (cvt_dir dir) where cvt_dir TH.InfixL = Hs.InfixL cvt_dir TH.InfixR = Hs.InfixR cvt_dir TH.InfixN = Hs.InfixN ----------------------------------------------------------- ----------------------------------------------------------- -- some useful things overloadedLit :: Lit -> Bool -- True for literals that Haskell treats as overloaded overloadedLit (IntegerL _) = True overloadedLit (RationalL _) = True overloadedLit _ = False -- Checks that are performed when converting unboxed sum expressions and -- patterns alike. unboxedSumChecks :: TH.SumAlt -> TH.SumArity -> CvtM () unboxedSumChecks alt arity | alt > arity = failWith $ text "Sum alternative" <+> text (show alt) <+> text "exceeds its arity," <+> text (show arity) | alt <= 0 = failWith $ vcat [ text "Illegal sum alternative:" <+> text (show alt) , nest 2 $ text "Sum alternatives must start from 1" ] | arity < 2 = failWith $ vcat [ text "Illegal sum arity:" <+> text (show arity) , nest 2 $ text "Sums must have an arity of at least 2" ] | otherwise = return () -- | If passed an empty list of 'TH.TyVarBndr's, this simply returns the -- third argument (an 'LHsType'). Otherwise, return an 'HsForAllTy' -- using the provided 'LHsQTyVars' and 'LHsType'. mkHsForAllTy :: [TH.TyVarBndr] -- ^ The original Template Haskell type variable binders -> SrcSpan -- ^ The location of the returned 'LHsType' if it needs an -- explicit forall -> ForallVisFlag -- ^ Whether this is @forall@ is visible (e.g., @forall a ->@) -- or invisible (e.g., @forall a.@) -> LHsQTyVars GhcPs -- ^ The converted type variable binders -> LHsType GhcPs -- ^ The converted rho type -> LHsType GhcPs -- ^ The complete type, quantified with a forall if necessary mkHsForAllTy tvs loc fvf tvs' rho_ty | null tvs = rho_ty | otherwise = cL loc $ HsForAllTy { hst_fvf = fvf , hst_bndrs = hsQTvExplicit tvs' , hst_xforall = noExt , hst_body = rho_ty } -- | If passed an empty 'TH.Cxt', this simply returns the third argument -- (an 'LHsType'). Otherwise, return an 'HsQualTy' using the provided -- 'LHsContext' and 'LHsType'. -- It's important that we don't build an HsQualTy if the context is empty, -- as the pretty-printer for HsType _always_ prints contexts, even if -- they're empty. See Trac #13183. mkHsQualTy :: TH.Cxt -- ^ The original Template Haskell context -> SrcSpan -- ^ The location of the returned 'LHsType' if it needs an -- explicit context -> LHsContext GhcPs -- ^ The converted context -> LHsType GhcPs -- ^ The converted tau type -> LHsType GhcPs -- ^ The complete type, qualified with a context if necessary mkHsQualTy ctxt loc ctxt' ty | null ctxt = ty | otherwise = cL loc $ HsQualTy { hst_xqual = noExt , hst_ctxt = ctxt' , hst_body = ty } -------------------------------------------------------------------- -- Turning Name back into RdrName -------------------------------------------------------------------- -- variable names vNameL, cNameL, vcNameL, tNameL, tconNameL :: TH.Name -> CvtM (Located RdrName) vName, cName, vcName, tName, tconName :: TH.Name -> CvtM RdrName -- Variable names vNameL n = wrapL (vName n) vName n = cvtName OccName.varName n -- Constructor function names; this is Haskell source, hence srcDataName cNameL n = wrapL (cName n) cName n = cvtName OccName.dataName n -- Variable *or* constructor names; check by looking at the first char vcNameL n = wrapL (vcName n) vcName n = if isVarName n then vName n else cName n -- Type variable names tNameL n = wrapL (tName n) tName n = cvtName OccName.tvName n -- Type Constructor names tconNameL n = wrapL (tconName n) tconName n = cvtName OccName.tcClsName n ipName :: String -> CvtM HsIPName ipName n = do { unless (okVarOcc n) (failWith (badOcc OccName.varName n)) ; return (HsIPName (fsLit n)) } cvtName :: OccName.NameSpace -> TH.Name -> CvtM RdrName cvtName ctxt_ns (TH.Name occ flavour) | not (okOcc ctxt_ns occ_str) = failWith (badOcc ctxt_ns occ_str) | otherwise = do { loc <- getL ; let rdr_name = thRdrName loc ctxt_ns occ_str flavour ; force rdr_name ; return rdr_name } where occ_str = TH.occString occ okOcc :: OccName.NameSpace -> String -> Bool okOcc ns str | OccName.isVarNameSpace ns = okVarOcc str | OccName.isDataConNameSpace ns = okConOcc str | otherwise = okTcOcc str -- Determine the name space of a name in a type -- isVarName :: TH.Name -> Bool isVarName (TH.Name occ _) = case TH.occString occ of "" -> False (c:_) -> startsVarId c || startsVarSym c badOcc :: OccName.NameSpace -> String -> SDoc badOcc ctxt_ns occ = text "Illegal" <+> pprNameSpace ctxt_ns <+> text "name:" <+> quotes (text occ) thRdrName :: SrcSpan -> OccName.NameSpace -> String -> TH.NameFlavour -> RdrName -- This turns a TH Name into a RdrName; used for both binders and occurrences -- See Note [Binders in Template Haskell] -- The passed-in name space tells what the context is expecting; -- use it unless the TH name knows what name-space it comes -- from, in which case use the latter -- -- We pass in a SrcSpan (gotten from the monad) because this function -- is used for *binders* and if we make an Exact Name we want it -- to have a binding site inside it. (cf Trac #5434) -- -- ToDo: we may generate silly RdrNames, by passing a name space -- that doesn't match the string, like VarName ":+", -- which will give confusing error messages later -- -- The strict applications ensure that any buried exceptions get forced thRdrName loc ctxt_ns th_occ th_name = case th_name of TH.NameG th_ns pkg mod -> thOrigRdrName th_occ th_ns pkg mod TH.NameQ mod -> (mkRdrQual $! mk_mod mod) $! occ TH.NameL uniq -> nameRdrName $! (((Name.mkInternalName $! mk_uniq uniq) $! occ) loc) TH.NameU uniq -> nameRdrName $! (((Name.mkSystemNameAt $! mk_uniq uniq) $! occ) loc) TH.NameS | Just name <- isBuiltInOcc_maybe occ -> nameRdrName $! name | otherwise -> mkRdrUnqual $! occ -- We check for built-in syntax here, because the TH -- user might have written a (NameS "(,,)"), for example where occ :: OccName.OccName occ = mk_occ ctxt_ns th_occ -- Return an unqualified exact RdrName if we're dealing with built-in syntax. -- See Trac #13776. thOrigRdrName :: String -> TH.NameSpace -> PkgName -> ModName -> RdrName thOrigRdrName occ th_ns pkg mod = let occ' = mk_occ (mk_ghc_ns th_ns) occ in case isBuiltInOcc_maybe occ' of Just name -> nameRdrName name Nothing -> (mkOrig $! (mkModule (mk_pkg pkg) (mk_mod mod))) $! occ' thRdrNameGuesses :: TH.Name -> [RdrName] thRdrNameGuesses (TH.Name occ flavour) -- This special case for NameG ensures that we don't generate duplicates in the output list | TH.NameG th_ns pkg mod <- flavour = [ thOrigRdrName occ_str th_ns pkg mod] | otherwise = [ thRdrName noSrcSpan gns occ_str flavour | gns <- guessed_nss] where -- guessed_ns are the name spaces guessed from looking at the TH name guessed_nss | isLexCon (mkFastString occ_str) = [OccName.tcName, OccName.dataName] | otherwise = [OccName.varName, OccName.tvName] occ_str = TH.occString occ -- The packing and unpacking is rather turgid :-( mk_occ :: OccName.NameSpace -> String -> OccName.OccName mk_occ ns occ = OccName.mkOccName ns occ mk_ghc_ns :: TH.NameSpace -> OccName.NameSpace mk_ghc_ns TH.DataName = OccName.dataName mk_ghc_ns TH.TcClsName = OccName.tcClsName mk_ghc_ns TH.VarName = OccName.varName mk_mod :: TH.ModName -> ModuleName mk_mod mod = mkModuleName (TH.modString mod) mk_pkg :: TH.PkgName -> UnitId mk_pkg pkg = stringToUnitId (TH.pkgString pkg) mk_uniq :: Int -> Unique mk_uniq u = mkUniqueGrimily u {- Note [Binders in Template Haskell] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider this TH term construction: do { x1 <- TH.newName "x" -- newName :: String -> Q TH.Name ; x2 <- TH.newName "x" -- Builds a NameU ; x3 <- TH.newName "x" ; let x = mkName "x" -- mkName :: String -> TH.Name -- Builds a NameS ; return (LamE (..pattern [x1,x2]..) $ LamE (VarPat x3) $ ..tuple (x1,x2,x3,x)) } It represents the term \[x1,x2]. \x3. (x1,x2,x3,x) a) We don't want to complain about "x" being bound twice in the pattern [x1,x2] b) We don't want x3 to shadow the x1,x2 c) We *do* want 'x' (dynamically bound with mkName) to bind to the innermost binding of "x", namely x3. d) When pretty printing, we want to print a unique with x1,x2 etc, else they'll all print as "x" which isn't very helpful When we convert all this to HsSyn, the TH.Names are converted with thRdrName. To achieve (b) we want the binders to be Exact RdrNames. Achieving (a) is a bit awkward, because - We must check for duplicate and shadowed names on Names, not RdrNames, *after* renaming. See Note [Collect binders only after renaming] in HsUtils - But to achieve (a) we must distinguish between the Exact RdrNames arising from TH and the Unqual RdrNames that would come from a user writing \[x,x] -> blah So in Convert.thRdrName we translate TH Name RdrName -------------------------------------------------------- NameU (arising from newName) --> Exact (Name{ System }) NameS (arising from mkName) --> Unqual Notice that the NameUs generate *System* Names. Then, when figuring out shadowing and duplicates, we can filter out System Names. This use of System Names fits with other uses of System Names, eg for temporary variables "a". Since there are lots of things called "a" we usually want to print the name with the unique, and that is indeed the way System Names are printed. There's a small complication of course; see Note [Looking up Exact RdrNames] in RnEnv. -} {- Note [Pattern synonym type signatures and Template Haskell] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In general, the type signature of a pattern synonym pattern P x1 x2 .. xn = is of the form forall univs. reqs => forall exis. provs => t1 -> t2 -> ... -> tn -> t with the following parts: 1) the (possibly empty lists of) universally quantified type variables `univs` and required constraints `reqs` on them. 2) the (possibly empty lists of) existentially quantified type variables `exis` and the provided constraints `provs` on them. 3) the types `t1`, `t2`, .., `tn` of the pattern synonym's arguments x1, x2, .., xn, respectively 4) the type `t` of , mentioning only universals from `univs`. Due to the two forall quantifiers and constraint contexts (either of which might be empty), pattern synonym type signatures are treated specially in `deSugar/DsMeta.hs`, `hsSyn/Convert.hs`, and `typecheck/TcSplice.hs`: (a) When desugaring a pattern synonym from HsSyn to TH.Dec in `deSugar/DsMeta.hs`, we represent its *full* type signature in TH, i.e.: ForallT univs reqs (ForallT exis provs ty) (where ty is the AST representation of t1 -> t2 -> ... -> tn -> t) (b) When converting pattern synonyms from TH.Dec to HsSyn in `hsSyn/Convert.hs`, we convert their TH type signatures back to an appropriate Haskell pattern synonym type of the form forall univs. reqs => forall exis. provs => t1 -> t2 -> ... -> tn -> t where initial empty `univs` type variables or an empty `reqs` constraint context are represented *explicitly* as `() =>`. (c) When reifying a pattern synonym in `typecheck/TcSplice.hs`, we always return its *full* type, i.e.: ForallT univs reqs (ForallT exis provs ty) (where ty is the AST representation of t1 -> t2 -> ... -> tn -> t) The key point is to always represent a pattern synonym's *full* type in cases (a) and (c) to make it clear which of the two forall quantifiers and/or constraint contexts are specified, and which are not. See GHC's user's guide on pattern synonyms for more information about pattern synonym type signatures. -}