deSugar/DsMeta.hs

    {-# LANGUAGE CPP, TypeFamilies #-}

    -----------------------------------------------------------------------------
    --
    -- (c) The University of Glasgow 2006
    --
    -- The purpose of this module is to transform an HsExpr into a CoreExpr which
    -- when evaluated, returns a (Meta.Q Meta.Exp) computation analogous to the
    -- input HsExpr. We do this in the DsM monad, which supplies access to
    -- CoreExpr's of the "smart constructors" of the Meta.Exp datatype.
    --
    -- It also defines a bunch of knownKeyNames, in the same way as is done
    -- in prelude/PrelNames.  It's much more convenient to do it here, because
    -- otherwise we have to recompile PrelNames whenever we add a Name, which is
    -- a Royal Pain (triggers other recompilation).
    -----------------------------------------------------------------------------

    module DsMeta( dsBracket ) where

    #include "HsVersions.h"

    import {-# SOURCE #-}   DsExpr ( dsExpr )

    import MatchLit
    import DsMonad

    import qualified Language.Haskell.TH as TH

    import HsSyn
    import Class
    import PrelNames
    -- To avoid clashes with DsMeta.varName we must make a local alias for
    -- OccName.varName we do this by removing varName from the import of
    -- OccName above, making a qualified instance of OccName and using
    -- OccNameAlias.varName where varName ws previously used in this file.
    import qualified OccName( isDataOcc, isVarOcc, isTcOcc )

    import Module
    import Id
    import Name hiding( isVarOcc, isTcOcc, varName, tcName )
    import THNames
    import NameEnv
    import NameSet
    import TcType
    import TyCon
    import TysWiredIn
    import CoreSyn
    import MkCore
    import CoreUtils
    import SrcLoc
    import Unique
    import BasicTypes
    import Outputable
    import Bag
    import DynFlags
    import FastString
    import ForeignCall
    import Util
    import Maybes
    import MonadUtils

    import Data.ByteString ( unpack )
    import Control.Monad
    import Data.List

    -----------------------------------------------------------------------------
    dsBracket :: HsBracket Name -> [PendingTcSplice] -> DsM CoreExpr
    -- Returns a CoreExpr of type TH.ExpQ
    -- The quoted thing is parameterised over Name, even though it has
    -- been type checked.  We don't want all those type decorations!

    dsBracket brack splices
      = dsExtendMetaEnv new_bit (do_brack brack)
      where
        new_bit = mkNameEnv [(n, DsSplice (unLoc e)) | PendingTcSplice n e <- splices]

        do_brack (VarBr _ n) = do { MkC e1  <- lookupOcc n ; return e1 }
        do_brack (ExpBr e)   = do { MkC e1  <- repLE e     ; return e1 }
        do_brack (PatBr p)   = do { MkC p1  <- repTopP p   ; return p1 }
        do_brack (TypBr t)   = do { MkC t1  <- repLTy t    ; return t1 }
        do_brack (DecBrG gp) = do { MkC ds1 <- repTopDs gp ; return ds1 }
        do_brack (DecBrL _)  = panic "dsBracket: unexpected DecBrL"
        do_brack (TExpBr e)  = do { MkC e1  <- repLE e     ; return e1 }

    {- -------------- Examples --------------------

      [| \x -> x |]
    ====>
      gensym (unpackString "x"#) `bindQ` \ x1::String ->
      lam (pvar x1) (var x1)

      [| \x -> $(f [| x |]) |]
    ====>
      gensym (unpackString "x"#) `bindQ` \ x1::String ->
      lam (pvar x1) (f (var x1))
    -}

    -------------------------------------------------------
    --                      Declarations
    -------------------------------------------------------

    repTopP :: LPat Name -> DsM (Core TH.PatQ)
    repTopP pat = do { ss <- mkGenSyms (collectPatBinders pat)
                     ; pat' <- addBinds ss (repLP pat)
                     ; wrapGenSyms ss pat' }

    repTopDs :: HsGroup Name -> DsM (Core (TH.Q [TH.Dec]))
    repTopDs group@(HsGroup { hs_valds   = valds
                            , hs_splcds  = splcds
                            , hs_tyclds  = tyclds
                            , hs_derivds = derivds
                            , hs_fixds   = fixds
                            , hs_defds   = defds
                            , hs_fords   = fords
                            , hs_warnds  = warnds
                            , hs_annds   = annds
                            , hs_ruleds  = ruleds
                            , hs_vects   = vects
                            , hs_docs    = docs })
     = do { let { bndrs  = hsSigTvBinders valds
                           ++ hsGroupBinders group
                           ++ hsPatSynSelectors valds
                ; instds = tyclds >>= group_instds } ;
            ss <- mkGenSyms bndrs ;

            -- Bind all the names mainly to avoid repeated use of explicit strings.
            -- Thus we get
            --      do { t :: String <- genSym "T" ;
            --           return (Data t [] ...more t's... }
            -- The other important reason is that the output must mention
            -- only "T", not "Foo:T" where Foo is the current module

            decls <- addBinds ss (
                      do { val_ds   <- rep_val_binds valds
                         ; _        <- mapM no_splice splcds
                         ; tycl_ds  <- mapM repTyClD (tyClGroupTyClDecls tyclds)
                         ; role_ds  <- mapM repRoleD (concatMap group_roles tyclds)
                         ; inst_ds  <- mapM repInstD instds
                         ; deriv_ds <- mapM repStandaloneDerivD derivds
                         ; fix_ds   <- mapM repFixD fixds
                         ; _        <- mapM no_default_decl defds
                         ; for_ds   <- mapM repForD fords
                         ; _        <- mapM no_warn (concatMap (wd_warnings . unLoc)
                                                               warnds)
                         ; ann_ds   <- mapM repAnnD annds
                         ; rule_ds  <- mapM repRuleD (concatMap (rds_rules . unLoc)
                                                                ruleds)
                         ; _        <- mapM no_vect vects
                         ; _        <- mapM no_doc docs

                            -- more needed
                         ;  return (de_loc $ sort_by_loc $
                                    val_ds ++ catMaybes tycl_ds ++ role_ds
                                           ++ (concat fix_ds)
                                           ++ inst_ds ++ rule_ds ++ for_ds
                                           ++ ann_ds ++ deriv_ds) }) ;

            decl_ty <- lookupType decQTyConName ;
            let { core_list = coreList' decl_ty decls } ;

            dec_ty <- lookupType decTyConName ;
            q_decs  <- repSequenceQ dec_ty core_list ;

            wrapGenSyms ss q_decs
          }
      where
        no_splice (L loc _)
          = notHandledL loc "Splices within declaration brackets" empty
        no_default_decl (L loc decl)
          = notHandledL loc "Default declarations" (ppr decl)
        no_warn (L loc (Warning thing _))
          = notHandledL loc "WARNING and DEPRECATION pragmas" $
                        text "Pragma for declaration of" <+> ppr thing
        no_vect (L loc decl)
          = notHandledL loc "Vectorisation pragmas" (ppr decl)
        no_doc (L loc _)
          = notHandledL loc "Haddock documentation" empty

    hsSigTvBinders :: HsValBinds Name -> [Name]
    -- See Note [Scoped type variables in bindings]
    hsSigTvBinders binds
      = concatMap get_scoped_tvs sigs
      where
        get_scoped_tvs :: LSig Name -> [Name]
        -- Both implicit and explicit quantified variables
        -- We need the implicit ones for   f :: forall (a::k). blah
        --    here 'k' scopes too
        get_scoped_tvs (L _ (TypeSig _ sig))
           | HsIB { hsib_vars = implicit_vars
                  , hsib_body = hs_ty } <- hswc_body sig
           , (explicit_vars, _) <- splitLHsForAllTy hs_ty
           = implicit_vars ++ map hsLTyVarName explicit_vars
        get_scoped_tvs _ = []

        sigs = case binds of
                 ValBindsIn  _ sigs -> sigs
                 ValBindsOut _ sigs -> sigs

    {- Notes

    Note [Scoped type variables in bindings]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Consider
       f :: forall a. a -> a
       f x = x::a
    Here the 'forall a' brings 'a' into scope over the binding group.
    To achieve this we

      a) Gensym a binding for 'a' at the same time as we do one for 'f'
         collecting the relevant binders with hsSigTvBinders

      b) When processing the 'forall', don't gensym

    The relevant places are signposted with references to this Note

    Note [Binders and occurrences]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    When we desugar [d| data T = MkT |]
    we want to get
            Data "T" [] [Con "MkT" []] []
    and *not*
            Data "Foo:T" [] [Con "Foo:MkT" []] []
    That is, the new data decl should fit into whatever new module it is
    asked to fit in.   We do *not* clone, though; no need for this:
            Data "T79" ....

    But if we see this:
            data T = MkT
            foo = reifyDecl T

    then we must desugar to
            foo = Data "Foo:T" [] [Con "Foo:MkT" []] []

    So in repTopDs we bring the binders into scope with mkGenSyms and addBinds.
    And we use lookupOcc, rather than lookupBinder
    in repTyClD and repC.

    Note [Don't quantify implicit type variables in quotes]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    If you're not careful, it's suprisingly easy to take this quoted declaration:

      [d| idProxy :: forall proxy (b :: k). proxy b -> proxy b
          idProxy x = x
        |]

    and have Template Haskell turn it into this:

      idProxy :: forall k proxy (b :: k). proxy b -> proxy b
      idProxy x = x

    Notice that we explicitly quantified the variable `k`! This is quite bad, as the
    latter declaration requires -XTypeInType, while the former does not. Not to
    mention that the latter declaration isn't even what the user wrote in the
    first place.

    Usually, the culprit behind these bugs is taking implicitly quantified type
    variables (often from the hsib_vars field of HsImplicitBinders) and putting
    them into a `ForallT` or `ForallC`. Doing so caused #13018 and #13123.
    -}

    -- represent associated family instances
    --
    repTyClD :: LTyClDecl Name -> DsM (Maybe (SrcSpan, Core TH.DecQ))

    repTyClD (L loc (FamDecl { tcdFam = fam })) = liftM Just $ repFamilyDecl (L loc fam)

    repTyClD (L loc (SynDecl { tcdLName = tc, tcdTyVars = tvs, tcdRhs = rhs }))
      = do { tc1 <- lookupLOcc tc           -- See note [Binders and occurrences]
           ; dec <- addTyClTyVarBinds tvs $ \bndrs ->
                    repSynDecl tc1 bndrs rhs
           ; return (Just (loc, dec)) }

    repTyClD (L loc (DataDecl { tcdLName = tc, tcdTyVars = tvs, tcdDataDefn = defn }))
      = do { tc1 <- lookupLOcc tc           -- See note [Binders and occurrences]
           ; dec <- addTyClTyVarBinds tvs $ \bndrs ->
                    repDataDefn tc1 bndrs Nothing defn
           ; return (Just (loc, dec)) }

    repTyClD (L loc (ClassDecl { tcdCtxt = cxt, tcdLName = cls,
                                 tcdTyVars = tvs, tcdFDs = fds,
                                 tcdSigs = sigs, tcdMeths = meth_binds,
                                 tcdATs = ats, tcdATDefs = atds }))
      = do { cls1 <- lookupLOcc cls         -- See note [Binders and occurrences]
           ; dec  <- addTyVarBinds tvs $ \bndrs ->
               do { cxt1   <- repLContext cxt
                  ; sigs1  <- rep_sigs sigs
                  ; binds1 <- rep_binds meth_binds
                  ; fds1   <- repLFunDeps fds
                  ; ats1   <- repFamilyDecls ats
                  ; atds1  <- repAssocTyFamDefaults atds
                  ; decls1 <- coreList decQTyConName (ats1 ++ atds1 ++ sigs1 ++ binds1)
                  ; repClass cxt1 cls1 bndrs fds1 decls1
                  }
           ; return $ Just (loc, dec)
           }

    -------------------------
    repRoleD :: LRoleAnnotDecl Name -> DsM (SrcSpan, Core TH.DecQ)
    repRoleD (L loc (RoleAnnotDecl tycon roles))
      = do { tycon1 <- lookupLOcc tycon
           ; roles1 <- mapM repRole roles
           ; roles2 <- coreList roleTyConName roles1
           ; dec <- repRoleAnnotD tycon1 roles2
           ; return (loc, dec) }

    -------------------------
    repDataDefn :: Core TH.Name -> Core [TH.TyVarBndr]
                -> Maybe (Core [TH.TypeQ])
                -> HsDataDefn Name
                -> DsM (Core TH.DecQ)
    repDataDefn tc bndrs opt_tys
              (HsDataDefn { dd_ND = new_or_data, dd_ctxt = cxt, dd_kindSig = ksig
                          , dd_cons = cons, dd_derivs = mb_derivs })
      = do { cxt1     <- repLContext cxt
           ; derivs1  <- repDerivs mb_derivs
           ; case (new_or_data, cons) of
               (NewType, [con])  -> do { con'  <- repC con
                                       ; ksig' <- repMaybeLKind ksig
                                       ; repNewtype cxt1 tc bndrs opt_tys ksig' con'
                                                    derivs1 }
               (NewType, _) -> failWithDs (text "Multiple constructors for newtype:"
                                           <+> pprQuotedList
                                           (getConNames $ unLoc $ head cons))
               (DataType, _) -> do { ksig' <- repMaybeLKind ksig
                                   ; consL <- mapM repC cons
                                   ; cons1 <- coreList conQTyConName consL
                                   ; repData cxt1 tc bndrs opt_tys ksig' cons1
                                             derivs1 }
           }

    repSynDecl :: Core TH.Name -> Core [TH.TyVarBndr]
               -> LHsType Name
               -> DsM (Core TH.DecQ)
    repSynDecl tc bndrs ty
      = do { ty1 <- repLTy ty
           ; repTySyn tc bndrs ty1 }

    repFamilyDecl :: LFamilyDecl Name -> DsM (SrcSpan, Core TH.DecQ)
    repFamilyDecl decl@(L loc (FamilyDecl { fdInfo      = info,
                                            fdLName     = tc,
                                            fdTyVars    = tvs,
                                            fdResultSig = L _ resultSig,
                                            fdInjectivityAnn = injectivity }))
      = do { tc1 <- lookupLOcc tc           -- See note [Binders and occurrences]
           ; let mkHsQTvs :: [LHsTyVarBndr Name] -> LHsQTyVars Name
                 mkHsQTvs tvs = HsQTvs { hsq_implicit = [], hsq_explicit = tvs
                                       , hsq_dependent = emptyNameSet }
                 resTyVar = case resultSig of
                         TyVarSig bndr -> mkHsQTvs [bndr]
                         _             -> mkHsQTvs []
           ; dec <- addTyClTyVarBinds tvs $ \bndrs ->
                    addTyClTyVarBinds resTyVar $ \_ ->
               case info of
                 ClosedTypeFamily Nothing ->
                     notHandled "abstract closed type family" (ppr decl)
                 ClosedTypeFamily (Just eqns) ->
                   do { eqns1  <- mapM repTyFamEqn eqns
                      ; eqns2  <- coreList tySynEqnQTyConName eqns1
                      ; result <- repFamilyResultSig resultSig
                      ; inj    <- repInjectivityAnn injectivity
                      ; repClosedFamilyD tc1 bndrs result inj eqns2 }
                 OpenTypeFamily ->
                   do { result <- repFamilyResultSig resultSig
                      ; inj    <- repInjectivityAnn injectivity
                      ; repOpenFamilyD tc1 bndrs result inj }
                 DataFamily ->
                   do { kind <- repFamilyResultSigToMaybeKind resultSig
                      ; repDataFamilyD tc1 bndrs kind }
           ; return (loc, dec)
           }

    -- | Represent result signature of a type family
    repFamilyResultSig :: FamilyResultSig Name -> DsM (Core TH.FamilyResultSig)
    repFamilyResultSig  NoSig          = repNoSig
    repFamilyResultSig (KindSig ki)    = do { ki' <- repLKind ki
                                            ; repKindSig ki' }
    repFamilyResultSig (TyVarSig bndr) = do { bndr' <- repTyVarBndr bndr
                                            ; repTyVarSig bndr' }

    -- | Represent result signature using a Maybe Kind. Used with data families,
    -- where the result signature can be either missing or a kind but never a named
    -- result variable.
    repFamilyResultSigToMaybeKind :: FamilyResultSig Name
                                  -> DsM (Core (Maybe TH.Kind))
    repFamilyResultSigToMaybeKind NoSig =
        do { coreNothing kindTyConName }
    repFamilyResultSigToMaybeKind (KindSig ki) =
        do { ki' <- repLKind ki
           ; coreJust kindTyConName ki' }
    repFamilyResultSigToMaybeKind _ = panic "repFamilyResultSigToMaybeKind"

    -- | Represent injectivity annotation of a type family
    repInjectivityAnn :: Maybe (LInjectivityAnn Name)
                      -> DsM (Core (Maybe TH.InjectivityAnn))
    repInjectivityAnn Nothing =
        do { coreNothing injAnnTyConName }
    repInjectivityAnn (Just (L _ (InjectivityAnn lhs rhs))) =
        do { lhs'   <- lookupBinder (unLoc lhs)
           ; rhs1   <- mapM (lookupBinder . unLoc) rhs
           ; rhs2   <- coreList nameTyConName rhs1
           ; injAnn <- rep2 injectivityAnnName [unC lhs', unC rhs2]
           ; coreJust injAnnTyConName injAnn }

    repFamilyDecls :: [LFamilyDecl Name] -> DsM [Core TH.DecQ]
    repFamilyDecls fds = liftM de_loc (mapM repFamilyDecl fds)

    repAssocTyFamDefaults :: [LTyFamDefltEqn Name] -> DsM [Core TH.DecQ]
    repAssocTyFamDefaults = mapM rep_deflt
      where
         -- very like repTyFamEqn, but different in the details
        rep_deflt :: LTyFamDefltEqn Name -> DsM (Core TH.DecQ)
        rep_deflt (L _ (TyFamEqn { tfe_tycon = tc
                                 , tfe_pats  = bndrs
                                 , tfe_rhs   = rhs }))
          = addTyClTyVarBinds bndrs $ \ _ ->
            do { tc1  <- lookupLOcc tc
               ; tys1 <- repLTys (hsLTyVarBndrsToTypes bndrs)
               ; tys2 <- coreList typeQTyConName tys1
               ; rhs1 <- repLTy rhs
               ; eqn1 <- repTySynEqn tys2 rhs1
               ; repTySynInst tc1 eqn1 }

    -------------------------
    -- represent fundeps
    --
    repLFunDeps :: [Located (FunDep (Located Name))] -> DsM (Core [TH.FunDep])
    repLFunDeps fds = repList funDepTyConName repLFunDep fds

    repLFunDep :: Located (FunDep (Located Name)) -> DsM (Core TH.FunDep)
    repLFunDep (L _ (xs, ys))
       = do xs' <- repList nameTyConName (lookupBinder . unLoc) xs
            ys' <- repList nameTyConName (lookupBinder . unLoc) ys
            repFunDep xs' ys'

    -- Represent instance declarations
    --
    repInstD :: LInstDecl Name -> DsM (SrcSpan, Core TH.DecQ)
    repInstD (L loc (TyFamInstD { tfid_inst = fi_decl }))
      = do { dec <- repTyFamInstD fi_decl
           ; return (loc, dec) }
    repInstD (L loc (DataFamInstD { dfid_inst = fi_decl }))
      = do { dec <- repDataFamInstD fi_decl
           ; return (loc, dec) }
    repInstD (L loc (ClsInstD { cid_inst = cls_decl }))
      = do { dec <- repClsInstD cls_decl
           ; return (loc, dec) }

    repClsInstD :: ClsInstDecl Name -> DsM (Core TH.DecQ)
    repClsInstD (ClsInstDecl { cid_poly_ty = ty, cid_binds = binds
                             , cid_sigs = prags, cid_tyfam_insts = ats
                             , cid_datafam_insts = adts
                             , cid_overlap_mode = overlap
                             })
      = addSimpleTyVarBinds tvs $
                -- We must bring the type variables into scope, so their
                -- occurrences don't fail, even though the binders don't
                -- appear in the resulting data structure
                --
                -- But we do NOT bring the binders of 'binds' into scope
                -- because they are properly regarded as occurrences
                -- For example, the method names should be bound to
                -- the selector Ids, not to fresh names (Trac #5410)
                --
                do { cxt1 <- repLContext cxt
                   ; inst_ty1 <- repLTy inst_ty
                   ; binds1 <- rep_binds binds
                   ; prags1 <- rep_sigs prags
                   ; ats1 <- mapM (repTyFamInstD . unLoc) ats
                   ; adts1 <- mapM (repDataFamInstD . unLoc) adts
                   ; decls <- coreList decQTyConName (ats1 ++ adts1 ++ binds1 ++ prags1)
                   ; rOver <- repOverlap (fmap unLoc overlap)
                   ; repInst rOver cxt1 inst_ty1 decls }
     where
       (tvs, cxt, inst_ty) = splitLHsInstDeclTy ty

    repStandaloneDerivD :: LDerivDecl Name -> DsM (SrcSpan, Core TH.DecQ)
    repStandaloneDerivD (L loc (DerivDecl { deriv_strategy = strat
                                          , deriv_type     = ty }))
      = do { dec <- addSimpleTyVarBinds tvs $
                    do { cxt'     <- repLContext cxt
                       ; strat'   <- repDerivStrategy strat
                       ; inst_ty' <- repLTy inst_ty
                       ; repDeriv strat' cxt' inst_ty' }
           ; return (loc, dec) }
      where
        (tvs, cxt, inst_ty) = splitLHsInstDeclTy ty

    repTyFamInstD :: TyFamInstDecl Name -> DsM (Core TH.DecQ)
    repTyFamInstD decl@(TyFamInstDecl { tfid_eqn = eqn })
      = do { let tc_name = tyFamInstDeclLName decl
           ; tc <- lookupLOcc tc_name               -- See note [Binders and occurrences]
           ; eqn1 <- repTyFamEqn eqn
           ; repTySynInst tc eqn1 }

    repTyFamEqn :: LTyFamInstEqn Name -> DsM (Core TH.TySynEqnQ)
    repTyFamEqn (L _ (TyFamEqn { tfe_pats = HsIB { hsib_body = tys
                                                 , hsib_vars = var_names }
                               , tfe_rhs = rhs }))
      = do { let hs_tvs = HsQTvs { hsq_implicit = var_names
                                 , hsq_explicit = []
                                 , hsq_dependent = emptyNameSet }   -- Yuk
           ; addTyClTyVarBinds hs_tvs $ \ _ ->
             do { tys1 <- repLTys tys
                ; tys2 <- coreList typeQTyConName tys1
                ; rhs1 <- repLTy rhs
                ; repTySynEqn tys2 rhs1 } }

    repDataFamInstD :: DataFamInstDecl Name -> DsM (Core TH.DecQ)
    repDataFamInstD (DataFamInstDecl { dfid_tycon = tc_name
                                     , dfid_pats = HsIB { hsib_body = tys, hsib_vars = var_names }
                                     , dfid_defn = defn })
      = do { tc <- lookupLOcc tc_name               -- See note [Binders and occurrences]
           ; let hs_tvs = HsQTvs { hsq_implicit = var_names
                                 , hsq_explicit = []
                                 , hsq_dependent = emptyNameSet }   -- Yuk
           ; addTyClTyVarBinds hs_tvs $ \ bndrs ->
             do { tys1 <- repList typeQTyConName repLTy tys
                ; repDataDefn tc bndrs (Just tys1) defn } }

    repForD :: Located (ForeignDecl Name) -> DsM (SrcSpan, Core TH.DecQ)
    repForD (L loc (ForeignImport { fd_name = name, fd_sig_ty = typ
                                  , fd_fi = CImport (L _ cc) (L _ s) mch cis _ }))
     = do MkC name' <- lookupLOcc name
          MkC typ' <- repHsSigType typ
          MkC cc' <- repCCallConv cc
          MkC s' <- repSafety s
          cis' <- conv_cimportspec cis
          MkC str <- coreStringLit (static ++ chStr ++ cis')
          dec <- rep2 forImpDName [cc', s', str, name', typ']
          return (loc, dec)
     where
        conv_cimportspec (CLabel cls) = notHandled "Foreign label" (doubleQuotes (ppr cls))
        conv_cimportspec (CFunction DynamicTarget) = return "dynamic"
        conv_cimportspec (CFunction (StaticTarget _ fs _ True))
                                = return (unpackFS fs)
        conv_cimportspec (CFunction (StaticTarget _ _  _ False))
                                = panic "conv_cimportspec: values not supported yet"
        conv_cimportspec CWrapper = return "wrapper"
        -- these calling conventions do not support headers and the static keyword
        raw_cconv = cc == PrimCallConv || cc == JavaScriptCallConv
        static = case cis of
                     CFunction (StaticTarget _ _ _ _) | not raw_cconv -> "static "
                     _ -> ""
        chStr = case mch of
                Just (Header _ h) | not raw_cconv -> unpackFS h ++ " "
                _ -> ""
    repForD decl = notHandled "Foreign declaration" (ppr decl)

    repCCallConv :: CCallConv -> DsM (Core TH.Callconv)
    repCCallConv CCallConv          = rep2 cCallName []
    repCCallConv StdCallConv        = rep2 stdCallName []
    repCCallConv CApiConv           = rep2 cApiCallName []
    repCCallConv PrimCallConv       = rep2 primCallName []
    repCCallConv JavaScriptCallConv = rep2 javaScriptCallName []

    repSafety :: Safety -> DsM (Core TH.Safety)
    repSafety PlayRisky = rep2 unsafeName []
    repSafety PlayInterruptible = rep2 interruptibleName []
    repSafety PlaySafe = rep2 safeName []

    repFixD :: LFixitySig Name -> DsM [(SrcSpan, Core TH.DecQ)]
    repFixD (L loc (FixitySig names (Fixity _ prec dir)))
      = do { MkC prec' <- coreIntLit prec
           ; let rep_fn = case dir of
                            InfixL -> infixLDName
                            InfixR -> infixRDName
                            InfixN -> infixNDName
           ; let do_one name
                  = do { MkC name' <- lookupLOcc name
                       ; dec <- rep2 rep_fn [prec', name']
                       ; return (loc,dec) }
           ; mapM do_one names }

    repRuleD :: LRuleDecl Name -> DsM (SrcSpan, Core TH.DecQ)
    repRuleD (L loc (HsRule n act bndrs lhs _ rhs _))
      = do { let bndr_names = concatMap ruleBndrNames bndrs
           ; ss <- mkGenSyms bndr_names
           ; rule1 <- addBinds ss $
                      do { bndrs' <- repList ruleBndrQTyConName repRuleBndr bndrs
                         ; n'   <- coreStringLit $ unpackFS $ snd $ unLoc n
                         ; act' <- repPhases act
                         ; lhs' <- repLE lhs
                         ; rhs' <- repLE rhs
                         ; repPragRule n' bndrs' lhs' rhs' act' }
           ; rule2 <- wrapGenSyms ss rule1
           ; return (loc, rule2) }

    ruleBndrNames :: LRuleBndr Name -> [Name]
    ruleBndrNames (L _ (RuleBndr n))      = [unLoc n]
    ruleBndrNames (L _ (RuleBndrSig n sig))
      | HsWC { hswc_body = HsIB { hsib_vars = vars }} <- sig
      = unLoc n : vars

    repRuleBndr :: LRuleBndr Name -> DsM (Core TH.RuleBndrQ)
    repRuleBndr (L _ (RuleBndr n))
      = do { MkC n' <- lookupLBinder n
           ; rep2 ruleVarName [n'] }
    repRuleBndr (L _ (RuleBndrSig n sig))
      = do { MkC n'  <- lookupLBinder n
           ; MkC ty' <- repLTy (hsSigWcType sig)
           ; rep2 typedRuleVarName [n', ty'] }

    repAnnD :: LAnnDecl Name -> DsM (SrcSpan, Core TH.DecQ)
    repAnnD (L loc (HsAnnotation _ ann_prov (L _ exp)))
      = do { target <- repAnnProv ann_prov
           ; exp'   <- repE exp
           ; dec    <- repPragAnn target exp'
           ; return (loc, dec) }

    repAnnProv :: AnnProvenance Name -> DsM (Core TH.AnnTarget)
    repAnnProv (ValueAnnProvenance (L _ n))
      = do { MkC n' <- globalVar n  -- ANNs are allowed only at top-level
           ; rep2 valueAnnotationName [ n' ] }
    repAnnProv (TypeAnnProvenance (L _ n))
      = do { MkC n' <- globalVar n
           ; rep2 typeAnnotationName [ n' ] }
    repAnnProv ModuleAnnProvenance
      = rep2 moduleAnnotationName []

    -------------------------------------------------------
    --                      Constructors
    -------------------------------------------------------

    repC :: LConDecl Name -> DsM (Core TH.ConQ)
    repC (L _ (ConDeclH98 { con_name = con
                          , con_qvars = Nothing, con_cxt = Nothing
                          , con_details = details }))
      = repDataCon con details

    repC (L _ (ConDeclH98 { con_name = con
                          , con_qvars = mcon_tvs, con_cxt = mcxt
                          , con_details = details }))
      = do { let con_tvs = fromMaybe emptyLHsQTvs mcon_tvs
                 ctxt    = unLoc $ fromMaybe (noLoc []) mcxt
           ; addTyVarBinds con_tvs $ \ ex_bndrs ->
             do { c'    <- repDataCon con details
                ; ctxt' <- repContext ctxt
                ; if isEmptyLHsQTvs con_tvs && null ctxt
                  then return c'
                  else rep2 forallCName ([unC ex_bndrs, unC ctxt', unC c'])
                }
           }

    repC (L _ (ConDeclGADT { con_names = cons
                           , con_type = res_ty@(HsIB { hsib_vars = imp_tvs })}))
      | (details, res_ty', L _ [] , []) <- gadtDetails
      , [] <- imp_tvs
        -- no implicit or explicit variables, no context = no need for a forall
      = do { let doc = text "In the constructor for " <+> ppr (head cons)
           ; (hs_details, gadt_res_ty) <-
               updateGadtResult failWithDs doc details res_ty'
           ; repGadtDataCons cons hs_details gadt_res_ty }

      | (details,res_ty',ctxt, exp_tvs) <- gadtDetails
      = do { let doc = text "In the constructor for " <+> ppr (head cons)
                 con_tvs = HsQTvs { hsq_implicit  = imp_tvs
                                  , hsq_explicit  = exp_tvs
                                  , hsq_dependent = emptyNameSet }
                 -- NB: Don't put imp_tvs into the hsq_explicit field above
                 -- See Note [Don't quantify implicit type variables in quotes]
           ; addTyVarBinds con_tvs $ \ ex_bndrs -> do
           { (hs_details, gadt_res_ty) <-
               updateGadtResult failWithDs doc details res_ty'
           ; c'    <- repGadtDataCons cons hs_details gadt_res_ty
           ; ctxt' <- repContext (unLoc ctxt)
           ; if null exp_tvs && null (unLoc ctxt)
             then return c'
             else rep2 forallCName ([unC ex_bndrs, unC ctxt', unC c']) } }
      where
         gadtDetails = gadtDeclDetails res_ty

    repSrcUnpackedness :: SrcUnpackedness -> DsM (Core TH.SourceUnpackednessQ)
    repSrcUnpackedness SrcUnpack   = rep2 sourceUnpackName         []
    repSrcUnpackedness SrcNoUnpack = rep2 sourceNoUnpackName       []
    repSrcUnpackedness NoSrcUnpack = rep2 noSourceUnpackednessName []

    repSrcStrictness :: SrcStrictness -> DsM (Core TH.SourceStrictnessQ)
    repSrcStrictness SrcLazy     = rep2 sourceLazyName         []
    repSrcStrictness SrcStrict   = rep2 sourceStrictName       []
    repSrcStrictness NoSrcStrict = rep2 noSourceStrictnessName []

    repBangTy :: LBangType Name -> DsM (Core (TH.BangTypeQ))
    repBangTy ty = do
      MkC u <- repSrcUnpackedness su'
      MkC s <- repSrcStrictness ss'
      MkC b <- rep2 bangName [u, s]
      MkC t <- repLTy ty'
      rep2 bangTypeName [b, t]
      where
        (su', ss', ty') = case ty of
                L _ (HsBangTy (HsSrcBang _ su ss) ty) -> (su, ss, ty)
                _ -> (NoSrcUnpack, NoSrcStrict, ty)

    -------------------------------------------------------
    --                      Deriving clauses
    -------------------------------------------------------

    repDerivs :: HsDeriving Name -> DsM (Core [TH.DerivClauseQ])
    repDerivs (L _ clauses) = repList derivClauseQTyConName repDerivClause clauses

    repDerivClause :: LHsDerivingClause Name
                   -> DsM (Core TH.DerivClauseQ)
    repDerivClause (L _ (HsDerivingClause { deriv_clause_strategy = dcs
                                          , deriv_clause_tys      = L _ dct }))
      = do MkC dcs' <- repDerivStrategy dcs
           MkC dct' <- repList typeQTyConName (rep_deriv_ty . hsSigType) dct
           rep2 derivClauseName [dcs',dct']
      where
        rep_deriv_ty :: LHsType Name -> DsM (Core TH.TypeQ)
        rep_deriv_ty (L _ ty) = repTy ty

    -------------------------------------------------------
    --   Signatures in a class decl, or a group of bindings
    -------------------------------------------------------

    rep_sigs :: [LSig Name] -> DsM [Core TH.DecQ]
    rep_sigs sigs = do locs_cores <- rep_sigs' sigs
                       return $ de_loc $ sort_by_loc locs_cores

    rep_sigs' :: [LSig Name] -> DsM [(SrcSpan, Core TH.DecQ)]
            -- We silently ignore ones we don't recognise
    rep_sigs' = concatMapM rep_sig

    rep_sig :: LSig Name -> DsM [(SrcSpan, Core TH.DecQ)]
    rep_sig (L loc (TypeSig nms ty))      = mapM (rep_wc_ty_sig sigDName loc ty) nms
    rep_sig (L loc (PatSynSig nms ty))    = mapM (rep_patsyn_ty_sig loc ty) nms
    rep_sig (L loc (ClassOpSig is_deflt nms ty))
      | is_deflt                          = mapM (rep_ty_sig defaultSigDName loc ty) nms
      | otherwise                         = mapM (rep_ty_sig sigDName loc ty) nms
    rep_sig d@(L _ (IdSig {}))            = pprPanic "rep_sig IdSig" (ppr d)
    rep_sig (L _   (FixSig {}))           = return [] -- fixity sigs at top level
    rep_sig (L loc (InlineSig nm ispec))  = rep_inline nm ispec loc
    rep_sig (L loc (SpecSig nm tys ispec))
      = concatMapM (\t -> rep_specialise nm t ispec loc) tys
    rep_sig (L loc (SpecInstSig _ ty))    = rep_specialiseInst ty loc
    rep_sig (L _   (MinimalSig {}))       = notHandled "MINIMAL pragmas" empty
    rep_sig (L _   (SCCFunSig {}))        = notHandled "SCC pragmas" empty
    rep_sig (L loc (CompleteMatchSig _st cls mty)) = rep_complete_sig cls mty loc

    rep_ty_sig :: Name -> SrcSpan -> LHsSigType Name -> Located Name
               -> DsM (SrcSpan, Core TH.DecQ)
    rep_ty_sig mk_sig loc sig_ty nm
      = do { nm1 <- lookupLOcc nm
           ; ty1 <- repHsSigType sig_ty
           ; sig <- repProto mk_sig nm1 ty1
           ; return (loc, sig) }

    rep_patsyn_ty_sig :: SrcSpan -> LHsSigType Name -> Located Name
                      -> DsM (SrcSpan, Core TH.DecQ)
    -- represents a pattern synonym type signature;
    -- see Note [Pattern synonym type signatures and Template Haskell] in Convert
    rep_patsyn_ty_sig loc sig_ty nm
      = do { nm1 <- lookupLOcc nm
           ; ty1 <- repHsPatSynSigType sig_ty
           ; sig <- repProto patSynSigDName nm1 ty1
           ; return (loc, sig) }

    rep_wc_ty_sig :: Name -> SrcSpan -> LHsSigWcType Name -> Located Name
                  -> DsM (SrcSpan, Core TH.DecQ)
        -- We must special-case the top-level explicit for-all of a TypeSig
        -- See Note [Scoped type variables in bindings]
    rep_wc_ty_sig mk_sig loc sig_ty nm
      | HsIB { hsib_body = hs_ty } <- hswc_body sig_ty
      , (explicit_tvs, ctxt, ty) <- splitLHsSigmaTy hs_ty
      = do { nm1 <- lookupLOcc nm
           ; let rep_in_scope_tv tv = do { name <- lookupBinder (hsLTyVarName tv)
                                         ; repTyVarBndrWithKind tv name }
           ; th_explicit_tvs <- repList tyVarBndrTyConName rep_in_scope_tv
                                        explicit_tvs
             -- NB: Don't pass any implicit type variables to repList above
             -- See Note [Don't quantify implicit type variables in quotes]

           ; th_ctxt <- repLContext ctxt
           ; th_ty   <- repLTy ty
           ; ty1 <- if null explicit_tvs && null (unLoc ctxt)
                    then return th_ty
                    else repTForall th_explicit_tvs th_ctxt th_ty
           ; sig <- repProto mk_sig nm1 ty1
           ; return (loc, sig) }

    rep_inline :: Located Name
               -> InlinePragma      -- Never defaultInlinePragma
               -> SrcSpan
               -> DsM [(SrcSpan, Core TH.DecQ)]
    rep_inline nm ispec loc
      = do { nm1    <- lookupLOcc nm
           ; inline <- repInline $ inl_inline ispec
           ; rm     <- repRuleMatch $ inl_rule ispec
           ; phases <- repPhases $ inl_act ispec
           ; pragma <- repPragInl nm1 inline rm phases
           ; return [(loc, pragma)]
           }

    rep_specialise :: Located Name -> LHsSigType Name -> InlinePragma -> SrcSpan
                   -> DsM [(SrcSpan, Core TH.DecQ)]
    rep_specialise nm ty ispec loc
      = do { nm1 <- lookupLOcc nm
           ; ty1 <- repHsSigType ty
           ; phases <- repPhases $ inl_act ispec
           ; let inline = inl_inline ispec
           ; pragma <- if isEmptyInlineSpec inline
                       then -- SPECIALISE
                         repPragSpec nm1 ty1 phases
                       else -- SPECIALISE INLINE
                         do { inline1 <- repInline inline
                            ; repPragSpecInl nm1 ty1 inline1 phases }
           ; return [(loc, pragma)]
           }

    rep_specialiseInst :: LHsSigType Name -> SrcSpan -> DsM [(SrcSpan, Core TH.DecQ)]
    rep_specialiseInst ty loc
      = do { ty1    <- repHsSigType ty
           ; pragma <- repPragSpecInst ty1
           ; return [(loc, pragma)] }

    repInline :: InlineSpec -> DsM (Core TH.Inline)
    repInline NoInline  = dataCon noInlineDataConName
    repInline Inline    = dataCon inlineDataConName
    repInline Inlinable = dataCon inlinableDataConName
    repInline spec      = notHandled "repInline" (ppr spec)

    repRuleMatch :: RuleMatchInfo -> DsM (Core TH.RuleMatch)
    repRuleMatch ConLike = dataCon conLikeDataConName
    repRuleMatch FunLike = dataCon funLikeDataConName

    repPhases :: Activation -> DsM (Core TH.Phases)
    repPhases (ActiveBefore _ i) = do { MkC arg <- coreIntLit i
                                      ; dataCon' beforePhaseDataConName [arg] }
    repPhases (ActiveAfter _ i)  = do { MkC arg <- coreIntLit i
                                      ; dataCon' fromPhaseDataConName [arg] }
    repPhases _                  = dataCon allPhasesDataConName

    rep_complete_sig :: Located [Located Name]
                     -> Maybe (Located Name)
                     -> SrcSpan
                     -> DsM [(SrcSpan, Core TH.DecQ)]
    rep_complete_sig (L _ cls) mty loc
      = do { mty' <- rep_maybe_name mty
           ; cls' <- repList nameTyConName lookupLOcc cls
           ; sig <- repPragComplete cls' mty'
           ; return [(loc, sig)] }
      where
        rep_maybe_name Nothing = coreNothing nameTyConName
        rep_maybe_name (Just n) = do
          cn <- lookupLOcc n
          coreJust nameTyConName cn

    -------------------------------------------------------
    --                      Types
    -------------------------------------------------------

    addSimpleTyVarBinds :: [Name]                -- the binders to be added
                        -> DsM (Core (TH.Q a))   -- action in the ext env
                        -> DsM (Core (TH.Q a))
    addSimpleTyVarBinds names thing_inside
      = do { fresh_names <- mkGenSyms names
           ; term <- addBinds fresh_names thing_inside
           ; wrapGenSyms fresh_names term }

    addTyVarBinds :: LHsQTyVars Name                            -- the binders to be added
                  -> (Core [TH.TyVarBndr] -> DsM (Core (TH.Q a)))  -- action in the ext env
                  -> DsM (Core (TH.Q a))
    -- gensym a list of type variables and enter them into the meta environment;
    -- the computations passed as the second argument is executed in that extended
    -- meta environment and gets the *new* names on Core-level as an argument

    addTyVarBinds (HsQTvs { hsq_implicit = imp_tvs, hsq_explicit = exp_tvs }) m
      = do { fresh_imp_names <- mkGenSyms imp_tvs
           ; fresh_exp_names <- mkGenSyms (map hsLTyVarName exp_tvs)
           ; let fresh_names = fresh_imp_names ++ fresh_exp_names
           ; term <- addBinds fresh_names $
                     do { kbs <- repList tyVarBndrTyConName mk_tv_bndr
                                         (exp_tvs `zip` fresh_exp_names)
                        ; m kbs }
           ; wrapGenSyms fresh_names term }
      where
        mk_tv_bndr (tv, (_,v)) = repTyVarBndrWithKind tv (coreVar v)

    addTyClTyVarBinds :: LHsQTyVars Name
                      -> (Core [TH.TyVarBndr] -> DsM (Core (TH.Q a)))
                      -> DsM (Core (TH.Q a))

    -- Used for data/newtype declarations, and family instances,
    -- so that the nested type variables work right
    --    instance C (T a) where
    --      type W (T a) = blah
    -- The 'a' in the type instance is the one bound by the instance decl
    addTyClTyVarBinds tvs m
      = do { let tv_names = hsAllLTyVarNames tvs
           ; env <- dsGetMetaEnv
           ; freshNames <- mkGenSyms (filterOut (`elemNameEnv` env) tv_names)
                -- Make fresh names for the ones that are not already in scope
                -- This makes things work for family declarations

           ; term <- addBinds freshNames $
                     do { kbs <- repList tyVarBndrTyConName mk_tv_bndr (hsQTvExplicit tvs)
                        ; m kbs }

           ; wrapGenSyms freshNames term }
      where
        mk_tv_bndr tv = do { v <- lookupBinder (hsLTyVarName tv)
                           ; repTyVarBndrWithKind tv v }

    -- Produce kinded binder constructors from the Haskell tyvar binders
    --
    repTyVarBndrWithKind :: LHsTyVarBndr Name
                         -> Core TH.Name -> DsM (Core TH.TyVarBndr)
    repTyVarBndrWithKind (L _ (UserTyVar _)) nm
      = repPlainTV nm
    repTyVarBndrWithKind (L _ (KindedTyVar _ ki)) nm
      = repLKind ki >>= repKindedTV nm

    -- | Represent a type variable binder
    repTyVarBndr :: LHsTyVarBndr Name -> DsM (Core TH.TyVarBndr)
    repTyVarBndr (L _ (UserTyVar (L _ nm)) )= do { nm' <- lookupBinder nm
                                                 ; repPlainTV nm' }
    repTyVarBndr (L _ (KindedTyVar (L _ nm) ki)) = do { nm' <- lookupBinder nm
                                                      ; ki' <- repLKind ki
                                                      ; repKindedTV nm' ki' }

    -- represent a type context
    --
    repLContext :: LHsContext Name -> DsM (Core TH.CxtQ)
    repLContext (L _ ctxt) = repContext ctxt

    repContext :: HsContext Name -> DsM (Core TH.CxtQ)
    repContext ctxt = do preds <- repList typeQTyConName repLTy ctxt
                         repCtxt preds

    repHsSigType :: LHsSigType Name -> DsM (Core TH.TypeQ)
    repHsSigType (HsIB { hsib_vars = implicit_tvs
                       , hsib_body = body })
      | (explicit_tvs, ctxt, ty) <- splitLHsSigmaTy body
      = addTyVarBinds (HsQTvs { hsq_implicit = implicit_tvs
                              , hsq_explicit = explicit_tvs
                              , hsq_dependent = emptyNameSet })
        -- NB: Don't pass implicit_tvs to the hsq_explicit field above
        -- See Note [Don't quantify implicit type variables in quotes]
                      $ \ th_explicit_tvs ->
        do { th_ctxt <- repLContext ctxt
           ; th_ty   <- repLTy ty
           ; if null explicit_tvs && null (unLoc ctxt)
             then return th_ty
             else repTForall th_explicit_tvs th_ctxt th_ty }

    repHsPatSynSigType :: LHsSigType Name -> DsM (Core TH.TypeQ)
    repHsPatSynSigType (HsIB { hsib_vars = implicit_tvs
                             , hsib_body = body })
      = addTyVarBinds (newTvs implicit_tvs univs) $ \th_univs ->
          addTyVarBinds (newTvs [] exis) $ \th_exis ->
        do { th_reqs  <- repLContext reqs
           ; th_provs <- repLContext provs
           ; th_ty    <- repLTy ty
           ; repTForall th_univs th_reqs =<< (repTForall th_exis th_provs th_ty) }
      where
        newTvs impl_tvs expl_tvs = HsQTvs
          { hsq_implicit  = impl_tvs
          , hsq_explicit  = expl_tvs
          , hsq_dependent = emptyNameSet }
        -- NB: Don't pass impl_tvs to the hsq_explicit field above
        -- See Note [Don't quantify implicit type variables in quotes]

        (univs, reqs, exis, provs, ty) = splitLHsPatSynTy body

    repHsSigWcType :: LHsSigWcType Name -> DsM (Core TH.TypeQ)
    repHsSigWcType (HsWC { hswc_body = sig1 })
      = repHsSigType sig1

    -- yield the representation of a list of types
    repLTys :: [LHsType Name] -> DsM [Core TH.TypeQ]
    repLTys tys = mapM repLTy tys

    -- represent a type
    repLTy :: LHsType Name -> DsM (Core TH.TypeQ)
    repLTy (L _ ty) = repTy ty

    repForall :: HsType Name -> DsM (Core TH.TypeQ)
    -- Arg of repForall is always HsForAllTy or HsQualTy
    repForall ty
     | (tvs, ctxt, tau) <- splitLHsSigmaTy (noLoc ty)
     = addTyVarBinds (HsQTvs { hsq_implicit = [], hsq_explicit = tvs
                             , hsq_dependent = emptyNameSet }) $ \bndrs ->
       do { ctxt1  <- repLContext ctxt
          ; ty1    <- repLTy tau
          ; repTForall bndrs ctxt1 ty1 }

    repTy :: HsType Name -> DsM (Core TH.TypeQ)
    repTy ty@(HsForAllTy {}) = repForall ty
    repTy ty@(HsQualTy {})   = repForall ty

    repTy (HsTyVar _ (L _ n))
      | isTvOcc occ   = do tv1 <- lookupOcc n
                           repTvar tv1
      | isDataOcc occ = do tc1 <- lookupOcc n
                           repPromotedDataCon tc1
      | n == eqTyConName = repTequality
      | otherwise     = do tc1 <- lookupOcc n
                           repNamedTyCon tc1
      where
        occ = nameOccName n

    repTy (HsAppTy f a)         = do
                                    f1 <- repLTy f
                                    a1 <- repLTy a
                                    repTapp f1 a1
    repTy (HsFunTy f a)         = do
                                    f1   <- repLTy f
                                    a1   <- repLTy a
                                    tcon <- repArrowTyCon
                                    repTapps tcon [f1, a1]
    repTy (HsListTy t)          = do
                                    t1   <- repLTy t
                                    tcon <- repListTyCon
                                    repTapp tcon t1
    repTy (HsPArrTy t)     = do
                               t1   <- repLTy t
                               tcon <- repTy (HsTyVar NotPromoted
                                                      (noLoc (tyConName parrTyCon)))
                               repTapp tcon t1
    repTy (HsTupleTy HsUnboxedTuple tys) = do
                                    tys1 <- repLTys tys
                                    tcon <- repUnboxedTupleTyCon (length tys)
                                    repTapps tcon tys1
    repTy (HsTupleTy _ tys)     = do tys1 <- repLTys tys
                                     tcon <- repTupleTyCon (length tys)
                                     repTapps tcon tys1
    repTy (HsSumTy tys)         = do tys1 <- repLTys tys
                                     tcon <- repUnboxedSumTyCon (length tys)
                                     repTapps tcon tys1
    repTy (HsOpTy ty1 n ty2)    = repLTy ((nlHsTyVar (unLoc n) `nlHsAppTy` ty1)
                                       `nlHsAppTy` ty2)
    repTy (HsParTy t)           = repLTy t
    repTy (HsEqTy t1 t2) = do
                             t1' <- repLTy t1
                             t2' <- repLTy t2
                             eq  <- repTequality
                             repTapps eq [t1', t2']
    repTy (HsKindSig t k)       = do
                                    t1 <- repLTy t
                                    k1 <- repLKind k
                                    repTSig t1 k1
    repTy (HsSpliceTy splice _)     = repSplice splice
    repTy (HsExplicitListTy _ _ tys) = do
                                        tys1 <- repLTys tys
                                        repTPromotedList tys1
    repTy (HsExplicitTupleTy _ tys) = do
                                        tys1 <- repLTys tys
                                        tcon <- repPromotedTupleTyCon (length tys)
                                        repTapps tcon tys1
    repTy (HsTyLit lit) = do
                            lit' <- repTyLit lit
                            repTLit lit'
    repTy (HsWildCardTy (AnonWildCard _)) = repTWildCard

    repTy ty                      = notHandled "Exotic form of type" (ppr ty)

    repTyLit :: HsTyLit -> DsM (Core TH.TyLitQ)
    repTyLit (HsNumTy _ i) = do iExpr <- mkIntegerExpr i
                                rep2 numTyLitName [iExpr]
    repTyLit (HsStrTy _ s) = do { s' <- mkStringExprFS s
                                ; rep2 strTyLitName [s']
                                }

    -- represent a kind
    --
    repLKind :: LHsKind Name -> DsM (Core TH.Kind)
    repLKind ki
      = do { let (kis, ki') = splitHsFunType ki
           ; kis_rep <- mapM repLKind kis
           ; ki'_rep <- repNonArrowLKind ki'
           ; kcon <- repKArrow
           ; let f k1 k2 = repKApp kcon k1 >>= flip repKApp k2
           ; foldrM f ki'_rep kis_rep
           }

    -- | Represent a kind wrapped in a Maybe
    repMaybeLKind :: Maybe (LHsKind Name)
                  -> DsM (Core (Maybe TH.Kind))
    repMaybeLKind Nothing =
        do { coreNothing kindTyConName }
    repMaybeLKind (Just ki) =
        do { ki' <- repLKind ki
           ; coreJust kindTyConName ki' }

    repNonArrowLKind :: LHsKind Name -> DsM (Core TH.Kind)
    repNonArrowLKind (L _ ki) = repNonArrowKind ki

    repNonArrowKind :: HsKind Name -> DsM (Core TH.Kind)
    repNonArrowKind (HsTyVar _ (L _ name))
      | isLiftedTypeKindTyConName name       = repKStar
      | name `hasKey` constraintKindTyConKey = repKConstraint
      | isTvOcc (nameOccName name)      = lookupOcc name >>= repKVar
      | otherwise                       = lookupOcc name >>= repKCon
    repNonArrowKind (HsAppTy f a)       = do  { f' <- repLKind f
                                              ; a' <- repLKind a
                                              ; repKApp f' a'
                                              }
    repNonArrowKind (HsListTy k)        = do  { k' <- repLKind k
                                              ; kcon <- repKList
                                              ; repKApp kcon k'
                                              }
    repNonArrowKind (HsTupleTy _ ks)    = do  { ks' <- mapM repLKind ks
                                              ; kcon <- repKTuple (length ks)
                                              ; repKApps kcon ks'
                                              }
    repNonArrowKind k                   = notHandled "Exotic form of kind" (ppr k)

    repRole :: Located (Maybe Role) -> DsM (Core TH.Role)
    repRole (L _ (Just Nominal))          = rep2 nominalRName []
    repRole (L _ (Just Representational)) = rep2 representationalRName []
    repRole (L _ (Just Phantom))          = rep2 phantomRName []
    repRole (L _ Nothing)                 = rep2 inferRName []

    -----------------------------------------------------------------------------
    --              Splices
    -----------------------------------------------------------------------------

    repSplice :: HsSplice Name -> DsM (Core a)
    -- See Note [How brackets and nested splices are handled] in TcSplice
    -- We return a CoreExpr of any old type; the context should know
    repSplice (HsTypedSplice   _ n _) = rep_splice n
    repSplice (HsUntypedSplice _ n _) = rep_splice n
    repSplice (HsQuasiQuote n _ _ _)  = rep_splice n
    repSplice e@(HsSpliced _ _)       = pprPanic "repSplice" (ppr e)

    rep_splice :: Name -> DsM (Core a)
    rep_splice splice_name
     = do { mb_val <- dsLookupMetaEnv splice_name
           ; case mb_val of
               Just (DsSplice e) -> do { e' <- dsExpr e
                                       ; return (MkC e') }
               _ -> pprPanic "HsSplice" (ppr splice_name) }
                            -- Should not happen; statically checked

    -----------------------------------------------------------------------------
    --              Expressions
    -----------------------------------------------------------------------------

    repLEs :: [LHsExpr Name] -> DsM (Core [TH.ExpQ])
    repLEs es = repList expQTyConName repLE es

    -- FIXME: some of these panics should be converted into proper error messages
    --        unless we can make sure that constructs, which are plainly not
    --        supported in TH already lead to error messages at an earlier stage
    repLE :: LHsExpr Name -> DsM (Core TH.ExpQ)
    repLE (L loc e) = putSrcSpanDs loc (repE e)

    repE :: HsExpr Name -> DsM (Core TH.ExpQ)
    repE (HsVar (L _ x))            =
      do { mb_val <- dsLookupMetaEnv x
         ; case mb_val of
            Nothing            -> do { str <- globalVar x
                                     ; repVarOrCon x str }
            Just (DsBound y)   -> repVarOrCon x (coreVar y)
            Just (DsSplice e)  -> do { e' <- dsExpr e
                                     ; return (MkC e') } }
    repE e@(HsIPVar _) = notHandled "Implicit parameters" (ppr e)
    repE e@(HsOverLabel{}) = notHandled "Overloaded labels" (ppr e)

    repE e@(HsRecFld f) = case f of
      Unambiguous _ x -> repE (HsVar (noLoc x))
      Ambiguous{}     -> notHandled "Ambiguous record selectors" (ppr e)

            -- Remember, we're desugaring renamer output here, so
            -- HsOverlit can definitely occur
    repE (HsOverLit l) = do { a <- repOverloadedLiteral l; repLit a }
    repE (HsLit l)     = do { a <- repLiteral l;           repLit a }
    repE (HsLam (MG { mg_alts = L _ [m] })) = repLambda m
    repE (HsLamCase (MG { mg_alts = L _ ms }))
                       = do { ms' <- mapM repMatchTup ms
                            ; core_ms <- coreList matchQTyConName ms'
                            ; repLamCase core_ms }
    repE (HsApp x y)   = do {a <- repLE x; b <- repLE y; repApp a b}
    repE (HsAppType e t) = do { a <- repLE e
                              ; s <- repLTy (hswc_body t)
                              ; repAppType a s }

    repE (OpApp e1 op _ e2) =
      do { arg1 <- repLE e1;
           arg2 <- repLE e2;
           the_op <- repLE op ;
           repInfixApp arg1 the_op arg2 }
    repE (NegApp x _)        = do
                                  a         <- repLE x
                                  negateVar <- lookupOcc negateName >>= repVar
                                  negateVar `repApp` a
    repE (HsPar x)            = repLE x
    repE (SectionL x y)       = do { a <- repLE x; b <- repLE y; repSectionL a b }
    repE (SectionR x y)       = do { a <- repLE x; b <- repLE y; repSectionR a b }
    repE (HsCase e (MG { mg_alts = L _ ms }))
                              = do { arg <- repLE e
                                   ; ms2 <- mapM repMatchTup ms
                                   ; core_ms2 <- coreList matchQTyConName ms2
                                   ; repCaseE arg core_ms2 }
    repE (HsIf _ x y z)         = do
                                  a <- repLE x
                                  b <- repLE y
                                  c <- repLE z
                                  repCond a b c
    repE (HsMultiIf _ alts)
      = do { (binds, alts') <- liftM unzip $ mapM repLGRHS alts
           ; expr' <- repMultiIf (nonEmptyCoreList alts')
           ; wrapGenSyms (concat binds) expr' }
    repE (HsLet (L _ bs) e)         = do { (ss,ds) <- repBinds bs
                                         ; e2 <- addBinds ss (repLE e)
                                         ; z <- repLetE ds e2
                                         ; wrapGenSyms ss z }

    -- FIXME: I haven't got the types here right yet
    repE e@(HsDo ctxt (L _ sts) _)
     | case ctxt of { DoExpr -> True; GhciStmtCtxt -> True; _ -> False }
     = do { (ss,zs) <- repLSts sts;
            e'      <- repDoE (nonEmptyCoreList zs);
            wrapGenSyms ss e' }

     | ListComp <- ctxt
     = do { (ss,zs) <- repLSts sts;
            e'      <- repComp (nonEmptyCoreList zs);
            wrapGenSyms ss e' }

      | otherwise
      = notHandled "mdo, monad comprehension and [: :]" (ppr e)

    repE (ExplicitList _ _ es) = do { xs <- repLEs es; repListExp xs }
    repE e@(ExplicitPArr _ _) = notHandled "Parallel arrays" (ppr e)
    repE e@(ExplicitTuple es boxed)
      | not (all tupArgPresent es) = notHandled "Tuple sections" (ppr e)
      | isBoxed boxed  = do { xs <- repLEs [e | L _ (Present e) <- es]; repTup xs }
      | otherwise      = do { xs <- repLEs [e | L _ (Present e) <- es]
                            ; repUnboxedTup xs }

    repE (ExplicitSum alt arity e _)
     = do { e1 <- repLE e
          ; repUnboxedSum e1 alt arity }

    repE (RecordCon { rcon_con_name = c, rcon_flds = flds })
     = do { x <- lookupLOcc c;
            fs <- repFields flds;
            repRecCon x fs }
    repE (RecordUpd { rupd_expr = e, rupd_flds = flds })
     = do { x <- repLE e;
            fs <- repUpdFields flds;
            repRecUpd x fs }

    repE (ExprWithTySig e ty)
      = do { e1 <- repLE e
           ; t1 <- repHsSigWcType ty
           ; repSigExp e1 t1 }

    repE (ArithSeq _ _ aseq) =
      case aseq of
        From e              -> do { ds1 <- repLE e; repFrom ds1 }
        FromThen e1 e2      -> do
                                 ds1 <- repLE e1
                                 ds2 <- repLE e2
                                 repFromThen ds1 ds2
        FromTo   e1 e2      -> do
                                 ds1 <- repLE e1
                                 ds2 <- repLE e2
                                 repFromTo ds1 ds2
        FromThenTo e1 e2 e3 -> do
                                 ds1 <- repLE e1
                                 ds2 <- repLE e2
                                 ds3 <- repLE e3
                                 repFromThenTo ds1 ds2 ds3

    repE (HsSpliceE splice)    = repSplice splice
    repE (HsStatic _ e)        = repLE e >>= rep2 staticEName . (:[]) . unC
    repE (HsUnboundVar uv)     = do
                                   occ   <- occNameLit (unboundVarOcc uv)
                                   sname <- repNameS occ
                                   repUnboundVar sname

    repE e@(PArrSeq {})        = notHandled "Parallel arrays" (ppr e)
    repE e@(HsCoreAnn {})      = notHandled "Core annotations" (ppr e)
    repE e@(HsSCC {})          = notHandled "Cost centres" (ppr e)
    repE e@(HsTickPragma {})   = notHandled "Tick Pragma" (ppr e)
    repE e@(HsTcBracketOut {}) = notHandled "TH brackets" (ppr e)
    repE e                     = notHandled "Expression form" (ppr e)

    -----------------------------------------------------------------------------
    -- Building representations of auxillary structures like Match, Clause, Stmt,

    repMatchTup ::  LMatch Name (LHsExpr Name) -> DsM (Core TH.MatchQ)
    repMatchTup (L _ (Match _ [p] _ (GRHSs guards (L _ wheres)))) =
      do { ss1 <- mkGenSyms (collectPatBinders p)
         ; addBinds ss1 $ do {
         ; p1 <- repLP p
         ; (ss2,ds) <- repBinds wheres
         ; addBinds ss2 $ do {
         ; gs    <- repGuards guards
         ; match <- repMatch p1 gs ds
         ; wrapGenSyms (ss1++ss2) match }}}
    repMatchTup _ = panic "repMatchTup: case alt with more than one arg"

    repClauseTup ::  LMatch Name (LHsExpr Name) -> DsM (Core TH.ClauseQ)
    repClauseTup (L _ (Match _ ps _ (GRHSs guards (L _ wheres)))) =
      do { ss1 <- mkGenSyms (collectPatsBinders ps)
         ; addBinds ss1 $ do {
           ps1 <- repLPs ps
         ; (ss2,ds) <- repBinds wheres
         ; addBinds ss2 $ do {
           gs <- repGuards guards
         ; clause <- repClause ps1 gs ds
         ; wrapGenSyms (ss1++ss2) clause }}}

    repGuards ::  [LGRHS Name (LHsExpr Name)] ->  DsM (Core TH.BodyQ)
    repGuards [L _ (GRHS [] e)]
      = do {a <- repLE e; repNormal a }
    repGuards other
      = do { zs <- mapM repLGRHS other
           ; let (xs, ys) = unzip zs
           ; gd <- repGuarded (nonEmptyCoreList ys)
           ; wrapGenSyms (concat xs) gd }

    repLGRHS :: LGRHS Name (LHsExpr Name) -> DsM ([GenSymBind], (Core (TH.Q (TH.Guard, TH.Exp))))
    repLGRHS (L _ (GRHS [L _ (BodyStmt e1 _ _ _)] e2))
      = do { guarded <- repLNormalGE e1 e2
           ; return ([], guarded) }
    repLGRHS (L _ (GRHS ss rhs))
      = do { (gs, ss') <- repLSts ss
           ; rhs' <- addBinds gs $ repLE rhs
           ; guarded <- repPatGE (nonEmptyCoreList ss') rhs'
           ; return (gs, guarded) }

    repFields :: HsRecordBinds Name -> DsM (Core [TH.Q TH.FieldExp])
    repFields (HsRecFields { rec_flds = flds })
      = repList fieldExpQTyConName rep_fld flds
      where
        rep_fld :: LHsRecField Name (LHsExpr Name) -> DsM (Core (TH.Q TH.FieldExp))
        rep_fld (L _ fld) = do { fn <- lookupLOcc (hsRecFieldSel fld)
                               ; e  <- repLE (hsRecFieldArg fld)
                               ; repFieldExp fn e }

    repUpdFields :: [LHsRecUpdField Name] -> DsM (Core [TH.Q TH.FieldExp])
    repUpdFields = repList fieldExpQTyConName rep_fld
      where
        rep_fld :: LHsRecUpdField Name -> DsM (Core (TH.Q TH.FieldExp))
        rep_fld (L l fld) = case unLoc (hsRecFieldLbl fld) of
          Unambiguous _ sel_name -> do { fn <- lookupLOcc (L l sel_name)
                                       ; e  <- repLE (hsRecFieldArg fld)
                                       ; repFieldExp fn e }
          _                      -> notHandled "Ambiguous record updates" (ppr fld)

    -----------------------------------------------------------------------------
    -- Representing Stmt's is tricky, especially if bound variables
    -- shadow each other. Consider:  [| do { x <- f 1; x <- f x; g x } |]
    -- First gensym new names for every variable in any of the patterns.
    -- both static (x'1 and x'2), and dynamic ((gensym "x") and (gensym "y"))
    -- if variables didn't shaddow, the static gensym wouldn't be necessary
    -- and we could reuse the original names (x and x).
    --
    -- do { x'1 <- gensym "x"
    --    ; x'2 <- gensym "x"
    --    ; doE [ BindSt (pvar x'1) [| f 1 |]
    --          , BindSt (pvar x'2) [| f x |]
    --          , NoBindSt [| g x |]
    --          ]
    --    }

    -- The strategy is to translate a whole list of do-bindings by building a
    -- bigger environment, and a bigger set of meta bindings
    -- (like:  x'1 <- gensym "x" ) and then combining these with the translations
    -- of the expressions within the Do

    -----------------------------------------------------------------------------
    -- The helper function repSts computes the translation of each sub expression
    -- and a bunch of prefix bindings denoting the dynamic renaming.

    repLSts :: [LStmt Name (LHsExpr Name)] -> DsM ([GenSymBind], [Core TH.StmtQ])
    repLSts stmts = repSts (map unLoc stmts)

    repSts :: [Stmt Name (LHsExpr Name)] -> DsM ([GenSymBind], [Core TH.StmtQ])
    repSts (BindStmt p e _ _ _ : ss) =
       do { e2 <- repLE e
          ; ss1 <- mkGenSyms (collectPatBinders p)
          ; addBinds ss1 $ do {
          ; p1 <- repLP p;
          ; (ss2,zs) <- repSts ss
          ; z <- repBindSt p1 e2
          ; return (ss1++ss2, z : zs) }}
    repSts (LetStmt (L _ bs) : ss) =
       do { (ss1,ds) <- repBinds bs
          ; z <- repLetSt ds
          ; (ss2,zs) <- addBinds ss1 (repSts ss)
          ; return (ss1++ss2, z : zs) }
    repSts (BodyStmt e _ _ _ : ss) =
       do { e2 <- repLE e
          ; z <- repNoBindSt e2
          ; (ss2,zs) <- repSts ss
          ; return (ss2, z : zs) }
    repSts (ParStmt stmt_blocks _ _ _ : ss) =
       do { (ss_s, stmt_blocks1) <- mapAndUnzipM rep_stmt_block stmt_blocks
          ; let stmt_blocks2 = nonEmptyCoreList stmt_blocks1
                ss1 = concat ss_s
          ; z <- repParSt stmt_blocks2
          ; (ss2, zs) <- addBinds ss1 (repSts ss)
          ; return (ss1++ss2, z : zs) }
       where
         rep_stmt_block :: ParStmtBlock Name Name -> DsM ([GenSymBind], Core [TH.StmtQ])
         rep_stmt_block (ParStmtBlock stmts _ _) =
           do { (ss1, zs) <- repSts (map unLoc stmts)
              ; zs1 <- coreList stmtQTyConName zs
              ; return (ss1, zs1) }
    repSts [LastStmt e _ _]
      = do { e2 <- repLE e
           ; z <- repNoBindSt e2
           ; return ([], [z]) }
    repSts []    = return ([],[])
    repSts other = notHandled "Exotic statement" (ppr other)

    -----------------------------------------------------------
    --                      Bindings
    -----------------------------------------------------------

    repBinds :: HsLocalBinds Name -> DsM ([GenSymBind], Core [TH.DecQ])
    repBinds EmptyLocalBinds
      = do  { core_list <- coreList decQTyConName []
            ; return ([], core_list) }

    repBinds b@(HsIPBinds _) = notHandled "Implicit parameters" (ppr b)

    repBinds (HsValBinds decs)
     = do   { let { bndrs = hsSigTvBinders decs ++ collectHsValBinders decs }
                    -- No need to worry about detailed scopes within
                    -- the binding group, because we are talking Names
                    -- here, so we can safely treat it as a mutually
                    -- recursive group
                    -- For hsSigTvBinders see Note [Scoped type variables in bindings]
            ; ss        <- mkGenSyms bndrs
            ; prs       <- addBinds ss (rep_val_binds decs)
            ; core_list <- coreList decQTyConName
                                    (de_loc (sort_by_loc prs))
            ; return (ss, core_list) }

    rep_val_binds :: HsValBinds Name -> DsM [(SrcSpan, Core TH.DecQ)]
    -- Assumes: all the binders of the binding are already in the meta-env
    rep_val_binds (ValBindsOut binds sigs)
     = do { core1 <- rep_binds' (unionManyBags (map snd binds))
          ; core2 <- rep_sigs' sigs
          ; return (core1 ++ core2) }
    rep_val_binds (ValBindsIn _ _)
     = panic "rep_val_binds: ValBindsIn"

    rep_binds :: LHsBinds Name -> DsM [Core TH.DecQ]
    rep_binds binds = do { binds_w_locs <- rep_binds' binds
                         ; return (de_loc (sort_by_loc binds_w_locs)) }

    rep_binds' :: LHsBinds Name -> DsM [(SrcSpan, Core TH.DecQ)]
    rep_binds' = mapM rep_bind . bagToList

    rep_bind :: LHsBind Name -> DsM (SrcSpan, Core TH.DecQ)
    -- Assumes: all the binders of the binding are already in the meta-env

    -- Note GHC treats declarations of a variable (not a pattern)
    -- e.g.  x = g 5 as a Fun MonoBinds. This is indicated by a single match
    -- with an empty list of patterns
    rep_bind (L loc (FunBind
                     { fun_id = fn,
                       fun_matches = MG { mg_alts
                               = L _ [L _ (Match _ [] _
                                                 (GRHSs guards (L _ wheres)))] } }))
     = do { (ss,wherecore) <- repBinds wheres
            ; guardcore <- addBinds ss (repGuards guards)
            ; fn'  <- lookupLBinder fn
            ; p    <- repPvar fn'
            ; ans  <- repVal p guardcore wherecore
            ; ans' <- wrapGenSyms ss ans
            ; return (loc, ans') }

    rep_bind (L loc (FunBind { fun_id = fn
                             , fun_matches = MG { mg_alts = L _ ms } }))
     =   do { ms1 <- mapM repClauseTup ms
            ; fn' <- lookupLBinder fn
            ; ans <- repFun fn' (nonEmptyCoreList ms1)
            ; return (loc, ans) }

    rep_bind (L loc (PatBind { pat_lhs = pat
                             , pat_rhs = GRHSs guards (L _ wheres) }))
     =   do { patcore <- repLP pat
            ; (ss,wherecore) <- repBinds wheres
            ; guardcore <- addBinds ss (repGuards guards)
            ; ans  <- repVal patcore guardcore wherecore
            ; ans' <- wrapGenSyms ss ans
            ; return (loc, ans') }

    rep_bind (L _ (VarBind { var_id = v, var_rhs = e}))
     =   do { v' <- lookupBinder v
            ; e2 <- repLE e
            ; x <- repNormal e2
            ; patcore <- repPvar v'
            ; empty_decls <- coreList decQTyConName []
            ; ans <- repVal patcore x empty_decls
            ; return (srcLocSpan (getSrcLoc v), ans) }

    rep_bind (L _ (AbsBinds {}))  = panic "rep_bind: AbsBinds"
    rep_bind (L _ (AbsBindsSig {})) = panic "rep_bind: AbsBindsSig"
    rep_bind (L loc (PatSynBind (PSB { psb_id   = syn
                                     , psb_fvs  = _fvs
                                     , psb_args = args
                                     , psb_def  = pat
                                     , psb_dir  = dir })))
      = do { syn'      <- lookupLBinder syn
           ; dir'      <- repPatSynDir dir
           ; ss        <- mkGenArgSyms args
           ; patSynD'  <- addBinds ss (
             do { args'  <- repPatSynArgs args
                ; pat'   <- repLP pat
                ; repPatSynD syn' args' dir' pat' })
           ; patSynD'' <- wrapGenArgSyms args ss patSynD'
           ; return (loc, patSynD'') }
      where
        mkGenArgSyms :: HsPatSynDetails (Located Name) -> DsM [GenSymBind]
        -- for Record Pattern Synonyms we want to conflate the selector
        -- and the pattern-only names in order to provide a nicer TH
        -- API. Whereas inside GHC, record pattern synonym selectors and
        -- their pattern-only bound right hand sides have different names,
        -- we want to treat them the same in TH. This is the reason why we
        -- need an adjusted mkGenArgSyms in the `RecordPatSyn` case below.
        mkGenArgSyms (PrefixPatSyn args)     = mkGenSyms (map unLoc args)
        mkGenArgSyms (InfixPatSyn arg1 arg2) = mkGenSyms [unLoc arg1, unLoc arg2]
        mkGenArgSyms (RecordPatSyn fields)
          = do { let pats = map (unLoc . recordPatSynPatVar) fields
                     sels = map (unLoc . recordPatSynSelectorId) fields
               ; ss <- mkGenSyms sels
               ; return $ replaceNames (zip sels pats) ss }

        replaceNames selsPats genSyms
          = [ (pat, id) | (sel, id) <- genSyms, (sel', pat) <- selsPats
                        , sel == sel' ]

        wrapGenArgSyms :: HsPatSynDetails (Located Name)
                       -> [GenSymBind] -> Core TH.DecQ -> DsM (Core TH.DecQ)
        wrapGenArgSyms (RecordPatSyn _) _  dec = return dec
        wrapGenArgSyms _                ss dec = wrapGenSyms ss dec

    repPatSynD :: Core TH.Name
               -> Core TH.PatSynArgsQ
               -> Core TH.PatSynDirQ
               -> Core TH.PatQ
               -> DsM (Core TH.DecQ)
    repPatSynD (MkC syn) (MkC args) (MkC dir) (MkC pat)
      = rep2 patSynDName [syn, args, dir, pat]

    repPatSynArgs :: HsPatSynDetails (Located Name) -> DsM (Core TH.PatSynArgsQ)
    repPatSynArgs (PrefixPatSyn args)
      = do { args' <- repList nameTyConName lookupLOcc args
           ; repPrefixPatSynArgs args' }
    repPatSynArgs (InfixPatSyn arg1 arg2)
      = do { arg1' <- lookupLOcc arg1
           ; arg2' <- lookupLOcc arg2
           ; repInfixPatSynArgs arg1' arg2' }
    repPatSynArgs (RecordPatSyn fields)
      = do { sels' <- repList nameTyConName lookupLOcc sels
           ; repRecordPatSynArgs sels' }
      where sels = map recordPatSynSelectorId fields

    repPrefixPatSynArgs :: Core [TH.Name] -> DsM (Core TH.PatSynArgsQ)
    repPrefixPatSynArgs (MkC nms) = rep2 prefixPatSynName [nms]

    repInfixPatSynArgs :: Core TH.Name -> Core TH.Name -> DsM (Core TH.PatSynArgsQ)
    repInfixPatSynArgs (MkC nm1) (MkC nm2) = rep2 infixPatSynName [nm1, nm2]

    repRecordPatSynArgs :: Core [TH.Name]
                        -> DsM (Core TH.PatSynArgsQ)
    repRecordPatSynArgs (MkC sels) = rep2 recordPatSynName [sels]

    repPatSynDir :: HsPatSynDir Name -> DsM (Core TH.PatSynDirQ)
    repPatSynDir Unidirectional        = rep2 unidirPatSynName []
    repPatSynDir ImplicitBidirectional = rep2 implBidirPatSynName []
    repPatSynDir (ExplicitBidirectional (MG { mg_alts = L _ clauses }))
      = do { clauses' <- mapM repClauseTup clauses
           ; repExplBidirPatSynDir (nonEmptyCoreList clauses') }

    repExplBidirPatSynDir :: Core [TH.ClauseQ] -> DsM (Core TH.PatSynDirQ)
    repExplBidirPatSynDir (MkC cls) = rep2 explBidirPatSynName [cls]

    -----------------------------------------------------------------------------
    -- Since everything in a Bind is mutually recursive we need rename all
    -- all the variables simultaneously. For example:
    -- [| AndMonoBinds (f x = x + g 2) (g x = f 1 + 2) |] would translate to
    -- do { f'1 <- gensym "f"
    --    ; g'2 <- gensym "g"
    --    ; [ do { x'3 <- gensym "x"; fun f'1 [pvar x'3] [| x + g2 |]},
    --        do { x'4 <- gensym "x"; fun g'2 [pvar x'4] [| f 1 + 2 |]}
    --      ]}
    -- This requires collecting the bindings (f'1 <- gensym "f"), and the
    -- environment ( f |-> f'1 ) from each binding, and then unioning them
    -- together. As we do this we collect GenSymBinds's which represent the renamed
    -- variables bound by the Bindings. In order not to lose track of these
    -- representations we build a shadow datatype MB with the same structure as
    -- MonoBinds, but which has slots for the representations

    -----------------------------------------------------------------------------
    -- GHC allows a more general form of lambda abstraction than specified
    -- by Haskell 98. In particular it allows guarded lambda's like :
    -- (\  x | even x -> 0 | odd x -> 1) at the moment we can't represent this in
    -- Haskell Template's Meta.Exp type so we punt if it isn't a simple thing like
    -- (\ p1 .. pn -> exp) by causing an error.

    repLambda :: LMatch Name (LHsExpr Name) -> DsM (Core TH.ExpQ)
    repLambda (L _ (Match _ ps _ (GRHSs [L _ (GRHS [] e)] (L _ EmptyLocalBinds))))
     = do { let bndrs = collectPatsBinders ps ;
          ; ss  <- mkGenSyms bndrs
          ; lam <- addBinds ss (
                    do { xs <- repLPs ps; body <- repLE e; repLam xs body })
          ; wrapGenSyms ss lam }

    repLambda (L _ m) = notHandled "Guarded labmdas" (pprMatch m)

    -----------------------------------------------------------------------------
    --                      Patterns
    -- repP deals with patterns.  It assumes that we have already
    -- walked over the pattern(s) once to collect the binders, and
    -- have extended the environment.  So every pattern-bound
    -- variable should already appear in the environment.

    -- Process a list of patterns
    repLPs :: [LPat Name] -> DsM (Core [TH.PatQ])
    repLPs ps = repList patQTyConName repLP ps

    repLP :: LPat Name -> DsM (Core TH.PatQ)
    repLP (L _ p) = repP p

    repP :: Pat Name -> DsM (Core TH.PatQ)
    repP (WildPat _)       = repPwild
    repP (LitPat l)        = do { l2 <- repLiteral l; repPlit l2 }
    repP (VarPat (L _ x))  = do { x' <- lookupBinder x; repPvar x' }
    repP (LazyPat p)       = do { p1 <- repLP p; repPtilde p1 }
    repP (BangPat p)       = do { p1 <- repLP p; repPbang p1 }
    repP (AsPat x p)       = do { x' <- lookupLBinder x; p1 <- repLP p; repPaspat x' p1 }
    repP (ParPat p)        = repLP p
    repP (ListPat ps _ Nothing)    = do { qs <- repLPs ps; repPlist qs }
    repP (ListPat ps ty1 (Just (_,e))) = do { p <- repP (ListPat ps ty1 Nothing); e' <- repE (syn_expr e); repPview e' p}
    repP (TuplePat ps boxed _)
      | isBoxed boxed       = do { qs <- repLPs ps; repPtup qs }
      | otherwise           = do { qs <- repLPs ps; repPunboxedTup qs }
    repP (SumPat p alt arity _) = do { p1 <- repLP p; repPunboxedSum p1 alt arity }
    repP (ConPatIn dc details)
     = do { con_str <- lookupLOcc dc
          ; case details of
             PrefixCon ps -> do { qs <- repLPs ps; repPcon con_str qs }
             RecCon rec   -> do { fps <- repList fieldPatQTyConName rep_fld (rec_flds rec)
                                ; repPrec con_str fps }
             InfixCon p1 p2 -> do { p1' <- repLP p1;
                                    p2' <- repLP p2;
                                    repPinfix p1' con_str p2' }
       }
     where
       rep_fld :: LHsRecField Name (LPat Name) -> DsM (Core (TH.Name,TH.PatQ))
       rep_fld (L _ fld) = do { MkC v <- lookupLOcc (hsRecFieldSel fld)
                              ; MkC p <- repLP (hsRecFieldArg fld)
                              ; rep2 fieldPatName [v,p] }

    repP (NPat (L _ l) Nothing _ _) = do { a <- repOverloadedLiteral l; repPlit a }
    repP (ViewPat e p _) = do { e' <- repLE e; p' <- repLP p; repPview e' p' }
    repP p@(NPat _ (Just _) _ _) = notHandled "Negative overloaded patterns" (ppr p)
    repP (SigPatIn p t) = do { p' <- repLP p
                             ; t' <- repLTy (hsSigWcType t)
                             ; repPsig p' t' }
    repP (SplicePat splice) = repSplice splice

    repP other = notHandled "Exotic pattern" (ppr other)

    ----------------------------------------------------------
    -- Declaration ordering helpers

    sort_by_loc :: [(SrcSpan, a)] -> [(SrcSpan, a)]
    sort_by_loc xs = sortBy comp xs
        where comp x y = compare (fst x) (fst y)

    de_loc :: [(a, b)] -> [b]
    de_loc = map snd

    ----------------------------------------------------------
    --      The meta-environment

    -- A name/identifier association for fresh names of locally bound entities
    type GenSymBind = (Name, Id)    -- Gensym the string and bind it to the Id
                                    -- I.e.         (x, x_id) means
                                    --      let x_id = gensym "x" in ...

    -- Generate a fresh name for a locally bound entity

    mkGenSyms :: [Name] -> DsM [GenSymBind]
    -- We can use the existing name.  For example:
    --      [| \x_77 -> x_77 + x_77 |]
    -- desugars to
    --      do { x_77 <- genSym "x"; .... }
    -- We use the same x_77 in the desugared program, but with the type Bndr
    -- instead of Int
    --
    -- We do make it an Internal name, though (hence localiseName)
    --
    -- Nevertheless, it's monadic because we have to generate nameTy
    mkGenSyms ns = do { var_ty <- lookupType nameTyConName
                      ; return [(nm, mkLocalId (localiseName nm) var_ty) | nm <- ns] }

    addBinds :: [GenSymBind] -> DsM a -> DsM a
    -- Add a list of fresh names for locally bound entities to the
    -- meta environment (which is part of the state carried around
    -- by the desugarer monad)
    addBinds bs m = dsExtendMetaEnv (mkNameEnv [(n,DsBound id) | (n,id) <- bs]) m

    -- Look up a locally bound name
    --
    lookupLBinder :: Located Name -> DsM (Core TH.Name)
    lookupLBinder (L _ n) = lookupBinder n

    lookupBinder :: Name -> DsM (Core TH.Name)
    lookupBinder = lookupOcc
      -- Binders are brought into scope before the pattern or what-not is
      -- desugared.  Moreover, in instance declaration the binder of a method
      -- will be the selector Id and hence a global; so we need the
      -- globalVar case of lookupOcc

    -- Look up a name that is either locally bound or a global name
    --
    --  * If it is a global name, generate the "original name" representation (ie,
    --   the <module>:<name> form) for the associated entity
    --
    lookupLOcc :: Located Name -> DsM (Core TH.Name)
    -- Lookup an occurrence; it can't be a splice.
    -- Use the in-scope bindings if they exist
    lookupLOcc (L _ n) = lookupOcc n

    lookupOcc :: Name -> DsM (Core TH.Name)
    lookupOcc n
      = do {  mb_val <- dsLookupMetaEnv n ;
              case mb_val of
                    Nothing           -> globalVar n
                    Just (DsBound x)  -> return (coreVar x)
                    Just (DsSplice _) -> pprPanic "repE:lookupOcc" (ppr n)
        }

    globalVar :: Name -> DsM (Core TH.Name)
    -- Not bound by the meta-env
    -- Could be top-level; or could be local
    --      f x = $(g [| x |])
    -- Here the x will be local
    globalVar name
      | isExternalName name
      = do  { MkC mod <- coreStringLit name_mod
            ; MkC pkg <- coreStringLit name_pkg
            ; MkC occ <- nameLit name
            ; rep2 mk_varg [pkg,mod,occ] }
      | otherwise
      = do  { MkC occ <- nameLit name
            ; MkC uni <- coreIntLit (getKey (getUnique name))
            ; rep2 mkNameLName [occ,uni] }
      where
          mod = ASSERT( isExternalName name) nameModule name
          name_mod = moduleNameString (moduleName mod)
          name_pkg = unitIdString (moduleUnitId mod)
          name_occ = nameOccName name
          mk_varg | OccName.isDataOcc name_occ = mkNameG_dName
                  | OccName.isVarOcc  name_occ = mkNameG_vName
                  | OccName.isTcOcc   name_occ = mkNameG_tcName
                  | otherwise                  = pprPanic "DsMeta.globalVar" (ppr name)

    lookupType :: Name      -- Name of type constructor (e.g. TH.ExpQ)
               -> DsM Type  -- The type
    lookupType tc_name = do { tc <- dsLookupTyCon tc_name ;
                              return (mkTyConApp tc []) }

    wrapGenSyms :: [GenSymBind]
                -> Core (TH.Q a) -> DsM (Core (TH.Q a))
    -- wrapGenSyms [(nm1,id1), (nm2,id2)] y
    --      --> bindQ (gensym nm1) (\ id1 ->
    --          bindQ (gensym nm2 (\ id2 ->
    --          y))

    wrapGenSyms binds body@(MkC b)
      = do  { var_ty <- lookupType nameTyConName
            ; go var_ty binds }
      where
        [elt_ty] = tcTyConAppArgs (exprType b)
            -- b :: Q a, so we can get the type 'a' by looking at the
            -- argument type. NB: this relies on Q being a data/newtype,
            -- not a type synonym

        go _ [] = return body
        go var_ty ((name,id) : binds)
          = do { MkC body'  <- go var_ty binds
               ; lit_str    <- nameLit name
               ; gensym_app <- repGensym lit_str
               ; repBindQ var_ty elt_ty
                          gensym_app (MkC (Lam id body')) }

    nameLit :: Name -> DsM (Core String)
    nameLit n = coreStringLit (occNameString (nameOccName n))

    occNameLit :: OccName -> DsM (Core String)
    occNameLit name = coreStringLit (occNameString name)

    -- %*********************************************************************
    -- %*                                                                   *
    --              Constructing code
    -- %*                                                                   *
    -- %*********************************************************************

    -----------------------------------------------------------------------------
    -- PHANTOM TYPES for consistency. In order to make sure we do this correct
    -- we invent a new datatype which uses phantom types.

    newtype Core a = MkC CoreExpr
    unC :: Core a -> CoreExpr
    unC (MkC x) = x

    rep2 :: Name -> [ CoreExpr ] -> DsM (Core a)
    rep2 n xs = do { id <- dsLookupGlobalId n
                   ; return (MkC (foldl App (Var id) xs)) }

    dataCon' :: Name -> [CoreExpr] -> DsM (Core a)
    dataCon' n args = do { id <- dsLookupDataCon n
                         ; return $ MkC $ mkCoreConApps id args }

    dataCon :: Name -> DsM (Core a)
    dataCon n = dataCon' n []

    -- %*********************************************************************
    -- %*                                                                   *
    --              The 'smart constructors'
    -- %*                                                                   *
    -- %*********************************************************************

    --------------- Patterns -----------------
    repPlit   :: Core TH.Lit -> DsM (Core TH.PatQ)
    repPlit (MkC l) = rep2 litPName [l]

    repPvar :: Core TH.Name -> DsM (Core TH.PatQ)
    repPvar (MkC s) = rep2 varPName [s]

    repPtup :: Core [TH.PatQ] -> DsM (Core TH.PatQ)
    repPtup (MkC ps) = rep2 tupPName [ps]

    repPunboxedTup :: Core [TH.PatQ] -> DsM (Core TH.PatQ)
    repPunboxedTup (MkC ps) = rep2 unboxedTupPName [ps]

    repPunboxedSum :: Core TH.PatQ -> TH.SumAlt -> TH.SumArity -> DsM (Core TH.PatQ)
    -- Note: not Core TH.SumAlt or Core TH.SumArity; it's easier to be direct here
    repPunboxedSum (MkC p) alt arity
     = do { dflags <- getDynFlags
          ; rep2 unboxedSumPName [ p
                                 , mkIntExprInt dflags alt
                                 , mkIntExprInt dflags arity ] }

    repPcon   :: Core TH.Name -> Core [TH.PatQ] -> DsM (Core TH.PatQ)
    repPcon (MkC s) (MkC ps) = rep2 conPName [s, ps]

    repPrec   :: Core TH.Name -> Core [(TH.Name,TH.PatQ)] -> DsM (Core TH.PatQ)
    repPrec (MkC c) (MkC rps) = rep2 recPName [c,rps]

    repPinfix :: Core TH.PatQ -> Core TH.Name -> Core TH.PatQ -> DsM (Core TH.PatQ)
    repPinfix (MkC p1) (MkC n) (MkC p2) = rep2 infixPName [p1, n, p2]

    repPtilde :: Core TH.PatQ -> DsM (Core TH.PatQ)
    repPtilde (MkC p) = rep2 tildePName [p]

    repPbang :: Core TH.PatQ -> DsM (Core TH.PatQ)
    repPbang (MkC p) = rep2 bangPName [p]

    repPaspat :: Core TH.Name -> Core TH.PatQ -> DsM (Core TH.PatQ)
    repPaspat (MkC s) (MkC p) = rep2 asPName [s, p]

    repPwild  :: DsM (Core TH.PatQ)
    repPwild = rep2 wildPName []

    repPlist :: Core [TH.PatQ] -> DsM (Core TH.PatQ)
    repPlist (MkC ps) = rep2 listPName [ps]

    repPview :: Core TH.ExpQ -> Core TH.PatQ -> DsM (Core TH.PatQ)
    repPview (MkC e) (MkC p) = rep2 viewPName [e,p]

    repPsig :: Core TH.PatQ -> Core TH.TypeQ -> DsM (Core TH.PatQ)
    repPsig (MkC p) (MkC t) = rep2 sigPName [p, t]

    --------------- Expressions -----------------
    repVarOrCon :: Name -> Core TH.Name -> DsM (Core TH.ExpQ)
    repVarOrCon vc str | isDataOcc (nameOccName vc) = repCon str
                       | otherwise                  = repVar str

    repVar :: Core TH.Name -> DsM (Core TH.ExpQ)
    repVar (MkC s) = rep2 varEName [s]

    repCon :: Core TH.Name -> DsM (Core TH.ExpQ)
    repCon (MkC s) = rep2 conEName [s]

    repLit :: Core TH.Lit -> DsM (Core TH.ExpQ)
    repLit (MkC c) = rep2 litEName [c]

    repApp :: Core TH.ExpQ -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repApp (MkC x) (MkC y) = rep2 appEName [x,y]

    repAppType :: Core TH.ExpQ -> Core TH.TypeQ -> DsM (Core TH.ExpQ)
    repAppType (MkC x) (MkC y) = rep2 appTypeEName [x,y]

    repLam :: Core [TH.PatQ] -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repLam (MkC ps) (MkC e) = rep2 lamEName [ps, e]

    repLamCase :: Core [TH.MatchQ] -> DsM (Core TH.ExpQ)
    repLamCase (MkC ms) = rep2 lamCaseEName [ms]

    repTup :: Core [TH.ExpQ] -> DsM (Core TH.ExpQ)
    repTup (MkC es) = rep2 tupEName [es]

    repUnboxedTup :: Core [TH.ExpQ] -> DsM (Core TH.ExpQ)
    repUnboxedTup (MkC es) = rep2 unboxedTupEName [es]

    repUnboxedSum :: Core TH.ExpQ -> TH.SumAlt -> TH.SumArity -> DsM (Core TH.ExpQ)
    -- Note: not Core TH.SumAlt or Core TH.SumArity; it's easier to be direct here
    repUnboxedSum (MkC e) alt arity
     = do { dflags <- getDynFlags
          ; rep2 unboxedSumEName [ e
                                 , mkIntExprInt dflags alt
                                 , mkIntExprInt dflags arity ] }

    repCond :: Core TH.ExpQ -> Core TH.ExpQ -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repCond (MkC x) (MkC y) (MkC z) = rep2 condEName [x,y,z]

    repMultiIf :: Core [TH.Q (TH.Guard, TH.Exp)] -> DsM (Core TH.ExpQ)
    repMultiIf (MkC alts) = rep2 multiIfEName [alts]

    repLetE :: Core [TH.DecQ] -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repLetE (MkC ds) (MkC e) = rep2 letEName [ds, e]

    repCaseE :: Core TH.ExpQ -> Core [TH.MatchQ] -> DsM( Core TH.ExpQ)
    repCaseE (MkC e) (MkC ms) = rep2 caseEName [e, ms]

    repDoE :: Core [TH.StmtQ] -> DsM (Core TH.ExpQ)
    repDoE (MkC ss) = rep2 doEName [ss]

    repComp :: Core [TH.StmtQ] -> DsM (Core TH.ExpQ)
    repComp (MkC ss) = rep2 compEName [ss]

    repListExp :: Core [TH.ExpQ] -> DsM (Core TH.ExpQ)
    repListExp (MkC es) = rep2 listEName [es]

    repSigExp :: Core TH.ExpQ -> Core TH.TypeQ -> DsM (Core TH.ExpQ)
    repSigExp (MkC e) (MkC t) = rep2 sigEName [e,t]

    repRecCon :: Core TH.Name -> Core [TH.Q TH.FieldExp]-> DsM (Core TH.ExpQ)
    repRecCon (MkC c) (MkC fs) = rep2 recConEName [c,fs]

    repRecUpd :: Core TH.ExpQ -> Core [TH.Q TH.FieldExp] -> DsM (Core TH.ExpQ)
    repRecUpd (MkC e) (MkC fs) = rep2 recUpdEName [e,fs]

    repFieldExp :: Core TH.Name -> Core TH.ExpQ -> DsM (Core (TH.Q TH.FieldExp))
    repFieldExp (MkC n) (MkC x) = rep2 fieldExpName [n,x]

    repInfixApp :: Core TH.ExpQ -> Core TH.ExpQ -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repInfixApp (MkC x) (MkC y) (MkC z) = rep2 infixAppName [x,y,z]

    repSectionL :: Core TH.ExpQ -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repSectionL (MkC x) (MkC y) = rep2 sectionLName [x,y]

    repSectionR :: Core TH.ExpQ -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repSectionR (MkC x) (MkC y) = rep2 sectionRName [x,y]

    ------------ Right hand sides (guarded expressions) ----
    repGuarded :: Core [TH.Q (TH.Guard, TH.Exp)] -> DsM (Core TH.BodyQ)
    repGuarded (MkC pairs) = rep2 guardedBName [pairs]

    repNormal :: Core TH.ExpQ -> DsM (Core TH.BodyQ)
    repNormal (MkC e) = rep2 normalBName [e]

    ------------ Guards ----
    repLNormalGE :: LHsExpr Name -> LHsExpr Name -> DsM (Core (TH.Q (TH.Guard, TH.Exp)))
    repLNormalGE g e = do g' <- repLE g
                          e' <- repLE e
                          repNormalGE g' e'

    repNormalGE :: Core TH.ExpQ -> Core TH.ExpQ -> DsM (Core (TH.Q (TH.Guard, TH.Exp)))
    repNormalGE (MkC g) (MkC e) = rep2 normalGEName [g, e]

    repPatGE :: Core [TH.StmtQ] -> Core TH.ExpQ -> DsM (Core (TH.Q (TH.Guard, TH.Exp)))
    repPatGE (MkC ss) (MkC e) = rep2 patGEName [ss, e]

    ------------- Stmts -------------------
    repBindSt :: Core TH.PatQ -> Core TH.ExpQ -> DsM (Core TH.StmtQ)
    repBindSt (MkC p) (MkC e) = rep2 bindSName [p,e]

    repLetSt :: Core [TH.DecQ] -> DsM (Core TH.StmtQ)
    repLetSt (MkC ds) = rep2 letSName [ds]

    repNoBindSt :: Core TH.ExpQ -> DsM (Core TH.StmtQ)
    repNoBindSt (MkC e) = rep2 noBindSName [e]

    repParSt :: Core [[TH.StmtQ]] -> DsM (Core TH.StmtQ)
    repParSt (MkC sss) = rep2 parSName [sss]

    -------------- Range (Arithmetic sequences) -----------
    repFrom :: Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repFrom (MkC x) = rep2 fromEName [x]

    repFromThen :: Core TH.ExpQ -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repFromThen (MkC x) (MkC y) = rep2 fromThenEName [x,y]

    repFromTo :: Core TH.ExpQ -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repFromTo (MkC x) (MkC y) = rep2 fromToEName [x,y]

    repFromThenTo :: Core TH.ExpQ -> Core TH.ExpQ -> Core TH.ExpQ -> DsM (Core TH.ExpQ)
    repFromThenTo (MkC x) (MkC y) (MkC z) = rep2 fromThenToEName [x,y,z]

    ------------ Match and Clause Tuples -----------
    repMatch :: Core TH.PatQ -> Core TH.BodyQ -> Core [TH.DecQ] -> DsM (Core TH.MatchQ)
    repMatch (MkC p) (MkC bod) (MkC ds) = rep2 matchName [p, bod, ds]

    repClause :: Core [TH.PatQ] -> Core TH.BodyQ -> Core [TH.DecQ] -> DsM (Core TH.ClauseQ)
    repClause (MkC ps) (MkC bod) (MkC ds) = rep2 clauseName [ps, bod, ds]

    -------------- Dec -----------------------------
    repVal :: Core TH.PatQ -> Core TH.BodyQ -> Core [TH.DecQ] -> DsM (Core TH.DecQ)
    repVal (MkC p) (MkC b) (MkC ds) = rep2 valDName [p, b, ds]

    repFun :: Core TH.Name -> Core [TH.ClauseQ] -> DsM (Core TH.DecQ)
    repFun (MkC nm) (MkC b) = rep2 funDName [nm, b]

    repData :: Core TH.CxtQ -> Core TH.Name -> Core [TH.TyVarBndr]
            -> Maybe (Core [TH.TypeQ]) -> Core (Maybe TH.Kind)
            -> Core [TH.ConQ] -> Core [TH.DerivClauseQ] -> DsM (Core TH.DecQ)
    repData (MkC cxt) (MkC nm) (MkC tvs) Nothing (MkC ksig) (MkC cons) (MkC derivs)
      = rep2 dataDName [cxt, nm, tvs, ksig, cons, derivs]
    repData (MkC cxt) (MkC nm) (MkC _) (Just (MkC tys)) (MkC ksig) (MkC cons)
            (MkC derivs)
      = rep2 dataInstDName [cxt, nm, tys, ksig, cons, derivs]

    repNewtype :: Core TH.CxtQ -> Core TH.Name -> Core [TH.TyVarBndr]
               -> Maybe (Core [TH.TypeQ]) -> Core (Maybe TH.Kind)
               -> Core TH.ConQ -> Core [TH.DerivClauseQ] -> DsM (Core TH.DecQ)
    repNewtype (MkC cxt) (MkC nm) (MkC tvs) Nothing (MkC ksig) (MkC con)
               (MkC derivs)
      = rep2 newtypeDName [cxt, nm, tvs, ksig, con, derivs]
    repNewtype (MkC cxt) (MkC nm) (MkC _) (Just (MkC tys)) (MkC ksig) (MkC con)
               (MkC derivs)
      = rep2 newtypeInstDName [cxt, nm, tys, ksig, con, derivs]

    repTySyn :: Core TH.Name -> Core [TH.TyVarBndr]
             -> Core TH.TypeQ -> DsM (Core TH.DecQ)
    repTySyn (MkC nm) (MkC tvs) (MkC rhs)
      = rep2 tySynDName [nm, tvs, rhs]

    repInst :: Core (Maybe TH.Overlap) ->
               Core TH.CxtQ -> Core TH.TypeQ -> Core [TH.DecQ] -> DsM (Core TH.DecQ)
    repInst (MkC o) (MkC cxt) (MkC ty) (MkC ds) = rep2 instanceWithOverlapDName
                                                                  [o, cxt, ty, ds]

    repDerivStrategy :: Maybe (Located DerivStrategy)
                     -> DsM (Core (Maybe TH.DerivStrategy))
    repDerivStrategy mds =
      case mds of
        Nothing -> nothing
        Just (L _ ds) ->
          case ds of
            StockStrategy    -> just =<< dataCon stockStrategyDataConName
            AnyclassStrategy -> just =<< dataCon anyclassStrategyDataConName
            NewtypeStrategy  -> just =<< dataCon newtypeStrategyDataConName
      where
      nothing = coreNothing derivStrategyTyConName
      just    = coreJust    derivStrategyTyConName

    repOverlap :: Maybe OverlapMode -> DsM (Core (Maybe TH.Overlap))
    repOverlap mb =
      case mb of
        Nothing -> nothing
        Just o ->
          case o of
            NoOverlap _    -> nothing
            Overlappable _ -> just =<< dataCon overlappableDataConName
            Overlapping _  -> just =<< dataCon overlappingDataConName
            Overlaps _     -> just =<< dataCon overlapsDataConName
            Incoherent _   -> just =<< dataCon incoherentDataConName
      where
      nothing = coreNothing overlapTyConName
      just    = coreJust overlapTyConName

    repClass :: Core TH.CxtQ -> Core TH.Name -> Core [TH.TyVarBndr]
             -> Core [TH.FunDep] -> Core [TH.DecQ]
             -> DsM (Core TH.DecQ)
    repClass (MkC cxt) (MkC cls) (MkC tvs) (MkC fds) (MkC ds)
      = rep2 classDName [cxt, cls, tvs, fds, ds]

    repDeriv :: Core (Maybe TH.DerivStrategy)
             -> Core TH.CxtQ -> Core TH.TypeQ
             -> DsM (Core TH.DecQ)
    repDeriv (MkC ds) (MkC cxt) (MkC ty)
      = rep2 standaloneDerivWithStrategyDName [ds, cxt, ty]

    repPragInl :: Core TH.Name -> Core TH.Inline -> Core TH.RuleMatch
               -> Core TH.Phases -> DsM (Core TH.DecQ)
    repPragInl (MkC nm) (MkC inline) (MkC rm) (MkC phases)
      = rep2 pragInlDName [nm, inline, rm, phases]

    repPragSpec :: Core TH.Name -> Core TH.TypeQ -> Core TH.Phases
                -> DsM (Core TH.DecQ)
    repPragSpec (MkC nm) (MkC ty) (MkC phases)
      = rep2 pragSpecDName [nm, ty, phases]

    repPragSpecInl :: Core TH.Name -> Core TH.TypeQ -> Core TH.Inline
                   -> Core TH.Phases -> DsM (Core TH.DecQ)
    repPragSpecInl (MkC nm) (MkC ty) (MkC inline) (MkC phases)
      = rep2 pragSpecInlDName [nm, ty, inline, phases]

    repPragSpecInst :: Core TH.TypeQ -> DsM (Core TH.DecQ)
    repPragSpecInst (MkC ty) = rep2 pragSpecInstDName [ty]

    repPragComplete :: Core [TH.Name] -> Core (Maybe TH.Name) -> DsM (Core TH.DecQ)
    repPragComplete (MkC cls) (MkC mty) = rep2 pragCompleteDName [cls, mty]

    repPragRule :: Core String -> Core [TH.RuleBndrQ] -> Core TH.ExpQ
                -> Core TH.ExpQ -> Core TH.Phases -> DsM (Core TH.DecQ)
    repPragRule (MkC nm) (MkC bndrs) (MkC lhs) (MkC rhs) (MkC phases)
      = rep2 pragRuleDName [nm, bndrs, lhs, rhs, phases]

    repPragAnn :: Core TH.AnnTarget -> Core TH.ExpQ -> DsM (Core TH.DecQ)
    repPragAnn (MkC targ) (MkC e) = rep2 pragAnnDName [targ, e]

    repTySynInst :: Core TH.Name -> Core TH.TySynEqnQ -> DsM (Core TH.DecQ)
    repTySynInst (MkC nm) (MkC eqn)
        = rep2 tySynInstDName [nm, eqn]

    repDataFamilyD :: Core TH.Name -> Core [TH.TyVarBndr]
                   -> Core (Maybe TH.Kind) -> DsM (Core TH.DecQ)
    repDataFamilyD (MkC nm) (MkC tvs) (MkC kind)
        = rep2 dataFamilyDName [nm, tvs, kind]

    repOpenFamilyD :: Core TH.Name
                   -> Core [TH.TyVarBndr]
                   -> Core TH.FamilyResultSig
                   -> Core (Maybe TH.InjectivityAnn)
                   -> DsM (Core TH.DecQ)
    repOpenFamilyD (MkC nm) (MkC tvs) (MkC result) (MkC inj)
        = rep2 openTypeFamilyDName [nm, tvs, result, inj]

    repClosedFamilyD :: Core TH.Name
                     -> Core [TH.TyVarBndr]
                     -> Core TH.FamilyResultSig
                     -> Core (Maybe TH.InjectivityAnn)
                     -> Core [TH.TySynEqnQ]
                     -> DsM (Core TH.DecQ)
    repClosedFamilyD (MkC nm) (MkC tvs) (MkC res) (MkC inj) (MkC eqns)
        = rep2 closedTypeFamilyDName [nm, tvs, res, inj, eqns]

    repTySynEqn :: Core [TH.TypeQ] -> Core TH.TypeQ -> DsM (Core TH.TySynEqnQ)
    repTySynEqn (MkC lhs) (MkC rhs)
      = rep2 tySynEqnName [lhs, rhs]

    repRoleAnnotD :: Core TH.Name -> Core [TH.Role] -> DsM (Core TH.DecQ)
    repRoleAnnotD (MkC n) (MkC roles) = rep2 roleAnnotDName [n, roles]

    repFunDep :: Core [TH.Name] -> Core [TH.Name] -> DsM (Core TH.FunDep)
    repFunDep (MkC xs) (MkC ys) = rep2 funDepName [xs, ys]

    repProto :: Name -> Core TH.Name -> Core TH.TypeQ -> DsM (Core TH.DecQ)
    repProto mk_sig (MkC s) (MkC ty) = rep2 mk_sig [s, ty]

    repCtxt :: Core [TH.PredQ] -> DsM (Core TH.CxtQ)
    repCtxt (MkC tys) = rep2 cxtName [tys]

    repDataCon :: Located Name
               -> HsConDeclDetails Name
               -> DsM (Core TH.ConQ)
    repDataCon con details
        = do con' <- lookupLOcc con -- See Note [Binders and occurrences]
             repConstr details Nothing [con']

    repGadtDataCons :: [Located Name]
                    -> HsConDeclDetails Name
                    -> LHsType Name
                    -> DsM (Core TH.ConQ)
    repGadtDataCons cons details res_ty
        = do cons' <- mapM lookupLOcc cons -- See Note [Binders and occurrences]
             repConstr details (Just res_ty) cons'

    -- Invariant:
    --   * for plain H98 data constructors second argument is Nothing and third
    --     argument is a singleton list
    --   * for GADTs data constructors second argument is (Just return_type) and
    --     third argument is a non-empty list
    repConstr :: HsConDeclDetails Name
              -> Maybe (LHsType Name)
              -> [Core TH.Name]
              -> DsM (Core TH.ConQ)
    repConstr (PrefixCon ps) Nothing [con]
        = do arg_tys  <- repList bangTypeQTyConName repBangTy ps
             rep2 normalCName [unC con, unC arg_tys]

    repConstr (PrefixCon ps) (Just (L _ res_ty)) cons
        = do arg_tys     <- repList bangTypeQTyConName repBangTy ps
             res_ty' <- repTy res_ty
             rep2 gadtCName [ unC (nonEmptyCoreList cons), unC arg_tys, unC res_ty']

    repConstr (RecCon (L _ ips)) resTy cons
        = do args     <- concatMapM rep_ip ips
             arg_vtys <- coreList varBangTypeQTyConName args
             case resTy of
               Nothing -> rep2 recCName [unC (head cons), unC arg_vtys]
               Just (L _ res_ty) -> do
                 res_ty' <- repTy res_ty
                 rep2 recGadtCName [unC (nonEmptyCoreList cons), unC arg_vtys,
                                    unC res_ty']

        where
          rep_ip (L _ ip) = mapM (rep_one_ip (cd_fld_type ip)) (cd_fld_names ip)

          rep_one_ip :: LBangType Name -> LFieldOcc Name -> DsM (Core a)
          rep_one_ip t n = do { MkC v  <- lookupOcc (selectorFieldOcc $ unLoc n)
                              ; MkC ty <- repBangTy  t
                              ; rep2 varBangTypeName [v,ty] }

    repConstr (InfixCon st1 st2) Nothing [con]
        = do arg1 <- repBangTy st1
             arg2 <- repBangTy st2
             rep2 infixCName [unC arg1, unC con, unC arg2]

    repConstr (InfixCon {}) (Just _) _ =
        panic "repConstr: infix GADT constructor should be in a PrefixCon"
    repConstr _ _ _ =
        panic "repConstr: invariant violated"

    ------------ Types -------------------

    repTForall :: Core [TH.TyVarBndr] -> Core TH.CxtQ -> Core TH.TypeQ
               -> DsM (Core TH.TypeQ)
    repTForall (MkC tvars) (MkC ctxt) (MkC ty)
        = rep2 forallTName [tvars, ctxt, ty]

    repTvar :: Core TH.Name -> DsM (Core TH.TypeQ)
    repTvar (MkC s) = rep2 varTName [s]

    repTapp :: Core TH.TypeQ -> Core TH.TypeQ -> DsM (Core TH.TypeQ)
    repTapp (MkC t1) (MkC t2) = rep2 appTName [t1, t2]

    repTapps :: Core TH.TypeQ -> [Core TH.TypeQ] -> DsM (Core TH.TypeQ)
    repTapps f []     = return f
    repTapps f (t:ts) = do { f1 <- repTapp f t; repTapps f1 ts }

    repTSig :: Core TH.TypeQ -> Core TH.Kind -> DsM (Core TH.TypeQ)
    repTSig (MkC ty) (MkC ki) = rep2 sigTName [ty, ki]

    repTequality :: DsM (Core TH.TypeQ)
    repTequality = rep2 equalityTName []

    repTPromotedList :: [Core TH.TypeQ] -> DsM (Core TH.TypeQ)
    repTPromotedList []     = repPromotedNilTyCon
    repTPromotedList (t:ts) = do  { tcon <- repPromotedConsTyCon
                                  ; f <- repTapp tcon t
                                  ; t' <- repTPromotedList ts
                                  ; repTapp f t'
                                  }

    repTLit :: Core TH.TyLitQ -> DsM (Core TH.TypeQ)
    repTLit (MkC lit) = rep2 litTName [lit]

    repTWildCard :: DsM (Core TH.TypeQ)
    repTWildCard = rep2 wildCardTName []

    --------- Type constructors --------------

    repNamedTyCon :: Core TH.Name -> DsM (Core TH.TypeQ)
    repNamedTyCon (MkC s) = rep2 conTName [s]

    repTupleTyCon :: Int -> DsM (Core TH.TypeQ)
    -- Note: not Core Int; it's easier to be direct here
    repTupleTyCon i = do dflags <- getDynFlags
                         rep2 tupleTName [mkIntExprInt dflags i]

    repUnboxedTupleTyCon :: Int -> DsM (Core TH.TypeQ)
    -- Note: not Core Int; it's easier to be direct here
    repUnboxedTupleTyCon i = do dflags <- getDynFlags
                                rep2 unboxedTupleTName [mkIntExprInt dflags i]

    repUnboxedSumTyCon :: TH.SumArity -> DsM (Core TH.TypeQ)
    -- Note: not Core TH.SumArity; it's easier to be direct here
    repUnboxedSumTyCon arity = do dflags <- getDynFlags
                                  rep2 unboxedSumTName [mkIntExprInt dflags arity]

    repArrowTyCon :: DsM (Core TH.TypeQ)
    repArrowTyCon = rep2 arrowTName []

    repListTyCon :: DsM (Core TH.TypeQ)
    repListTyCon = rep2 listTName []

    repPromotedDataCon :: Core TH.Name -> DsM (Core TH.TypeQ)
    repPromotedDataCon (MkC s) = rep2 promotedTName [s]

    repPromotedTupleTyCon :: Int -> DsM (Core TH.TypeQ)
    repPromotedTupleTyCon i = do dflags <- getDynFlags
                                 rep2 promotedTupleTName [mkIntExprInt dflags i]

    repPromotedNilTyCon :: DsM (Core TH.TypeQ)
    repPromotedNilTyCon = rep2 promotedNilTName []

    repPromotedConsTyCon :: DsM (Core TH.TypeQ)
    repPromotedConsTyCon = rep2 promotedConsTName []

    ------------ Kinds -------------------

    repPlainTV :: Core TH.Name -> DsM (Core TH.TyVarBndr)
    repPlainTV (MkC nm) = rep2 plainTVName [nm]

    repKindedTV :: Core TH.Name -> Core TH.Kind -> DsM (Core TH.TyVarBndr)
    repKindedTV (MkC nm) (MkC ki) = rep2 kindedTVName [nm, ki]

    repKVar :: Core TH.Name -> DsM (Core TH.Kind)
    repKVar (MkC s) = rep2 varKName [s]

    repKCon :: Core TH.Name -> DsM (Core TH.Kind)
    repKCon (MkC s) = rep2 conKName [s]

    repKTuple :: Int -> DsM (Core TH.Kind)
    repKTuple i = do dflags <- getDynFlags
                     rep2 tupleKName [mkIntExprInt dflags i]

    repKArrow :: DsM (Core TH.Kind)
    repKArrow = rep2 arrowKName []

    repKList :: DsM (Core TH.Kind)
    repKList = rep2 listKName []

    repKApp :: Core TH.Kind -> Core TH.Kind -> DsM (Core TH.Kind)
    repKApp (MkC k1) (MkC k2) = rep2 appKName [k1, k2]

    repKApps :: Core TH.Kind -> [Core TH.Kind] -> DsM (Core TH.Kind)
    repKApps f []     = return f
    repKApps f (k:ks) = do { f' <- repKApp f k; repKApps f' ks }

    repKStar :: DsM (Core TH.Kind)
    repKStar = rep2 starKName []

    repKConstraint :: DsM (Core TH.Kind)
    repKConstraint = rep2 constraintKName []

    ----------------------------------------------------------
    --       Type family result signature

    repNoSig :: DsM (Core TH.FamilyResultSig)
    repNoSig = rep2 noSigName []

    repKindSig :: Core TH.Kind -> DsM (Core TH.FamilyResultSig)
    repKindSig (MkC ki) = rep2 kindSigName [ki]

    repTyVarSig :: Core TH.TyVarBndr -> DsM (Core TH.FamilyResultSig)
    repTyVarSig (MkC bndr) = rep2 tyVarSigName [bndr]

    ----------------------------------------------------------
    --              Literals

    repLiteral :: HsLit -> DsM (Core TH.Lit)
    repLiteral (HsStringPrim _ bs)
      = do dflags   <- getDynFlags
           word8_ty <- lookupType word8TyConName
           let w8s = unpack bs
               w8s_expr = map (\w8 -> mkCoreConApps word8DataCon
                                      [mkWordLit dflags (toInteger w8)]) w8s
           rep2 stringPrimLName [mkListExpr word8_ty w8s_expr]
    repLiteral lit
      = do lit' <- case lit of
                       HsIntPrim _ i    -> mk_integer i
                       HsWordPrim _ w   -> mk_integer w
                       HsInt _ i        -> mk_integer i
                       HsFloatPrim r    -> mk_rational r
                       HsDoublePrim r   -> mk_rational r
                       HsCharPrim _ c   -> mk_char c
                       _ -> return lit
           lit_expr <- dsLit lit'
           case mb_lit_name of
              Just lit_name -> rep2 lit_name [lit_expr]
              Nothing -> notHandled "Exotic literal" (ppr lit)
      where
        mb_lit_name = case lit of
                     HsInteger _ _ _  -> Just integerLName
                     HsInt     _ _    -> Just integerLName
                     HsIntPrim _ _    -> Just intPrimLName
                     HsWordPrim _ _   -> Just wordPrimLName
                     HsFloatPrim _    -> Just floatPrimLName
                     HsDoublePrim _   -> Just doublePrimLName
                     HsChar _ _       -> Just charLName
                     HsCharPrim _ _   -> Just charPrimLName
                     HsString _ _     -> Just stringLName
                     HsRat _ _        -> Just rationalLName
                     _                -> Nothing

    mk_integer :: Integer -> DsM HsLit
    mk_integer  i = do integer_ty <- lookupType integerTyConName
                       return $ HsInteger NoSourceText i integer_ty
    mk_rational :: FractionalLit -> DsM HsLit
    mk_rational r = do rat_ty <- lookupType rationalTyConName
                       return $ HsRat r rat_ty
    mk_string :: FastString -> DsM HsLit
    mk_string s = return $ HsString NoSourceText s

    mk_char :: Char -> DsM HsLit
    mk_char c = return $ HsChar NoSourceText c

    repOverloadedLiteral :: HsOverLit Name -> DsM (Core TH.Lit)
    repOverloadedLiteral (OverLit { ol_val = val})
      = do { lit <- mk_lit val; repLiteral lit }
            -- The type Rational will be in the environment, because
            -- the smart constructor 'TH.Syntax.rationalL' uses it in its type,
            -- and rationalL is sucked in when any TH stuff is used

    mk_lit :: OverLitVal -> DsM HsLit
    mk_lit (HsIntegral _ i)   = mk_integer  i
    mk_lit (HsFractional f)   = mk_rational f
    mk_lit (HsIsString _ s)   = mk_string   s

    repNameS :: Core String -> DsM (Core TH.Name)
    repNameS (MkC name) = rep2 mkNameSName [name]

    --------------- Miscellaneous -------------------

    repGensym :: Core String -> DsM (Core (TH.Q TH.Name))
    repGensym (MkC lit_str) = rep2 newNameName [lit_str]

    repBindQ :: Type -> Type        -- a and b
             -> Core (TH.Q a) -> Core (a -> TH.Q b) -> DsM (Core (TH.Q b))
    repBindQ ty_a ty_b (MkC x) (MkC y)
      = rep2 bindQName [Type ty_a, Type ty_b, x, y]

    repSequenceQ :: Type -> Core [TH.Q a] -> DsM (Core (TH.Q [a]))
    repSequenceQ ty_a (MkC list)
      = rep2 sequenceQName [Type ty_a, list]

    repUnboundVar :: Core TH.Name -> DsM (Core TH.ExpQ)
    repUnboundVar (MkC name) = rep2 unboundVarEName [name]

    ------------ Lists -------------------
    -- turn a list of patterns into a single pattern matching a list

    repList :: Name -> (a  -> DsM (Core b))
                    -> [a] -> DsM (Core [b])
    repList tc_name f args
      = do { args1 <- mapM f args
           ; coreList tc_name args1 }

    coreList :: Name        -- Of the TyCon of the element type
             -> [Core a] -> DsM (Core [a])
    coreList tc_name es
      = do { elt_ty <- lookupType tc_name; return (coreList' elt_ty es) }

    coreList' :: Type       -- The element type
              -> [Core a] -> Core [a]
    coreList' elt_ty es = MkC (mkListExpr elt_ty (map unC es ))

    nonEmptyCoreList :: [Core a] -> Core [a]
      -- The list must be non-empty so we can get the element type
      -- Otherwise use coreList
    nonEmptyCoreList []           = panic "coreList: empty argument"
    nonEmptyCoreList xs@(MkC x:_) = MkC (mkListExpr (exprType x) (map unC xs))

    coreStringLit :: String -> DsM (Core String)
    coreStringLit s = do { z <- mkStringExpr s; return(MkC z) }

    ------------------- Maybe ------------------

    -- | Construct Core expression for Nothing of a given type name
    coreNothing :: Name        -- ^ Name of the TyCon of the element type
                -> DsM (Core (Maybe a))
    coreNothing tc_name =
        do { elt_ty <- lookupType tc_name; return (coreNothing' elt_ty) }

    -- | Construct Core expression for Nothing of a given type
    coreNothing' :: Type       -- ^ The element type
                 -> Core (Maybe a)
    coreNothing' elt_ty = MkC (mkNothingExpr elt_ty)

    -- | Store given Core expression in a Just of a given type name
    coreJust :: Name        -- ^ Name of the TyCon of the element type
             -> Core a -> DsM (Core (Maybe a))
    coreJust tc_name es
      = do { elt_ty <- lookupType tc_name; return (coreJust' elt_ty es) }

    -- | Store given Core expression in a Just of a given type
    coreJust' :: Type       -- ^ The element type
              -> Core a -> Core (Maybe a)
    coreJust' elt_ty es = MkC (mkJustExpr elt_ty (unC es))

    ------------ Literals & Variables -------------------

    coreIntLit :: Int -> DsM (Core Int)
    coreIntLit i = do dflags <- getDynFlags
                      return (MkC (mkIntExprInt dflags i))

    coreVar :: Id -> Core TH.Name   -- The Id has type Name
    coreVar id = MkC (Var id)

    ----------------- Failure -----------------------
    notHandledL :: SrcSpan -> String -> SDoc -> DsM a
    notHandledL loc what doc
      | isGoodSrcSpan loc
      = putSrcSpanDs loc $ notHandled what doc
      | otherwise
      = notHandled what doc

    notHandled :: String -> SDoc -> DsM a
    notHandled what doc = failWithDs msg
      where
        msg = hang (text what <+> text "not (yet) handled by Template Haskell")
                 2 doc