2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[TcSplice]{Template Haskell splices}
7 module TcSplice( tcSpliceExpr, tcSpliceDecls, tcBracket ) where
9 #include "HsVersions.h"
11 import HscMain ( compileExpr )
12 import TcRnDriver ( tcTopSrcDecls )
13 -- These imports are the reason that TcSplice
14 -- is very high up the module hierarchy
16 import qualified Language.Haskell.TH as TH
17 -- THSyntax gives access to internal functions and data types
18 import qualified Language.Haskell.TH.Syntax as TH
20 import HsSyn ( HsBracket(..), HsExpr(..), HsSplice(..), LHsExpr, LHsDecl,
22 import Convert ( convertToHsExpr, convertToHsDecls, convertToHsType, thRdrName )
23 import RnExpr ( rnLExpr )
24 import RnEnv ( lookupFixityRn, lookupSrcOcc_maybe, lookupImportedName )
25 import RdrName ( RdrName, lookupLocalRdrEnv, isSrcRdrName )
26 import RnTypes ( rnLHsType )
27 import TcExpr ( tcMonoExpr )
28 import TcHsSyn ( mkHsDictLet, zonkTopLExpr )
29 import TcSimplify ( tcSimplifyTop, tcSimplifyBracket )
30 import TcUnify ( boxyUnify, unBox )
31 import TcType ( TcType, TcKind, BoxyRhoType, liftedTypeKind, mkAppTy, tcSplitSigmaTy )
32 import TcEnv ( spliceOK, tcMetaTy, bracketOK )
33 import TcMType ( newFlexiTyVarTy, newKindVar, UserTypeCtxt(ExprSigCtxt), zonkTcType )
34 import TcHsType ( tcHsSigType, kcHsType )
35 import TcIface ( tcImportDecl )
36 import TypeRep ( Type(..), PredType(..), TyThing(..) ) -- For reification
37 import PrelNames ( thFAKE )
38 import Name ( Name, NamedThing(..), nameOccName, nameModule, isExternalName,
40 import NameEnv ( lookupNameEnv )
41 import HscTypes ( lookupType, ExternalPackageState(..), emptyModDetails )
43 import Var ( Id, TyVar, idType )
44 import Module ( moduleString )
46 import IfaceEnv ( lookupOrig )
47 import Class ( Class, classExtraBigSig )
48 import TyCon ( TyCon, tyConTyVars, synTyConDefn,
49 isSynTyCon, isNewTyCon, tyConDataCons, isPrimTyCon, isFunTyCon,
50 tyConArity, tyConStupidTheta, isUnLiftedTyCon )
51 import DataCon ( DataCon, dataConTyCon, dataConOrigArgTys, dataConStrictMarks,
52 dataConName, dataConFieldLabels, dataConWrapId, dataConIsInfix,
54 import Id ( idName, globalIdDetails )
55 import IdInfo ( GlobalIdDetails(..) )
56 import TysWiredIn ( mkListTy )
57 import DsMeta ( expQTyConName, typeQTyConName, decTyConName, qTyConName, nameTyConName )
58 import ErrUtils ( Message )
59 import SrcLoc ( SrcSpan, noLoc, unLoc, getLoc )
61 import Unique ( Unique, Uniquable(..), getKey, mkUniqueGrimily )
63 import BasicTypes ( StrictnessMark(..), Fixity(..), FixityDirection(..) )
64 import Panic ( showException )
65 import FastString ( LitString )
67 import GHC.Base ( unsafeCoerce#, Int#, Int(..) ) -- Should have a better home in the module hierarchy
68 import Monad ( liftM )
71 import FastString ( mkFastString )
76 %************************************************************************
78 \subsection{Main interface + stubs for the non-GHCI case
80 %************************************************************************
83 tcSpliceDecls :: LHsExpr Name -> TcM [LHsDecl RdrName]
84 tcSpliceExpr :: HsSplice Name -> BoxyRhoType -> TcM (HsExpr TcId)
85 kcSpliceType :: HsSplice Name -> TcM (HsType Name, TcKind)
88 tcSpliceExpr n e ty = pprPanic "Cant do tcSpliceExpr without GHCi" (ppr e)
89 tcSpliceDecls e = pprPanic "Cant do tcSpliceDecls without GHCi" (ppr e)
93 %************************************************************************
95 \subsection{Quoting an expression}
97 %************************************************************************
100 tcBracket :: HsBracket Name -> BoxyRhoType -> TcM (LHsExpr Id)
101 tcBracket brack res_ty
102 = getStage `thenM` \ level ->
103 case bracketOK level of {
104 Nothing -> failWithTc (illegalBracket level) ;
107 -- Typecheck expr to make sure it is valid,
108 -- but throw away the results. We'll type check
109 -- it again when we actually use it.
111 newMutVar [] `thenM` \ pending_splices ->
112 getLIEVar `thenM` \ lie_var ->
114 setStage (Brack next_level pending_splices lie_var) (
115 getLIE (tc_bracket brack)
116 ) `thenM` \ (meta_ty, lie) ->
117 tcSimplifyBracket lie `thenM_`
119 -- Make the expected type have the right shape
120 boxyUnify meta_ty res_ty `thenM_`
122 -- Return the original expression, not the type-decorated one
123 readMutVar pending_splices `thenM` \ pendings ->
124 returnM (noLoc (HsBracketOut brack pendings))
127 tc_bracket :: HsBracket Name -> TcM TcType
129 = tcMetaTy nameTyConName -- Result type is Var (not Q-monadic)
131 tc_bracket (ExpBr expr)
132 = newFlexiTyVarTy liftedTypeKind `thenM` \ any_ty ->
133 tcMonoExpr expr any_ty `thenM_`
134 tcMetaTy expQTyConName
135 -- Result type is Expr (= Q Exp)
137 tc_bracket (TypBr typ)
138 = tcHsSigType ExprSigCtxt typ `thenM_`
139 tcMetaTy typeQTyConName
140 -- Result type is Type (= Q Typ)
142 tc_bracket (DecBr decls)
143 = do { tcTopSrcDecls emptyModDetails decls
144 -- Typecheck the declarations, dicarding the result
145 -- We'll get all that stuff later, when we splice it in
147 ; decl_ty <- tcMetaTy decTyConName
148 ; q_ty <- tcMetaTy qTyConName
149 ; return (mkAppTy q_ty (mkListTy decl_ty))
150 -- Result type is Q [Dec]
154 = failWithTc (ptext SLIT("Tempate Haskell pattern brackets are not supported yet"))
158 %************************************************************************
160 \subsection{Splicing an expression}
162 %************************************************************************
165 tcSpliceExpr (HsSplice name expr) res_ty
166 = setSrcSpan (getLoc expr) $
167 getStage `thenM` \ level ->
168 case spliceOK level of {
169 Nothing -> failWithTc (illegalSplice level) ;
173 Comp -> do { e <- tcTopSplice expr res_ty
174 ; returnM (unLoc e) } ;
175 Brack _ ps_var lie_var ->
177 -- A splice inside brackets
178 -- NB: ignore res_ty, apart from zapping it to a mono-type
179 -- e.g. [| reverse $(h 4) |]
180 -- Here (h 4) :: Q Exp
181 -- but $(h 4) :: forall a.a i.e. anything!
183 unBox res_ty `thenM_`
184 tcMetaTy expQTyConName `thenM` \ meta_exp_ty ->
185 setStage (Splice next_level) (
187 tcMonoExpr expr meta_exp_ty
190 -- Write the pending splice into the bucket
191 readMutVar ps_var `thenM` \ ps ->
192 writeMutVar ps_var ((name,expr') : ps) `thenM_`
194 returnM (panic "tcSpliceExpr") -- The returned expression is ignored
197 -- tcTopSplice used to have this:
198 -- Note that we do not decrement the level (to -1) before
199 -- typechecking the expression. For example:
200 -- f x = $( ...$(g 3) ... )
201 -- The recursive call to tcMonoExpr will simply expand the
202 -- inner escape before dealing with the outer one
204 tcTopSplice :: LHsExpr Name -> BoxyRhoType -> TcM (LHsExpr Id)
205 tcTopSplice expr res_ty
206 = tcMetaTy expQTyConName `thenM` \ meta_exp_ty ->
208 -- Typecheck the expression
209 tcTopSpliceExpr expr meta_exp_ty `thenM` \ zonked_q_expr ->
211 -- Run the expression
212 traceTc (text "About to run" <+> ppr zonked_q_expr) `thenM_`
213 runMetaE convertToHsExpr zonked_q_expr `thenM` \ expr2 ->
215 traceTc (text "Got result" <+> ppr expr2) `thenM_`
217 showSplice "expression"
218 zonked_q_expr (ppr expr2) `thenM_`
220 -- Rename it, but bale out if there are errors
221 -- otherwise the type checker just gives more spurious errors
222 checkNoErrs (rnLExpr expr2) `thenM` \ (exp3, fvs) ->
224 tcMonoExpr exp3 res_ty
227 tcTopSpliceExpr :: LHsExpr Name -> TcType -> TcM (LHsExpr Id)
228 -- Type check an expression that is the body of a top-level splice
229 -- (the caller will compile and run it)
230 tcTopSpliceExpr expr meta_ty
231 = checkNoErrs $ -- checkNoErrs: must not try to run the thing
232 -- if the type checker fails!
234 setStage topSpliceStage $ do
237 do { recordThUse -- Record that TH is used (for pkg depdendency)
239 -- Typecheck the expression
240 ; (expr', lie) <- getLIE (tcMonoExpr expr meta_ty)
242 -- Solve the constraints
243 ; const_binds <- tcSimplifyTop lie
246 ; zonkTopLExpr (mkHsDictLet const_binds expr') }
250 %************************************************************************
254 %************************************************************************
256 Very like splicing an expression, but we don't yet share code.
259 kcSpliceType (HsSplice name hs_expr)
260 = setSrcSpan (getLoc hs_expr) $ do
262 ; case spliceOK level of {
263 Nothing -> failWithTc (illegalSplice level) ;
264 Just next_level -> do
267 Comp -> do { (t,k) <- kcTopSpliceType hs_expr
268 ; return (unLoc t, k) } ;
269 Brack _ ps_var lie_var -> do
271 { -- A splice inside brackets
272 ; meta_ty <- tcMetaTy typeQTyConName
273 ; expr' <- setStage (Splice next_level) $
275 tcMonoExpr hs_expr meta_ty
277 -- Write the pending splice into the bucket
278 ; ps <- readMutVar ps_var
279 ; writeMutVar ps_var ((name,expr') : ps)
281 -- e.g. [| Int -> $(h 4) |]
282 -- Here (h 4) :: Q Type
283 -- but $(h 4) :: forall a.a i.e. any kind
285 ; returnM (panic "kcSpliceType", kind) -- The returned type is ignored
288 kcTopSpliceType :: LHsExpr Name -> TcM (LHsType Name, TcKind)
290 = do { meta_ty <- tcMetaTy typeQTyConName
292 -- Typecheck the expression
293 ; zonked_q_expr <- tcTopSpliceExpr expr meta_ty
295 -- Run the expression
296 ; traceTc (text "About to run" <+> ppr zonked_q_expr)
297 ; hs_ty2 <- runMetaT convertToHsType zonked_q_expr
299 ; traceTc (text "Got result" <+> ppr hs_ty2)
301 ; showSplice "type" zonked_q_expr (ppr hs_ty2)
303 -- Rename it, but bale out if there are errors
304 -- otherwise the type checker just gives more spurious errors
305 ; let doc = ptext SLIT("In the spliced type") <+> ppr hs_ty2
306 ; hs_ty3 <- checkNoErrs (rnLHsType doc hs_ty2)
311 %************************************************************************
313 \subsection{Splicing an expression}
315 %************************************************************************
318 -- Always at top level
319 -- Type sig at top of file:
320 -- tcSpliceDecls :: LHsExpr Name -> TcM [LHsDecl RdrName]
322 = do { meta_dec_ty <- tcMetaTy decTyConName
323 ; meta_q_ty <- tcMetaTy qTyConName
324 ; let list_q = mkAppTy meta_q_ty (mkListTy meta_dec_ty)
325 ; zonked_q_expr <- tcTopSpliceExpr expr list_q
327 -- Run the expression
328 ; traceTc (text "About to run" <+> ppr zonked_q_expr)
329 ; decls <- runMetaD convertToHsDecls zonked_q_expr
331 ; traceTc (text "Got result" <+> vcat (map ppr decls))
332 ; showSplice "declarations"
334 (ppr (getLoc expr) $$ (vcat (map ppr decls)))
337 where handleErrors :: [Either a Message] -> TcM [a]
338 handleErrors [] = return []
339 handleErrors (Left x:xs) = liftM (x:) (handleErrors xs)
340 handleErrors (Right m:xs) = do addErrTc m
345 %************************************************************************
347 \subsection{Running an expression}
349 %************************************************************************
352 runMetaE :: (SrcSpan -> TH.Exp -> Either Message (LHsExpr RdrName))
353 -> LHsExpr Id -- Of type (Q Exp)
354 -> TcM (LHsExpr RdrName)
357 runMetaT :: (SrcSpan -> TH.Type -> Either Message (LHsType RdrName))
358 -> LHsExpr Id -- Of type (Q Type)
359 -> TcM (LHsType RdrName)
362 runMetaD :: (SrcSpan -> [TH.Dec] -> Either Message [LHsDecl RdrName])
363 -> LHsExpr Id -- Of type Q [Dec]
364 -> TcM [LHsDecl RdrName]
367 runMeta :: (SrcSpan -> th_syn -> Either Message hs_syn)
368 -> LHsExpr Id -- Of type X
369 -> TcM hs_syn -- Of type t
371 = do { hsc_env <- getTopEnv
372 ; tcg_env <- getGblEnv
373 ; this_mod <- getModule
374 ; let type_env = tcg_type_env tcg_env
375 rdr_env = tcg_rdr_env tcg_env
377 -- Compile and link it; might fail if linking fails
378 ; either_hval <- tryM $ ioToTcRn $
381 rdr_env type_env expr
382 ; case either_hval of {
383 Left exn -> failWithTc (mk_msg "compile and link" exn) ;
386 { -- Coerce it to Q t, and run it
387 -- Running might fail if it throws an exception of any kind (hence tryAllM)
388 -- including, say, a pattern-match exception in the code we are running
390 -- We also do the TH -> HS syntax conversion inside the same
391 -- exception-cacthing thing so that if there are any lurking
392 -- exceptions in the data structure returned by hval, we'll
393 -- encounter them inside the try
394 either_tval <- tryAllM $ do
395 { th_syn <- TH.runQ (unsafeCoerce# hval)
396 ; case convert (getLoc expr) th_syn of
397 Left err -> do { addErrTc err; return Nothing }
398 Right hs_syn -> return (Just hs_syn) }
400 ; case either_tval of
401 Right (Just v) -> return v
402 Right Nothing -> failM -- Error already in Tc monad
403 Left exn -> failWithTc (mk_msg "run" exn) -- Exception
406 mk_msg s exn = vcat [text "Exception when trying to" <+> text s <+> text "compile-time code:",
407 nest 2 (text (Panic.showException exn)),
408 nest 2 (text "Code:" <+> ppr expr)]
411 To call runQ in the Tc monad, we need to make TcM an instance of Quasi:
414 instance TH.Quasi (IOEnv (Env TcGblEnv TcLclEnv)) where
415 qNewName s = do { u <- newUnique
417 ; return (TH.mkNameU s i) }
419 qReport True msg = addErr (text msg)
420 qReport False msg = addReport (text msg)
422 qCurrentModule = do { m <- getModule; return (moduleString m) }
425 -- For qRecover, discard error messages if
426 -- the recovery action is chosen. Otherwise
427 -- we'll only fail higher up. c.f. tryTcLIE_
428 qRecover recover main = do { (msgs, mb_res) <- tryTcErrs main
430 Just val -> do { addMessages msgs -- There might be warnings
432 Nothing -> recover -- Discard all msgs
435 qRunIO io = ioToTcRn io
439 %************************************************************************
441 \subsection{Errors and contexts}
443 %************************************************************************
446 showSplice :: String -> LHsExpr Id -> SDoc -> TcM ()
447 showSplice what before after
448 = getSrcSpanM `thenM` \ loc ->
449 traceSplice (vcat [ppr loc <> colon <+> text "Splicing" <+> text what,
450 nest 2 (sep [nest 2 (ppr before),
455 = ptext SLIT("Illegal bracket at level") <+> ppr level
458 = ptext SLIT("Illegal splice at level") <+> ppr level
464 %************************************************************************
468 %************************************************************************
472 reify :: TH.Name -> TcM TH.Info
474 = do { name <- lookupThName th_name
475 ; thing <- tcLookupTh name
476 -- ToDo: this tcLookup could fail, which would give a
477 -- rather unhelpful error message
478 ; traceIf (text "reify" <+> text (show th_name) <+> brackets (ppr_ns th_name) <+> ppr name)
482 ppr_ns (TH.Name _ (TH.NameG TH.DataName mod)) = text "data"
483 ppr_ns (TH.Name _ (TH.NameG TH.TcClsName mod)) = text "tc"
484 ppr_ns (TH.Name _ (TH.NameG TH.VarName mod)) = text "var"
486 lookupThName :: TH.Name -> TcM Name
487 lookupThName th_name@(TH.Name occ flavour)
488 = do { let rdr_name = thRdrName guessed_ns occ_str flavour
490 -- Repeat much of lookupOccRn, becase we want
491 -- to report errors in a TH-relevant way
492 ; rdr_env <- getLocalRdrEnv
493 ; case lookupLocalRdrEnv rdr_env rdr_name of
494 Just name -> return name
495 Nothing | not (isSrcRdrName rdr_name) -- Exact, Orig
496 -> lookupImportedName rdr_name
497 | otherwise -- Unqual, Qual
499 mb_name <- lookupSrcOcc_maybe rdr_name
501 Just name -> return name
502 Nothing -> failWithTc (notInScope th_name) }
505 -- guessed_ns is the name space guessed from looking at the TH name
506 guessed_ns | isLexCon (mkFastString occ_str) = OccName.dataName
507 | otherwise = OccName.varName
508 occ_str = TH.occString occ
510 tcLookupTh :: Name -> TcM TcTyThing
511 -- This is a specialised version of TcEnv.tcLookup; specialised mainly in that
512 -- it gives a reify-related error message on failure, whereas in the normal
513 -- tcLookup, failure is a bug.
515 = do { (gbl_env, lcl_env) <- getEnvs
516 ; case lookupNameEnv (tcl_env lcl_env) name of {
517 Just thing -> returnM thing;
519 { if nameIsLocalOrFrom (tcg_mod gbl_env) name
520 then -- It's defined in this module
521 case lookupNameEnv (tcg_type_env gbl_env) name of
522 Just thing -> return (AGlobal thing)
523 Nothing -> failWithTc (notInEnv name)
525 else do -- It's imported
526 { (eps,hpt) <- getEpsAndHpt
527 ; case lookupType hpt (eps_PTE eps) name of
528 Just thing -> return (AGlobal thing)
529 Nothing -> do { thing <- tcImportDecl name
530 ; return (AGlobal thing) }
531 -- Imported names should always be findable;
532 -- if not, we fail hard in tcImportDecl
535 notInScope :: TH.Name -> SDoc
536 notInScope th_name = quotes (text (TH.pprint th_name)) <+>
537 ptext SLIT("is not in scope at a reify")
538 -- Ugh! Rather an indirect way to display the name
540 notInEnv :: Name -> SDoc
541 notInEnv name = quotes (ppr name) <+>
542 ptext SLIT("is not in the type environment at a reify")
544 ------------------------------
545 reifyThing :: TcTyThing -> TcM TH.Info
546 -- The only reason this is monadic is for error reporting,
547 -- which in turn is mainly for the case when TH can't express
548 -- some random GHC extension
550 reifyThing (AGlobal (AnId id))
551 = do { ty <- reifyType (idType id)
552 ; fix <- reifyFixity (idName id)
553 ; let v = reifyName id
554 ; case globalIdDetails id of
555 ClassOpId cls -> return (TH.ClassOpI v ty (reifyName cls) fix)
556 other -> return (TH.VarI v ty Nothing fix)
559 reifyThing (AGlobal (ATyCon tc)) = reifyTyCon tc
560 reifyThing (AGlobal (AClass cls)) = reifyClass cls
561 reifyThing (AGlobal (ADataCon dc))
562 = do { let name = dataConName dc
563 ; ty <- reifyType (idType (dataConWrapId dc))
564 ; fix <- reifyFixity name
565 ; return (TH.DataConI (reifyName name) ty (reifyName (dataConTyCon dc)) fix) }
567 reifyThing (ATcId id _ _)
568 = do { ty1 <- zonkTcType (idType id) -- Make use of all the info we have, even
569 -- though it may be incomplete
570 ; ty2 <- reifyType ty1
571 ; fix <- reifyFixity (idName id)
572 ; return (TH.VarI (reifyName id) ty2 Nothing fix) }
574 reifyThing (ATyVar tv ty)
575 = do { ty1 <- zonkTcType ty
576 ; ty2 <- reifyType ty1
577 ; return (TH.TyVarI (reifyName tv) ty2) }
579 ------------------------------
580 reifyTyCon :: TyCon -> TcM TH.Info
582 | isFunTyCon tc = return (TH.PrimTyConI (reifyName tc) 2 False)
583 | isPrimTyCon tc = return (TH.PrimTyConI (reifyName tc) (tyConArity tc) (isUnLiftedTyCon tc))
585 = do { let (tvs, rhs) = synTyConDefn tc
586 ; rhs' <- reifyType rhs
587 ; return (TH.TyConI $ TH.TySynD (reifyName tc) (reifyTyVars tvs) rhs') }
590 = do { cxt <- reifyCxt (tyConStupidTheta tc)
591 ; cons <- mapM reifyDataCon (tyConDataCons tc)
592 ; let name = reifyName tc
593 tvs = reifyTyVars (tyConTyVars tc)
594 deriv = [] -- Don't know about deriving
595 decl | isNewTyCon tc = TH.NewtypeD cxt name tvs (head cons) deriv
596 | otherwise = TH.DataD cxt name tvs cons deriv
597 ; return (TH.TyConI decl) }
599 reifyDataCon :: DataCon -> TcM TH.Con
601 | isVanillaDataCon dc
602 = do { arg_tys <- reifyTypes (dataConOrigArgTys dc)
603 ; let stricts = map reifyStrict (dataConStrictMarks dc)
604 fields = dataConFieldLabels dc
608 ; ASSERT( length arg_tys == length stricts )
609 if not (null fields) then
610 return (TH.RecC name (zip3 (map reifyName fields) stricts arg_tys))
612 if dataConIsInfix dc then
613 ASSERT( length arg_tys == 2 )
614 return (TH.InfixC (s1,a1) name (s2,a2))
616 return (TH.NormalC name (stricts `zip` arg_tys)) }
618 = failWithTc (ptext SLIT("Can't reify a non-Haskell-98 data constructor:")
621 ------------------------------
622 reifyClass :: Class -> TcM TH.Info
624 = do { cxt <- reifyCxt theta
625 ; ops <- mapM reify_op op_stuff
626 ; return (TH.ClassI $ TH.ClassD cxt (reifyName cls) (reifyTyVars tvs) fds' ops) }
628 (tvs, fds, theta, _, op_stuff) = classExtraBigSig cls
629 fds' = map reifyFunDep fds
630 reify_op (op, _) = do { ty <- reifyType (idType op)
631 ; return (TH.SigD (reifyName op) ty) }
633 ------------------------------
634 reifyType :: TypeRep.Type -> TcM TH.Type
635 reifyType (TyVarTy tv) = return (TH.VarT (reifyName tv))
636 reifyType (TyConApp tc tys) = reify_tc_app (reifyName tc) tys
637 reifyType (NoteTy _ ty) = reifyType ty
638 reifyType (AppTy t1 t2) = do { [r1,r2] <- reifyTypes [t1,t2] ; return (r1 `TH.AppT` r2) }
639 reifyType (FunTy t1 t2) = do { [r1,r2] <- reifyTypes [t1,t2] ; return (TH.ArrowT `TH.AppT` r1 `TH.AppT` r2) }
640 reifyType ty@(ForAllTy _ _) = do { cxt' <- reifyCxt cxt;
641 ; tau' <- reifyType tau
642 ; return (TH.ForallT (reifyTyVars tvs) cxt' tau') }
644 (tvs, cxt, tau) = tcSplitSigmaTy ty
645 reifyTypes = mapM reifyType
646 reifyCxt = mapM reifyPred
648 reifyFunDep :: ([TyVar], [TyVar]) -> TH.FunDep
649 reifyFunDep (xs, ys) = TH.FunDep (map reifyName xs) (map reifyName ys)
651 reifyTyVars :: [TyVar] -> [TH.Name]
652 reifyTyVars = map reifyName
654 reify_tc_app :: TH.Name -> [TypeRep.Type] -> TcM TH.Type
655 reify_tc_app tc tys = do { tys' <- reifyTypes tys
656 ; return (foldl TH.AppT (TH.ConT tc) tys') }
658 reifyPred :: TypeRep.PredType -> TcM TH.Type
659 reifyPred (ClassP cls tys) = reify_tc_app (reifyName cls) tys
660 reifyPred p@(IParam _ _) = noTH SLIT("implicit parameters") (ppr p)
663 ------------------------------
664 reifyName :: NamedThing n => n -> TH.Name
666 | isExternalName name = mk_varg mod occ_str
667 | otherwise = TH.mkNameU occ_str (getKey (getUnique name))
668 -- Many of the things we reify have local bindings, and
669 -- NameL's aren't supposed to appear in binding positions, so
670 -- we use NameU. When/if we start to reify nested things, that
671 -- have free variables, we may need to generate NameL's for them.
674 mod = moduleString (nameModule name)
675 occ_str = occNameString occ
676 occ = nameOccName name
677 mk_varg | OccName.isDataOcc occ = TH.mkNameG_d
678 | OccName.isVarOcc occ = TH.mkNameG_v
679 | OccName.isTcOcc occ = TH.mkNameG_tc
680 | otherwise = pprPanic "reifyName" (ppr name)
682 ------------------------------
683 reifyFixity :: Name -> TcM TH.Fixity
685 = do { fix <- lookupFixityRn name
686 ; return (conv_fix fix) }
688 conv_fix (BasicTypes.Fixity i d) = TH.Fixity i (conv_dir d)
689 conv_dir BasicTypes.InfixR = TH.InfixR
690 conv_dir BasicTypes.InfixL = TH.InfixL
691 conv_dir BasicTypes.InfixN = TH.InfixN
693 reifyStrict :: BasicTypes.StrictnessMark -> TH.Strict
694 reifyStrict MarkedStrict = TH.IsStrict
695 reifyStrict MarkedUnboxed = TH.IsStrict
696 reifyStrict NotMarkedStrict = TH.NotStrict
698 ------------------------------
699 noTH :: LitString -> SDoc -> TcM a
700 noTH s d = failWithTc (hsep [ptext SLIT("Can't represent") <+> ptext s <+>
701 ptext SLIT("in Template Haskell:"),