2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
5 \section[TcModule]{Typechecking a whole module}
10 tcRnStmt, tcRnExpr, tcRnType,
22 #include "HsVersions.h"
26 import {-# SOURCE #-} TcSplice ( tcSpliceDecls )
88 import {- Kind parts of -} Type
98 import Control.Monad ( unless )
99 import Data.Maybe ( isJust )
104 %************************************************************************
106 Typecheck and rename a module
108 %************************************************************************
114 -> Bool -- True <=> save renamed syntax
115 -> Located (HsModule RdrName)
116 -> IO (Messages, Maybe TcGblEnv)
118 tcRnModule hsc_env hsc_src save_rn_syntax
119 (L loc (HsModule maybe_mod export_ies
120 import_decls local_decls mod_deprec _
121 module_info maybe_doc))
122 = do { showPass (hsc_dflags hsc_env) "Renamer/typechecker" ;
124 let { this_pkg = thisPackage (hsc_dflags hsc_env) ;
125 this_mod = case maybe_mod of
126 Nothing -> mAIN -- 'module M where' is omitted
127 Just (L _ mod) -> mkModule this_pkg mod } ;
130 initTc hsc_env hsc_src save_rn_syntax this_mod $
132 do { -- Deal with imports;
133 tcg_env <- tcRnImports hsc_env this_mod import_decls ;
134 setGblEnv tcg_env $ do {
136 -- Load the hi-boot interface for this module, if any
137 -- We do this now so that the boot_names can be passed
138 -- to tcTyAndClassDecls, because the boot_names are
139 -- automatically considered to be loop breakers
141 -- Do this *after* tcRnImports, so that we know whether
142 -- a module that we import imports us; and hence whether to
143 -- look for a hi-boot file
144 boot_iface <- tcHiBootIface hsc_src this_mod ;
146 -- Rename and type check the declarations
147 traceRn (text "rn1a") ;
148 tcg_env <- if isHsBoot hsc_src then
149 tcRnHsBootDecls local_decls
151 tcRnSrcDecls boot_iface local_decls ;
152 setGblEnv tcg_env $ do {
154 -- Report the use of any deprecated things
155 -- We do this *before* processsing the export list so
156 -- that we don't bleat about re-exporting a deprecated
157 -- thing (especially via 'module Foo' export item)
158 -- That is, only uses in the *body* of the module are complained about
159 traceRn (text "rn3") ;
160 failIfErrsM ; -- finishDeprecations crashes sometimes
161 -- as a result of typechecker repairs (e.g. unboundNames)
162 tcg_env <- finishDeprecations (hsc_dflags hsc_env) mod_deprec tcg_env ;
164 -- Process the export list
165 tcg_env <- rnExports (isJust maybe_mod) export_ies tcg_env ;
166 traceRn (text "rn4") ;
168 -- Compare the hi-boot iface (if any) with the real thing
169 -- Must be done after processing the exports
170 tcg_env <- checkHiBootIface tcg_env boot_iface ;
172 -- Rename the Haddock documentation
173 tcg_env <- rnHaddock module_info maybe_doc tcg_env ;
175 -- Report unused names
176 reportUnusedNames export_ies tcg_env ;
178 -- Dump output and return
185 %************************************************************************
189 %************************************************************************
192 tcRnImports :: HscEnv -> Module -> [LImportDecl RdrName] -> TcM TcGblEnv
193 tcRnImports hsc_env this_mod import_decls
194 = do { (rn_imports, rdr_env, imports) <- rnImports import_decls ;
196 ; let { dep_mods :: ModuleNameEnv (ModuleName, IsBootInterface)
197 ; dep_mods = imp_dep_mods imports
199 -- We want instance declarations from all home-package
200 -- modules below this one, including boot modules, except
201 -- ourselves. The 'except ourselves' is so that we don't
202 -- get the instances from this module's hs-boot file
203 ; want_instances :: ModuleName -> Bool
204 ; want_instances mod = mod `elemUFM` dep_mods
205 && mod /= moduleName this_mod
206 ; home_insts = hptInstances hsc_env want_instances
209 -- Record boot-file info in the EPS, so that it's
210 -- visible to loadHiBootInterface in tcRnSrcDecls,
211 -- and any other incrementally-performed imports
212 ; updateEps_ (\eps -> eps { eps_is_boot = dep_mods }) ;
214 -- Update the gbl env
215 ; updGblEnv ( \ gbl ->
216 gbl { tcg_rdr_env = plusOccEnv (tcg_rdr_env gbl) rdr_env,
217 tcg_imports = tcg_imports gbl `plusImportAvails` imports,
218 tcg_rn_imports = fmap (const rn_imports) (tcg_rn_imports gbl),
219 tcg_inst_env = extendInstEnvList (tcg_inst_env gbl) home_insts
222 ; traceRn (text "rn1" <+> ppr (imp_dep_mods imports))
223 -- Fail if there are any errors so far
224 -- The error printing (if needed) takes advantage
225 -- of the tcg_env we have now set
226 -- ; traceIf (text "rdr_env: " <+> ppr rdr_env)
229 -- Load any orphan-module and family instance-module
230 -- interfaces, so that their rules and instance decls will be
232 ; loadOrphanModules (imp_orphs imports) False
233 ; loadOrphanModules (imp_finsts imports) True
235 -- Check type-familily consistency
236 ; traceRn (text "rn1: checking family instance consistency")
237 ; let { dir_imp_mods = map (\ (mod, _, _) -> mod)
241 ; checkFamInstConsistency (imp_finsts imports) dir_imp_mods ;
247 %************************************************************************
249 Type-checking external-core modules
251 %************************************************************************
254 tcRnExtCore :: HscEnv
256 -> IO (Messages, Maybe ModGuts)
257 -- Nothing => some error occurred
259 tcRnExtCore hsc_env (HsExtCore this_mod decls src_binds)
260 -- The decls are IfaceDecls; all names are original names
261 = do { showPass (hsc_dflags hsc_env) "Renamer/typechecker" ;
263 initTc hsc_env ExtCoreFile False this_mod $ do {
265 let { ldecls = map noLoc decls } ;
267 -- Deal with the type declarations; first bring their stuff
268 -- into scope, then rname them, then type check them
269 tcg_env <- importsFromLocalDecls (mkFakeGroup ldecls) ;
271 setGblEnv tcg_env $ do {
273 rn_decls <- rnTyClDecls ldecls ;
276 -- Dump trace of renaming part
277 rnDump (ppr rn_decls) ;
279 -- Typecheck them all together so that
280 -- any mutually recursive types are done right
281 tcg_env <- checkNoErrs (tcTyAndClassDecls emptyModDetails rn_decls) ;
282 -- Make the new type env available to stuff slurped from interface files
284 setGblEnv tcg_env $ do {
286 -- Now the core bindings
287 core_binds <- initIfaceExtCore (tcExtCoreBindings src_binds) ;
291 bndrs = bindersOfBinds core_binds ;
292 my_exports = map (Avail . idName) bndrs ;
293 -- ToDo: export the data types also?
295 final_type_env = extendTypeEnvWithIds (tcg_type_env tcg_env) bndrs ;
297 mod_guts = ModGuts { mg_module = this_mod,
299 mg_usages = [], -- ToDo: compute usage
300 mg_dir_imps = [], -- ??
301 mg_deps = noDependencies, -- ??
302 mg_exports = my_exports,
303 mg_types = final_type_env,
304 mg_insts = tcg_insts tcg_env,
305 mg_fam_insts = tcg_fam_insts tcg_env,
306 mg_fam_inst_env = tcg_fam_inst_env tcg_env,
308 mg_binds = core_binds,
311 mg_rdr_env = emptyGlobalRdrEnv,
312 mg_fix_env = emptyFixityEnv,
313 mg_deprecs = NoDeprecs,
314 mg_foreign = NoStubs,
315 mg_hpc_info = noHpcInfo,
316 mg_dbg_sites = noDbgSites
319 tcCoreDump mod_guts ;
324 mkFakeGroup decls -- Rather clumsy; lots of unused fields
325 = emptyRdrGroup { hs_tyclds = decls }
329 %************************************************************************
331 Type-checking the top level of a module
333 %************************************************************************
336 tcRnSrcDecls :: ModDetails -> [LHsDecl RdrName] -> TcM TcGblEnv
337 -- Returns the variables free in the decls
338 -- Reason: solely to report unused imports and bindings
339 tcRnSrcDecls boot_iface decls
340 = do { -- Do all the declarations
341 (tc_envs, lie) <- getLIE $ tc_rn_src_decls boot_iface decls ;
343 -- Finish simplifying class constraints
345 -- tcSimplifyTop deals with constant or ambiguous InstIds.
346 -- How could there be ambiguous ones? They can only arise if a
347 -- top-level decl falls under the monomorphism restriction
348 -- and no subsequent decl instantiates its type.
350 -- We do this after checkMain, so that we use the type info
351 -- thaat checkMain adds
353 -- We do it with both global and local env in scope:
354 -- * the global env exposes the instances to tcSimplifyTop
355 -- * the local env exposes the local Ids to tcSimplifyTop,
356 -- so that we get better error messages (monomorphism restriction)
357 traceTc (text "Tc8") ;
358 inst_binds <- setEnvs tc_envs (tcSimplifyTop lie) ;
360 -- Backsubstitution. This must be done last.
361 -- Even tcSimplifyTop may do some unification.
362 traceTc (text "Tc9") ;
363 let { (tcg_env, _) = tc_envs
364 ; TcGblEnv { tcg_type_env = type_env, tcg_binds = binds,
365 tcg_rules = rules, tcg_fords = fords } = tcg_env
366 ; all_binds = binds `unionBags` inst_binds } ;
368 (bind_ids, binds', fords', rules') <- zonkTopDecls all_binds rules fords ;
370 let { final_type_env = extendTypeEnvWithIds type_env bind_ids
371 ; tcg_env' = tcg_env { tcg_type_env = final_type_env,
374 tcg_fords = fords' } } ;
376 -- Make the new type env available to stuff slurped from interface files
377 writeMutVar (tcg_type_env_var tcg_env) final_type_env ;
379 return (tcg_env' { tcg_binds = tcg_binds tcg_env' })
382 tc_rn_src_decls :: ModDetails -> [LHsDecl RdrName] -> TcM (TcGblEnv, TcLclEnv)
383 -- Loops around dealing with each top level inter-splice group
384 -- in turn, until it's dealt with the entire module
385 tc_rn_src_decls boot_details ds
386 = do { let { (first_group, group_tail) = findSplice ds } ;
387 -- If ds is [] we get ([], Nothing)
389 -- Deal with decls up to, but not including, the first splice
390 (tcg_env, rn_decls) <- checkNoErrs $ rnTopSrcDecls first_group ;
391 -- checkNoErrs: stop if renaming fails
393 (tcg_env, tcl_env) <- setGblEnv tcg_env $
394 tcTopSrcDecls boot_details rn_decls ;
396 -- If there is no splice, we're nearly done
397 setEnvs (tcg_env, tcl_env) $
399 Nothing -> do { tcg_env <- checkMain ; -- Check for `main'
400 return (tcg_env, tcl_env)
403 -- If there's a splice, we must carry on
404 Just (SpliceDecl splice_expr, rest_ds) -> do {
406 failWithTc (text "Can't do a top-level splice; need a bootstrapped compiler")
409 -- Rename the splice expression, and get its supporting decls
410 (rn_splice_expr, splice_fvs) <- checkNoErrs (rnLExpr splice_expr) ;
411 -- checkNoErrs: don't typecheck if renaming failed
412 rnDump (ppr rn_splice_expr) ;
414 -- Execute the splice
415 spliced_decls <- tcSpliceDecls rn_splice_expr ;
417 -- Glue them on the front of the remaining decls and loop
418 setGblEnv (tcg_env `addTcgDUs` usesOnly splice_fvs) $
419 tc_rn_src_decls boot_details (spliced_decls ++ rest_ds)
424 %************************************************************************
426 Compiling hs-boot source files, and
427 comparing the hi-boot interface with the real thing
429 %************************************************************************
432 tcRnHsBootDecls :: [LHsDecl RdrName] -> TcM TcGblEnv
433 tcRnHsBootDecls decls
434 = do { let { (first_group, group_tail) = findSplice decls }
437 Just stuff -> spliceInHsBootErr stuff
440 -- Rename the declarations
441 ; (tcg_env, rn_group) <- rnTopSrcDecls first_group
442 ; setGblEnv tcg_env $ do {
444 -- Todo: check no foreign decls, no rules, no default decls
446 -- Typecheck type/class decls
447 ; traceTc (text "Tc2")
448 ; let tycl_decls = hs_tyclds rn_group
449 ; tcg_env <- checkNoErrs (tcTyAndClassDecls emptyModDetails tycl_decls)
450 ; setGblEnv tcg_env $ do {
452 -- Typecheck instance decls
453 ; traceTc (text "Tc3")
454 ; (tcg_env, inst_infos, _deriv_binds)
455 <- tcInstDecls1 tycl_decls (hs_instds rn_group) (hs_derivds rn_group)
456 ; setGblEnv tcg_env $ do {
458 -- Typecheck value declarations
459 ; traceTc (text "Tc5")
460 ; val_ids <- tcHsBootSigs (hs_valds rn_group)
463 -- No simplification or zonking to do
464 ; traceTc (text "Tc7a")
465 ; gbl_env <- getGblEnv
467 -- Make the final type-env
468 -- Include the dfun_ids so that their type sigs
469 -- are written into the interface file
470 ; let { type_env0 = tcg_type_env gbl_env
471 ; type_env1 = extendTypeEnvWithIds type_env0 val_ids
472 ; type_env2 = extendTypeEnvWithIds type_env1 dfun_ids
473 ; dfun_ids = map iDFunId inst_infos }
474 ; return (gbl_env { tcg_type_env = type_env2 })
477 spliceInHsBootErr (SpliceDecl (L loc _), _)
478 = addErrAt loc (ptext SLIT("Splices are not allowed in hs-boot files"))
481 Once we've typechecked the body of the module, we want to compare what
482 we've found (gathered in a TypeEnv) with the hi-boot details (if any).
485 checkHiBootIface :: TcGblEnv -> ModDetails -> TcM TcGblEnv
486 -- Compare the hi-boot file for this module (if there is one)
487 -- with the type environment we've just come up with
488 -- In the common case where there is no hi-boot file, the list
489 -- of boot_names is empty.
491 -- The bindings we return give bindings for the dfuns defined in the
492 -- hs-boot file, such as $fbEqT = $fEqT
495 tcg_env@(TcGblEnv { tcg_src = hs_src, tcg_binds = binds,
496 tcg_insts = local_insts, tcg_fam_insts = local_fam_insts,
497 tcg_type_env = local_type_env, tcg_exports = local_exports })
498 (ModDetails { md_insts = boot_insts, md_fam_insts = boot_fam_insts,
499 md_types = boot_type_env, md_exports = boot_exports })
500 | isHsBoot hs_src -- Current module is already a hs-boot file!
504 = do { traceTc (text "checkHiBootIface" <+> (ppr boot_type_env $$ ppr boot_insts $$
505 ppr local_export_set $$ ppr boot_exports)) ;
506 ; mapM_ check_export (concatMap availNames boot_exports)
507 ; dfun_binds <- mapM check_inst boot_insts
508 ; unless (null boot_fam_insts) $
509 panic ("TcRnDriver.checkHiBootIface: Cannot handle family " ++
510 "instances in boot files yet...")
511 -- FIXME: Why? The actual comparison is not hard, but what would
512 -- be the equivalent to the dfun bindings returned for class
513 -- instances? We can't easily equate tycons...
514 ; return (tcg_env { tcg_binds = binds `unionBags` unionManyBags dfun_binds }) }
516 check_export name -- Name is exported by the boot iface
517 | name `elem` dfun_names = return ()
518 | isWiredInName name = return () -- No checking for wired-in names. In particular,
519 -- 'error' is handled by a rather gross hack
520 -- (see comments in GHC.Err.hs-boot)
522 -- Check that the actual module exports the same thing
523 | not (name `elemNameSet` local_export_set)
524 = addErrTc (missingBootThing name "exported by")
526 -- If the boot module does not *define* the thing, we are done
527 -- (it simply re-exports it, and names match, so nothing further to do)
528 | isNothing mb_boot_thing = return ()
530 -- Check that the actual module also defines the thing, and
531 -- then compare the definitions
532 | Just real_thing <- lookupTypeEnv local_type_env name
533 = do { let boot_decl = tyThingToIfaceDecl (fromJust mb_boot_thing)
534 real_decl = tyThingToIfaceDecl real_thing
535 ; checkTc (checkBootDecl boot_decl real_decl)
536 (bootMisMatch real_thing boot_decl real_decl) }
537 -- The easiest way to check compatibility is to convert to
538 -- iface syntax, where we already have good comparison functions
541 = addErrTc (missingBootThing name "defined in")
543 mb_boot_thing = lookupTypeEnv boot_type_env name
545 dfun_names = map getName boot_insts
547 local_export_set :: NameSet
548 local_export_set = availsToNameSet local_exports
551 = case [dfun | inst <- local_insts,
552 let dfun = instanceDFunId inst,
553 idType dfun `tcEqType` boot_inst_ty ] of
554 [] -> do { addErrTc (instMisMatch boot_inst); return emptyBag }
555 (dfun:_) -> return (unitBag $ noLoc $ VarBind local_boot_dfun (nlHsVar dfun))
557 boot_dfun = instanceDFunId boot_inst
558 boot_inst_ty = idType boot_dfun
559 local_boot_dfun = Id.mkExportedLocalId (idName boot_dfun) boot_inst_ty
563 missingBootThing thing what
564 = ppr thing <+> ptext SLIT("is exported by the hs-boot file, but not")
565 <+> text what <+> ptext SLIT("the module")
567 bootMisMatch thing boot_decl real_decl
568 = vcat [ppr thing <+> ptext SLIT("has conflicting definitions in the module and its hs-boot file"),
569 ptext SLIT("Main module:") <+> ppr real_decl,
570 ptext SLIT("Boot file: ") <+> ppr boot_decl]
574 2 (ptext SLIT("is defined in the hs-boot file, but not in the module itself"))
578 %************************************************************************
580 Type-checking the top level of a module
582 %************************************************************************
584 tcRnGroup takes a bunch of top-level source-code declarations, and
586 * gets supporting declarations from interface files
589 * and augments the TcGblEnv with the results
591 In Template Haskell it may be called repeatedly for each group of
592 declarations. It expects there to be an incoming TcGblEnv in the
593 monad; it augments it and returns the new TcGblEnv.
596 ------------------------------------------------
597 rnTopSrcDecls :: HsGroup RdrName -> TcM (TcGblEnv, HsGroup Name)
599 = do { -- Bring top level binders into scope
600 tcg_env <- importsFromLocalDecls group ;
601 setGblEnv tcg_env $ do {
603 failIfErrsM ; -- No point in continuing if (say) we have duplicate declarations
605 -- Rename the source decls
606 (tcg_env, rn_decls) <- rnSrcDecls group ;
609 -- save the renamed syntax, if we want it
611 | Just grp <- tcg_rn_decls tcg_env
612 = tcg_env{ tcg_rn_decls = Just (appendGroups grp rn_decls) }
616 -- Dump trace of renaming part
617 rnDump (ppr rn_decls) ;
619 return (tcg_env', rn_decls)
622 ------------------------------------------------
623 tcTopSrcDecls :: ModDetails -> HsGroup Name -> TcM (TcGblEnv, TcLclEnv)
624 tcTopSrcDecls boot_details
625 (HsGroup { hs_tyclds = tycl_decls,
626 hs_instds = inst_decls,
627 hs_derivds = deriv_decls,
628 hs_fords = foreign_decls,
629 hs_defds = default_decls,
630 hs_ruleds = rule_decls,
631 hs_valds = val_binds })
632 = do { -- Type-check the type and class decls, and all imported decls
633 -- The latter come in via tycl_decls
634 traceTc (text "Tc2") ;
636 tcg_env <- checkNoErrs (tcTyAndClassDecls boot_details tycl_decls) ;
637 -- tcTyAndClassDecls recovers internally, but if anything gave rise to
638 -- an error we'd better stop now, to avoid a cascade
640 -- Make these type and class decls available to stuff slurped from interface files
641 writeMutVar (tcg_type_env_var tcg_env) (tcg_type_env tcg_env) ;
644 setGblEnv tcg_env $ do {
645 -- Source-language instances, including derivings,
646 -- and import the supporting declarations
647 traceTc (text "Tc3") ;
648 (tcg_env, inst_infos, deriv_binds)
649 <- tcInstDecls1 tycl_decls inst_decls deriv_decls;
650 setGblEnv tcg_env $ do {
652 -- Foreign import declarations next. No zonking necessary
653 -- here; we can tuck them straight into the global environment.
654 traceTc (text "Tc4") ;
655 (fi_ids, fi_decls) <- tcForeignImports foreign_decls ;
656 tcExtendGlobalValEnv fi_ids $ do {
658 -- Default declarations
659 traceTc (text "Tc4a") ;
660 default_tys <- tcDefaults default_decls ;
661 updGblEnv (\gbl -> gbl { tcg_default = default_tys }) $ do {
663 -- Value declarations next
664 -- We also typecheck any extra binds that came out
665 -- of the "deriving" process (deriv_binds)
666 traceTc (text "Tc5") ;
667 (tc_val_binds, tcl_env) <- tcTopBinds (val_binds `plusHsValBinds` deriv_binds) ;
668 setLclTypeEnv tcl_env $ do {
670 -- Second pass over class and instance declarations,
671 traceTc (text "Tc6") ;
672 (inst_binds, tcl_env) <- tcInstDecls2 tycl_decls inst_infos ;
673 showLIE (text "after instDecls2") ;
676 -- They need to be zonked, so we return them
677 traceTc (text "Tc7") ;
678 (foe_binds, foe_decls) <- tcForeignExports foreign_decls ;
681 rules <- tcRules rule_decls ;
684 traceTc (text "Tc7a") ;
685 tcg_env <- getGblEnv ;
686 let { all_binds = tc_val_binds `unionBags`
687 inst_binds `unionBags`
690 -- Extend the GblEnv with the (as yet un-zonked)
691 -- bindings, rules, foreign decls
692 tcg_env' = tcg_env { tcg_binds = tcg_binds tcg_env `unionBags` all_binds,
693 tcg_rules = tcg_rules tcg_env ++ rules,
694 tcg_fords = tcg_fords tcg_env ++ foe_decls ++ fi_decls } } ;
695 return (tcg_env', tcl_env)
700 %************************************************************************
704 %************************************************************************
707 checkMain :: TcM TcGblEnv
708 -- If we are in module Main, check that 'main' is defined.
710 = do { ghc_mode <- getGhcMode ;
711 tcg_env <- getGblEnv ;
713 let { main_mod = mainModIs dflags ;
714 main_fn = case mainFunIs dflags of {
715 Just fn -> mkRdrUnqual (mkVarOccFS (mkFastString fn)) ;
716 Nothing -> main_RDR_Unqual } } ;
718 check_main ghc_mode tcg_env main_mod main_fn
722 check_main ghc_mode tcg_env main_mod main_fn
724 = traceTc (text "checkMain not" <+> ppr main_mod <+> ppr mod) >>
728 = addErrCtxt mainCtxt $
729 do { mb_main <- lookupSrcOcc_maybe main_fn
730 -- Check that 'main' is in scope
731 -- It might be imported from another module!
733 Nothing -> do { traceTc (text "checkMain fail" <+> ppr main_mod <+> ppr main_fn)
737 { traceTc (text "checkMain found" <+> ppr main_mod <+> ppr main_fn)
738 ; let { rhs = nlHsApp (nlHsVar runMainIOName) (nlHsVar main_name) }
739 -- :Main.main :: IO () = runMainIO main
741 ; (main_expr, ty) <- setSrcSpan (srcLocSpan (getSrcLoc main_name)) $
744 -- See Note [Root-main Id]
745 ; let { root_main_name = mkExternalName rootMainKey rOOT_MAIN
746 (mkVarOccFS FSLIT("main"))
747 (getSrcLoc main_name)
748 ; root_main_id = Id.mkExportedLocalId root_main_name ty
749 ; main_bind = noLoc (VarBind root_main_id main_expr) }
751 ; return (tcg_env { tcg_binds = tcg_binds tcg_env
753 tcg_dus = tcg_dus tcg_env
754 `plusDU` usesOnly (unitFV main_name)
755 -- Record the use of 'main', so that we don't
756 -- complain about it being defined but not used
760 mod = tcg_mod tcg_env
762 complain_no_main | ghc_mode == Interactive = return ()
763 | otherwise = failWithTc noMainMsg
764 -- In interactive mode, don't worry about the absence of 'main'
765 -- In other modes, fail altogether, so that we don't go on
766 -- and complain a second time when processing the export list.
768 mainCtxt = ptext SLIT("When checking the type of the main function") <+> quotes (ppr main_fn)
769 noMainMsg = ptext SLIT("The main function") <+> quotes (ppr main_fn)
770 <+> ptext SLIT("is not defined in module") <+> quotes (ppr main_mod)
775 The function that the RTS invokes is always :Main.main, which we call
776 root_main_id. (Because GHC allows the user to have a module not
777 called Main as the main module, we can't rely on the main function
778 being called "Main.main". That's why root_main_id has a fixed module
781 This is unusual: it's a LocalId whose Name has a Module from another
782 module. Tiresomely, we must filter it out again in MkIface, les we
783 get two defns for 'main' in the interface file!
786 %*********************************************************
790 %*********************************************************
794 setInteractiveContext :: HscEnv -> InteractiveContext -> TcRn a -> TcRn a
795 setInteractiveContext hsc_env icxt thing_inside
797 -- Initialise the tcg_inst_env with instances
798 -- from all home modules. This mimics the more selective
799 -- call to hptInstances in tcRnModule
800 dfuns = hptInstances hsc_env (\mod -> True)
802 updGblEnv (\env -> env {
803 tcg_rdr_env = ic_rn_gbl_env icxt,
804 tcg_type_env = ic_type_env icxt,
805 tcg_inst_env = extendInstEnvList (tcg_inst_env env) dfuns }) $
807 updLclEnv (\env -> env { tcl_rdr = ic_rn_local_env icxt }) $
809 do { traceTc (text "setIC" <+> ppr (ic_type_env icxt))
816 -> InteractiveContext
818 -> IO (Maybe (InteractiveContext, [Name], LHsExpr Id))
819 -- The returned [Name] is the same as the input except for
820 -- ExprStmt, in which case the returned [Name] is [itName]
822 -- The returned TypecheckedHsExpr is of type IO [ () ],
823 -- a list of the bound values, coerced to ().
825 tcRnStmt hsc_env ictxt rdr_stmt
826 = initTcPrintErrors hsc_env iNTERACTIVE $
827 setInteractiveContext hsc_env ictxt $ do {
829 -- Rename; use CmdLineMode because tcRnStmt is only used interactively
830 (([rn_stmt], _), fvs) <- rnStmts DoExpr [rdr_stmt] (return ((), emptyFVs)) ;
831 traceRn (text "tcRnStmt" <+> vcat [ppr rdr_stmt, ppr rn_stmt, ppr fvs]) ;
834 -- The real work is done here
835 (bound_ids, tc_expr) <- mkPlan rn_stmt ;
836 zonked_expr <- zonkTopLExpr tc_expr ;
837 zonked_ids <- zonkTopBndrs bound_ids ;
839 -- None of the Ids should be of unboxed type, because we
840 -- cast them all to HValues in the end!
841 mappM bad_unboxed (filter (isUnLiftedType . idType) zonked_ids) ;
843 traceTc (text "tcs 1") ;
844 let { -- (a) Make all the bound ids "global" ids, now that
845 -- they're notionally top-level bindings. This is
846 -- important: otherwise when we come to compile an expression
847 -- using these ids later, the byte code generator will consider
848 -- the occurrences to be free rather than global.
850 -- (b) Tidy their types; this is important, because :info may
851 -- ask to look at them, and :info expects the things it looks
852 -- up to have tidy types
853 global_ids = map globaliseAndTidy zonked_ids ;
855 -- Update the interactive context
856 rn_env = ic_rn_local_env ictxt ;
857 type_env = ic_type_env ictxt ;
859 bound_names = map idName global_ids ;
860 new_rn_env = extendLocalRdrEnv rn_env bound_names ;
862 {- ---------------------------------------------
863 At one stage I removed any shadowed bindings from the type_env;
864 they are inaccessible but might, I suppose, cause a space leak if we leave them there.
865 However, with Template Haskell they aren't necessarily inaccessible. Consider this
867 Prelude> let f n = n * 2 :: Int
868 Prelude> fName <- runQ [| f |]
869 Prelude> $(return $ AppE fName (LitE (IntegerL 7)))
871 Prelude> let f n = n * 3 :: Int
872 Prelude> $(return $ AppE fName (LitE (IntegerL 7)))
873 In the last line we use 'fName', which resolves to the *first* 'f'
874 in scope. If we delete it from the type env, GHCi crashes because
875 it doesn't expect that.
877 Hence this code is commented out
879 shadowed = [ n | name <- bound_names,
880 let rdr_name = mkRdrUnqual (nameOccName name),
881 Just n <- [lookupLocalRdrEnv rn_env rdr_name] ] ;
882 filtered_type_env = delListFromNameEnv type_env shadowed ;
883 -------------------------------------------------- -}
885 new_type_env = extendTypeEnvWithIds type_env global_ids ;
886 new_ic = ictxt { ic_rn_local_env = new_rn_env,
887 ic_type_env = new_type_env }
890 dumpOptTcRn Opt_D_dump_tc
891 (vcat [text "Bound Ids" <+> pprWithCommas ppr global_ids,
892 text "Typechecked expr" <+> ppr zonked_expr]) ;
894 returnM (new_ic, bound_names, zonked_expr)
897 bad_unboxed id = addErr (sep [ptext SLIT("GHCi can't bind a variable of unlifted type:"),
898 nest 2 (ppr id <+> dcolon <+> ppr (idType id))])
900 globaliseAndTidy :: Id -> Id
902 -- Give the Id a Global Name, and tidy its type
903 = Id.setIdType (globaliseId VanillaGlobal id) tidy_type
905 tidy_type = tidyTopType (idType id)
908 Here is the grand plan, implemented in tcUserStmt
910 What you type The IO [HValue] that hscStmt returns
911 ------------- ------------------------------------
912 let pat = expr ==> let pat = expr in return [coerce HVal x, coerce HVal y, ...]
915 pat <- expr ==> expr >>= \ pat -> return [coerce HVal x, coerce HVal y, ...]
918 expr (of IO type) ==> expr >>= \ it -> return [coerce HVal it]
919 [NB: result not printed] bindings: [it]
921 expr (of non-IO type, ==> let it = expr in print it >> return [coerce HVal it]
922 result showable) bindings: [it]
924 expr (of non-IO type,
925 result not showable) ==> error
929 ---------------------------
930 type PlanResult = ([Id], LHsExpr Id)
931 type Plan = TcM PlanResult
933 runPlans :: [Plan] -> TcM PlanResult
934 -- Try the plans in order. If one fails (by raising an exn), try the next.
935 -- If one succeeds, take it.
936 runPlans [] = panic "runPlans"
938 runPlans (p:ps) = tryTcLIE_ (runPlans ps) p
941 mkPlan :: LStmt Name -> TcM PlanResult
942 mkPlan (L loc (ExprStmt expr _ _)) -- An expression typed at the prompt
943 = do { uniq <- newUnique -- is treated very specially
944 ; let fresh_it = itName uniq
945 the_bind = L loc $ mkFunBind (L loc fresh_it) matches
946 matches = [mkMatch [] expr emptyLocalBinds]
947 let_stmt = L loc $ LetStmt (HsValBinds (ValBindsOut [(NonRecursive,unitBag the_bind)] []))
948 bind_stmt = L loc $ BindStmt (nlVarPat fresh_it) expr
949 (HsVar bindIOName) noSyntaxExpr
950 print_it = L loc $ ExprStmt (nlHsApp (nlHsVar printName) (nlHsVar fresh_it))
951 (HsVar thenIOName) placeHolderType
954 -- [it <- e; print it] but not if it::()
956 -- [let it = e; print it]
957 ; runPlans [ -- Plan A
958 do { stuff@([it_id], _) <- tcGhciStmts [bind_stmt, print_it]
959 ; it_ty <- zonkTcType (idType it_id)
960 ; ifM (isUnitTy it_ty) failM
963 -- Plan B; a naked bind statment
964 tcGhciStmts [bind_stmt],
966 -- Plan C; check that the let-binding is typeable all by itself.
967 -- If not, fail; if so, try to print it.
968 -- The two-step process avoids getting two errors: one from
969 -- the expression itself, and one from the 'print it' part
970 -- This two-step story is very clunky, alas
971 do { checkNoErrs (tcGhciStmts [let_stmt])
972 --- checkNoErrs defeats the error recovery of let-bindings
973 ; tcGhciStmts [let_stmt, print_it] }
976 mkPlan stmt@(L loc (BindStmt {}))
977 | [L _ v] <- collectLStmtBinders stmt -- One binder, for a bind stmt
978 = do { let print_v = L loc $ ExprStmt (nlHsApp (nlHsVar printName) (nlHsVar v))
979 (HsVar thenIOName) placeHolderType
981 ; print_bind_result <- doptM Opt_PrintBindResult
982 ; let print_plan = do
983 { stuff@([v_id], _) <- tcGhciStmts [stmt, print_v]
984 ; v_ty <- zonkTcType (idType v_id)
985 ; ifM (isUnitTy v_ty || not (isTauTy v_ty)) failM
989 -- [stmt; print v] but not if v::()
991 ; runPlans ((if print_bind_result then [print_plan] else []) ++
992 [tcGhciStmts [stmt]])
998 ---------------------------
999 tcGhciStmts :: [LStmt Name] -> TcM PlanResult
1001 = do { ioTyCon <- tcLookupTyCon ioTyConName ;
1002 ret_id <- tcLookupId returnIOName ; -- return @ IO
1004 io_ty = mkTyConApp ioTyCon [] ;
1005 ret_ty = mkListTy unitTy ;
1006 io_ret_ty = mkTyConApp ioTyCon [ret_ty] ;
1007 tc_io_stmts stmts = tcStmts DoExpr (tcDoStmt io_ty) stmts
1008 (emptyRefinement, io_ret_ty) ;
1010 names = map unLoc (collectLStmtsBinders stmts) ;
1012 -- mk_return builds the expression
1013 -- returnIO @ [()] [coerce () x, .., coerce () z]
1015 -- Despite the inconvenience of building the type applications etc,
1016 -- this *has* to be done in type-annotated post-typecheck form
1017 -- because we are going to return a list of *polymorphic* values
1018 -- coerced to type (). If we built a *source* stmt
1019 -- return [coerce x, ..., coerce z]
1020 -- then the type checker would instantiate x..z, and we wouldn't
1021 -- get their *polymorphic* values. (And we'd get ambiguity errs
1022 -- if they were overloaded, since they aren't applied to anything.)
1023 mk_return ids = nlHsApp (nlHsTyApp ret_id [ret_ty])
1024 (noLoc $ ExplicitList unitTy (map mk_item ids)) ;
1025 mk_item id = nlHsApp (nlHsTyApp unsafeCoerceId [idType id, unitTy])
1029 -- OK, we're ready to typecheck the stmts
1030 traceTc (text "tcs 2") ;
1031 ((tc_stmts, ids), lie) <- getLIE $ tc_io_stmts stmts $ \ _ ->
1032 mappM tcLookupId names ;
1033 -- Look up the names right in the middle,
1034 -- where they will all be in scope
1036 -- Simplify the context
1037 const_binds <- checkNoErrs (tcSimplifyInteractive lie) ;
1038 -- checkNoErrs ensures that the plan fails if context redn fails
1040 return (ids, mkHsDictLet const_binds $
1041 noLoc (HsDo DoExpr tc_stmts (mk_return ids) io_ret_ty))
1046 tcRnExpr just finds the type of an expression
1050 -> InteractiveContext
1053 tcRnExpr hsc_env ictxt rdr_expr
1054 = initTcPrintErrors hsc_env iNTERACTIVE $
1055 setInteractiveContext hsc_env ictxt $ do {
1057 (rn_expr, fvs) <- rnLExpr rdr_expr ;
1060 -- Now typecheck the expression;
1061 -- it might have a rank-2 type (e.g. :t runST)
1062 ((tc_expr, res_ty), lie) <- getLIE (tcInferRho rn_expr) ;
1063 ((qtvs, dict_insts, _), lie_top) <- getLIE (tcSimplifyInfer smpl_doc (tyVarsOfType res_ty) lie) ;
1064 tcSimplifyInteractive lie_top ;
1066 let { all_expr_ty = mkForAllTys qtvs $
1067 mkFunTys (map (idType . instToId) dict_insts) $
1069 zonkTcType all_expr_ty
1072 smpl_doc = ptext SLIT("main expression")
1075 tcRnType just finds the kind of a type
1079 -> InteractiveContext
1082 tcRnType hsc_env ictxt rdr_type
1083 = initTcPrintErrors hsc_env iNTERACTIVE $
1084 setInteractiveContext hsc_env ictxt $ do {
1086 rn_type <- rnLHsType doc rdr_type ;
1089 -- Now kind-check the type
1090 (ty', kind) <- kcHsType rn_type ;
1094 doc = ptext SLIT("In GHCi input")
1100 %************************************************************************
1102 More GHCi stuff, to do with browsing and getting info
1104 %************************************************************************
1108 -- ASSUMES that the module is either in the HomePackageTable or is
1109 -- a package module with an interface on disk. If neither of these is
1110 -- true, then the result will be an error indicating the interface
1111 -- could not be found.
1112 getModuleExports :: HscEnv -> Module -> IO (Messages, Maybe [AvailInfo])
1113 getModuleExports hsc_env mod
1116 checkMods = ic_toplev_scope ic ++ ic_exports ic
1118 initTc hsc_env HsSrcFile iNTERACTIVE (tcGetModuleExports mod checkMods)
1120 -- Get the export avail info and also load all orphan and family-instance
1121 -- modules. Finally, check that the family instances of all modules in the
1122 -- interactive context are consistent (these modules are in the second
1124 tcGetModuleExports :: Module -> [Module] -> TcM [AvailInfo]
1125 tcGetModuleExports mod directlyImpMods
1126 = do { let doc = ptext SLIT("context for compiling statements")
1127 ; iface <- initIfaceTcRn $ loadSysInterface doc mod
1129 -- Load any orphan-module and family instance-module
1130 -- interfaces, so their instances are visible.
1131 ; loadOrphanModules (dep_orphs (mi_deps iface)) False
1132 ; loadOrphanModules (dep_finsts (mi_deps iface)) True
1134 -- Check that the family instances of all directly loaded
1135 -- modules are consistent.
1136 ; checkFamInstConsistency (dep_finsts (mi_deps iface)) directlyImpMods
1138 ; ifaceExportNames (mi_exports iface)
1141 tcRnLookupRdrName :: HscEnv -> RdrName -> IO (Maybe [Name])
1142 tcRnLookupRdrName hsc_env rdr_name
1143 = initTcPrintErrors hsc_env iNTERACTIVE $
1144 setInteractiveContext hsc_env (hsc_IC hsc_env) $
1145 lookup_rdr_name rdr_name
1147 lookup_rdr_name rdr_name = do {
1148 -- If the identifier is a constructor (begins with an
1149 -- upper-case letter), then we need to consider both
1150 -- constructor and type class identifiers.
1151 let { rdr_names = dataTcOccs rdr_name } ;
1153 -- results :: [Either Messages Name]
1154 results <- mapM (tryTcErrs . lookupOccRn) rdr_names ;
1156 traceRn (text "xx" <+> vcat [ppr rdr_names, ppr (map snd results)]);
1157 -- The successful lookups will be (Just name)
1158 let { (warns_s, good_names) = unzip [ (msgs, name)
1159 | (msgs, Just name) <- results] ;
1160 errs_s = [msgs | (msgs, Nothing) <- results] } ;
1162 -- Fail if nothing good happened, else add warnings
1163 if null good_names then
1164 -- No lookup succeeded, so
1165 -- pick the first error message and report it
1166 -- ToDo: If one of the errors is "could be Foo.X or Baz.X",
1167 -- while the other is "X is not in scope",
1168 -- we definitely want the former; but we might pick the latter
1169 do { addMessages (head errs_s) ; failM }
1170 else -- Add deprecation warnings
1171 mapM_ addMessages warns_s ;
1176 tcRnRecoverDataCon :: HscEnv -> a -> IO (Maybe DataCon)
1177 tcRnRecoverDataCon hsc_env a
1178 = initTcPrintErrors hsc_env iNTERACTIVE $
1179 setInteractiveContext hsc_env (hsc_IC hsc_env) $
1180 do name <- recoverDataCon a
1181 tcLookupDataCon name
1183 tcRnLookupName :: HscEnv -> Name -> IO (Maybe TyThing)
1184 tcRnLookupName hsc_env name
1185 = initTcPrintErrors hsc_env iNTERACTIVE $
1186 setInteractiveContext hsc_env (hsc_IC hsc_env) $
1190 tcRnGetInfo :: HscEnv
1192 -> IO (Maybe (TyThing, Fixity, [Instance]))
1194 -- Used to implemnent :info in GHCi
1196 -- Look up a RdrName and return all the TyThings it might be
1197 -- A capitalised RdrName is given to us in the DataName namespace,
1198 -- but we want to treat it as *both* a data constructor
1199 -- *and* as a type or class constructor;
1200 -- hence the call to dataTcOccs, and we return up to two results
1201 tcRnGetInfo hsc_env name
1202 = initTcPrintErrors hsc_env iNTERACTIVE $
1203 let ictxt = hsc_IC hsc_env in
1204 setInteractiveContext hsc_env ictxt $ do
1206 -- Load the interface for all unqualified types and classes
1207 -- That way we will find all the instance declarations
1208 -- (Packages have not orphan modules, and we assume that
1209 -- in the home package all relevant modules are loaded.)
1210 loadUnqualIfaces ictxt
1212 thing <- tcLookupGlobal name
1213 fixity <- lookupFixityRn name
1214 ispecs <- lookupInsts (icPrintUnqual ictxt) thing
1215 return (thing, fixity, ispecs)
1217 lookupInsts :: PrintUnqualified -> TyThing -> TcM [Instance]
1218 -- Filter the instances by the ones whose tycons (or clases resp)
1219 -- are in scope unqualified. Otherwise we list a whole lot too many!
1220 lookupInsts print_unqual (AClass cls)
1221 = do { inst_envs <- tcGetInstEnvs
1223 | ispec <- classInstances inst_envs cls
1224 , plausibleDFun print_unqual (instanceDFunId ispec) ] }
1226 lookupInsts print_unqual (ATyCon tc)
1227 = do { eps <- getEps -- Load all instances for all classes that are
1228 -- in the type environment (which are all the ones
1229 -- we've seen in any interface file so far)
1230 ; (pkg_ie, home_ie) <- tcGetInstEnvs -- Search all
1232 | ispec <- instEnvElts home_ie ++ instEnvElts pkg_ie
1233 , let dfun = instanceDFunId ispec
1235 , plausibleDFun print_unqual dfun ] }
1237 relevant df = tc_name `elemNameSet` tyClsNamesOfDFunHead (idType df)
1238 tc_name = tyConName tc
1240 lookupInsts print_unqual other = return []
1242 plausibleDFun print_unqual dfun -- Dfun involving only names that print unqualified
1243 = all ok (nameSetToList (tyClsNamesOfType (idType dfun)))
1245 ok name | isBuiltInSyntax name = True
1246 | isExternalName name =
1247 isNothing $ fst print_unqual (nameModule name)
1251 loadUnqualIfaces :: InteractiveContext -> TcM ()
1252 -- Load the home module for everything that is in scope unqualified
1253 -- This is so that we can accurately report the instances for
1255 loadUnqualIfaces ictxt
1257 mapM_ (loadSysInterface doc) (moduleSetElts (mkModuleSet unqual_mods))
1259 unqual_mods = [ nameModule name
1260 | gre <- globalRdrEnvElts (ic_rn_gbl_env ictxt),
1261 let name = gre_name gre,
1262 not (isInternalName name),
1263 isTcOcc (nameOccName name), -- Types and classes only
1264 unQualOK gre ] -- In scope unqualified
1265 doc = ptext SLIT("Need interface for module whose export(s) are in scope unqualified")
1269 %************************************************************************
1273 %************************************************************************
1276 rnDump :: SDoc -> TcRn ()
1277 -- Dump, with a banner, if -ddump-rn
1278 rnDump doc = do { dumpOptTcRn Opt_D_dump_rn (mkDumpDoc "Renamer" doc) }
1280 tcDump :: TcGblEnv -> TcRn ()
1282 = do { dflags <- getDOpts ;
1284 -- Dump short output if -ddump-types or -ddump-tc
1285 ifM (dopt Opt_D_dump_types dflags || dopt Opt_D_dump_tc dflags)
1286 (dumpTcRn short_dump) ;
1288 -- Dump bindings if -ddump-tc
1289 dumpOptTcRn Opt_D_dump_tc (mkDumpDoc "Typechecker" full_dump)
1292 short_dump = pprTcGblEnv env
1293 full_dump = pprLHsBinds (tcg_binds env)
1294 -- NB: foreign x-d's have undefined's in their types;
1295 -- hence can't show the tc_fords
1298 = do { dflags <- getDOpts ;
1299 ifM (dopt Opt_D_dump_types dflags || dopt Opt_D_dump_tc dflags)
1300 (dumpTcRn (pprModGuts mod_guts)) ;
1302 -- Dump bindings if -ddump-tc
1303 dumpOptTcRn Opt_D_dump_tc (mkDumpDoc "Typechecker" full_dump) }
1305 full_dump = pprCoreBindings (mg_binds mod_guts)
1307 -- It's unpleasant having both pprModGuts and pprModDetails here
1308 pprTcGblEnv :: TcGblEnv -> SDoc
1309 pprTcGblEnv (TcGblEnv { tcg_type_env = type_env,
1311 tcg_fam_insts = fam_insts,
1313 tcg_imports = imports })
1314 = vcat [ ppr_types insts type_env
1315 , ppr_tycons fam_insts type_env
1317 , ppr_fam_insts fam_insts
1318 , vcat (map ppr rules)
1319 , ppr_gen_tycons (typeEnvTyCons type_env)
1320 , ptext SLIT("Dependent modules:") <+> ppr (eltsUFM (imp_dep_mods imports))
1321 , ptext SLIT("Dependent packages:") <+> ppr (imp_dep_pkgs imports)]
1323 pprModGuts :: ModGuts -> SDoc
1324 pprModGuts (ModGuts { mg_types = type_env,
1326 = vcat [ ppr_types [] type_env,
1329 ppr_types :: [Instance] -> TypeEnv -> SDoc
1330 ppr_types insts type_env
1331 = text "TYPE SIGNATURES" $$ nest 4 (ppr_sigs ids)
1333 dfun_ids = map instanceDFunId insts
1334 ids = [id | id <- typeEnvIds type_env, want_sig id]
1335 want_sig id | opt_PprStyle_Debug = True
1336 | otherwise = isLocalId id &&
1337 isExternalName (idName id) &&
1338 not (id `elem` dfun_ids)
1339 -- isLocalId ignores data constructors, records selectors etc.
1340 -- The isExternalName ignores local dictionary and method bindings
1341 -- that the type checker has invented. Top-level user-defined things
1342 -- have External names.
1344 ppr_tycons :: [FamInst] -> TypeEnv -> SDoc
1345 ppr_tycons fam_insts type_env
1346 = text "TYPE CONSTRUCTORS" $$ nest 4 (ppr_tydecls tycons)
1348 fi_tycons = map famInstTyCon fam_insts
1349 tycons = [tycon | tycon <- typeEnvTyCons type_env, want_tycon tycon]
1350 want_tycon tycon | opt_PprStyle_Debug = True
1351 | otherwise = not (isImplicitTyCon tycon) &&
1352 isExternalName (tyConName tycon) &&
1353 not (tycon `elem` fi_tycons)
1355 ppr_insts :: [Instance] -> SDoc
1356 ppr_insts [] = empty
1357 ppr_insts ispecs = text "INSTANCES" $$ nest 2 (pprInstances ispecs)
1359 ppr_fam_insts :: [FamInst] -> SDoc
1360 ppr_fam_insts [] = empty
1361 ppr_fam_insts fam_insts =
1362 text "FAMILY INSTANCES" $$ nest 2 (pprFamInsts fam_insts)
1364 ppr_sigs :: [Var] -> SDoc
1366 -- Print type signatures; sort by OccName
1367 = vcat (map ppr_sig (sortLe le_sig ids))
1369 le_sig id1 id2 = getOccName id1 <= getOccName id2
1370 ppr_sig id = ppr id <+> dcolon <+> ppr (tidyTopType (idType id))
1372 ppr_tydecls :: [TyCon] -> SDoc
1374 -- Print type constructor info; sort by OccName
1375 = vcat (map ppr_tycon (sortLe le_sig tycons))
1377 le_sig tycon1 tycon2 = getOccName tycon1 <= getOccName tycon2
1379 | isCoercionTyCon tycon = ptext SLIT("coercion") <+> ppr tycon
1380 | otherwise = ppr (tyThingToIfaceDecl (ATyCon tycon))
1382 ppr_rules :: [CoreRule] -> SDoc
1383 ppr_rules [] = empty
1384 ppr_rules rs = vcat [ptext SLIT("{-# RULES"),
1385 nest 4 (pprRules rs),
1388 ppr_gen_tycons [] = empty
1389 ppr_gen_tycons tcs = vcat [ptext SLIT("Tycons with generics:"),
1390 nest 2 (fsep (map ppr (filter tyConHasGenerics tcs)))]