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,
21 #include "HsVersions.h"
25 import {-# SOURCE #-} TcSplice ( tcSpliceDecls )
84 import {- Kind parts of -} Type
93 import Control.Monad ( unless )
94 import Data.Maybe ( isJust )
99 %************************************************************************
101 Typecheck and rename a module
103 %************************************************************************
109 -> Bool -- True <=> save renamed syntax
110 -> Located (HsModule RdrName)
111 -> IO (Messages, Maybe TcGblEnv)
113 tcRnModule hsc_env hsc_src save_rn_syntax
114 (L loc (HsModule maybe_mod export_ies
115 import_decls local_decls mod_deprec _ module_info maybe_doc))
116 = do { showPass (hsc_dflags hsc_env) "Renamer/typechecker" ;
118 let { this_pkg = thisPackage (hsc_dflags hsc_env) ;
119 this_mod = case maybe_mod of
120 Nothing -> mAIN -- 'module M where' is omitted
121 Just (L _ mod) -> mkModule this_pkg mod } ;
124 initTc hsc_env hsc_src this_mod $
127 -- Deal with imports;
128 (rn_imports, rdr_env, imports) <- rnImports import_decls ;
130 let { dep_mods :: ModuleNameEnv (ModuleName, IsBootInterface)
131 ; dep_mods = imp_dep_mods imports
133 -- We want instance declarations from all home-package
134 -- modules below this one, including boot modules, except
135 -- ourselves. The 'except ourselves' is so that we don't
136 -- get the instances from this module's hs-boot file
137 ; want_instances :: ModuleName -> Bool
138 ; want_instances mod = mod `elemUFM` dep_mods
139 && mod /= moduleName this_mod
140 ; home_insts = hptInstances hsc_env want_instances
143 -- Record boot-file info in the EPS, so that it's
144 -- visible to loadHiBootInterface in tcRnSrcDecls,
145 -- and any other incrementally-performed imports
146 updateEps_ (\eps -> eps { eps_is_boot = dep_mods }) ;
148 -- Update the gbl env
150 gbl { tcg_rdr_env = plusOccEnv (tcg_rdr_env gbl) rdr_env,
151 tcg_inst_env = extendInstEnvList (tcg_inst_env gbl) home_insts,
152 tcg_imports = tcg_imports gbl `plusImportAvails` imports,
153 tcg_rn_imports = if save_rn_syntax then
157 tcg_rn_decls = if save_rn_syntax then
163 traceRn (text "rn1" <+> ppr (imp_dep_mods imports)) ;
164 -- Fail if there are any errors so far
165 -- The error printing (if needed) takes advantage
166 -- of the tcg_env we have now set
167 traceIf (text "rdr_env: " <+> ppr rdr_env) ;
170 -- Load any orphan-module and family instance-module
171 -- interfaces, so that their rules and instance decls will be
173 loadOrphanModules (imp_orphs imports) False ;
174 loadOrphanModules (imp_finsts imports) True ;
176 let { directlyImpMods = map (\(mod, _, _) -> mod)
180 checkFamInstConsistency (imp_finsts imports) directlyImpMods ;
182 traceRn (text "rn1a") ;
183 -- Rename and type check the declarations
184 tcg_env <- if isHsBoot hsc_src then
185 tcRnHsBootDecls local_decls
187 tcRnSrcDecls local_decls ;
188 setGblEnv tcg_env $ do {
190 failIfErrsM ; -- reportDeprecations crashes sometimes
191 -- as a result of typechecker repairs (e.g. unboundNames)
192 traceRn (text "rn3") ;
194 -- Report the use of any deprecated things
195 -- We do this before processsing the export list so
196 -- that we don't bleat about re-exporting a deprecated
197 -- thing (especially via 'module Foo' export item)
198 -- Only uses in the body of the module are complained about
199 reportDeprecations (hsc_dflags hsc_env) tcg_env ;
201 -- Process the export list
202 (rn_exports, exports) <- rnExports (isJust maybe_mod) export_ies ;
204 traceRn (text "rn4") ;
206 -- Rename the Haddock documentation header
207 rn_module_doc <- rnMbHsDoc maybe_doc ;
209 -- Rename the Haddock module info
210 rn_description <- rnMbHsDoc (hmi_description module_info) ;
211 let { rn_module_info = module_info { hmi_description = rn_description } } ;
213 -- Check whether the entire module is deprecated
214 -- This happens only once per module
215 let { mod_deprecs = checkModDeprec mod_deprec } ;
217 -- Add exports and deprecations to envt
218 let { final_env = tcg_env { tcg_exports = exports,
219 tcg_rn_exports = if save_rn_syntax then
222 tcg_dus = tcg_dus tcg_env `plusDU` usesOnly (availsToNameSet exports),
223 tcg_deprecs = tcg_deprecs tcg_env `plusDeprecs`
225 tcg_doc = rn_module_doc,
226 tcg_hmi = rn_module_info
228 -- A module deprecation over-rides the earlier ones
231 -- Report unused names
232 reportUnusedNames export_ies final_env ;
234 -- Dump output and return
241 %************************************************************************
243 Type-checking external-core modules
245 %************************************************************************
248 tcRnExtCore :: HscEnv
250 -> IO (Messages, Maybe ModGuts)
251 -- Nothing => some error occurred
253 tcRnExtCore hsc_env (HsExtCore this_mod decls src_binds)
254 -- The decls are IfaceDecls; all names are original names
255 = do { showPass (hsc_dflags hsc_env) "Renamer/typechecker" ;
257 initTc hsc_env ExtCoreFile this_mod $ do {
259 let { ldecls = map noLoc decls } ;
261 -- Deal with the type declarations; first bring their stuff
262 -- into scope, then rname them, then type check them
263 tcg_env <- importsFromLocalDecls (mkFakeGroup ldecls) ;
265 setGblEnv tcg_env $ do {
267 rn_decls <- rnTyClDecls ldecls ;
270 -- Dump trace of renaming part
271 rnDump (ppr rn_decls) ;
273 -- Typecheck them all together so that
274 -- any mutually recursive types are done right
275 tcg_env <- checkNoErrs (tcTyAndClassDecls emptyModDetails rn_decls) ;
276 -- Make the new type env available to stuff slurped from interface files
278 setGblEnv tcg_env $ do {
280 -- Now the core bindings
281 core_binds <- initIfaceExtCore (tcExtCoreBindings src_binds) ;
285 bndrs = bindersOfBinds core_binds ;
286 my_exports = map (Avail . idName) bndrs ;
287 -- ToDo: export the data types also?
289 final_type_env = extendTypeEnvWithIds (tcg_type_env tcg_env) bndrs ;
291 mod_guts = ModGuts { mg_module = this_mod,
293 mg_usages = [], -- ToDo: compute usage
294 mg_dir_imps = [], -- ??
295 mg_deps = noDependencies, -- ??
296 mg_exports = my_exports,
297 mg_types = final_type_env,
298 mg_insts = tcg_insts tcg_env,
299 mg_fam_insts = tcg_fam_insts tcg_env,
301 mg_binds = core_binds,
304 mg_rdr_env = emptyGlobalRdrEnv,
305 mg_fix_env = emptyFixityEnv,
306 mg_deprecs = NoDeprecs,
307 mg_foreign = NoStubs,
308 mg_hpc_info = noHpcInfo
311 tcCoreDump mod_guts ;
316 mkFakeGroup decls -- Rather clumsy; lots of unused fields
317 = emptyRdrGroup { hs_tyclds = decls }
321 %************************************************************************
323 Type-checking the top level of a module
325 %************************************************************************
328 tcRnSrcDecls :: [LHsDecl RdrName] -> TcM TcGblEnv
329 -- Returns the variables free in the decls
330 -- Reason: solely to report unused imports and bindings
332 = do { -- Load the hi-boot interface for this module, if any
333 -- We do this now so that the boot_names can be passed
334 -- to tcTyAndClassDecls, because the boot_names are
335 -- automatically considered to be loop breakers
337 boot_iface <- tcHiBootIface mod ;
339 -- Do all the declarations
340 (tc_envs, lie) <- getLIE $ tc_rn_src_decls boot_iface decls ;
342 -- Finish simplifying class constraints
344 -- tcSimplifyTop deals with constant or ambiguous InstIds.
345 -- How could there be ambiguous ones? They can only arise if a
346 -- top-level decl falls under the monomorphism restriction
347 -- and no subsequent decl instantiates its type.
349 -- We do this after checkMain, so that we use the type info
350 -- thaat checkMain adds
352 -- We do it with both global and local env in scope:
353 -- * the global env exposes the instances to tcSimplifyTop
354 -- * the local env exposes the local Ids to tcSimplifyTop,
355 -- so that we get better error messages (monomorphism restriction)
356 traceTc (text "Tc8") ;
357 inst_binds <- setEnvs tc_envs (tcSimplifyTop lie) ;
359 -- Backsubstitution. This must be done last.
360 -- Even tcSimplifyTop may do some unification.
361 traceTc (text "Tc9") ;
362 let { (tcg_env, _) = tc_envs
363 ; TcGblEnv { tcg_type_env = type_env, tcg_binds = binds,
364 tcg_rules = rules, tcg_fords = fords } = tcg_env
365 ; all_binds = binds `unionBags` inst_binds } ;
367 (bind_ids, binds', fords', rules') <- zonkTopDecls all_binds rules fords ;
369 let { final_type_env = extendTypeEnvWithIds type_env bind_ids
370 ; tcg_env' = tcg_env { tcg_type_env = final_type_env,
373 tcg_fords = fords' } } ;
375 -- Make the new type env available to stuff slurped from interface files
376 writeMutVar (tcg_type_env_var tcg_env) final_type_env ;
378 -- Compare the hi-boot iface (if any) with the real thing
379 dfun_binds <- checkHiBootIface tcg_env' boot_iface ;
381 return (tcg_env' { tcg_binds = tcg_binds tcg_env' `unionBags` dfun_binds })
384 tc_rn_src_decls :: ModDetails -> [LHsDecl RdrName] -> TcM (TcGblEnv, TcLclEnv)
385 -- Loops around dealing with each top level inter-splice group
386 -- in turn, until it's dealt with the entire module
387 tc_rn_src_decls boot_details ds
388 = do { let { (first_group, group_tail) = findSplice ds } ;
389 -- If ds is [] we get ([], Nothing)
391 -- Deal with decls up to, but not including, the first splice
392 (tcg_env, rn_decls) <- checkNoErrs $ rnTopSrcDecls first_group ;
393 -- checkNoErrs: don't typecheck if renaming failed
394 tc_envs <- setGblEnv tcg_env $
395 tcTopSrcDecls boot_details rn_decls ;
397 -- If there is no splice, we're nearly done
400 Nothing -> do { tcg_env <- checkMain ; -- Check for `main'
401 return (tcg_env, snd tc_envs)
404 -- If there's a splice, we must carry on
405 Just (SpliceDecl splice_expr, rest_ds) -> do {
407 failWithTc (text "Can't do a top-level splice; need a bootstrapped compiler")
410 -- Rename the splice expression, and get its supporting decls
411 (rn_splice_expr, splice_fvs) <- checkNoErrs (rnLExpr splice_expr) ;
412 -- checkNoErrs: don't typecheck if renaming failed
413 rnDump (ppr rn_splice_expr) ;
415 -- Execute the splice
416 spliced_decls <- tcSpliceDecls rn_splice_expr ;
418 -- Glue them on the front of the remaining decls and loop
419 setGblEnv (tcg_env `addTcgDUs` usesOnly splice_fvs) $
420 tc_rn_src_decls boot_details (spliced_decls ++ rest_ds)
425 %************************************************************************
427 Compiling hs-boot source files, and
428 comparing the hi-boot interface with the real thing
430 %************************************************************************
433 tcRnHsBootDecls :: [LHsDecl RdrName] -> TcM TcGblEnv
434 tcRnHsBootDecls decls
435 = do { let { (first_group, group_tail) = findSplice decls }
438 Just stuff -> spliceInHsBootErr stuff
441 -- Rename the declarations
442 ; (tcg_env, rn_group) <- rnTopSrcDecls first_group
443 ; setGblEnv tcg_env $ do {
445 -- Todo: check no foreign decls, no rules, no default decls
447 -- Typecheck type/class decls
448 ; traceTc (text "Tc2")
449 ; let tycl_decls = hs_tyclds rn_group
450 ; tcg_env <- checkNoErrs (tcTyAndClassDecls emptyModDetails tycl_decls)
451 ; setGblEnv tcg_env $ do {
453 -- Typecheck instance decls
454 ; traceTc (text "Tc3")
455 ; (tcg_env, inst_infos, _binds)
456 <- tcInstDecls1 tycl_decls (hs_instds rn_group) (hs_derivds rn_group)
457 ; setGblEnv tcg_env $ do {
459 -- Typecheck value declarations
460 ; traceTc (text "Tc5")
461 ; val_ids <- tcHsBootSigs (hs_valds rn_group)
464 -- No simplification or zonking to do
465 ; traceTc (text "Tc7a")
466 ; gbl_env <- getGblEnv
468 -- Make the final type-env
469 -- Include the dfun_ids so that their type sigs
470 -- are written into the interface file
471 ; let { type_env0 = tcg_type_env gbl_env
472 ; type_env1 = extendTypeEnvWithIds type_env0 val_ids
473 ; type_env2 = extendTypeEnvWithIds type_env1 dfun_ids
474 ; dfun_ids = map iDFunId inst_infos }
475 ; return (gbl_env { tcg_type_env = type_env2 })
478 spliceInHsBootErr (SpliceDecl (L loc _), _)
479 = addErrAt loc (ptext SLIT("Splices are not allowed in hs-boot files"))
482 Once we've typechecked the body of the module, we want to compare what
483 we've found (gathered in a TypeEnv) with the hi-boot details (if any).
486 checkHiBootIface :: TcGblEnv -> ModDetails -> TcM (LHsBinds Id)
487 -- Compare the hi-boot file for this module (if there is one)
488 -- with the type environment we've just come up with
489 -- In the common case where there is no hi-boot file, the list
490 -- of boot_names is empty.
492 -- The bindings we return give bindings for the dfuns defined in the
493 -- hs-boot file, such as $fbEqT = $fEqT
496 (TcGblEnv { tcg_insts = local_insts, tcg_fam_insts = local_fam_insts,
497 tcg_type_env = local_type_env })
498 (ModDetails { md_insts = boot_insts, md_fam_insts = boot_fam_insts,
499 md_types = boot_type_env })
500 = do { traceTc (text "checkHiBootIface" <+> (ppr boot_type_env $$ ppr boot_insts)) ;
501 ; mapM_ check_one (typeEnvElts boot_type_env)
502 ; dfun_binds <- mapM check_inst boot_insts
503 ; unless (null boot_fam_insts) $
504 panic ("TcRnDriver.checkHiBootIface: Cannot handle family " ++
505 "instances in boot files yet...")
506 -- FIXME: Why? The actual comparison is not hard, but what would
507 -- be the equivalent to the dfun bindings returned for class
508 -- instances? We can't easily equate tycons...
509 ; return (unionManyBags dfun_binds) }
512 | isImplicitTyThing boot_thing = return ()
513 | name `elem` dfun_names = return ()
514 | isWiredInName name = return () -- No checking for wired-in names. In particular,
515 -- 'error' is handled by a rather gross hack
516 -- (see comments in GHC.Err.hs-boot)
517 | Just real_thing <- lookupTypeEnv local_type_env name
518 = do { let boot_decl = tyThingToIfaceDecl boot_thing
519 real_decl = tyThingToIfaceDecl real_thing
520 ; checkTc (checkBootDecl boot_decl real_decl)
521 (bootMisMatch boot_thing boot_decl real_decl) }
522 -- The easiest way to check compatibility is to convert to
523 -- iface syntax, where we already have good comparison functions
525 = addErrTc (missingBootThing boot_thing)
527 name = getName boot_thing
529 dfun_names = map getName boot_insts
532 = case [dfun | inst <- local_insts,
533 let dfun = instanceDFunId inst,
534 idType dfun `tcEqType` boot_inst_ty ] of
535 [] -> do { addErrTc (instMisMatch boot_inst); return emptyBag }
536 (dfun:_) -> return (unitBag $ noLoc $ VarBind local_boot_dfun (nlHsVar dfun))
538 boot_dfun = instanceDFunId boot_inst
539 boot_inst_ty = idType boot_dfun
540 local_boot_dfun = Id.mkExportedLocalId (idName boot_dfun) boot_inst_ty
543 missingBootThing thing
544 = ppr thing <+> ptext SLIT("is defined in the hs-boot file, but not in the module")
545 bootMisMatch thing boot_decl real_decl
546 = vcat [ppr thing <+> ptext SLIT("has conflicting definitions in the module and its hs-boot file"),
547 ptext SLIT("Decl") <+> ppr real_decl,
548 ptext SLIT("Boot file:") <+> ppr boot_decl]
551 2 (ptext SLIT("is defined in the hs-boot file, but not in the module"))
555 %************************************************************************
557 Type-checking the top level of a module
559 %************************************************************************
561 tcRnGroup takes a bunch of top-level source-code declarations, and
563 * gets supporting declarations from interface files
566 * and augments the TcGblEnv with the results
568 In Template Haskell it may be called repeatedly for each group of
569 declarations. It expects there to be an incoming TcGblEnv in the
570 monad; it augments it and returns the new TcGblEnv.
573 ------------------------------------------------
574 rnTopSrcDecls :: HsGroup RdrName -> TcM (TcGblEnv, HsGroup Name)
576 = do { -- Bring top level binders into scope
577 tcg_env <- importsFromLocalDecls group ;
578 setGblEnv tcg_env $ do {
580 failIfErrsM ; -- No point in continuing if (say) we have duplicate declarations
582 -- Rename the source decls
583 (tcg_env, rn_decls) <- rnSrcDecls group ;
586 -- save the renamed syntax, if we want it
588 | Just grp <- tcg_rn_decls tcg_env
589 = tcg_env{ tcg_rn_decls = Just (appendGroups grp rn_decls) }
593 -- Dump trace of renaming part
594 rnDump (ppr rn_decls) ;
596 return (tcg_env', rn_decls)
599 ------------------------------------------------
600 tcTopSrcDecls :: ModDetails -> HsGroup Name -> TcM (TcGblEnv, TcLclEnv)
601 tcTopSrcDecls boot_details
602 (HsGroup { hs_tyclds = tycl_decls,
603 hs_instds = inst_decls,
604 hs_derivds = deriv_decls,
605 hs_fords = foreign_decls,
606 hs_defds = default_decls,
607 hs_ruleds = rule_decls,
608 hs_valds = val_binds })
609 = do { -- Type-check the type and class decls, and all imported decls
610 -- The latter come in via tycl_decls
611 traceTc (text "Tc2") ;
613 tcg_env <- checkNoErrs (tcTyAndClassDecls boot_details tycl_decls) ;
614 -- tcTyAndClassDecls recovers internally, but if anything gave rise to
615 -- an error we'd better stop now, to avoid a cascade
617 -- Make these type and class decls available to stuff slurped from interface files
618 writeMutVar (tcg_type_env_var tcg_env) (tcg_type_env tcg_env) ;
621 setGblEnv tcg_env $ do {
622 -- Source-language instances, including derivings,
623 -- and import the supporting declarations
624 traceTc (text "Tc3") ;
625 (tcg_env, inst_infos, deriv_binds)
626 <- tcInstDecls1 tycl_decls inst_decls deriv_decls;
627 setGblEnv tcg_env $ do {
629 -- Foreign import declarations next. No zonking necessary
630 -- here; we can tuck them straight into the global environment.
631 traceTc (text "Tc4") ;
632 (fi_ids, fi_decls) <- tcForeignImports foreign_decls ;
633 tcExtendGlobalValEnv fi_ids $ do {
635 -- Default declarations
636 traceTc (text "Tc4a") ;
637 default_tys <- tcDefaults default_decls ;
638 updGblEnv (\gbl -> gbl { tcg_default = default_tys }) $ do {
640 -- Value declarations next
641 -- We also typecheck any extra binds that came out
642 -- of the "deriving" process (deriv_binds)
643 traceTc (text "Tc5") ;
644 (tc_val_binds, tcl_env) <- tcTopBinds (val_binds `plusHsValBinds` deriv_binds) ;
645 setLclTypeEnv tcl_env $ do {
647 -- Second pass over class and instance declarations,
648 traceTc (text "Tc6") ;
649 (inst_binds, tcl_env) <- tcInstDecls2 tycl_decls inst_infos ;
650 showLIE (text "after instDecls2") ;
653 -- They need to be zonked, so we return them
654 traceTc (text "Tc7") ;
655 (foe_binds, foe_decls) <- tcForeignExports foreign_decls ;
658 rules <- tcRules rule_decls ;
661 traceTc (text "Tc7a") ;
662 tcg_env <- getGblEnv ;
663 let { all_binds = tc_val_binds `unionBags`
664 inst_binds `unionBags`
667 -- Extend the GblEnv with the (as yet un-zonked)
668 -- bindings, rules, foreign decls
669 tcg_env' = tcg_env { tcg_binds = tcg_binds tcg_env `unionBags` all_binds,
670 tcg_rules = tcg_rules tcg_env ++ rules,
671 tcg_fords = tcg_fords tcg_env ++ foe_decls ++ fi_decls } } ;
672 return (tcg_env', tcl_env)
677 %************************************************************************
681 %************************************************************************
684 checkMain :: TcM TcGblEnv
685 -- If we are in module Main, check that 'main' is defined.
687 = do { ghc_mode <- getGhcMode ;
688 tcg_env <- getGblEnv ;
690 let { main_mod = mainModIs dflags ;
691 main_fn = case mainFunIs dflags of {
692 Just fn -> mkRdrUnqual (mkVarOccFS (mkFastString fn)) ;
693 Nothing -> main_RDR_Unqual } } ;
695 check_main ghc_mode tcg_env main_mod main_fn
699 check_main ghc_mode tcg_env main_mod main_fn
701 = traceTc (text "checkMain not" <+> ppr main_mod <+> ppr mod) >>
705 = addErrCtxt mainCtxt $
706 do { mb_main <- lookupSrcOcc_maybe main_fn
707 -- Check that 'main' is in scope
708 -- It might be imported from another module!
710 Nothing -> do { traceTc (text "checkMain fail" <+> ppr main_mod <+> ppr main_fn)
714 { traceTc (text "checkMain found" <+> ppr main_mod <+> ppr main_fn)
715 ; let { rhs = nlHsApp (nlHsVar runMainIOName) (nlHsVar main_name) }
716 -- :Main.main :: IO () = runMainIO main
718 ; (main_expr, ty) <- setSrcSpan (srcLocSpan (getSrcLoc main_name)) $
721 -- The function that the RTS invokes is always :Main.main,
722 -- which we call root_main_id.
723 -- (Because GHC allows the user to have a module not called
724 -- Main as the main module, we can't rely on the main function
725 -- being called "Main.main". That's why root_main_id has a fixed
727 -- We also make root_main_id an implicit Id, by making main_name
728 -- its parent (hence (Just main_name)). That has the effect
729 -- of preventing its type and unfolding from getting out into
730 -- the interface file. Otherwise we can end up with two defns
731 -- for 'main' in the interface file!
733 ; let { root_main_name = mkExternalName rootMainKey rOOT_MAIN
734 (mkVarOccFS FSLIT("main"))
735 (getSrcLoc main_name)
736 ; root_main_id = Id.mkExportedLocalId root_main_name ty
737 ; main_bind = noLoc (VarBind root_main_id main_expr) }
739 ; return (tcg_env { tcg_binds = tcg_binds tcg_env
741 tcg_dus = tcg_dus tcg_env
742 `plusDU` usesOnly (unitFV main_name)
743 -- Record the use of 'main', so that we don't
744 -- complain about it being defined but not used
748 mod = tcg_mod tcg_env
750 complain_no_main | ghc_mode == Interactive = return ()
751 | otherwise = failWithTc noMainMsg
752 -- In interactive mode, don't worry about the absence of 'main'
753 -- In other modes, fail altogether, so that we don't go on
754 -- and complain a second time when processing the export list.
756 mainCtxt = ptext SLIT("When checking the type of the main function") <+> quotes (ppr main_fn)
757 noMainMsg = ptext SLIT("The main function") <+> quotes (ppr main_fn)
758 <+> ptext SLIT("is not defined in module") <+> quotes (ppr main_mod)
761 %*********************************************************
765 %*********************************************************
769 setInteractiveContext :: HscEnv -> InteractiveContext -> TcRn a -> TcRn a
770 setInteractiveContext hsc_env icxt thing_inside
772 -- Initialise the tcg_inst_env with instances
773 -- from all home modules. This mimics the more selective
774 -- call to hptInstances in tcRnModule
775 dfuns = hptInstances hsc_env (\mod -> True)
777 updGblEnv (\env -> env {
778 tcg_rdr_env = ic_rn_gbl_env icxt,
779 tcg_type_env = ic_type_env icxt,
780 tcg_inst_env = extendInstEnvList (tcg_inst_env env) dfuns }) $
782 updLclEnv (\env -> env { tcl_rdr = ic_rn_local_env icxt }) $
784 do { traceTc (text "setIC" <+> ppr (ic_type_env icxt))
791 -> InteractiveContext
793 -> IO (Maybe (InteractiveContext, [Name], LHsExpr Id))
794 -- The returned [Name] is the same as the input except for
795 -- ExprStmt, in which case the returned [Name] is [itName]
797 -- The returned TypecheckedHsExpr is of type IO [ () ],
798 -- a list of the bound values, coerced to ().
800 tcRnStmt hsc_env ictxt rdr_stmt
801 = initTcPrintErrors hsc_env iNTERACTIVE $
802 setInteractiveContext hsc_env ictxt $ do {
804 -- Rename; use CmdLineMode because tcRnStmt is only used interactively
805 (([rn_stmt], _), fvs) <- rnStmts DoExpr [rdr_stmt] (return ((), emptyFVs)) ;
806 traceRn (text "tcRnStmt" <+> vcat [ppr rdr_stmt, ppr rn_stmt, ppr fvs]) ;
809 -- The real work is done here
810 (bound_ids, tc_expr) <- mkPlan rn_stmt ;
811 zonked_expr <- zonkTopLExpr tc_expr ;
812 zonked_ids <- zonkTopBndrs bound_ids ;
814 -- None of the Ids should be of unboxed type, because we
815 -- cast them all to HValues in the end!
816 mappM bad_unboxed (filter (isUnLiftedType . idType) zonked_ids) ;
818 traceTc (text "tcs 1") ;
819 let { -- (a) Make all the bound ids "global" ids, now that
820 -- they're notionally top-level bindings. This is
821 -- important: otherwise when we come to compile an expression
822 -- using these ids later, the byte code generator will consider
823 -- the occurrences to be free rather than global.
825 -- (b) Tidy their types; this is important, because :info may
826 -- ask to look at them, and :info expects the things it looks
827 -- up to have tidy types
828 global_ids = map globaliseAndTidy zonked_ids ;
830 -- Update the interactive context
831 rn_env = ic_rn_local_env ictxt ;
832 type_env = ic_type_env ictxt ;
834 bound_names = map idName global_ids ;
835 new_rn_env = extendLocalRdrEnv rn_env bound_names ;
837 {- ---------------------------------------------
838 At one stage I removed any shadowed bindings from the type_env;
839 they are inaccessible but might, I suppose, cause a space leak if we leave them there.
840 However, with Template Haskell they aren't necessarily inaccessible. Consider this
842 Prelude> let f n = n * 2 :: Int
843 Prelude> fName <- runQ [| f |]
844 Prelude> $(return $ AppE fName (LitE (IntegerL 7)))
846 Prelude> let f n = n * 3 :: Int
847 Prelude> $(return $ AppE fName (LitE (IntegerL 7)))
848 In the last line we use 'fName', which resolves to the *first* 'f'
849 in scope. If we delete it from the type env, GHCi crashes because
850 it doesn't expect that.
852 Hence this code is commented out
854 shadowed = [ n | name <- bound_names,
855 let rdr_name = mkRdrUnqual (nameOccName name),
856 Just n <- [lookupLocalRdrEnv rn_env rdr_name] ] ;
857 filtered_type_env = delListFromNameEnv type_env shadowed ;
858 -------------------------------------------------- -}
860 new_type_env = extendTypeEnvWithIds type_env global_ids ;
861 new_ic = ictxt { ic_rn_local_env = new_rn_env,
862 ic_type_env = new_type_env }
865 dumpOptTcRn Opt_D_dump_tc
866 (vcat [text "Bound Ids" <+> pprWithCommas ppr global_ids,
867 text "Typechecked expr" <+> ppr zonked_expr]) ;
869 returnM (new_ic, bound_names, zonked_expr)
872 bad_unboxed id = addErr (sep [ptext SLIT("GHCi can't bind a variable of unlifted type:"),
873 nest 2 (ppr id <+> dcolon <+> ppr (idType id))])
875 globaliseAndTidy :: Id -> Id
877 -- Give the Id a Global Name, and tidy its type
878 = Id.setIdType (globaliseId VanillaGlobal id) tidy_type
880 tidy_type = tidyTopType (idType id)
883 Here is the grand plan, implemented in tcUserStmt
885 What you type The IO [HValue] that hscStmt returns
886 ------------- ------------------------------------
887 let pat = expr ==> let pat = expr in return [coerce HVal x, coerce HVal y, ...]
890 pat <- expr ==> expr >>= \ pat -> return [coerce HVal x, coerce HVal y, ...]
893 expr (of IO type) ==> expr >>= \ it -> return [coerce HVal it]
894 [NB: result not printed] bindings: [it]
896 expr (of non-IO type, ==> let it = expr in print it >> return [coerce HVal it]
897 result showable) bindings: [it]
899 expr (of non-IO type,
900 result not showable) ==> error
904 ---------------------------
905 type PlanResult = ([Id], LHsExpr Id)
906 type Plan = TcM PlanResult
908 runPlans :: [Plan] -> TcM PlanResult
909 -- Try the plans in order. If one fails (by raising an exn), try the next.
910 -- If one succeeds, take it.
911 runPlans [] = panic "runPlans"
913 runPlans (p:ps) = tryTcLIE_ (runPlans ps) p
916 mkPlan :: LStmt Name -> TcM PlanResult
917 mkPlan (L loc (ExprStmt expr _ _)) -- An expression typed at the prompt
918 = do { uniq <- newUnique -- is treated very specially
919 ; let fresh_it = itName uniq
920 the_bind = L loc $ mkFunBind (L loc fresh_it) matches
921 matches = [mkMatch [] expr emptyLocalBinds]
922 let_stmt = L loc $ LetStmt (HsValBinds (ValBindsOut [(NonRecursive,unitBag the_bind)] []))
923 bind_stmt = L loc $ BindStmt (nlVarPat fresh_it) expr
924 (HsVar bindIOName) noSyntaxExpr
925 print_it = L loc $ ExprStmt (nlHsApp (nlHsVar printName) (nlHsVar fresh_it))
926 (HsVar thenIOName) placeHolderType
929 -- [it <- e; print it] but not if it::()
931 -- [let it = e; print it]
932 ; runPlans [ -- Plan A
933 do { stuff@([it_id], _) <- tcGhciStmts [bind_stmt, print_it]
934 ; it_ty <- zonkTcType (idType it_id)
935 ; ifM (isUnitTy it_ty) failM
938 -- Plan B; a naked bind statment
939 tcGhciStmts [bind_stmt],
941 -- Plan C; check that the let-binding is typeable all by itself.
942 -- If not, fail; if so, try to print it.
943 -- The two-step process avoids getting two errors: one from
944 -- the expression itself, and one from the 'print it' part
945 -- This two-step story is very clunky, alas
946 do { checkNoErrs (tcGhciStmts [let_stmt])
947 --- checkNoErrs defeats the error recovery of let-bindings
948 ; tcGhciStmts [let_stmt, print_it] }
951 mkPlan stmt@(L loc (BindStmt {}))
952 | [L _ v] <- collectLStmtBinders stmt -- One binder, for a bind stmt
953 = do { let print_v = L loc $ ExprStmt (nlHsApp (nlHsVar printName) (nlHsVar v))
954 (HsVar thenIOName) placeHolderType
956 ; print_bind_result <- doptM Opt_PrintBindResult
957 ; let print_plan = do
958 { stuff@([v_id], _) <- tcGhciStmts [stmt, print_v]
959 ; v_ty <- zonkTcType (idType v_id)
960 ; ifM (isUnitTy v_ty || not (isTauTy v_ty)) failM
964 -- [stmt; print v] but not if v::()
966 ; runPlans ((if print_bind_result then [print_plan] else []) ++
967 [tcGhciStmts [stmt]])
973 ---------------------------
974 tcGhciStmts :: [LStmt Name] -> TcM PlanResult
976 = do { ioTyCon <- tcLookupTyCon ioTyConName ;
977 ret_id <- tcLookupId returnIOName ; -- return @ IO
979 io_ty = mkTyConApp ioTyCon [] ;
980 ret_ty = mkListTy unitTy ;
981 io_ret_ty = mkTyConApp ioTyCon [ret_ty] ;
982 tc_io_stmts stmts = tcStmts DoExpr (tcDoStmt io_ty) stmts
983 (emptyRefinement, io_ret_ty) ;
985 names = map unLoc (collectLStmtsBinders stmts) ;
987 -- mk_return builds the expression
988 -- returnIO @ [()] [coerce () x, .., coerce () z]
990 -- Despite the inconvenience of building the type applications etc,
991 -- this *has* to be done in type-annotated post-typecheck form
992 -- because we are going to return a list of *polymorphic* values
993 -- coerced to type (). If we built a *source* stmt
994 -- return [coerce x, ..., coerce z]
995 -- then the type checker would instantiate x..z, and we wouldn't
996 -- get their *polymorphic* values. (And we'd get ambiguity errs
997 -- if they were overloaded, since they aren't applied to anything.)
998 mk_return ids = nlHsApp (nlHsTyApp ret_id [ret_ty])
999 (noLoc $ ExplicitList unitTy (map mk_item ids)) ;
1000 mk_item id = nlHsApp (nlHsTyApp unsafeCoerceId [idType id, unitTy])
1004 -- OK, we're ready to typecheck the stmts
1005 traceTc (text "tcs 2") ;
1006 ((tc_stmts, ids), lie) <- getLIE $ tc_io_stmts stmts $ \ _ ->
1007 mappM tcLookupId names ;
1008 -- Look up the names right in the middle,
1009 -- where they will all be in scope
1011 -- Simplify the context
1012 const_binds <- checkNoErrs (tcSimplifyInteractive lie) ;
1013 -- checkNoErrs ensures that the plan fails if context redn fails
1015 return (ids, mkHsDictLet const_binds $
1016 noLoc (HsDo DoExpr tc_stmts (mk_return ids) io_ret_ty))
1021 tcRnExpr just finds the type of an expression
1025 -> InteractiveContext
1028 tcRnExpr hsc_env ictxt rdr_expr
1029 = initTcPrintErrors hsc_env iNTERACTIVE $
1030 setInteractiveContext hsc_env ictxt $ do {
1032 (rn_expr, fvs) <- rnLExpr rdr_expr ;
1035 -- Now typecheck the expression;
1036 -- it might have a rank-2 type (e.g. :t runST)
1037 ((tc_expr, res_ty), lie) <- getLIE (tcInferRho rn_expr) ;
1038 ((qtvs, _, dict_ids), lie_top) <- getLIE (tcSimplifyInfer smpl_doc (tyVarsOfType res_ty) lie) ;
1039 tcSimplifyInteractive lie_top ;
1040 qtvs' <- mappM zonkQuantifiedTyVar qtvs ;
1042 let { all_expr_ty = mkForAllTys qtvs' $
1043 mkFunTys (map idType dict_ids) $
1045 zonkTcType all_expr_ty
1048 smpl_doc = ptext SLIT("main expression")
1051 tcRnType just finds the kind of a type
1055 -> InteractiveContext
1058 tcRnType hsc_env ictxt rdr_type
1059 = initTcPrintErrors hsc_env iNTERACTIVE $
1060 setInteractiveContext hsc_env ictxt $ do {
1062 rn_type <- rnLHsType doc rdr_type ;
1065 -- Now kind-check the type
1066 (ty', kind) <- kcHsType rn_type ;
1070 doc = ptext SLIT("In GHCi input")
1076 %************************************************************************
1078 More GHCi stuff, to do with browsing and getting info
1080 %************************************************************************
1084 -- ASSUMES that the module is either in the HomePackageTable or is
1085 -- a package module with an interface on disk. If neither of these is
1086 -- true, then the result will be an error indicating the interface
1087 -- could not be found.
1088 getModuleExports :: HscEnv -> Module -> IO (Messages, Maybe [AvailInfo])
1089 getModuleExports hsc_env mod
1090 = initTc hsc_env HsSrcFile iNTERACTIVE (tcGetModuleExports mod)
1092 tcGetModuleExports :: Module -> TcM [AvailInfo]
1093 tcGetModuleExports mod = do
1094 let doc = ptext SLIT("context for compiling statements")
1095 iface <- initIfaceTcRn $ loadSysInterface doc mod
1096 loadOrphanModules (dep_orphs (mi_deps iface)) False
1097 -- Load any orphan-module interfaces,
1098 -- so their instances are visible
1099 loadOrphanModules (dep_finsts (mi_deps iface)) True
1100 -- Load any family instance-module interfaces,
1101 -- so all family instances are visible
1102 ifaceExportNames (mi_exports iface)
1104 tcRnLookupRdrName :: HscEnv -> RdrName -> IO (Maybe [Name])
1105 tcRnLookupRdrName hsc_env rdr_name
1106 = initTcPrintErrors hsc_env iNTERACTIVE $
1107 setInteractiveContext hsc_env (hsc_IC hsc_env) $
1108 lookup_rdr_name rdr_name
1110 lookup_rdr_name rdr_name = do {
1111 -- If the identifier is a constructor (begins with an
1112 -- upper-case letter), then we need to consider both
1113 -- constructor and type class identifiers.
1114 let { rdr_names = dataTcOccs rdr_name } ;
1116 -- results :: [Either Messages Name]
1117 results <- mapM (tryTcErrs . lookupOccRn) rdr_names ;
1119 traceRn (text "xx" <+> vcat [ppr rdr_names, ppr (map snd results)]);
1120 -- The successful lookups will be (Just name)
1121 let { (warns_s, good_names) = unzip [ (msgs, name)
1122 | (msgs, Just name) <- results] ;
1123 errs_s = [msgs | (msgs, Nothing) <- results] } ;
1125 -- Fail if nothing good happened, else add warnings
1126 if null good_names then
1127 -- No lookup succeeded, so
1128 -- pick the first error message and report it
1129 -- ToDo: If one of the errors is "could be Foo.X or Baz.X",
1130 -- while the other is "X is not in scope",
1131 -- we definitely want the former; but we might pick the latter
1132 do { addMessages (head errs_s) ; failM }
1133 else -- Add deprecation warnings
1134 mapM_ addMessages warns_s ;
1140 tcRnLookupName :: HscEnv -> Name -> IO (Maybe TyThing)
1141 tcRnLookupName hsc_env name
1142 = initTcPrintErrors hsc_env iNTERACTIVE $
1143 setInteractiveContext hsc_env (hsc_IC hsc_env) $
1147 tcRnGetInfo :: HscEnv
1149 -> IO (Maybe (TyThing, Fixity, [Instance]))
1151 -- Used to implemnent :info in GHCi
1153 -- Look up a RdrName and return all the TyThings it might be
1154 -- A capitalised RdrName is given to us in the DataName namespace,
1155 -- but we want to treat it as *both* a data constructor
1156 -- *and* as a type or class constructor;
1157 -- hence the call to dataTcOccs, and we return up to two results
1158 tcRnGetInfo hsc_env name
1159 = initTcPrintErrors hsc_env iNTERACTIVE $
1160 let ictxt = hsc_IC hsc_env in
1161 setInteractiveContext hsc_env ictxt $ do
1163 -- Load the interface for all unqualified types and classes
1164 -- That way we will find all the instance declarations
1165 -- (Packages have not orphan modules, and we assume that
1166 -- in the home package all relevant modules are loaded.)
1167 loadUnqualIfaces ictxt
1169 thing <- tcLookupGlobal name
1170 fixity <- lookupFixityRn name
1171 ispecs <- lookupInsts (icPrintUnqual ictxt) thing
1172 return (thing, fixity, ispecs)
1175 lookupInsts :: PrintUnqualified -> TyThing -> TcM [Instance]
1176 -- Filter the instances by the ones whose tycons (or clases resp)
1177 -- are in scope unqualified. Otherwise we list a whole lot too many!
1178 lookupInsts print_unqual (AClass cls)
1179 = do { inst_envs <- tcGetInstEnvs
1181 | ispec <- classInstances inst_envs cls
1182 , plausibleDFun print_unqual (instanceDFunId ispec) ] }
1184 lookupInsts print_unqual (ATyCon tc)
1185 = do { eps <- getEps -- Load all instances for all classes that are
1186 -- in the type environment (which are all the ones
1187 -- we've seen in any interface file so far)
1188 ; (pkg_ie, home_ie) <- tcGetInstEnvs -- Search all
1190 | ispec <- instEnvElts home_ie ++ instEnvElts pkg_ie
1191 , let dfun = instanceDFunId ispec
1193 , plausibleDFun print_unqual dfun ] }
1195 relevant df = tc_name `elemNameSet` tyClsNamesOfDFunHead (idType df)
1196 tc_name = tyConName tc
1198 lookupInsts print_unqual other = return []
1200 plausibleDFun print_unqual dfun -- Dfun involving only names that print unqualified
1201 = all ok (nameSetToList (tyClsNamesOfType (idType dfun)))
1203 ok name | isBuiltInSyntax name = True
1204 | isExternalName name =
1205 isNothing $ fst print_unqual (nameModule name)
1209 loadUnqualIfaces :: InteractiveContext -> TcM ()
1210 -- Load the home module for everything that is in scope unqualified
1211 -- This is so that we can accurately report the instances for
1213 loadUnqualIfaces ictxt
1215 mapM_ (loadSysInterface doc) (moduleSetElts (mkModuleSet unqual_mods))
1217 unqual_mods = [ nameModule name
1218 | gre <- globalRdrEnvElts (ic_rn_gbl_env ictxt),
1219 let name = gre_name gre,
1220 not (isInternalName name),
1221 isTcOcc (nameOccName name), -- Types and classes only
1222 unQualOK gre ] -- In scope unqualified
1223 doc = ptext SLIT("Need interface for module whose export(s) are in scope unqualified")
1227 %************************************************************************
1231 %************************************************************************
1234 rnDump :: SDoc -> TcRn ()
1235 -- Dump, with a banner, if -ddump-rn
1236 rnDump doc = do { dumpOptTcRn Opt_D_dump_rn (mkDumpDoc "Renamer" doc) }
1238 tcDump :: TcGblEnv -> TcRn ()
1240 = do { dflags <- getDOpts ;
1242 -- Dump short output if -ddump-types or -ddump-tc
1243 ifM (dopt Opt_D_dump_types dflags || dopt Opt_D_dump_tc dflags)
1244 (dumpTcRn short_dump) ;
1246 -- Dump bindings if -ddump-tc
1247 dumpOptTcRn Opt_D_dump_tc (mkDumpDoc "Typechecker" full_dump)
1250 short_dump = pprTcGblEnv env
1251 full_dump = pprLHsBinds (tcg_binds env)
1252 -- NB: foreign x-d's have undefined's in their types;
1253 -- hence can't show the tc_fords
1256 = do { dflags <- getDOpts ;
1257 ifM (dopt Opt_D_dump_types dflags || dopt Opt_D_dump_tc dflags)
1258 (dumpTcRn (pprModGuts mod_guts)) ;
1260 -- Dump bindings if -ddump-tc
1261 dumpOptTcRn Opt_D_dump_tc (mkDumpDoc "Typechecker" full_dump) }
1263 full_dump = pprCoreBindings (mg_binds mod_guts)
1265 -- It's unpleasant having both pprModGuts and pprModDetails here
1266 pprTcGblEnv :: TcGblEnv -> SDoc
1267 pprTcGblEnv (TcGblEnv { tcg_type_env = type_env,
1269 tcg_fam_insts = fam_insts,
1271 tcg_imports = imports })
1272 = vcat [ ppr_types insts type_env
1273 , ppr_tycons fam_insts type_env
1275 , ppr_fam_insts fam_insts
1276 , vcat (map ppr rules)
1277 , ppr_gen_tycons (typeEnvTyCons type_env)
1278 , ptext SLIT("Dependent modules:") <+> ppr (eltsUFM (imp_dep_mods imports))
1279 , ptext SLIT("Dependent packages:") <+> ppr (imp_dep_pkgs imports)]
1281 pprModGuts :: ModGuts -> SDoc
1282 pprModGuts (ModGuts { mg_types = type_env,
1284 = vcat [ ppr_types [] type_env,
1287 ppr_types :: [Instance] -> TypeEnv -> SDoc
1288 ppr_types insts type_env
1289 = text "TYPE SIGNATURES" $$ nest 4 (ppr_sigs ids)
1291 dfun_ids = map instanceDFunId insts
1292 ids = [id | id <- typeEnvIds type_env, want_sig id]
1293 want_sig id | opt_PprStyle_Debug = True
1294 | otherwise = isLocalId id &&
1295 isExternalName (idName id) &&
1296 not (id `elem` dfun_ids)
1297 -- isLocalId ignores data constructors, records selectors etc.
1298 -- The isExternalName ignores local dictionary and method bindings
1299 -- that the type checker has invented. Top-level user-defined things
1300 -- have External names.
1302 ppr_tycons :: [FamInst] -> TypeEnv -> SDoc
1303 ppr_tycons fam_insts type_env
1304 = text "TYPE CONSTRUCTORS" $$ nest 4 (ppr_tydecls tycons)
1306 fi_tycons = map famInstTyCon fam_insts
1307 tycons = [tycon | tycon <- typeEnvTyCons type_env, want_tycon tycon]
1308 want_tycon tycon | opt_PprStyle_Debug = True
1309 | otherwise = not (isImplicitTyCon tycon) &&
1310 isExternalName (tyConName tycon) &&
1311 not (tycon `elem` fi_tycons)
1313 ppr_insts :: [Instance] -> SDoc
1314 ppr_insts [] = empty
1315 ppr_insts ispecs = text "INSTANCES" $$ nest 2 (pprInstances ispecs)
1317 ppr_fam_insts :: [FamInst] -> SDoc
1318 ppr_fam_insts [] = empty
1319 ppr_fam_insts fam_insts =
1320 text "FAMILY INSTANCES" $$ nest 2 (pprFamInsts fam_insts)
1322 ppr_sigs :: [Var] -> SDoc
1324 -- Print type signatures; sort by OccName
1325 = vcat (map ppr_sig (sortLe le_sig ids))
1327 le_sig id1 id2 = getOccName id1 <= getOccName id2
1328 ppr_sig id = ppr id <+> dcolon <+> ppr (tidyTopType (idType id))
1330 ppr_tydecls :: [TyCon] -> SDoc
1332 -- Print type constructor info; sort by OccName
1333 = vcat (map ppr_tycon (sortLe le_sig tycons))
1335 le_sig tycon1 tycon2 = getOccName tycon1 <= getOccName tycon2
1337 | isCoercionTyCon tycon = ptext SLIT("coercion") <+> ppr tycon
1338 | otherwise = ppr (tyThingToIfaceDecl (ATyCon tycon))
1340 ppr_rules :: [CoreRule] -> SDoc
1341 ppr_rules [] = empty
1342 ppr_rules rs = vcat [ptext SLIT("{-# RULES"),
1343 nest 4 (pprRules rs),
1346 ppr_gen_tycons [] = empty
1347 ppr_gen_tycons tcs = vcat [ptext SLIT("Tycons with generics:"),
1348 nest 2 (fsep (map ppr (filter tyConHasGenerics tcs)))]