import TcHsSyn ( TcMonoBinds, TcId, zonkId, mkHsLet )
import TcMonad
-import Inst ( LIE, emptyLIE, mkLIE, plusLIE, lieToList, InstOrigin(..),
- newDicts, tyVarsOfInsts, instToId
+import Inst ( LIE, emptyLIE, mkLIE, plusLIE, InstOrigin(..),
+ newDicts, instToId
)
import TcEnv ( tcExtendLocalValEnv,
- newSpecPragmaId, newLocalId,
- tcGetGlobalTyVars
+ newSpecPragmaId, newLocalId
)
-import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyToDicts )
+import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyCheck, tcSimplifyToDicts )
import TcMonoType ( tcHsSigType, checkSigTyVars,
TcSigInfo(..), tcTySig, maybeSig, sigCtxt
)
import TcPat ( tcPat )
import TcSimplify ( bindInstsOfLocalFuns )
-import TcType ( newTyVarTy, newTyVar, zonkTcTyVarsAndFV,
+import TcType ( newTyVarTy, newTyVar,
zonkTcTyVarToTyVar
)
import TcUnify ( unifyTauTy, unifyTauTyLists )
import IdInfo ( InlinePragInfo(..) )
import Name ( Name, getOccName, getSrcLoc )
import NameSet
-import Type ( mkTyVarTy,
+import Type ( mkTyVarTy, tyVarsOfTypes,
mkForAllTys, mkFunTys, tyVarsOfType,
mkPredTy, mkForAllTy, isUnLiftedType,
unliftedTypeKind, liftedTypeKind, openTypeKind
import VarSet
import Bag
import Util ( isIn )
+import ListSetOps ( minusList )
import Maybes ( maybeToBool )
import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isNotTopLevel )
import FiniteMap ( listToFM, lookupFM )
%************************************************************************
\begin{code}
-generalise binder_names mbind tau_tvs lie_req sigs
+generalise_help doc tau_tvs lie_req sigs
-----------------------
- | is_unrestricted && null sigs
+ | null sigs
= -- INFERENCE CASE: Unrestricted group, no type signatures
- tcSimplifyInfer (ptext SLIT("bindings for") <+> pprBinders binder_names)
+ tcSimplifyInfer doc
tau_tvs lie_req
-----------------------
- | is_unrestricted
+ | otherwise
= -- CHECKING CASE: Unrestricted group, there are type signatures
-- Check signature contexts are empty
checkSigsCtxts sigs `thenTc` \ (sig_avails, sig_dicts) ->
-- Check that the needed dicts can be
-- expressed in terms of the signature ones
- tcSimplifyInferCheck check_doc tau_tvs sig_avails lie_req `thenTc` \ (forall_tvs, lie_free, dict_binds) ->
+ tcSimplifyInferCheck doc tau_tvs sig_avails lie_req `thenTc` \ (forall_tvs, lie_free, dict_binds) ->
-- Check that signature type variables are OK
checkSigsTyVars sigs `thenTc_`
returnTc (forall_tvs, lie_free, dict_binds, sig_dicts)
------------------------
- | otherwise -- RESTRICTED CASE: Restricted group
- = -- Check signature contexts are empty
- (if null sigs then
- returnTc ()
- else
- checkSigsCtxts sigs `thenTc` \ (_, sig_dicts) ->
- checkTc (null sig_dicts)
- (restrictedBindCtxtErr binder_names)
- ) `thenTc_`
+generalise binder_names mbind tau_tvs lie_req sigs
+ | is_unrestricted -- UNRESTRICTED CASE
+ = generalise_help doc tau_tvs lie_req sigs
+
+ | otherwise -- RESTRICTED CASE
+ = -- Do a simplification to decide what type variables
+ -- are constrained. We can't just take the free vars
+ -- of lie_req because that'll have methods that may
+ -- incidentally mention entirely unconstrained variables
+ -- e.g. a call to f :: Eq a => a -> b -> b
+ -- Here, b is unconstrained. A good example would be
+ -- foo = f (3::Int)
+ -- We want to infer the polymorphic type
+ -- foo :: forall b. b -> b
+ generalise_help doc tau_tvs lie_req sigs `thenTc` \ (forall_tvs, lie_free, dict_binds, dict_ids) ->
+
+ -- Check signature contexts are empty
+ checkTc (null sigs || null dict_ids)
+ (restrictedBindCtxtErr binder_names) `thenTc_`
-- Identify constrained tyvars
- tcGetGlobalTyVars `thenNF_Tc` \ gbl_tvs ->
- zonkTcTyVarsAndFV tau_tvs `thenNF_Tc` \ tau_tvs' ->
- zonkTcTyVarsAndFV lie_tvs `thenNF_Tc` \ lie_tvs' ->
let
- forall_tvs = tau_tvs' `minusVarSet` (lie_tvs' `unionVarSet` gbl_tvs)
- -- Don't bother to oclose the gbl_tvs; this is a rare case
+ constrained_tvs = varSetElems (tyVarsOfTypes (map idType dict_ids))
+ -- The dict_ids are fully zonked
+ final_forall_tvs = forall_tvs `minusList` constrained_tvs
in
- returnTc (varSetElems forall_tvs, lie_req, EmptyMonoBinds, [])
+
+ -- Now simplify with exactly that set of tyvars
+ -- We have to squash those Methods
+ tcSimplifyCheck doc final_forall_tvs [] lie_req `thenTc` \ (lie_free, binds) ->
+
+ returnTc (final_forall_tvs, lie_free, binds, [])
where
- tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- sigs]
is_unrestricted | opt_NoMonomorphismRestriction = True
| otherwise = isUnRestrictedGroup tysig_names mbind
- lie_tvs = varSetElems (tyVarsOfInsts (lieToList lie_req))
- check_doc = case tysig_names of
- [n] -> ptext SLIT("type signature for") <+> quotes (ppr n)
- other -> ptext SLIT("type signature(s) for") <+> pprBinders tysig_names
+ tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- sigs]
+ doc | null sigs = ptext SLIT("banding(s) for") <+> pprBinders binder_names
+ | otherwise = ptext SLIT("type signature(s) for") <+> pprBinders binder_names
+
+-----------------------
-- CHECK THAT ALL THE SIGNATURE CONTEXTS ARE UNIFIABLE
-- The type signatures on a mutually-recursive group of definitions
-- must all have the same context (or none).
-- We unify them because, with polymorphic recursion, their types
-- might not otherwise be related. This is a rather subtle issue.
-- ToDo: amplify
- --
- -- We return a representative
checkSigsCtxts sigs@(TySigInfo _ id1 sig_tvs theta1 _ _ _ _ : other_sigs)
= mapTc_ check_one other_sigs `thenTc_`
if null theta1 then
isIfaceRuleDecl, nullBinds, andMonoBindList
)
import HsTypes ( toHsType )
-import PrelNames ( mAIN_Name, mainName, ioTyConName, printName )
+import PrelNames ( SyntaxMap, mAIN_Name, mainName, ioTyConName, printName )
import RnHsSyn ( RenamedHsBinds, RenamedHsDecl, RenamedHsExpr )
import TcHsSyn ( TypecheckedMonoBinds, TypecheckedHsExpr,
TypecheckedForeignDecl, TypecheckedRuleDecl,
import TcClassDcl ( tcClassDecls2 )
import TcDefaults ( tcDefaults, defaultDefaultTys )
import TcExpr ( tcMonoExpr )
-import TcEnv ( TcEnv, InstInfo, tcExtendGlobalValEnv, tcLookup_maybe,
+import TcEnv ( TcEnv, RecTcEnv, InstInfo, tcExtendGlobalValEnv, tcLookup_maybe,
isLocalThing, tcSetEnv, tcSetInstEnv, initTcEnv, getTcGEnv,
TcTyThing(..), tcLookupTyCon
)
-> HomeSymbolTable
-> ModIface -- Iface for this module
-> PrintUnqualified -- For error printing
- -> [RenamedHsDecl]
+ -> (SyntaxMap, [RenamedHsDecl])
-> Bool -- True <=> check for Main.main if Module==Main
-> IO (Maybe (PersistentCompilerState, TcResults))
-- The new PCS is Augmented with imported information,
-- (but not stuff from this module)
-typecheckModule dflags pcs hst mod_iface unqual decls check_main
- = do { maybe_tc_result <- typecheck dflags pcs hst unqual $
+typecheckModule dflags pcs hst mod_iface unqual (syn_map, decls) check_main
+ = do { maybe_tc_result <- typecheck dflags syn_map pcs hst unqual $
tcModule pcs hst get_fixity this_mod decls check_main
; printTcDump dflags maybe_tc_result
; return maybe_tc_result }
-> HomeSymbolTable
-> PrintUnqualified -- For error printing
-> Module
- -> (RenamedHsExpr, -- The expression itself
+ -> (SyntaxMap,
+ RenamedHsExpr, -- The expression itself
[RenamedHsDecl]) -- Plus extra decls it sucked in from interface files
-> IO (Maybe (PersistentCompilerState, TypecheckedHsExpr, TcType))
-typecheckExpr dflags wrap_io pcs hst unqual this_mod (expr, decls)
- = typecheck dflags pcs hst unqual $
+typecheckExpr dflags wrap_io pcs hst unqual this_mod (syn_map, expr, decls)
+ = typecheck dflags syn_map pcs hst unqual $
-- use the default default settings, i.e. [Integer, Double]
tcSetDefaultTys defaultDefaultTys $
- tcImports pcs hst get_fixity this_mod decls `thenTc` \ (env, new_pcs, local_inst_info, deriv_binds, local_rules) ->
+
+ -- Typecheck the extra declarations
+ fixTc (\ ~(unf_env, _, _, _, _) ->
+ tcImports unf_env pcs hst get_fixity this_mod decls
+ ) `thenTc` \ (env, new_pcs, local_inst_info, deriv_binds, local_rules) ->
ASSERT( null local_inst_info && nullBinds deriv_binds && null local_rules )
+ -- Now typecheck the expression
tcSetEnv env $
tc_expr expr `thenTc` \ (expr', expr_ty) ->
zonkExpr expr' `thenNF_Tc` \ zonked_expr ->
---------------
typecheck :: DynFlags
+ -> SyntaxMap
-> PersistentCompilerState
-> HomeSymbolTable
-> PrintUnqualified -- For error printing
-> TcM r
-> IO (Maybe r)
-typecheck dflags pcs hst unqual thing_inside
+typecheck dflags syn_map pcs hst unqual thing_inside
= do { showPass dflags "Typechecker";
- ; env <- initTcEnv hst (pcs_PTE pcs)
+ ; env <- initTcEnv syn_map hst (pcs_PTE pcs)
; (maybe_tc_result, errs) <- initTc dflags env thing_inside
-> TcM (PersistentCompilerState, TcResults)
tcModule pcs hst get_fixity this_mod decls check_main
- = -- Type-check the type and class decls, and all imported decls
- -- tcImports recovers internally, but if anything gave rise to
- -- an error we'd better stop now, to avoid a cascade
- checkNoErrsTc (
- tcImports pcs hst get_fixity this_mod decls
- ) `thenTc` \ (env, new_pcs, local_inst_info, deriv_binds, local_rules) ->
+ = fixTc (\ ~(unf_env, _, _) ->
+ -- Loop back the final environment, including the fully zonkec
+ -- versions of bindings from this module. In the presence of mutual
+ -- recursion, interface type signatures may mention variables defined
+ -- in this module, which is why the knot is so big
- tcSetEnv env $
+ -- Type-check the type and class decls, and all imported decls
+ tcImports unf_env pcs hst get_fixity this_mod decls
+ `thenTc` \ (env, new_pcs, local_insts, deriv_binds, local_rules) ->
+
+ tcSetEnv env $
-- Foreign import declarations next
--- traceTc (text "Tc4") `thenNF_Tc_`
- tcForeignImports decls `thenTc` \ (fo_ids, foi_decls) ->
- tcExtendGlobalValEnv fo_ids $
+ traceTc (text "Tc4") `thenNF_Tc_`
+ tcForeignImports decls `thenTc` \ (fo_ids, foi_decls) ->
+ tcExtendGlobalValEnv fo_ids $
-- Default declarations
- tcDefaults decls `thenTc` \ defaulting_tys ->
- tcSetDefaultTys defaulting_tys $
+ tcDefaults decls `thenTc` \ defaulting_tys ->
+ tcSetDefaultTys defaulting_tys $
-- Value declarations next.
-- We also typecheck any extra binds that came out of the "deriving" process
--- traceTc (text "Tc5") `thenNF_Tc_`
- tcTopBinds (val_binds `ThenBinds` deriv_binds) `thenTc` \ ((val_binds, env), lie_valdecls) ->
- tcSetEnv env $
-
- -- Foreign export declarations next
--- traceTc (text "Tc6") `thenNF_Tc_`
- tcForeignExports decls `thenTc` \ (lie_fodecls, foe_binds, foe_decls) ->
-
- -- Second pass over class and instance declarations,
- -- to compile the bindings themselves.
- tcInstDecls2 local_inst_info `thenNF_Tc` \ (lie_instdecls, inst_binds) ->
- tcClassDecls2 this_mod tycl_decls `thenNF_Tc` \ (lie_clasdecls, cls_dm_binds) ->
- tcSourceRules source_rules `thenNF_Tc` \ (lie_rules, more_local_rules) ->
-
- -- Deal with constant or ambiguous InstIds. How could
- -- there be ambiguous ones? They can only arise if a
- -- top-level decl falls under the monomorphism
- -- restriction, and no subsequent decl instantiates its
- -- type. (Usually, ambiguous type variables are resolved
- -- during the generalisation step.)
- let
- lie_alldecls = lie_valdecls `plusLIE`
- lie_instdecls `plusLIE`
- lie_clasdecls `plusLIE`
- lie_fodecls `plusLIE`
- lie_rules
- in
- tcSimplifyTop lie_alldecls `thenTc` \ const_inst_binds ->
-
- -- CHECK THAT main IS DEFINED WITH RIGHT TYPE, IF REQUIRED
- (if check_main
- then tcCheckMain this_mod
- else returnTc ()) `thenTc_`
-
- -- Backsubstitution. This must be done last.
- -- Even tcSimplifyTop may do some unification.
- let
- all_binds = val_binds `AndMonoBinds`
- inst_binds `AndMonoBinds`
- cls_dm_binds `AndMonoBinds`
- const_inst_binds `AndMonoBinds`
- foe_binds
- in
--- traceTc (text "Tc9") `thenNF_Tc_`
- zonkTopBinds all_binds `thenNF_Tc` \ (all_binds', final_env) ->
- tcSetEnv final_env $
- -- zonkTopBinds puts all the top-level Ids into the tcGEnv
- zonkForeignExports foe_decls `thenNF_Tc` \ foe_decls' ->
- zonkRules more_local_rules `thenNF_Tc` \ more_local_rules' ->
-
-
- let local_things = filter (isLocalThing this_mod) (nameEnvElts (getTcGEnv final_env))
-
- -- Create any necessary "implicit" bindings (data constructors etc)
- -- Should we create bindings for dictionary constructors?
- -- They are always fully applied, and the bindings are just there
- -- to support partial applications. But it's easier to let them through.
- implicit_binds = andMonoBindList [ CoreMonoBind id (unfoldingTemplate unf)
- | id <- implicitTyThingIds local_things
- , let unf = idUnfolding id
- , hasUnfolding unf
- ]
-
- local_type_env :: TypeEnv
- local_type_env = mkTypeEnv local_things
-
- all_local_rules = local_rules ++ more_local_rules'
- in
--- traceTc (text "Tc10") `thenNF_Tc_`
- returnTc (new_pcs,
- TcResults { tc_env = local_type_env,
- tc_binds = implicit_binds `AndMonoBinds` all_binds',
- tc_fords = foi_decls ++ foe_decls',
- tc_rules = all_local_rules
- }
- )
+ traceTc (text "Tc5") `thenNF_Tc_`
+ tcTopBinds (val_binds `ThenBinds` deriv_binds) `thenTc` \ ((val_binds, env), lie_valdecls) ->
+
+ -- Second pass over class and instance declarations,
+ -- plus rules and foreign exports, to generate bindings
+ tcSetEnv env $
+ tcInstDecls2 local_insts `thenNF_Tc` \ (lie_instdecls, inst_binds) ->
+ tcClassDecls2 this_mod tycl_decls `thenNF_Tc` \ (lie_clasdecls, cls_dm_binds) ->
+ tcForeignExports decls `thenTc` \ (lie_fodecls, foe_binds, foe_decls) ->
+ tcSourceRules source_rules `thenNF_Tc` \ (lie_rules, more_local_rules) ->
+
+ -- Deal with constant or ambiguous InstIds. How could
+ -- there be ambiguous ones? They can only arise if a
+ -- top-level decl falls under the monomorphism
+ -- restriction, and no subsequent decl instantiates its
+ -- type. (Usually, ambiguous type variables are resolved
+ -- during the generalisation step.)
+ let
+ lie_alldecls = lie_valdecls `plusLIE`
+ lie_instdecls `plusLIE`
+ lie_clasdecls `plusLIE`
+ lie_fodecls `plusLIE`
+ lie_rules
+ in
+ traceTc (text "Tc6") `thenNF_Tc_`
+ tcSimplifyTop lie_alldecls `thenTc` \ const_inst_binds ->
+
+ -- CHECK THAT main IS DEFINED WITH RIGHT TYPE, IF REQUIRED
+ (if check_main
+ then tcCheckMain this_mod
+ else returnTc ()) `thenTc_`
+
+ -- Backsubstitution. This must be done last.
+ -- Even tcSimplifyTop may do some unification.
+ let
+ all_binds = val_binds `AndMonoBinds`
+ inst_binds `AndMonoBinds`
+ cls_dm_binds `AndMonoBinds`
+ const_inst_binds `AndMonoBinds`
+ foe_binds
+ in
+ traceTc (text "Tc7") `thenNF_Tc_`
+ zonkTopBinds all_binds `thenNF_Tc` \ (all_binds', final_env) ->
+ tcSetEnv final_env $
+ -- zonkTopBinds puts all the top-level Ids into the tcGEnv
+ traceTc (text "Tc8") `thenNF_Tc_`
+ zonkForeignExports foe_decls `thenNF_Tc` \ foe_decls' ->
+ traceTc (text "Tc9") `thenNF_Tc_`
+ zonkRules more_local_rules `thenNF_Tc` \ more_local_rules' ->
+
+
+ let local_things = filter (isLocalThing this_mod) (nameEnvElts (getTcGEnv final_env))
+
+ -- Create any necessary "implicit" bindings (data constructors etc)
+ -- Should we create bindings for dictionary constructors?
+ -- They are always fully applied, and the bindings are just there
+ -- to support partial applications. But it's easier to let them through.
+ implicit_binds = andMonoBindList [ CoreMonoBind id (unfoldingTemplate unf)
+ | id <- implicitTyThingIds local_things
+ , let unf = idUnfolding id
+ , hasUnfolding unf
+ ]
+
+ local_type_env :: TypeEnv
+ local_type_env = mkTypeEnv local_things
+
+ all_local_rules = local_rules ++ more_local_rules'
+ in
+ traceTc (text "Tc10") `thenNF_Tc_`
+ returnTc (final_env,
+ new_pcs,
+ TcResults { tc_env = local_type_env,
+ tc_binds = implicit_binds `AndMonoBinds` all_binds',
+ tc_fords = foi_decls ++ foe_decls',
+ tc_rules = all_local_rules
+ }
+ )
+ ) `thenTc` \ (_, pcs, tc_result) ->
+ returnTc (pcs, tc_result)
where
tycl_decls = [d | TyClD d <- decls]
val_binds = foldr ThenBinds EmptyBinds [binds | ValD binds <- decls]
\begin{code}
-tcImports :: PersistentCompilerState
+tcImports :: RecTcEnv
+ -> PersistentCompilerState
-> HomeSymbolTable
-> (Name -> Maybe Fixity)
-> Module
-> [RenamedHsDecl]
- -> TcM (TcEnv, PersistentCompilerState,
- [InstInfo], RenamedHsBinds, [TypecheckedRuleDecl])
+ -> TcM (TcEnv, PersistentCompilerState, [InstInfo],
+ RenamedHsBinds, [TypecheckedRuleDecl])
-- tcImports is a slight mis-nomer.
-- It deals with everythign that could be an import:
-- rule decls
-- These can occur in source code too, of course
-tcImports pcs hst get_fixity this_mod decls
- = fixTc (\ ~(unf_env, _, _, _, _) ->
- -- (unf_env :: RecTcEnv) is used for type-checking interface pragmas
+tcImports unf_env pcs hst get_fixity this_mod decls
+ -- (unf_env :: RecTcEnv) is used for type-checking interface pragmas
-- which is done lazily [ie failure just drops the pragma
-- without having any global-failure effect].
--
-- unf_env is also used to get the pragama info
-- for imported dfuns and default methods
-
--- traceTc (text "Tc1") `thenNF_Tc_`
- tcTyAndClassDecls unf_env tycl_decls `thenTc` \ env ->
- tcSetEnv env $
-
- -- Typecheck the instance decls, includes deriving
--- traceTc (text "Tc2") `thenNF_Tc_`
- tcInstDecls1 (pcs_insts pcs) (pcs_PRS pcs)
- hst unf_env get_fixity this_mod
- decls `thenTc` \ (new_pcs_insts, inst_env, local_inst_info, deriv_binds) ->
- tcSetInstEnv inst_env $
-
- -- Interface type signatures
- -- We tie a knot so that the Ids read out of interfaces are in scope
- -- when we read their pragmas.
- -- What we rely on is that pragmas are typechecked lazily; if
- -- any type errors are found (ie there's an inconsistency)
- -- we silently discard the pragma
--- traceTc (text "Tc3") `thenNF_Tc_`
- tcInterfaceSigs unf_env tycl_decls `thenTc` \ sig_ids ->
- tcExtendGlobalValEnv sig_ids $
-
-
- tcIfaceRules (pcs_rules pcs) this_mod iface_rules `thenNF_Tc` \ (new_pcs_rules, local_rules) ->
- -- When relinking this module from its interface-file decls
- -- we'll have IfaceRules that are in fact local to this module
- -- That's the reason we we get any local_rules out here
- tcGetEnv `thenTc` \ unf_env ->
- let
- all_things = nameEnvElts (getTcGEnv unf_env)
-
- -- sometimes we're compiling in the context of a package module
- -- (on the GHCi command line, for example). In this case, we
- -- want to treat everything we pulled in as an imported thing.
- imported_things
- | isHomeModule this_mod
- = filter (not . isLocalThing this_mod) all_things
- | otherwise
- = all_things
-
- new_pte :: PackageTypeEnv
- new_pte = extendTypeEnvList (pcs_PTE pcs) imported_things
-
- new_pcs :: PersistentCompilerState
- new_pcs = pcs { pcs_PTE = new_pte,
- pcs_insts = new_pcs_insts,
- pcs_rules = new_pcs_rules
- }
- in
- returnTc (unf_env, new_pcs, local_inst_info, deriv_binds, local_rules)
- )
+ = checkNoErrsTc $
+ -- tcImports recovers internally, but if anything gave rise to
+ -- an error we'd better stop now, to avoid a cascade
+
+ traceTc (text "Tc1") `thenNF_Tc_`
+ tcTyAndClassDecls unf_env tycl_decls `thenTc` \ env ->
+ tcSetEnv env $
+
+ -- Typecheck the instance decls, includes deriving
+ traceTc (text "Tc2") `thenNF_Tc_`
+ tcInstDecls1 (pcs_insts pcs) (pcs_PRS pcs)
+ hst unf_env get_fixity this_mod
+ decls `thenTc` \ (new_pcs_insts, inst_env, local_insts, deriv_binds) ->
+ tcSetInstEnv inst_env $
+
+ -- Interface type signatures
+ -- We tie a knot so that the Ids read out of interfaces are in scope
+ -- when we read their pragmas.
+ -- What we rely on is that pragmas are typechecked lazily; if
+ -- any type errors are found (ie there's an inconsistency)
+ -- we silently discard the pragma
+ traceTc (text "Tc3") `thenNF_Tc_`
+ tcInterfaceSigs unf_env tycl_decls `thenTc` \ sig_ids ->
+ tcExtendGlobalValEnv sig_ids $
+
+
+ tcIfaceRules (pcs_rules pcs) this_mod iface_rules `thenNF_Tc` \ (new_pcs_rules, local_rules) ->
+ -- When relinking this module from its interface-file decls
+ -- we'll have IfaceRules that are in fact local to this module
+ -- That's the reason we we get any local_rules out here
+
+ tcGetEnv `thenTc` \ unf_env ->
+ let
+ all_things = nameEnvElts (getTcGEnv unf_env)
+
+ -- sometimes we're compiling in the context of a package module
+ -- (on the GHCi command line, for example). In this case, we
+ -- want to treat everything we pulled in as an imported thing.
+ imported_things
+ | isHomeModule this_mod
+ = filter (not . isLocalThing this_mod) all_things
+ | otherwise
+ = all_things
+
+ new_pte :: PackageTypeEnv
+ new_pte = extendTypeEnvList (pcs_PTE pcs) imported_things
+
+ new_pcs :: PersistentCompilerState
+ new_pcs = pcs { pcs_PTE = new_pte,
+ pcs_insts = new_pcs_insts,
+ pcs_rules = new_pcs_rules
+ }
+ in
+ returnTc (unf_env, new_pcs, local_insts, deriv_binds, local_rules)
where
tycl_decls = [d | TyClD d <- decls]
iface_rules = [d | RuleD d <- decls, isIfaceRuleDecl d]
getDictClassTys, getIPs, isTyVarDict,
instLoc, pprInst, zonkInst, tidyInst, tidyInsts,
Inst, LIE, pprInsts, pprInstsInFull,
- mkLIE, plusLIE, isEmptyLIE,
- lieToList
+ mkLIE, lieToList
)
import TcEnv ( tcGetGlobalTyVars, tcGetInstEnv )
import InstEnv ( lookupInstEnv, classInstEnv, InstLookupResult(..) )
-- Check for non-generalisable insts
mapTc_ addCantGenErr (filter (not . instCanBeGeneralised) irreds) `thenTc_`
- returnTc (qtvs, frees, binds, map instToId irreds)
+ returnTc (qtvs, mkLIE frees, binds, map instToId irreds)
inferLoop doc tau_tvs wanteds
= -- Step 1
-- Step 3
if no_improvement then
- returnTc (varSetElems qtvs, frees, binds, irreds)
+ returnTc (varSetElems qtvs, frees, binds, irreds)
else
- -- We start again with irreds, not wanteds
- -- Using an instance decl might have introduced a fresh type variable
- -- which might have been unified, so we'd get an infinite loop
- -- if we started again with wanteds! See example [LOOP]
- inferLoop doc tau_tvs irreds `thenTc` \ (qtvs1, frees1, binds1, irreds1) ->
- returnTc (qtvs1, frees1 `plusLIE` frees, binds `AndMonoBinds` binds1, irreds1)
+ -- If improvement did some unification, we go round again. There
+ -- are two subtleties:
+ -- a) We start again with irreds, not wanteds
+ -- Using an instance decl might have introduced a fresh type variable
+ -- which might have been unified, so we'd get an infinite loop
+ -- if we started again with wanteds! See example [LOOP]
+ --
+ -- b) It's also essential to re-process frees, because unification
+ -- might mean that a type variable that looked free isn't now.
+ --
+ -- Hence the (irreds ++ frees)
+
+ inferLoop doc tau_tvs (irreds ++ frees) `thenTc` \ (qtvs1, frees1, binds1, irreds1) ->
+ returnTc (qtvs1, frees1, binds `AndMonoBinds` binds1, irreds1)
\end{code}
Example [LOOP]
%************************************************************************
@tcSimplifyCheck@ is used when we know exactly the set of variables
-we are going to quantify over.
+we are going to quantify over. For example, a class or instance declaration.
\begin{code}
tcSimplifyCheck
complainCheck doc givens irreds `thenNF_Tc_`
-- Done
- returnTc (frees, binds)
+ returnTc (mkLIE frees, binds)
checkLoop doc qtvs givens wanteds
= -- Step 1
-- Step 3
if no_improvement then
- returnTc (frees, binds, irreds)
+ returnTc (frees, binds, irreds)
else
- checkLoop doc qtvs givens irreds `thenTc` \ (frees1, binds1, irreds1) ->
- returnTc (frees `plusLIE` frees1, binds `AndMonoBinds` binds1, irreds1)
+ checkLoop doc qtvs givens' (irreds ++ frees) `thenTc` \ (frees1, binds1, irreds1) ->
+ returnTc (frees1, binds `AndMonoBinds` binds1, irreds1)
complainCheck doc givens irreds
= mapNF_Tc zonkInst given_dicts `thenNF_Tc` \ givens' ->
@tcSimplifyInferCheck@ is used when we know the consraints we are to simplify
against, but we don't know the type variables over which we are going to quantify.
+This happens when we have a type signature for a mutually recursive
+group.
\begin{code}
tcSimplifyInferCheck
complainCheck doc givens irreds `thenNF_Tc_`
-- Done
- returnTc (qtvs, frees, binds)
+ returnTc (qtvs, mkLIE frees, binds)
inferCheckLoop doc tau_tvs givens wanteds
= -- Step 1
-- Step 3
if no_improvement then
- returnTc (varSetElems qtvs, frees, binds, irreds)
+ returnTc (varSetElems qtvs, frees, binds, irreds)
else
- inferCheckLoop doc tau_tvs givens wanteds `thenTc` \ (qtvs1, frees1, binds1, irreds1) ->
- returnTc (qtvs1, frees1 `plusLIE` frees, binds `AndMonoBinds` binds1, irreds1)
+ inferCheckLoop doc tau_tvs givens' (irreds ++ frees) `thenTc` \ (qtvs1, frees1, binds1, irreds1) ->
+ returnTc (qtvs1, frees1, binds `AndMonoBinds` binds1, irreds1)
\end{code}
-
%************************************************************************
%* *
\subsection{tcSimplifyToDicts}
= simpleReduceLoop doc try_me wanteds `thenTc` \ (frees, binds, irreds) ->
-- Since try_me doesn't look at types, we don't need to
-- do any zonking, so it's safe to call reduceContext directly
- ASSERT( isEmptyLIE frees )
+ ASSERT( null frees )
returnTc (irreds, binds)
where
-- The irreducible ones should be a subset of the implicit
-- parameters we provided
ASSERT( all here_ip irreds )
- returnTc (frees, binds)
+ returnTc (mkLIE frees, binds)
where
doc = text "tcSimplifyIPs" <+> ppr ip_names
| otherwise
= simpleReduceLoop doc try_me wanteds `thenTc` \ (frees, binds, irreds) ->
ASSERT( null irreds )
- returnTc (frees, binds)
+ returnTc (mkLIE frees, binds)
where
doc = text "bindInsts" <+> ppr local_ids
wanteds = lieToList init_lie
simpleReduceLoop :: SDoc
-> (Inst -> WhatToDo) -- What to do, *not* based on the quantified type variables
-> [Inst] -- Wanted
- -> TcM (LIE, -- Free
+ -> TcM ([Inst], -- Free
TcDictBinds,
[Inst]) -- Irreducible
if no_improvement then
returnTc (frees, binds, irreds)
else
- simpleReduceLoop doc try_me irreds `thenTc` \ (frees1, binds1, irreds1) ->
- returnTc (frees `plusLIE` frees1, binds `AndMonoBinds` binds1, irreds1)
+ simpleReduceLoop doc try_me (irreds ++ frees) `thenTc` \ (frees1, binds1, irreds1) ->
+ returnTc (frees1, binds `AndMonoBinds` binds1, irreds1)
\end{code}
-> [Inst] -- Given
-> [Inst] -- Wanted
-> NF_TcM (Bool, -- True <=> improve step did no unification
- LIE, -- Free
+ [Inst], -- Free
TcDictBinds, -- Dictionary bindings
[Inst]) -- Irreducible
let
(binds, irreds) = bindsAndIrreds avails wanteds
in
- returnTc (no_improvement, mkLIE frees, binds, irreds)
+ returnTc (no_improvement, frees, binds, irreds)
tcImprove avails
= tcGetInstEnv `thenTc` \ inst_env ->
tcSimplifyTop :: LIE -> TcM TcDictBinds
tcSimplifyTop wanted_lie
= simpleReduceLoop (text "tcSimplTop") try_me wanteds `thenTc` \ (frees, binds, irreds) ->
- ASSERT( isEmptyLIE frees )
+ ASSERT( null frees )
let
-- All the non-std ones are definite errors
unifyTauTy chosen_default_ty (mkTyVarTy tyvar) `thenTc_`
simpleReduceLoop (text "disambig" <+> ppr dicts)
try_me dicts `thenTc` \ (frees, binds, ambigs) ->
- WARN( not (isEmptyLIE frees && null ambigs), ppr frees $$ ppr ambigs )
+ WARN( not (null frees && null ambigs), ppr frees $$ ppr ambigs )
warnDefault dicts chosen_default_ty `thenTc_`
returnTc binds
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