\begin{code}
module TcModule (
- typecheckModule,
- TcResults(..)
+ typecheckModule, typecheckExpr, TcResults(..)
) where
#include "HsVersions.h"
import CmdLineOpts ( DynFlag(..), DynFlags, opt_PprStyle_Debug )
-import HsSyn ( HsBinds(..), MonoBinds(..), HsDecl(..) )
+import HsSyn ( HsBinds(..), MonoBinds(..), HsDecl(..), HsExpr(..),
+ isIfaceRuleDecl, nullBinds, andMonoBindList
+ )
import HsTypes ( toHsType )
-import RnHsSyn ( RenamedHsDecl )
-import TcHsSyn ( TypecheckedMonoBinds,
+import PrelNames ( mAIN_Name, mainName, ioTyConName, printName )
+import RnHsSyn ( RenamedHsBinds, RenamedHsDecl, RenamedHsExpr )
+import TcHsSyn ( TypecheckedMonoBinds, TypecheckedHsExpr,
TypecheckedForeignDecl, TypecheckedRuleDecl,
- zonkTopBinds, zonkForeignExports, zonkRules
+ zonkTopBinds, zonkForeignExports, zonkRules, mkHsLet,
+ zonkExpr
)
+
import TcMonad
+import TcType ( newTyVarTy, zonkTcType, tcInstType )
+import TcUnify ( unifyTauTy )
import Inst ( plusLIE )
+import VarSet ( varSetElems )
import TcBinds ( tcTopBinds )
-import TcClassDcl ( tcClassDecls2, mkImplicitClassBinds )
-import TcDefaults ( tcDefaults )
-import TcEnv ( TcEnv, InstInfo(iDFunId), tcExtendGlobalValEnv,
- tcEnvTyCons, tcEnvClasses, isLocalThing,
- RecTcEnv, tcSetEnv, tcSetInstEnv, initTcEnv, getTcGEnv
+import TcClassDcl ( tcClassDecls2 )
+import TcDefaults ( tcDefaults, defaultDefaultTys )
+import TcExpr ( tcMonoExpr )
+import TcEnv ( TcEnv, InstInfo, tcExtendGlobalValEnv, tcLookup_maybe,
+ isLocalThing, tcSetEnv, tcSetInstEnv, initTcEnv, getTcGEnv,
+ TcTyThing(..), tcLookupTyCon
)
-import TcRules ( tcRules )
+import TcRules ( tcIfaceRules, tcSourceRules )
import TcForeign ( tcForeignImports, tcForeignExports )
import TcIfaceSig ( tcInterfaceSigs )
import TcInstDcls ( tcInstDecls1, tcInstDecls2 )
-import TcSimplify ( tcSimplifyTop )
+import TcSimplify ( tcSimplifyTop, tcSimplifyInfer )
import TcTyClsDecls ( tcTyAndClassDecls )
-import TcTyDecls ( mkImplicitDataBinds )
-
-import CoreUnfold ( unfoldingTemplate )
-import Type ( funResultTy, splitForAllTys )
-import Bag ( isEmptyBag )
-import ErrUtils ( printErrorsAndWarnings, dumpIfSet_dyn, showPass )
-import Id ( idType, idUnfolding )
-import Module ( Module )
-import Name ( Name, toRdrName )
+
+import CoreUnfold ( unfoldingTemplate, hasUnfolding )
+import Type ( funResultTy, splitForAllTys, mkForAllTys, mkFunTys,
+ liftedTypeKind, openTypeKind, mkTyConApp, tyVarsOfType, tidyType )
+import ErrUtils ( printErrorsAndWarnings, errorsFound, dumpIfSet_dyn, showPass )
+import Id ( idType, idName, isLocalId, idUnfolding )
+import Module ( Module, isHomeModule, moduleName )
+import Name ( Name, toRdrName, isGlobalName )
import Name ( nameEnvElts, lookupNameEnv )
import TyCon ( tyConGenInfo )
import Util
import BasicTypes ( EP(..), Fixity )
-import Bag ( isEmptyBag )
import Outputable
import HscTypes ( PersistentCompilerState(..), HomeSymbolTable,
- PackageTypeEnv, DFunId, ModIface(..),
+ PackageTypeEnv, ModIface(..),
TypeEnv, extendTypeEnvList,
- TyThing(..), mkTypeEnv )
-import List ( partition )
+ TyThing(..), implicitTyThingIds,
+ mkTypeEnv
+ )
\end{code}
Outside-world interface:
-- Convenient type synonyms first:
data TcResults
= TcResults {
- tc_pcs :: PersistentCompilerState, -- Augmented with imported information,
- -- (but not stuff from this module)
-
-- All these fields have info *just for this module*
tc_env :: TypeEnv, -- The top level TypeEnv
- tc_insts :: [DFunId], -- Instances
tc_binds :: TypecheckedMonoBinds, -- Bindings
tc_fords :: [TypecheckedForeignDecl], -- Foreign import & exports.
tc_rules :: [TypecheckedRuleDecl] -- Transformation rules
---------------
typecheckModule
:: DynFlags
- -> Module
-> PersistentCompilerState
-> HomeSymbolTable
-> ModIface -- Iface for this module
-> PrintUnqualified -- For error printing
-> [RenamedHsDecl]
- -> IO (Maybe TcResults)
-
-typecheckModule dflags this_mod pcs hst mod_iface unqual decls
- = do { showPass dflags "Typechecker";
- ; env <- initTcEnv hst (pcs_PTE pcs)
-
- ; (maybe_result, (warns,errs)) <- initTc dflags env tc_module
+ -> IO (Maybe (PersistentCompilerState, TcResults))
+ -- The new PCS is Augmented with imported information,
+ -- (but not stuff from this module)
- ; let { maybe_tc_result :: Maybe TcResults ;
- maybe_tc_result = case maybe_result of
- Nothing -> Nothing
- Just (_,r) -> Just r }
- ; printErrorsAndWarnings unqual (errs,warns)
+typecheckModule dflags pcs hst mod_iface unqual decls
+ = do { maybe_tc_result <- typecheck dflags pcs hst unqual $
+ tcModule pcs hst get_fixity this_mod decls
; printTcDump dflags maybe_tc_result
-
- ; if isEmptyBag errs then
- return maybe_tc_result
- else
- return Nothing
- }
+ ; return maybe_tc_result }
where
- tc_module :: TcM (RecTcEnv, TcResults)
- tc_module = fixTc (\ ~(unf_env ,_) -> tcModule pcs hst get_fixity this_mod decls unf_env)
-
+ this_mod = mi_module mod_iface
fixity_env = mi_fixities mod_iface
get_fixity :: Name -> Maybe Fixity
get_fixity nm = lookupNameEnv fixity_env nm
+
+---------------
+typecheckExpr :: DynFlags
+ -> Bool -- True <=> wrap in 'print' to get a result of IO type
+ -> PersistentCompilerState
+ -> HomeSymbolTable
+ -> PrintUnqualified -- For error printing
+ -> Module
+ -> (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 $
+
+ -- 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) ->
+ ASSERT( null local_inst_info && nullBinds deriv_binds && null local_rules )
+
+ tcSetEnv env $
+ tc_expr expr `thenTc` \ (expr', lie, expr_ty) ->
+ tcSimplifyInfer smpl_doc
+ (varSetElems (tyVarsOfType expr_ty)) lie `thenTc` \ (qtvs, lie_free, dict_binds, dict_ids) ->
+ tcSimplifyTop lie_free `thenTc` \ const_binds ->
+ let all_expr = mkHsLet const_binds $
+ TyLam qtvs $
+ DictLam dict_ids $
+ mkHsLet dict_binds $
+ expr'
+ all_expr_ty = mkForAllTys qtvs (mkFunTys (map idType dict_ids) expr_ty)
+ in
+ zonkExpr all_expr `thenNF_Tc` \ zonked_expr ->
+ zonkTcType all_expr_ty `thenNF_Tc` \ zonked_ty ->
+ ioToTc (dumpIfSet_dyn dflags
+ Opt_D_dump_tc "Typechecked" (ppr zonked_expr)) `thenNF_Tc_`
+ returnTc (new_pcs, zonked_expr, zonked_ty)
+
+ where
+ get_fixity :: Name -> Maybe Fixity
+ get_fixity n = pprPanic "typecheckExpr" (ppr n)
+
+ smpl_doc = ptext SLIT("main expression")
+
+ -- Typecheck it, wrapping in 'print' if necessary to
+ -- get a result of type IO t. Returns the result type
+ -- that is free in the result type
+ tc_expr e
+ | wrap_io = tryTc_ (tc_io_expr (HsApp (HsVar printName) e)) -- Recovery case
+ (tc_io_expr e) -- Main case
+ | otherwise = newTyVarTy openTypeKind `thenTc` \ ty ->
+ tcMonoExpr expr ty `thenTc` \ (expr', lie) ->
+ returnTc (expr', lie, ty)
+
+ where
+ -- (tc_io_expr e) typechecks 'e' if that gives a result of IO t,
+ -- or 'print e' otherwise. Either way the result is of type IO t
+ tc_io_expr e = newTyVarTy openTypeKind `thenTc` \ ty ->
+ tcLookupTyCon ioTyConName `thenNF_Tc` \ ioTyCon ->
+ let
+ res_ty = mkTyConApp ioTyCon [ty]
+ in
+ tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
+ returnTc (expr', lie, res_ty)
+
+---------------
+typecheck :: DynFlags
+ -> PersistentCompilerState
+ -> HomeSymbolTable
+ -> PrintUnqualified -- For error printing
+ -> TcM r
+ -> IO (Maybe r)
+
+typecheck dflags pcs hst unqual thing_inside
+ = do { showPass dflags "Typechecker";
+ ; env <- initTcEnv hst (pcs_PTE pcs)
+
+ ; (maybe_tc_result, errs) <- initTc dflags env thing_inside
+
+ ; printErrorsAndWarnings unqual errs
+
+ ; if errorsFound errs then
+ return Nothing
+ else
+ return maybe_tc_result
+ }
\end{code}
The internal monster:
-> (Name -> Maybe Fixity)
-> Module
-> [RenamedHsDecl]
- -> RecTcEnv -- The knot-tied environment
- -> TcM (TcEnv, TcResults)
-
- -- (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
-
-tcModule pcs hst get_fixity this_mod decls unf_env
- = -- Type-check the type and class decls
- tcTyAndClassDecls unf_env decls `thenTc` \ env ->
- tcSetEnv env $
- let
- classes = tcEnvClasses env
- tycons = tcEnvTyCons env -- INCLUDES tycons derived from classes
- in
-
- -- Typecheck the instance decls, includes deriving
- tcInstDecls1 (pcs_insts pcs) (pcs_PRS pcs)
- hst unf_env get_fixity this_mod
- tycons decls `thenTc` \ (new_pcs_insts, inst_env, local_inst_info, deriv_binds) ->
- tcSetInstEnv inst_env $
-
- -- Default declarations
- tcDefaults decls `thenTc` \ defaulting_tys ->
- tcSetDefaultTys defaulting_tys $
-
- -- 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
- -- We must do this before mkImplicitDataBinds (which comes next), since
- -- the latter looks up unpackCStringId, for example, which is usually
- -- imported
- tcInterfaceSigs unf_env decls `thenTc` \ sig_ids ->
- tcExtendGlobalValEnv sig_ids $
-
- -- Create any necessary record selector Ids and their bindings
- -- "Necessary" includes data and newtype declarations
- -- We don't create bindings for dictionary constructors;
- -- they are always fully applied, and the bindings are just there
- -- to support partial applications
- mkImplicitDataBinds this_mod tycons `thenTc` \ (data_ids, imp_data_binds) ->
- mkImplicitClassBinds this_mod classes `thenNF_Tc` \ (cls_ids, imp_cls_binds) ->
-
- -- Extend the global value environment with
- -- (a) constructors
- -- (b) record selectors
- -- (c) class op selectors
- -- (d) default-method ids... where? I can't see where these are
- -- put into the envt, and I'm worried that the zonking phase
- -- will find they aren't there and complain.
- tcExtendGlobalValEnv data_ids $
- tcExtendGlobalValEnv cls_ids $
- tcGetEnv `thenTc` \ unf_env ->
-
+ -> TcM (PersistentCompilerState, TcResults)
+
+tcModule pcs hst get_fixity this_mod decls
+ = -- 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) ->
+
+ tcSetEnv env $
+
-- Foreign import declarations next
+-- traceTc (text "Tc4") `thenNF_Tc_`
tcForeignImports decls `thenTc` \ (fo_ids, foi_decls) ->
tcExtendGlobalValEnv fo_ids $
- -- Value declarations next.
- -- We also typecheck any extra binds that came out of the "deriving" process
- tcTopBinds (get_binds decls `ThenBinds` deriv_binds) `thenTc` \ ((val_binds, env), lie_valdecls) ->
+ -- Default declarations
+ 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
+ -- 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 decls `thenNF_Tc` \ (lie_clasdecls, cls_dm_binds) ->
- tcRules (pcs_rules pcs) this_mod decls `thenNF_Tc` \ (new_pcs_rules, lie_rules, local_rules) ->
+ 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
-- during the generalisation step.)
let
lie_alldecls = lie_valdecls `plusLIE`
- lie_instdecls `plusLIE`
- lie_clasdecls `plusLIE`
- lie_fodecls `plusLIE`
- lie_rules
+ 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
+ tcCheckMain this_mod `thenTc_`
-- Backsubstitution. This must be done last.
-- Even tcSimplifyTop may do some unification.
let
- all_binds = imp_data_binds `AndMonoBinds`
- imp_cls_binds `AndMonoBinds`
- val_binds `AndMonoBinds`
+ 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 local_rules `thenNF_Tc` \ local_rules' ->
-
+ zonkRules more_local_rules `thenNF_Tc` \ more_local_rules' ->
- let (local_things, imported_things) = partition (isLocalThing this_mod)
- (nameEnvElts (getTcGEnv final_env))
-
- local_type_env :: TypeEnv
- local_type_env = mkTypeEnv local_things
- new_pte :: PackageTypeEnv
- new_pte = extendTypeEnvList (pcs_PTE pcs) imported_things
-
- final_pcs :: PersistentCompilerState
- final_pcs = pcs { pcs_PTE = new_pte,
- pcs_insts = new_pcs_insts,
- pcs_rules = new_pcs_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
- returnTc (unf_env,
- TcResults { tc_pcs = final_pcs,
- tc_env = local_type_env,
- tc_binds = all_binds',
- tc_insts = map iDFunId local_inst_info,
+-- 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 = local_rules'
+ tc_rules = all_local_rules
}
)
-
-get_binds decls = foldr ThenBinds EmptyBinds [binds | ValD binds <- decls]
+ where
+ tycl_decls = [d | TyClD d <- decls]
+ val_binds = foldr ThenBinds EmptyBinds [binds | ValD binds <- decls]
+ source_rules = [d | RuleD d <- decls, not (isIfaceRuleDecl d)]
\end{code}
+\begin{code}
+tcImports :: PersistentCompilerState
+ -> HomeSymbolTable
+ -> (Name -> Maybe Fixity)
+ -> Module
+ -> [RenamedHsDecl]
+ -> TcM (TcEnv, PersistentCompilerState,
+ [InstInfo], RenamedHsBinds, [TypecheckedRuleDecl])
+
+-- tcImports is a slight mis-nomer.
+-- It deals with everythign that could be an import:
+-- type and class decls
+-- interface signatures
+-- instance decls
+-- 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
+ -- 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) ->
+
+ 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)
+ )
+ where
+ tycl_decls = [d | TyClD d <- decls]
+ iface_rules = [d | RuleD d <- decls, isIfaceRuleDecl d]
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{Checking the type of main}
+%* *
+%************************************************************************
+
+We must check that in module Main,
+ a) main is defined
+ b) main :: forall a1...an. IO t, for some type t
+
+If we have
+ main = error "Urk"
+then the type of main will be
+ main :: forall a. a
+and that should pass the test too.
+
+So we just instantiate the type and unify with IO t, and declare
+victory if doing so succeeds.
+
+\begin{code}
+tcCheckMain :: Module -> TcM ()
+tcCheckMain this_mod
+ | not (moduleName this_mod == mAIN_Name )
+ = returnTc ()
+
+ | otherwise
+ = -- First unify the main_id with IO t, for any old t
+ tcLookup_maybe mainName `thenNF_Tc` \ maybe_thing ->
+ case maybe_thing of
+ Just (ATcId main_id) -> check_main_ty (idType main_id)
+ other -> addErrTc noMainErr
+ where
+ check_main_ty main_ty
+ = tcInstType main_ty `thenNF_Tc` \ (tvs, theta, main_tau) ->
+ newTyVarTy liftedTypeKind `thenNF_Tc` \ arg_ty ->
+ tcLookupTyCon ioTyConName `thenNF_Tc` \ ioTyCon ->
+ tcAddErrCtxtM (mainTypeCtxt main_ty) $
+ if not (null theta) then
+ failWithTc empty -- Context has the error message
+ else
+ unifyTauTy main_tau (mkTyConApp ioTyCon [arg_ty])
+
+mainTypeCtxt main_ty tidy_env
+ = zonkTcType main_ty `thenNF_Tc` \ main_ty' ->
+ returnNF_Tc (tidy_env, ptext SLIT("`main' has the illegal type") <+>
+ quotes (ppr (tidyType tidy_env main_ty')))
+
+noMainErr = hsep [ptext SLIT("Module") <+> quotes (ppr mAIN_Name),
+ ptext SLIT("must include a definition for") <+> quotes (ptext SLIT("main"))]
+\end{code}
+
%************************************************************************
%* *
\begin{code}
printTcDump dflags Nothing = return ()
-printTcDump dflags (Just results)
+printTcDump dflags (Just (_, results))
= do dumpIfSet_dyn dflags Opt_D_dump_types
"Type signatures" (dump_sigs results)
dumpIfSet_dyn dflags Opt_D_dump_tc
ppr_sig (n,t) = ppr n <+> dcolon <+> ppr t
want_sig id | opt_PprStyle_Debug = True
- | otherwise = True -- For now
+ | otherwise = isLocalId id && isGlobalName (idName id)
+ -- isLocalId ignores data constructors, records selectors etc
+ -- The isGlobalName ignores local dictionary and method bindings
+ -- that the type checker has invented. User-defined things have
+ -- Global names.
ppr_gen_tycons tcs = vcat [ptext SLIT("{-# Generic type constructor details"),
vcat (map ppr_gen_tycon tcs),