\begin{code}
module TcMonoType ( tcHsType, tcHsSigType, tcHsBoxedSigType,
- tcContext, tcClassContext,
+ tcContext, tcClassContext, checkAmbiguity,
-- Kind checking
kcHsTyVar, kcHsTyVars, mkTyClTyVars,
#include "HsVersions.h"
-import HsSyn ( HsType(..), HsTyVarBndr(..), HsUsageAnn(..),
+import HsSyn ( HsType(..), HsTyVarBndr(..),
Sig(..), HsPred(..), pprParendHsType, HsTupCon(..), hsTyVarNames )
import RnHsSyn ( RenamedHsType, RenamedHsPred, RenamedContext, RenamedSig )
import TcHsSyn ( TcId )
import TcMonad
-import TcEnv ( tcExtendTyVarEnv, tcLookupTy, tcGetValueEnv, tcGetInScopeTyVars,
- tcExtendUVarEnv, tcLookupUVar,
- tcGetGlobalTyVars, valueEnvIds,
- TyThing(..), tcExtendKindEnv
+import TcEnv ( tcExtendTyVarEnv, tcExtendKindEnv,
+ tcLookupGlobal, tcLookup,
+ tcEnvTcIds, tcEnvTyVars,
+ tcGetGlobalTyVars,
+ TyThing(..), TcTyThing(..)
)
import TcType ( TcType, TcKind, TcTyVar, TcThetaType, TcTauType,
newKindVar, tcInstSigVar,
instFunDeps, instFunDepsOfTheta )
import FunDeps ( tyVarFunDep, oclose )
import TcUnify ( unifyKind, unifyOpenTypeKind )
-import Type ( Type, Kind, PredType(..), ThetaType, UsageAnn(..),
- mkTyVarTy, mkTyVarTys, mkFunTy, mkSynTy, mkUsgTy,
- mkUsForAllTy, zipFunTys, hoistForAllTys,
+import Type ( Type, Kind, PredType(..), ThetaType,
+ mkTyVarTy, mkTyVarTys, mkFunTy, mkSynTy,
+ zipFunTys, hoistForAllTys,
mkSigmaTy, mkPredTy, mkTyConApp,
mkAppTys, splitForAllTys, splitRhoTy, mkRhoTy,
boxedTypeKind, unboxedTypeKind, mkArrowKind,
mkArrowKinds, getTyVar_maybe, getTyVar, splitFunTy_maybe,
tidyOpenType, tidyOpenTypes, tidyTyVar, tidyTyVars,
tyVarsOfType, tyVarsOfPred, mkForAllTys,
- classesOfPreds, isUnboxedTupleType
+ classesOfPreds,
)
import PprType ( pprType, pprPred )
import Subst ( mkTopTyVarSubst, substTy )
-import Id ( mkVanillaId, idName, idType, idFreeTyVars )
-import Var ( TyVar, mkTyVar, tyVarKind, mkNamedUVar )
+import Id ( Id, mkVanillaId, idName, idType, idFreeTyVars )
+import Var ( Var, TyVar, mkTyVar, tyVarKind )
import VarEnv
import VarSet
import ErrUtils ( Message )
-import TyCon ( TyCon, isSynTyCon, tyConArity, tyConKind, tyConName )
+import TyCon ( TyCon, isSynTyCon, tyConArity, tyConKind )
import Class ( ClassContext, classArity, classTyCon )
-import Name ( Name, isLocallyDefined )
+import Name ( Name )
import TysWiredIn ( mkListTy, mkTupleTy, genUnitTyCon )
import UniqFM ( elemUFM )
import BasicTypes ( Boxity(..) )
import SrcLoc ( SrcLoc )
import Util ( mapAccumL, isSingleton )
import Outputable
-
+import HscTypes ( TyThing(..) )
\end{code}
\begin{code}
tcHsTyVars :: [HsTyVarBndr Name]
- -> TcM s a -- The kind checker
- -> ([TyVar] -> TcM s b)
- -> TcM s b
+ -> TcM a -- The kind checker
+ -> ([TyVar] -> TcM b)
+ -> TcM b
tcHsTyVars [] kind_check thing_inside = thing_inside []
-- A useful short cut for a common case!
tcExtendTyVarEnv tyvars (thing_inside tyvars)
tcTyVars :: [Name]
- -> TcM s a -- The kind checker
- -> TcM s [TyVar]
+ -> TcM a -- The kind checker
+ -> TcM [TyVar]
tcTyVars [] kind_check = returnTc []
tcTyVars tv_names kind_check
\begin{code}
-kcHsTyVar :: HsTyVarBndr name -> NF_TcM s (name, TcKind)
-kcHsTyVars :: [HsTyVarBndr name] -> NF_TcM s [(name, TcKind)]
+kcHsTyVar :: HsTyVarBndr name -> NF_TcM (name, TcKind)
+kcHsTyVars :: [HsTyVarBndr name] -> NF_TcM [(name, TcKind)]
kcHsTyVar (UserTyVar name) = newNamedKindVar name
kcHsTyVar (IfaceTyVar name kind) = returnNF_Tc (name, kind)
returnNF_Tc (name, kind)
---------------------------
-kcBoxedType :: RenamedHsType -> TcM s ()
+kcBoxedType :: RenamedHsType -> TcM ()
-- The type ty must be a *boxed* *type*
kcBoxedType ty
= kcHsType ty `thenTc` \ kind ->
unifyKind boxedTypeKind kind
---------------------------
-kcTypeType :: RenamedHsType -> TcM s ()
+kcTypeType :: RenamedHsType -> TcM ()
-- The type ty must be a *type*, but it can be boxed or unboxed.
kcTypeType ty
= kcHsType ty `thenTc` \ kind ->
unifyOpenTypeKind kind
---------------------------
-kcHsSigType, kcHsBoxedSigType :: RenamedHsType -> TcM s ()
+kcHsSigType, kcHsBoxedSigType :: RenamedHsType -> TcM ()
-- Used for type signatures
kcHsSigType = kcTypeType
kcHsBoxedSigType = kcBoxedType
---------------------------
-kcHsType :: RenamedHsType -> TcM s TcKind
+kcHsType :: RenamedHsType -> TcM TcKind
kcHsType (HsTyVar name) = kcTyVar name
kcHsType (HsUsgTy _ ty) = kcHsType ty
kcHsType (HsUsgForAllTy _ ty) = kcHsType ty
returnTc boxedTypeKind
---------------------------
-kcTyVar name
- = tcLookupTy name `thenTc` \ thing ->
- case thing of
- ATyVar tv -> returnTc (tyVarKind tv)
- ATyCon tc -> returnTc (tyConKind tc)
- AThing k -> returnTc k
- other -> failWithTc (wrongThingErr "type" thing name)
-
----------------------------
-kcFunResType :: RenamedHsType -> TcM s TcKind
+kcFunResType :: RenamedHsType -> TcM TcKind
-- The only place an unboxed tuple type is allowed
-- is at the right hand end of an arrow
kcFunResType (HsTupleTy (HsTupCon _ Unboxed) tys)
---------------------------
kcHsContext ctxt = mapTc_ kcHsPred ctxt
-kcHsPred :: RenamedHsPred -> TcM s ()
+kcHsPred :: RenamedHsPred -> TcM ()
kcHsPred pred@(HsPIParam name ty)
= tcAddErrCtxt (appKindCtxt (ppr pred)) $
kcBoxedType ty
kcHsPred pred@(HsPClass cls tys)
= tcAddErrCtxt (appKindCtxt (ppr pred)) $
- tcLookupTy cls `thenNF_Tc` \ thing ->
- (case thing of
- AClass cls -> returnTc (tyConKind (classTyCon cls))
- AThing kind -> returnTc kind
- other -> failWithTc (wrongThingErr "class" thing cls)) `thenTc` \ kind ->
- mapTc kcHsType tys `thenTc` \ arg_kinds ->
+ kcClass cls `thenTc` \ kind ->
+ mapTc kcHsType tys `thenTc` \ arg_kinds ->
unifyKind kind (mkArrowKinds arg_kinds boxedTypeKind)
+
+---------------------------
+kcTyVar name -- Could be a tyvar or a tycon
+ = tcLookup name `thenTc` \ thing ->
+ case thing of
+ AThing kind -> returnTc kind
+ ATyVar tv -> returnTc (tyVarKind tv)
+ AGlobal (ATyCon tc) -> returnTc (tyConKind tc)
+ other -> failWithTc (wrongThingErr "type" thing name)
+
+kcClass cls -- Must be a class
+ = tcLookup cls `thenNF_Tc` \ thing ->
+ case thing of
+ AThing kind -> returnTc kind
+ AGlobal (AClass cls) -> returnTc (tyConKind (classTyCon cls))
+ other -> failWithTc (wrongThingErr "class" thing cls)
\end{code}
%************************************************************************
so the kind returned is indeed a Kind not a TcKind
\begin{code}
-tcHsSigType :: RenamedHsType -> TcM s TcType
+tcHsSigType :: RenamedHsType -> TcM TcType
tcHsSigType ty
= kcTypeType ty `thenTc_`
tcHsType ty `thenTc` \ ty' ->
returnTc (hoistForAllTys ty')
-tcHsBoxedSigType :: RenamedHsType -> TcM s Type
+tcHsBoxedSigType :: RenamedHsType -> TcM Type
tcHsBoxedSigType ty
= kcBoxedType ty `thenTc_`
tcHsType ty `thenTc` \ ty' ->
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\begin{code}
-tcHsType :: RenamedHsType -> TcM s Type
+tcHsType :: RenamedHsType -> TcM Type
tcHsType ty@(HsTyVar name)
= tc_app ty []
= tcClassAssertion True pred `thenTc` \ pred' ->
returnTc (mkPredTy pred')
-tcHsType (HsUsgTy usg ty)
- = newUsg usg `thenTc` \ usg' ->
- tcHsType ty `thenTc` \ tc_ty ->
- returnTc (mkUsgTy usg' tc_ty)
- where
- newUsg usg = case usg of
- HsUsOnce -> returnTc UsOnce
- HsUsMany -> returnTc UsMany
- HsUsVar uv_name -> tcLookupUVar uv_name `thenTc` \ uv ->
- returnTc (UsVar uv)
-
-tcHsType (HsUsgForAllTy uv_name ty)
- = let
- uv = mkNamedUVar uv_name
- in
- tcExtendUVarEnv uv_name uv $
- tcHsType ty `thenTc` \ tc_ty ->
- returnTc (mkUsForAllTy uv tc_ty)
-
tcHsType full_ty@(HsForAllTy (Just tv_names) ctxt ty)
= let
kind_check = kcHsContext ctxt `thenTc_` kcFunResType ty
tcHsTyVars tv_names kind_check $ \ tyvars ->
tcContext ctxt `thenTc` \ theta ->
tcHsType ty `thenTc` \ tau ->
- checkAmbiguity full_ty tyvars theta tau `thenTc_`
- returnTc (mkSigmaTy tyvars theta tau)
+ checkAmbiguity is_source tyvars theta tau
+ where
+ is_source = case tv_names of
+ (UserTyVar _ : _) -> True
+ other -> False
+checkAmbiguity :: Bool -> [TyVar] -> ThetaType -> Type -> TcM Type
-- Check for ambiguity
-- forall V. P => tau
-- is ambiguous if P contains generic variables
-- even in a scope where b is in scope.
-- This is the is_free test below.
-checkAmbiguity full_ty forall_tyvars theta tau
- = mapTc check_pred theta
- where
- tau_vars = tyVarsOfType tau
- fds = instFunDepsOfTheta theta
- tvFundep = tyVarFunDep fds
- extended_tau_vars = oclose tvFundep tau_vars
-
- is_ambig ct_var = (ct_var `elem` forall_tyvars) &&
- not (ct_var `elemUFM` extended_tau_vars)
- is_free ct_var = not (ct_var `elem` forall_tyvars)
-
- check_pred pred = checkTc (not any_ambig) (ambigErr pred full_ty) `thenTc_`
- checkTc (not all_free) (freeErr pred full_ty)
- where
- ct_vars = varSetElems (tyVarsOfPred pred)
- all_free = all is_free ct_vars
- any_ambig = is_source_polytype && any is_ambig ct_vars
-
-- Notes on the 'is_source_polytype' test above
-- Check ambiguity only for source-program types, not
-- for types coming from inteface files. The latter can
-- If the list of tv_names is empty, we have a monotype,
-- and then we don't need to check for ambiguity either,
-- because the test can't fail (see is_ambig).
- is_source_polytype
- = case full_ty of
- HsForAllTy (Just (UserTyVar _ : _)) _ _ -> True
- other -> False
+
+checkAmbiguity is_source_polytype forall_tyvars theta tau
+ = mapTc_ check_pred theta `thenTc_`
+ returnTc sigma_ty
+ where
+ sigma_ty = mkSigmaTy forall_tyvars theta tau
+ tau_vars = tyVarsOfType tau
+ fds = instFunDepsOfTheta theta
+ tvFundep = tyVarFunDep fds
+ extended_tau_vars = oclose tvFundep tau_vars
+
+ is_ambig ct_var = (ct_var `elem` forall_tyvars) &&
+ not (ct_var `elemUFM` extended_tau_vars)
+ is_free ct_var = not (ct_var `elem` forall_tyvars)
+
+ check_pred pred = checkTc (not any_ambig) (ambigErr pred sigma_ty) `thenTc_`
+ checkTc (not all_free) (freeErr pred sigma_ty)
+ where
+ ct_vars = varSetElems (tyVarsOfPred pred)
+ all_free = all is_free ct_vars
+ any_ambig = is_source_polytype && any is_ambig ct_vars
\end{code}
Help functions for type applications
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\begin{code}
-tc_app :: RenamedHsType -> [RenamedHsType] -> TcM s Type
+tc_app :: RenamedHsType -> [RenamedHsType] -> TcM Type
tc_app (HsAppTy ty1 ty2) tys
= tc_app ty1 (ty2:tys)
-- hence the rather strange functionality.
tc_fun_type name arg_tys
- = tcLookupTy name `thenTc` \ thing ->
+ = tcLookup name `thenTc` \ thing ->
case thing of
ATyVar tv -> returnTc (mkAppTys (mkTyVarTy tv) arg_tys)
- ATyCon tc | isSynTyCon tc -> checkTc arity_ok err_msg `thenTc_`
- returnTc (mkAppTys (mkSynTy tc (take arity arg_tys))
+ AGlobal (ATyCon tc)
+ | isSynTyCon tc -> checkTc arity_ok err_msg `thenTc_`
+ returnTc (mkAppTys (mkSynTy tc (take arity arg_tys))
(drop arity arg_tys))
- | otherwise -> returnTc (mkTyConApp tc arg_tys)
- where
+ | otherwise -> returnTc (mkTyConApp tc arg_tys)
+ where
arity_ok = arity <= n_args
arity = tyConArity tc
Contexts
~~~~~~~~
\begin{code}
-tcClassContext :: RenamedContext -> TcM s ClassContext
+tcClassContext :: RenamedContext -> TcM ClassContext
-- Used when we are expecting a ClassContext (i.e. no implicit params)
tcClassContext context
= tcContext context `thenTc` \ theta ->
returnTc (classesOfPreds theta)
-tcContext :: RenamedContext -> TcM s ThetaType
+tcContext :: RenamedContext -> TcM ThetaType
tcContext context = mapTc (tcClassAssertion False) context
tcClassAssertion ccall_ok assn@(HsPClass class_name tys)
= tcAddErrCtxt (appKindCtxt (ppr assn)) $
mapTc tcHsType tys `thenTc` \ arg_tys ->
- tcLookupTy class_name `thenTc` \ thing ->
+ tcLookupGlobal class_name `thenTc` \ thing ->
case thing of
AClass clas -> checkTc (arity == n_tys) err `thenTc_`
returnTc (Class clas arg_tys)
n_tys = length tys
err = arityErr "Class" class_name arity n_tys
- other -> failWithTc (wrongThingErr "class" thing class_name)
+ other -> failWithTc (wrongThingErr "class" (AGlobal thing) class_name)
tcClassAssertion ccall_ok assn@(HsPIParam name ty)
= tcAddErrCtxt (appKindCtxt (ppr assn)) $
\begin{code}
-tcTySig :: RenamedSig -> TcM s TcSigInfo
+tcTySig :: RenamedSig -> TcM TcSigInfo
tcTySig (Sig v ty src_loc)
= tcAddSrcLoc src_loc $
mkTcSig (mkVanillaId v sigma_tc_ty) src_loc `thenNF_Tc` \ sig ->
returnTc sig
-mkTcSig :: TcId -> SrcLoc -> NF_TcM s TcSigInfo
+mkTcSig :: TcId -> SrcLoc -> NF_TcM TcSigInfo
mkTcSig poly_id src_loc
= -- Instantiate this type
-- It's important to do this even though in the error-free case
-> TcTyVarSet -- Tyvars that are free in the type signature
-- These should *already* be in the global-var set, and are
-- used here only to improve the error message
- -> TcM s [TcTyVar] -- Zonked signature type variables
+ -> TcM [TcTyVar] -- Zonked signature type variables
checkSigTyVars [] free = returnTc []
-- from the zonked tyvar to the in-scope one
-- If any of the in-scope tyvars zonk to a type, then ignore them;
-- that'll be caught later when we back up to their type sig
- tcGetInScopeTyVars `thenNF_Tc` \ in_scope_tvs ->
+ tcGetEnv `thenNF_Tc` \ env ->
+ let
+ in_scope_tvs = tcEnvTyVars env
+ in
zonkTcTyVars in_scope_tvs `thenNF_Tc` \ in_scope_tys ->
let
in_scope_assoc = [ (zonked_tv, in_scope_tv)
main_msg = ptext SLIT("Inferred type is less polymorphic than expected")
- check (env, acc, msgs) (sig_tyvar,ty)
+ check (tidy_env, acc, msgs) (sig_tyvar,ty)
-- sig_tyvar is from the signature;
-- ty is what you get if you zonk sig_tyvar and then tidy it
--
-- acc maps a zonked type variable back to a signature type variable
= case getTyVar_maybe ty of {
Nothing -> -- Error (a)!
- returnNF_Tc (env, acc, unify_msg sig_tyvar (ppr ty) : msgs) ;
+ returnNF_Tc (tidy_env, acc, unify_msg sig_tyvar (ppr ty) : msgs) ;
Just tv ->
case lookupVarEnv acc tv of {
Just sig_tyvar' -> -- Error (b) or (d)!
- returnNF_Tc (env, acc, unify_msg sig_tyvar (ppr sig_tyvar') : msgs) ;
+ returnNF_Tc (tidy_env, acc, unify_msg sig_tyvar (ppr sig_tyvar') : msgs) ;
Nothing ->
if tv `elemVarSet` globals -- Error (c)! Type variable escapes
-- The least comprehensible, so put it last
- then tcGetValueEnv `thenNF_Tc` \ ve ->
- find_globals tv env [] (valueEnvIds ve) `thenNF_Tc` \ (env1, globs) ->
- find_frees tv env1 [] (varSetElems free_tyvars) `thenNF_Tc` \ (env2, frees) ->
- returnNF_Tc (env2, acc, escape_msg sig_tyvar tv globs frees : msgs)
+ -- Game plan:
+ -- a) get the local TcIds from the environment,
+ -- and pass them to find_globals (they might have tv free)
+ -- b) similarly, find any free_tyvars that mention tv
+ then tcGetEnv `thenNF_Tc` \ tc_env ->
+ find_globals tv tidy_env [] (tcEnvTcIds tc_env) `thenNF_Tc` \ (tidy_env1, globs) ->
+ find_frees tv tidy_env1 [] (varSetElems free_tyvars) `thenNF_Tc` \ (tidy_env2, frees) ->
+ returnNF_Tc (tidy_env2, acc, escape_msg sig_tyvar tv globs frees : msgs)
else -- All OK
- returnNF_Tc (env, extendVarEnv acc tv sig_tyvar, msgs)
+ returnNF_Tc (tidy_env, extendVarEnv acc tv sig_tyvar, msgs)
}}
-- find_globals looks at the value environment and finds values
-- whose types mention the offending type variable. It has to be
-- careful to zonk the Id's type first, so it has to be in the monad.
-- We must be careful to pass it a zonked type variable, too.
+
+find_globals :: Var
+ -> TidyEnv
+ -> [(Name,Type)]
+ -> [Id]
+ -> NF_TcM (TidyEnv,[(Name,Type)])
+
find_globals tv tidy_env acc []
= returnNF_Tc (tidy_env, acc)
find_globals tv tidy_env acc (id:ids)
- | not (isLocallyDefined id) ||
- isEmptyVarSet (idFreeTyVars id)
+ | isEmptyVarSet (idFreeTyVars id)
= find_globals tv tidy_env acc ids
| otherwise
\begin{code}
sigCtxt :: Message -> [TcTyVar] -> TcThetaType -> TcTauType
- -> TidyEnv -> NF_TcM s (TidyEnv, Message)
+ -> TidyEnv -> NF_TcM (TidyEnv, Message)
sigCtxt when sig_tyvars sig_theta sig_tau tidy_env
= zonkTcType sig_tau `thenNF_Tc` \ actual_tau ->
let
appKindCtxt :: SDoc -> Message
appKindCtxt pp = ptext SLIT("When checking kinds in") <+> quotes pp
-wrongThingErr expected actual name
- = pp_actual actual <+> quotes (ppr name) <+> ptext SLIT("used as a") <+> text expected
+wrongThingErr expected thing name
+ = pp_thing thing <+> quotes (ppr name) <+> ptext SLIT("used as a") <+> text expected
where
- pp_actual (ATyCon _) = ptext SLIT("Type constructor")
- pp_actual (AClass _) = ptext SLIT("Class")
- pp_actual (ATyVar _) = ptext SLIT("Type variable")
- pp_actual (AThing _) = ptext SLIT("Utterly bogus")
+ pp_thing (AGlobal (ATyCon _)) = ptext SLIT("Type constructor")
+ pp_thing (AGlobal (AClass _)) = ptext SLIT("Class")
+ pp_thing (AGlobal (AnId _)) = ptext SLIT("Identifier")
+ pp_thing (ATyVar _) = ptext SLIT("Type variable")
+ pp_thing (ATcId _) = ptext SLIT("Local identifier")
+ pp_thing (AThing _) = ptext SLIT("Utterly bogus")
ambigErr pred ty
= sep [ptext SLIT("Ambiguous constraint") <+> quotes (pprPred pred),
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