\section[TcMonoType]{Typechecking user-specified @MonoTypes@}
\begin{code}
-module TcMonoType ( tcHsSigType, tcHsType, tcIfaceType, tcHsTheta,
+module TcMonoType ( tcHsSigType, tcHsType, tcIfaceType, tcHsTheta, tcHsPred,
UserTypeCtxt(..),
-- Kind checking
kcHsLiftedSigType, kcHsContext,
tcAddScopedTyVars, tcHsTyVars, mkImmutTyVars,
- TcSigInfo(..), tcTySig, mkTcSig, maybeSig
+ TcSigInfo(..), tcTySig, mkTcSig, maybeSig, tcSigPolyId, tcSigMonoId
) where
#include "HsVersions.h"
-import HsSyn ( HsType(..), HsTyVarBndr(..),
+import HsSyn ( HsType(..), HsTyVarBndr(..), HsTyOp(..),
Sig(..), HsPred(..), pprParendHsType, HsTupCon(..), hsTyVarNames )
import RnHsSyn ( RenamedHsType, RenamedHsPred, RenamedContext, RenamedSig, extractHsTyVars )
import TcHsSyn ( TcId )
tcInLocalScope,
TyThing(..), TcTyThing(..), tcExtendKindEnv
)
-import TcMType ( newKindVar, tcInstSigTyVars, zonkKindEnv,
+import TcMType ( newKindVar, zonkKindEnv, tcInstType,
checkValidType, UserTypeCtxt(..), pprUserTypeCtxt
)
import TcUnify ( unifyKind, unifyOpenTypeKind )
import TcType ( Type, Kind, SourceType(..), ThetaType, TyVarDetails(..),
TcTyVar, TcKind, TcThetaType, TcTauType,
- mkTyVarTy, mkTyVarTys, mkFunTy, mkSynTy,
- tcSplitForAllTys, tcSplitRhoTy,
- hoistForAllTys, zipFunTys,
- mkSigmaTy, mkPredTy, mkTyConApp, mkAppTys,
+ mkTyVarTy, mkTyVarTys, mkFunTy,
+ zipFunTys, mkForAllTys, mkFunTys, tcEqType, isPredTy,
+ mkSigmaTy, mkPredTy, mkGenTyConApp, mkTyConApp, mkAppTys,
liftedTypeKind, unliftedTypeKind, mkArrowKind,
- mkArrowKinds, tcSplitFunTy_maybe
+ mkArrowKinds, tcSplitFunTy_maybe, tcSplitForAllTys
)
-
import Inst ( Inst, InstOrigin(..), newMethodWithGivenTy, instToId )
-import Subst ( mkTopTyVarSubst, substTy )
+
import Id ( mkLocalId, idName, idType )
import Var ( TyVar, mkTyVar, tyVarKind )
import ErrUtils ( Message )
-import TyCon ( TyCon, isSynTyCon, tyConKind )
+import TyCon ( TyCon, tyConKind )
import Class ( classTyCon )
import Name ( Name )
import NameSet
-import TysWiredIn ( mkListTy, mkTupleTy, genUnitTyCon )
+import Subst ( deShadowTy )
+import TysWiredIn ( mkListTy, mkPArrTy, mkTupleTy, genUnitTyCon )
import BasicTypes ( Boxity(..) )
import SrcLoc ( SrcLoc )
import Util ( lengthIs )
import Outputable
-
+import List ( nubBy )
\end{code}
kcHsType :: RenamedHsType -> TcM TcKind
kcHsType (HsTyVar name) = kcTyVar name
+kcHsType (HsKindSig ty k)
+ = kcHsType ty `thenTc` \ k' ->
+ unifyKind k k' `thenTc_`
+ returnTc k
+
kcHsType (HsListTy ty)
= kcLiftedType ty `thenTc` \ tau_ty ->
returnTc liftedTypeKind
+kcHsType (HsPArrTy ty)
+ = kcLiftedType ty `thenTc` \ tau_ty ->
+ returnTc liftedTypeKind
+
kcHsType (HsTupleTy (HsTupCon _ boxity _) tys)
= mapTc kcTypeType tys `thenTc_`
returnTc (case boxity of
kcTypeType ty2 `thenTc_`
returnTc liftedTypeKind
-kcHsType (HsNumTy _) -- The unit type for generics
- = returnTc liftedTypeKind
+kcHsType (HsOpTy ty1 HsArrow ty2)
+ = kcTypeType ty1 `thenTc_`
+ kcTypeType ty2 `thenTc_`
+ returnTc liftedTypeKind
-kcHsType ty@(HsOpTy ty1 op ty2)
+kcHsType ty@(HsOpTy ty1 (HsTyOp op) ty2)
= kcTyVar op `thenTc` \ op_kind ->
kcHsType ty1 `thenTc` \ ty1_kind ->
kcHsType ty2 `thenTc` \ ty2_kind ->
tcAddErrCtxt (appKindCtxt (ppr ty)) $
kcAppKind op_kind ty1_kind `thenTc` \ op_kind' ->
kcAppKind op_kind' ty2_kind
+
+kcHsType (HsParTy ty) -- Skip parentheses markers
+ = kcHsType ty
+kcHsType (HsNumTy _) -- The unit type for generics
+ = returnTc liftedTypeKind
+
kcHsType (HsPredTy pred)
= kcHsPred pred `thenTc_`
returnTc liftedTypeKind
= kcHsTyVars tv_names `thenNF_Tc` \ kind_env ->
tcExtendKindEnv kind_env $
kcHsContext context `thenTc_`
- kcHsType ty `thenTc_`
+ kcLiftedType ty `thenTc_`
+ -- The body of a forall must be of kind *
+ -- In principle, I suppose, we could allow unlifted types,
+ -- but it seems simpler to stick to lifted types for now.
returnTc liftedTypeKind
---------------------------
---------------------------
-kcHsContext ctxt = mapTc_ kcHsPred ctxt
+kc_pred :: RenamedHsPred -> TcM TcKind -- Does *not* check for a saturated
+ -- application (reason: used from TcDeriv)
+kc_pred pred@(HsIParam name ty)
+ = kcHsType ty
+
+kc_pred pred@(HsClassP cls tys)
+ = kcClass cls `thenTc` \ kind ->
+ mapTc kcHsType tys `thenTc` \ arg_kinds ->
+ newKindVar `thenNF_Tc` \ kv ->
+ unifyKind kind (mkArrowKinds arg_kinds kv) `thenTc_`
+ returnTc kv
-kcHsPred :: RenamedHsPred -> TcM ()
-kcHsPred pred@(HsIParam name ty)
- = tcAddErrCtxt (appKindCtxt (ppr pred)) $
- kcLiftedType ty
+---------------------------
+kcHsContext ctxt = mapTc_ kcHsPred ctxt
-kcHsPred pred@(HsClassP cls tys)
+kcHsPred pred -- Checks that the result is of kind liftedType
= tcAddErrCtxt (appKindCtxt (ppr pred)) $
- kcClass cls `thenTc` \ kind ->
- mapTc kcHsType tys `thenTc` \ arg_kinds ->
- unifyKind kind (mkArrowKinds arg_kinds liftedTypeKind)
+ kc_pred pred `thenTc` \ kind ->
+ unifyKind liftedTypeKind kind `thenTc_`
+ returnTc ()
+
---------------------------
kcTyVar name -- Could be a tyvar or a tycon
tc_type ty@(HsTyVar name)
= tc_app ty []
+tc_type (HsKindSig ty k)
+ = tc_type ty -- Kind checking done already
+
tc_type (HsListTy ty)
= tc_type ty `thenTc` \ tau_ty ->
returnTc (mkListTy tau_ty)
+tc_type (HsPArrTy ty)
+ = tc_type ty `thenTc` \ tau_ty ->
+ returnTc (mkPArrTy tau_ty)
+
tc_type (HsTupleTy (HsTupCon _ boxity arity) tys)
= ASSERT( tys `lengthIs` arity )
tc_types tys `thenTc` \ tau_tys ->
tc_type ty2 `thenTc` \ tau_ty2 ->
returnTc (mkFunTy tau_ty1 tau_ty2)
-tc_type (HsNumTy n)
- = ASSERT(n== 1)
- returnTc (mkTyConApp genUnitTyCon [])
+tc_type (HsOpTy ty1 HsArrow ty2)
+ = tc_type ty1 `thenTc` \ tau_ty1 ->
+ tc_type ty2 `thenTc` \ tau_ty2 ->
+ returnTc (mkFunTy tau_ty1 tau_ty2)
-tc_type (HsOpTy ty1 op ty2)
+tc_type (HsOpTy ty1 (HsTyOp op) ty2)
= tc_type ty1 `thenTc` \ tau_ty1 ->
tc_type ty2 `thenTc` \ tau_ty2 ->
tc_fun_type op [tau_ty1,tau_ty2]
+tc_type (HsParTy ty) -- Remove the parentheses markers
+ = tc_type ty
+
+tc_type (HsNumTy n)
+ = ASSERT(n== 1)
+ returnTc (mkTyConApp genUnitTyCon [])
+
tc_type (HsAppTy ty1 ty2) = tc_app ty1 [ty2]
tc_type (HsPredTy pred)
case thing of
ATyVar tv -> returnTc (mkAppTys (mkTyVarTy tv) arg_tys)
- AGlobal (ATyCon tc)
- | isSynTyCon tc -> returnTc (mkSynTy tc arg_tys)
- | otherwise -> returnTc (mkTyConApp tc arg_tys)
+ AGlobal (ATyCon tc) -> returnTc (mkGenTyConApp tc arg_tys)
other -> failWithTc (wrongThingErr "type constructor" thing name)
\end{code}
Contexts
~~~~~~~~
\begin{code}
+tcHsPred pred = kc_pred pred `thenTc_` tc_pred pred
+ -- Is happy with a partial application, e.g. (ST s)
+ -- Used from TcDeriv
+
tc_pred assn@(HsClassP class_name tys)
= tcAddErrCtxt (appKindCtxt (ppr assn)) $
tc_types tys `thenTc` \ arg_tys ->
\begin{code}
data TcSigInfo
= TySigInfo
- Name -- N, the Name in corresponding binding
-
TcId -- *Polymorphic* binder for this value...
-- Has name = N
SrcLoc -- Of the signature
instance Outputable TcSigInfo where
- ppr (TySigInfo nm id tyvars theta tau _ inst loc) =
- ppr nm <+> ptext SLIT("::") <+> ppr tyvars <+> ppr theta <+> ptext SLIT("=>") <+> ppr tau
+ ppr (TySigInfo id tyvars theta tau _ inst loc) =
+ ppr id <+> ptext SLIT("::") <+> ppr tyvars <+> ppr theta <+> ptext SLIT("=>") <+> ppr tau
+
+tcSigPolyId :: TcSigInfo -> TcId
+tcSigPolyId (TySigInfo id _ _ _ _ _ _) = id
+
+tcSigMonoId :: TcSigInfo -> TcId
+tcSigMonoId (TySigInfo _ _ _ _ id _ _) = id
maybeSig :: [TcSigInfo] -> Name -> Maybe (TcSigInfo)
-- Search for a particular signature
maybeSig [] name = Nothing
-maybeSig (sig@(TySigInfo sig_name _ _ _ _ _ _ _) : sigs) name
- | name == sig_name = Just sig
- | otherwise = maybeSig sigs name
+maybeSig (sig@(TySigInfo sig_id _ _ _ _ _ _) : sigs) name
+ | name == idName sig_id = Just sig
+ | otherwise = maybeSig sigs name
\end{code}
-- the tyvars *do* get unified with something, we want to carry on
-- typechecking the rest of the program with the function bound
-- to a pristine type, namely sigma_tc_ty
- let
- (tyvars, rho) = tcSplitForAllTys (idType poly_id)
- in
- tcInstSigTyVars SigTv tyvars `thenNF_Tc` \ tyvars' ->
- -- Make *signature* type variables
-
- let
- tyvar_tys' = mkTyVarTys tyvars'
- rho' = substTy (mkTopTyVarSubst tyvars tyvar_tys') rho
- -- mkTopTyVarSubst because the tyvars' are fresh
-
- (theta', tau') = tcSplitRhoTy rho'
- -- This splitRhoTy tries hard to make sure that tau' is a type synonym
- -- wherever possible, which can improve interface files.
- in
+ tcInstType SigTv (idType poly_id) `thenNF_Tc` \ (tyvars', theta', tau') ->
+
newMethodWithGivenTy SignatureOrigin
- poly_id
- tyvar_tys'
- theta' tau' `thenNF_Tc` \ inst ->
+ poly_id
+ (mkTyVarTys tyvars')
+ theta' tau' `thenNF_Tc` \ inst ->
-- We make a Method even if it's not overloaded; no harm
- returnNF_Tc (TySigInfo name poly_id tyvars' theta' tau' (instToId inst) [inst] src_loc)
- where
- name = idName poly_id
+ returnNF_Tc (TySigInfo poly_id tyvars' theta' tau'
+ (instToId inst) [inst] src_loc)
\end{code}
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
+
+
+\begin{code}
+hoistForAllTys :: Type -> Type
+-- Used for user-written type signatures only
+-- Move all the foralls and constraints to the top
+-- e.g. T -> forall a. a ==> forall a. T -> a
+-- T -> (?x::Int) -> Int ==> (?x::Int) -> T -> Int
+--
+-- Also: eliminate duplicate constraints. These can show up
+-- when hoisting constraints, notably implicit parameters.
+--
+-- We want to 'look through' type synonyms when doing this
+-- so it's better done on the Type than the HsType
+
+hoistForAllTys ty
+ = let
+ no_shadow_ty = deShadowTy ty
+ -- Running over ty with an empty substitution gives it the
+ -- no-shadowing property. This is important. For example:
+ -- type Foo r = forall a. a -> r
+ -- foo :: Foo (Foo ())
+ -- Here the hoisting should give
+ -- foo :: forall a a1. a -> a1 -> ()
+ --
+ -- What about type vars that are lexically in scope in the envt?
+ -- We simply rely on them having a different unique to any
+ -- binder in 'ty'. Otherwise we'd have to slurp the in-scope-tyvars
+ -- out of the envt, which is boring and (I think) not necessary.
+ in
+ case hoist no_shadow_ty of
+ (tvs, theta, body) -> mkForAllTys tvs (mkFunTys (nubBy tcEqType theta) body)
+ -- The 'nubBy' eliminates duplicate constraints,
+ -- notably implicit parameters
+ where
+ hoist ty
+ | (tvs1, body_ty) <- tcSplitForAllTys ty,
+ not (null tvs1)
+ = case hoist body_ty of
+ (tvs2,theta,tau) -> (tvs1 ++ tvs2, theta, tau)
+
+ | Just (arg, res) <- tcSplitFunTy_maybe ty
+ = let
+ arg' = hoistForAllTys arg -- Don't forget to apply hoist recursively
+ in -- to the argument type
+ if (isPredTy arg') then
+ case hoist res of
+ (tvs,theta,tau) -> (tvs, arg':theta, tau)
+ else
+ case hoist res of
+ (tvs,theta,tau) -> (tvs, theta, mkFunTy arg' tau)
+
+ | otherwise = ([], [], ty)
+\end{code}
+
%************************************************************************
%* *
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