DynFlag(Opt_MonomorphismRestriction, Opt_MonoPatBinds, Opt_GlasgowExts) )
import HsSyn ( HsExpr(..), HsBind(..), LHsBinds, LHsBind, Sig(..),
HsLocalBinds(..), HsValBinds(..), HsIPBinds(..),
- LSig, Match(..), IPBind(..), Prag(..),
- HsType(..), LHsType, HsExplicitForAll(..), hsLTyVarNames,
+ LSig, Match(..), IPBind(..), Prag(..), LHsType,
isVanillaLSig, sigName, placeHolderNames, isPragLSig,
- LPat, GRHSs, MatchGroup(..), pprLHsBinds, mkHsCoerce,
+ LPat, GRHSs, MatchGroup(..), pprLHsBinds, mkHsWrap, hsExplicitTvs,
collectHsBindBinders, collectPatBinders, pprPatBind, isBangHsBind
)
import TcHsSyn ( zonkId )
import TcRnMonad
-import Inst ( newDictsAtLoc, newIPDict, instToId )
+import Inst ( newDictBndrs, newIPDict, instToId )
import TcEnv ( tcExtendIdEnv, tcExtendIdEnv2, tcExtendTyVarEnv2,
- pprBinders, tcLookupLocalId_maybe, tcLookupId,
+ pprBinders, tcLookupId,
tcGetGlobalTyVars )
import TcUnify ( tcInfer, tcSubExp, unifyTheta,
bleatEscapedTvs, sigCtxt )
import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck,
tcSimplifyRestricted, tcSimplifyIPs )
import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
-import TcPat ( tcPat, PatCtxt(..) )
+import TcPat ( tcLetPat )
import TcSimplify ( bindInstsOfLocalFuns )
import TcMType ( newFlexiTyVarTy, zonkQuantifiedTyVar, zonkSigTyVar,
tcInstSigTyVars, tcInstSkolTyVars, tcInstType,
- zonkTcType, zonkTcTypes, zonkTcTyVars )
+ zonkTcType, zonkTcTypes, zonkTcTyVar )
import TcType ( TcType, TcTyVar, TcThetaType,
SkolemInfo(SigSkol), UserTypeCtxt(FunSigCtxt),
TcTauType, TcSigmaType, isUnboxedTupleType,
mkTyVarTy, mkForAllTys, mkFunTys, exactTyVarsOfType,
mkForAllTy, isUnLiftedType, tcGetTyVar,
mkTyVarTys, tidyOpenTyVar )
-import Kind ( argTypeKind )
+import {- Kind parts of -} Type ( argTypeKind )
import VarEnv ( TyVarEnv, emptyVarEnv, lookupVarEnv, extendVarEnv )
-import TysWiredIn ( unitTy )
import TysPrim ( alphaTyVar )
import Id ( Id, mkLocalId, mkVanillaGlobal )
import IdInfo ( vanillaIdInfo )
in
-- SET UP THE MAIN RECOVERY; take advantage of any type sigs
setSrcSpan loc $
- recoverM (recoveryCode binder_names) $ do
+ recoverM (recoveryCode binder_names sig_fn) $ do
{ traceTc (ptext SLIT("------------------------------------------------"))
; traceTc (ptext SLIT("Bindings for") <+> ppr binder_names)
; exports <- mapM (mkExport prag_fn tyvars_to_gen' (map idType dict_ids))
mono_bind_infos
- -- ZONK THE poly_ids, because they are used to extend the type
- -- environment; see the invariant on TcEnv.tcExtendIdEnv
; let poly_ids = [poly_id | (_, poly_id, _, _) <- exports]
- ; zonked_poly_ids <- mappM zonkId poly_ids
-
- ; traceTc (text "binding:" <+> ppr (zonked_poly_ids `zip` map idType zonked_poly_ids))
+ ; traceTc (text "binding:" <+> ppr (poly_ids `zip` map idType poly_ids))
; let abs_bind = L loc $ AbsBinds tyvars_to_gen'
dict_ids exports
(dict_binds `unionBags` binds')
- ; return ([unitBag abs_bind], zonked_poly_ids)
+ ; return ([unitBag abs_bind], poly_ids) -- poly_ids are guaranteed zonked by mkExport
} }
--------------
mkExport :: TcPragFun -> [TyVar] -> [TcType] -> MonoBindInfo
-> TcM ([TyVar], Id, Id, [Prag])
+-- mkExport generates exports with
+-- zonked type variables,
+-- zonked poly_ids
+-- The former is just because no further unifications will change
+-- the quantified type variables, so we can fix their final form
+-- right now.
+-- The latter is needed because the poly_ids are used to extend the
+-- type environment; see the invariant on TcEnv.tcExtendIdEnv
+
+-- Pre-condition: the inferred_tvs are already zonked
+
mkExport prag_fn inferred_tvs dict_tys (poly_name, mb_sig, mono_id)
- = case mb_sig of
- Nothing -> do { prags <- tcPrags poly_id (prag_fn poly_name)
- ; return (inferred_tvs, poly_id, mono_id, prags) }
- where
- poly_id = mkLocalId poly_name poly_ty
- poly_ty = mkForAllTys inferred_tvs
- $ mkFunTys dict_tys
- $ idType mono_id
-
- Just sig -> do { let poly_id = sig_id sig
- ; prags <- tcPrags poly_id (prag_fn poly_name)
- ; sig_tys <- zonkTcTyVars (sig_tvs sig)
- ; let sig_tvs' = map (tcGetTyVar "mkExport") sig_tys
- ; return (sig_tvs', poly_id, mono_id, prags) }
- -- We zonk the sig_tvs here so that the export triple
- -- always has zonked type variables;
- -- a convenient invariant
+ = do { (tvs, poly_id) <- mk_poly_id mb_sig
+
+ ; poly_id' <- zonkId poly_id
+ ; prags <- tcPrags poly_id' (prag_fn poly_name)
+ -- tcPrags requires a zonked poly_id
+
+ ; return (tvs, poly_id', mono_id, prags) }
+ where
+ poly_ty = mkForAllTys inferred_tvs (mkFunTys dict_tys (idType mono_id))
+ mk_poly_id Nothing = return (inferred_tvs, mkLocalId poly_name poly_ty)
+ mk_poly_id (Just sig) = do { tvs <- mapM zonk_tv (sig_tvs sig)
+ ; return (tvs, sig_id sig) }
+
+ zonk_tv tv = do { ty <- zonkTcTyVar tv; return (tcGetTyVar "mkExport" ty) }
------------------------
type TcPragFun = Name -> [LSig Name]
pragSigCtxt prag = hang (ptext SLIT("In the pragma")) 2 (ppr prag)
tcPrag :: TcId -> Sig Name -> TcM Prag
+-- Pre-condition: the poly_id is zonked
+-- Reason: required by tcSubExp
tcPrag poly_id (SpecSig orig_name hs_ty inl) = tcSpecPrag poly_id hs_ty inl
tcPrag poly_id (SpecInstSig hs_ty) = tcSpecPrag poly_id hs_ty defaultInlineSpec
tcPrag poly_id (InlineSig v inl) = return (InlinePrag inl)
; (co_fn, lie) <- getLIE (tcSubExp (idType poly_id) spec_ty)
; extendLIEs lie
; let const_dicts = map instToId lie
- ; return (SpecPrag (mkHsCoerce co_fn (HsVar poly_id)) spec_ty const_dicts inl) }
+ ; return (SpecPrag (mkHsWrap co_fn (HsVar poly_id)) spec_ty const_dicts inl) }
-- Most of the work of specialisation is done by
-- the desugarer, guided by the SpecPrag
-- If typechecking the binds fails, then return with each
-- signature-less binder given type (forall a.a), to minimise
-- subsequent error messages
-recoveryCode binder_names
+recoveryCode binder_names sig_fn
= do { traceTc (text "tcBindsWithSigs: error recovery" <+> ppr binder_names)
; poly_ids <- mapM mk_dummy binder_names
; return ([], poly_ids) }
where
- mk_dummy name = do { mb_id <- tcLookupLocalId_maybe name
- ; case mb_id of
- Just id -> return id -- Had signature, was in envt
- Nothing -> return (mkLocalId name forall_a_a) } -- No signature
+ mk_dummy name
+ | isJust (sig_fn name) = tcLookupId name -- Had signature; look it up
+ | otherwise = return (mkLocalId name forall_a_a) -- No signature
forall_a_a :: TcType
forall_a_a = mkForAllTy alphaTyVar (mkTyVarTy alphaTyVar)
| (name, Just sig) <- nm_sig_prs]
sig_tau_fn = lookupNameEnv tau_sig_env
- tc_pat exp_ty = tcPat (LetPat sig_tau_fn) pat exp_ty unitTy $ \ _ ->
+ tc_pat exp_ty = tcLetPat sig_tau_fn pat exp_ty $
mapM lookup_info nm_sig_prs
- -- The unitTy is a bit bogus; it's the "result type" for lookup_info.
-- After typechecking the pattern, look up the binder
-- names, which the pattern has brought into scope.
unifyCtxts :: [TcSigInfo] -> TcM [Inst]
unifyCtxts (sig1 : sigs) -- Argument is always non-empty
= do { mapM unify_ctxt sigs
- ; newDictsAtLoc (sig_loc sig1) (sig_theta sig1) }
+ ; newDictBndrs (sig_loc sig1) (sig_theta sig1) }
where
theta1 = sig_theta sig1
unify_ctxt :: TcSigInfo -> TcM ()
-- Precondition: no duplicates
mkTcSigFun sigs = lookupNameEnv env
where
- env = mkNameEnv [(name, scoped_tyvars hs_ty)
- | L span (TypeSig (L _ name) (L _ hs_ty)) <- sigs]
- scoped_tyvars (HsForAllTy Explicit tvs _ _) = hsLTyVarNames tvs
- scoped_tyvars other = []
+ env = mkNameEnv [(name, hsExplicitTvs lhs_ty)
+ | L span (TypeSig (L _ name) lhs_ty) <- sigs]
-- The scoped names are the ones explicitly mentioned
-- in the HsForAll. (There may be more in sigma_ty, because
-- of nested type synonyms. See Note [Scoped] with TcSigInfo.)
+ -- See Note [Only scoped tyvars are in the TyVarEnv]
---------------
data TcSigInfo
sig_loc :: InstLoc -- The location of the signature
}
+
+-- Note [Only scoped tyvars are in the TyVarEnv]
+-- We are careful to keep only the *lexically scoped* type variables in
+-- the type environment. Why? After all, the renamer has ensured
+-- that only legal occurrences occur, so we could put all type variables
+-- into the type env.
+--
+-- But we want to check that two distinct lexically scoped type variables
+-- do not map to the same internal type variable. So we need to know which
+-- the lexically-scoped ones are... and at the moment we do that by putting
+-- only the lexically scoped ones into the environment.
+
+
-- Note [Scoped]
-- There may be more instantiated type variables than scoped
-- ones. For example:
-- and remember the names from the original HsForAllTy in sig_scoped
-- Note [Instantiate sig]
--- It's vital to instantiate a type signature with fresh variable.
+-- It's vital to instantiate a type signature with fresh variables.
-- For example:
-- type S = forall a. a->a
-- f,g :: S
tcInstSig :: Bool -> Name -> [Name] -> TcM TcSigInfo
-- Instantiate the signature, with either skolems or meta-type variables
--- depending on the use_skols boolean
+-- depending on the use_skols boolean. This variable is set True
+-- when we are typechecking a single function binding; and False for
+-- pattern bindings and a group of several function bindings.
+-- Reason: in the latter cases, the "skolems" can be unified together,
+-- so they aren't properly rigid in the type-refinement sense.
+-- NB: unless we are doing H98, each function with a sig will be done
+-- separately, even if it's mutually recursive, so use_skols will be True
--
--- We always instantiate with freshs uniques,
+-- We always instantiate with fresh uniques,
-- although we keep the same print-name
--
-- type T = forall a. [a] -> [a]
projects / ghc-hetmet.git / blobdiff