%
+% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcBinds]{TcBinds}
import {-# SOURCE #-} TcMatches ( tcGRHSsPat, tcMatchesFun )
import {-# SOURCE #-} TcExpr ( tcMonoExpr )
-import DynFlags ( dopt, DynFlags,
- 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,
- isVanillaLSig, sigName, placeHolderNames, isPragLSig,
- LPat, GRHSs, MatchGroup(..), pprLHsBinds, mkHsCoerce,
- collectHsBindBinders, collectPatBinders, pprPatBind, isBangHsBind
- )
-import TcHsSyn ( zonkId )
+import DynFlags
+import HsSyn
+import TcHsSyn
import TcRnMonad
-import Inst ( newDictsAtLoc, newIPDict, instToId )
-import TcEnv ( tcExtendIdEnv, tcExtendIdEnv2, tcExtendTyVarEnv2,
- pprBinders, tcLookupLocalId_maybe, tcLookupId,
- tcGetGlobalTyVars )
-import TcUnify ( tcInfer, tcSubExp, unifyTheta,
- bleatEscapedTvs, sigCtxt )
-import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck,
- tcSimplifyRestricted, tcSimplifyIPs )
-import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
-import TcPat ( tcPat, PatCtxt(..) )
-import TcSimplify ( bindInstsOfLocalFuns )
-import TcMType ( newFlexiTyVarTy, zonkQuantifiedTyVar, zonkSigTyVar,
- tcInstSigTyVars, tcInstSkolTyVars, tcInstType,
- 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 VarEnv ( TyVarEnv, emptyVarEnv, lookupVarEnv, extendVarEnv )
-import TysWiredIn ( unitTy )
-import TysPrim ( alphaTyVar )
-import Id ( Id, mkLocalId, mkVanillaGlobal )
-import IdInfo ( vanillaIdInfo )
-import Var ( TyVar, idType, idName )
-import Name ( Name )
+import Inst
+import TcEnv
+import TcUnify
+import TcSimplify
+import TcHsType
+import TcPat
+import TcMType
+import TcType
+import {- Kind parts of -} Type
+import VarEnv
+import TysPrim
+import Id
+import IdInfo
+import Var ( TyVar )
+import Name
import NameSet
import NameEnv
import VarSet
-import SrcLoc ( Located(..), unLoc, getLoc )
+import SrcLoc
import Bag
-import ErrUtils ( Message )
-import Digraph ( SCC(..), stronglyConnComp )
-import Maybes ( expectJust, isJust, isNothing, orElse )
-import Util ( singleton )
-import BasicTypes ( TopLevelFlag(..), isTopLevel, isNotTopLevel,
- RecFlag(..), isNonRec, InlineSpec, defaultInlineSpec )
+import ErrUtils
+import Digraph
+import Maybes
+import Util
+import BasicTypes
import Outputable
\end{code}
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)
; (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
-- Instantiate the signature, with either skolems or meta-type variables
-- depending on the use_skols boolean. This variable is set True
-- when we are typechecking a single function binding; and False for
--- pattern bindigs and a group of several function bindings.
+-- 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
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