\section[TcBinds]{TcBinds}
\begin{code}
-{-# OPTIONS -w #-}
--- The above warning supression flag is a temporary kludge.
--- While working on this module you are encouraged to remove it and fix
--- any warnings in the module. See
--- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
--- for details
-
module TcBinds ( tcLocalBinds, tcTopBinds,
- tcHsBootSigs, tcMonoBinds,
+ tcHsBootSigs, tcMonoBinds, tcPolyBinds,
TcPragFun, tcSpecPrag, tcPrags, mkPragFun,
TcSigInfo(..), TcSigFun, mkTcSigFun,
badBootDeclErr ) where
import DynFlags
import HsSyn
-import TcHsSyn
import TcRnMonad
import Inst
import VarEnv
import TysPrim
import Id
-import IdInfo
-import Var ( TyVar, varType )
+import Var
import Name
import NameSet
import NameEnv
-- signatures in it. The renamer checked all this
tcHsBootSigs (ValBindsOut binds sigs)
= do { checkTc (null binds) badBootDeclErr
- ; mapM (addLocM tc_boot_sig) (filter isVanillaLSig sigs) }
+ ; mapM (addLocM tc_boot_sig) (filter isTypeLSig sigs) }
where
tc_boot_sig (TypeSig (L _ name) ty)
= do { sigma_ty <- tcHsSigType (FunSigCtxt name) ty
- ; return (mkVanillaGlobal name sigma_ty vanillaIdInfo) }
+ ; return (mkVanillaGlobal name sigma_ty) }
-- Notice that we make GlobalIds, not LocalIds
+ tc_boot_sig s = pprPanic "tcHsBootSigs/tc_boot_sig" (ppr s)
tcHsBootSigs groups = pprPanic "tcHsBootSigs" (ppr groups)
badBootDeclErr :: Message
-> HsValBinds Name -> TcM thing
-> TcM (HsValBinds TcId, thing)
-tcValBinds top_lvl (ValBindsIn binds sigs) thing_inside
+tcValBinds _ (ValBindsIn binds _) _
= pprPanic "tcValBinds" (ppr binds)
tcValBinds top_lvl (ValBindsOut binds sigs) thing_inside
= do { -- Typecheck the signature
; let { prag_fn = mkPragFun sigs
- ; ty_sigs = filter isVanillaLSig sigs
+ ; ty_sigs = filter isTypeLSig sigs
; sig_fn = mkTcSigFun ty_sigs }
- ; poly_ids <- mapM tcTySig ty_sigs
+ ; poly_ids <- checkNoErrs (mapAndRecoverM tcTySig ty_sigs)
-- No recovery from bad signatures, because the type sigs
-- may bind type variables, so proceeding without them
-- can lead to a cascade of errors
-- the Ids declared with type signatures
; poly_rec <- doptM Opt_RelaxedPolyRec
; (binds', thing) <- tcExtendIdEnv poly_ids $
- tc_val_binds poly_rec top_lvl sig_fn prag_fn
+ tcBindGroups poly_rec top_lvl sig_fn prag_fn
binds thing_inside
; return (ValBindsOut binds' sigs, thing) }
------------------------
-tc_val_binds :: Bool -> TopLevelFlag -> TcSigFun -> TcPragFun
+tcBindGroups :: Bool -> TopLevelFlag -> TcSigFun -> TcPragFun
-> [(RecFlag, LHsBinds Name)] -> TcM thing
-> TcM ([(RecFlag, LHsBinds TcId)], thing)
-- Typecheck a whole lot of value bindings,
-- one strongly-connected component at a time
+-- Here a "strongly connected component" has the strightforward
+-- meaning of a group of bindings that mention each other,
+-- ignoring type signatures (that part comes later)
-tc_val_binds poly_rec top_lvl sig_fn prag_fn [] thing_inside
+tcBindGroups _ _ _ _ [] thing_inside
= do { thing <- thing_inside
; return ([], thing) }
-tc_val_binds poly_rec top_lvl sig_fn prag_fn (group : groups) thing_inside
+tcBindGroups poly_rec top_lvl sig_fn prag_fn (group : groups) thing_inside
= do { (group', (groups', thing))
<- tc_group poly_rec top_lvl sig_fn prag_fn group $
- tc_val_binds poly_rec top_lvl sig_fn prag_fn groups thing_inside
+ tcBindGroups poly_rec top_lvl sig_fn prag_fn groups thing_inside
; return (group' ++ groups', thing) }
------------------------
-- We get a list of groups back, because there may
-- be specialisations etc as well
-tc_group poly_rec top_lvl sig_fn prag_fn (NonRecursive, binds) thing_inside
+tc_group _ top_lvl sig_fn prag_fn (NonRecursive, binds) thing_inside
-- A single non-recursive binding
-- We want to keep non-recursive things non-recursive
-- so that we desugar unlifted bindings correctly
- = do { (binds, thing) <- tc_haskell98 top_lvl sig_fn prag_fn NonRecursive binds thing_inside
- ; return ([(NonRecursive, b) | b <- binds], thing) }
+ = do { (binds1, lie_binds, thing) <- tc_haskell98 top_lvl sig_fn prag_fn
+ NonRecursive binds thing_inside
+ ; return ( [(NonRecursive, unitBag b) | b <- bagToList binds1]
+ ++ [(Recursive, lie_binds)] -- TcDictBinds have scrambled dependency order
+ , thing) }
tc_group poly_rec top_lvl sig_fn prag_fn (Recursive, binds) thing_inside
| not poly_rec -- Recursive group, normal Haskell 98 route
- = do { (binds1, thing) <- tc_haskell98 top_lvl sig_fn prag_fn Recursive binds thing_inside
- ; return ([(Recursive, unionManyBags binds1)], thing) }
+ = do { (binds1, lie_binds, thing) <- tc_haskell98 top_lvl sig_fn prag_fn
+ Recursive binds thing_inside
+ ; return ([(Recursive, binds1 `unionBags` lie_binds)], thing) }
- | otherwise -- Recursive group, with gla-exts
- = -- To maximise polymorphism (with -fglasgow-exts), we do a new
+ | otherwise -- Recursive group, with -XRelaxedPolyRec
+ = -- To maximise polymorphism (with -XRelaxedPolyRec), we do a new
-- strongly-connected-component analysis, this time omitting
-- any references to variables with type signatures.
--
- -- Notice that the bindInsts thing covers *all* the bindings in the original
- -- group at once; an earlier one may use a later one!
+ -- Notice that the bindInsts thing covers *all* the bindings in
+ -- the original group at once; an earlier one may use a later one!
do { traceTc (text "tc_group rec" <+> pprLHsBinds binds)
- ; (binds1,thing) <- bindLocalInsts top_lvl $
- go (stronglyConnComp (mkEdges sig_fn binds))
- ; return ([(Recursive, unionManyBags binds1)], thing) }
+ ; (binds1,lie_binds,thing) <- bindLocalInsts top_lvl $
+ go (stronglyConnCompFromEdgedVertices (mkEdges sig_fn binds))
+ ; return ([(Recursive, binds1 `unionBags` lie_binds)], thing) }
-- Rec them all together
where
--- go :: SCC (LHsBind Name) -> TcM ([LHsBind TcId], [TcId], thing)
+-- go :: SCC (LHsBind Name) -> TcM (LHsBinds TcId, [TcId], thing)
go (scc:sccs) = do { (binds1, ids1) <- tc_scc scc
; (binds2, ids2, thing) <- tcExtendIdEnv ids1 $ go sccs
- ; return (binds1 ++ binds2, ids1 ++ ids2, thing) }
- go [] = do { thing <- thing_inside; return ([], [], thing) }
+ ; return (binds1 `unionBags` binds2, ids1 ++ ids2, thing) }
+ go [] = do { thing <- thing_inside; return (emptyBag, [], thing) }
tc_scc (AcyclicSCC bind) = tc_sub_group NonRecursive (unitBag bind)
tc_scc (CyclicSCC binds) = tc_sub_group Recursive (listToBag binds)
tc_sub_group = tcPolyBinds top_lvl sig_fn prag_fn Recursive
+tc_haskell98 :: TopLevelFlag -> TcSigFun -> TcPragFun -> RecFlag
+ -> LHsBinds Name -> TcM a -> TcM (LHsBinds TcId, TcDictBinds, a)
tc_haskell98 top_lvl sig_fn prag_fn rec_flag binds thing_inside
- = bindLocalInsts top_lvl $ do
- { (binds1, ids) <- tcPolyBinds top_lvl sig_fn prag_fn rec_flag rec_flag binds
- ; thing <- tcExtendIdEnv ids thing_inside
- ; return (binds1, ids, thing) }
+ = bindLocalInsts top_lvl $
+ do { (binds1, ids) <- tcPolyBinds top_lvl sig_fn prag_fn rec_flag rec_flag binds
+ ; thing <- tcExtendIdEnv ids thing_inside
+ ; return (binds1, ids, thing) }
------------------------
-bindLocalInsts :: TopLevelFlag -> TcM ([LHsBinds TcId], [TcId], a) -> TcM ([LHsBinds TcId], a)
+bindLocalInsts :: TopLevelFlag
+ -> TcM (LHsBinds TcId, [TcId], a)
+ -> TcM (LHsBinds TcId, TcDictBinds, a)
bindLocalInsts top_lvl thing_inside
- | isTopLevel top_lvl = do { (binds, ids, thing) <- thing_inside; return (binds, thing) }
+ | isTopLevel top_lvl
+ = do { (binds, _, thing) <- thing_inside; return (binds, emptyBag, thing) }
-- For the top level don't bother with all this bindInstsOfLocalFuns stuff.
-- All the top level things are rec'd together anyway, so it's fine to
-- leave them to the tcSimplifyTop, and quite a bit faster too
| otherwise -- Nested case
= do { ((binds, ids, thing), lie) <- getLIE thing_inside
; lie_binds <- bindInstsOfLocalFuns lie ids
- ; return (binds ++ [lie_binds], thing) }
+ ; return (binds, lie_binds, thing) }
------------------------
mkEdges :: TcSigFun -> LHsBinds Name
bindersOfHsBind :: HsBind Name -> [Name]
bindersOfHsBind (PatBind { pat_lhs = pat }) = collectPatBinders pat
bindersOfHsBind (FunBind { fun_id = L _ f }) = [f]
+bindersOfHsBind (AbsBinds {}) = panic "bindersOfHsBind AbsBinds"
+bindersOfHsBind (VarBind {}) = panic "bindersOfHsBind VarBind"
------------------------
tcPolyBinds :: TopLevelFlag -> TcSigFun -> TcPragFun
-> RecFlag -- Whether it's recursive after breaking
-- dependencies based on type signatures
-> LHsBinds Name
- -> TcM ([LHsBinds TcId], [TcId])
+ -> TcM (LHsBinds TcId, [TcId])
-- Typechecks a single bunch of bindings all together,
-- and generalises them. The bunch may be only part of a recursive
do { extendLIEs lie_req
; let exports = zipWith mk_export mono_bind_infos zonked_mono_tys
mk_export (name, Nothing, mono_id) mono_ty = ([], mkLocalId name mono_ty, mono_id, [])
- mk_export (name, Just sig, mono_id) mono_ty = ([], sig_id sig, mono_id, [])
+ mk_export (_, Just sig, mono_id) _ = ([], sig_id sig, mono_id, [])
-- ToDo: prags for unlifted bindings
- ; return ( [unitBag $ L loc $ AbsBinds [] [] exports binds'],
+ ; return ( unitBag $ L loc $ AbsBinds [] [] exports binds',
[poly_id | (_, poly_id, _, _) <- exports]) } -- Guaranteed zonked
else do -- The normal lifted case: GENERALISE
dict_vars exports
(dict_binds `unionBags` binds')
- ; return ([unitBag abs_bind], poly_ids) -- poly_ids are guaranteed zonked by mkExport
+ ; return (unitBag abs_bind, poly_ids) -- poly_ids are guaranteed zonked by mkExport
} }
mk_poly_id warn Nothing = do { poly_ty' <- zonkTcType poly_ty
; missingSigWarn warn poly_name poly_ty'
; return (inferred_tvs, mkLocalId poly_name poly_ty') }
- mk_poly_id warn (Just sig) = do { tvs <- mapM zonk_tv (sig_tvs sig)
+ 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) }
tc_prag prag = addErrCtxt (pragSigCtxt prag) $
tcPrag poly_id prag
+pragSigCtxt :: Sig Name -> SDoc
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)
+tcPrag poly_id (SpecSig _ hs_ty inl) = tcSpecPrag poly_id hs_ty inl
+tcPrag poly_id (SpecInstSig hs_ty) = tcSpecPrag poly_id hs_ty defaultInlineSpec
+tcPrag _ (InlineSig _ inl) = return (InlinePrag inl)
+tcPrag _ sig = pprPanic "tcPrag" (ppr sig)
tcSpecPrag :: TcId -> LHsType Name -> InlineSpec -> TcM Prag
-- If typechecking the binds fails, then return with each
-- signature-less binder given type (forall a.a), to minimise
-- subsequent error messages
+recoveryCode :: [Name] -> (Name -> Maybe [Name])
+ -> TcM (LHsBinds TcId, [Id])
recoveryCode binder_names sig_fn
= do { traceTc (text "tcBindsWithSigs: error recovery" <+> ppr binder_names)
; poly_ids <- mapM mk_dummy binder_names
- ; return ([], poly_ids) }
+ ; return (emptyBag, poly_ids) }
where
mk_dummy name
| isJust (sig_fn name) = tcLookupId name -- Had signature; look it up
bang_pat = anyBag (isBangHsBind . unLoc) mbind
check_sig (_, Just sig, _) = checkTc (null (sig_tvs sig) && null (sig_theta sig))
(badStrictSig unlifted sig)
- check_sig other = return ()
+ check_sig _ = return ()
+strictBindErr :: String -> Bool -> LHsBindsLR Var Var -> SDoc
strictBindErr flavour unlifted mbind
= hang (text flavour <+> msg <+> ptext (sLit "aren't allowed:"))
4 (pprLHsBinds mbind)
msg | unlifted = ptext (sLit "bindings for unlifted types")
| otherwise = ptext (sLit "bang-pattern bindings")
+badStrictSig :: Bool -> TcSigInfo -> SDoc
badStrictSig unlifted sig
= hang (ptext (sLit "Illegal polymorphic signature in") <+> msg)
4 (ppr sig)
[(name, Nothing, mono_id)]) }
tcMonoBinds [L b_loc (FunBind { fun_id = L nm_loc name, fun_infix = inf,
- fun_matches = matches, bind_fvs = fvs })]
+ fun_matches = matches })]
sig_fn -- Single function binding
- non_rec
+ _
| Just scoped_tvs <- sig_fn name -- ...with a type signature
= -- When we have a single function binding, with a type signature
-- we can (a) use genuine, rigid skolem constants for the type variables
-- Note that the scoped_tvs and the (sig_tvs sig)
-- may have different Names. That's quite ok.
+ ; traceTc (text "tcMoonBinds" <+> ppr scoped_tvs $$ ppr tc_sig)
; (co_fn, matches') <- tcExtendTyVarEnv2 rhs_tvs $
tcMatchesFun mono_name inf matches mono_ty
+ -- Note that "mono_ty" might actually be a polymorphic type,
+ -- if the original function had a signature like
+ -- forall a. Eq a => forall b. Ord b => ....
+ -- But that's ok: tcMatchesFun can deal with that
+ -- It happens, too! See Note [Polymorphic methods] in TcClassDcl.
; let fun_bind' = FunBind { fun_id = L nm_loc mono_id,
fun_infix = inf, fun_matches = matches',
; return (unitBag (L b_loc fun_bind'),
[(name, Just tc_sig, mono_id)]) }
-tcMonoBinds binds sig_fn non_rec
+tcMonoBinds binds sig_fn _
= do { tc_binds <- mapM (wrapLocM (tcLhs sig_fn)) binds
-- Bring the monomorphic Ids, into scope for the RHSs
mk_mono_ty (Just sig) = return (sig_tau sig)
mk_mono_ty Nothing = newFlexiTyVarTy argTypeKind
-tcLhs sig_fn bind@(PatBind { pat_lhs = pat, pat_rhs = grhss })
+tcLhs sig_fn (PatBind { pat_lhs = pat, pat_rhs = grhss })
= do { mb_sigs <- mapM (tcInstSig_maybe sig_fn) names
; mono_pat_binds <- doptM Opt_MonoPatBinds
- -- With -fmono-pat-binds, we do no generalisation of pattern bindings
+ -- With -XMonoPatBinds, we do no generalisation of pattern bindings
-- But the signature can still be polymoprhic!
-- data T = MkT (forall a. a->a)
-- x :: forall a. a->a
-- MkT x = <rhs>
-- The function get_sig_ty decides whether the pattern-bound variables
- -- should have exactly the type in the type signature (-fmono-pat-binds),
- -- or the instantiated version (-fmono-pat-binds)
+ -- should have exactly the type in the type signature (-XMonoPatBinds),
+ -- or the instantiated version (-XMonoPatBinds)
; let nm_sig_prs = names `zip` mb_sigs
get_sig_ty | mono_pat_binds = idType . sig_id
names = collectPatBinders pat
-tcLhs sig_fn other_bind = pprPanic "tcLhs" (ppr other_bind)
+tcLhs _ other_bind = pprPanic "tcLhs" (ppr other_bind)
-- AbsBind, VarBind impossible
-------------------
bind_fvs = placeHolderNames, fun_co_fn = co_fn,
fun_tick = Nothing }) }
-tcRhs bind@(TcPatBind _ pat' grhss pat_ty)
+tcRhs (TcPatBind _ pat' grhss pat_ty)
= do { grhss' <- addErrCtxt (patMonoBindsCtxt pat' grhss) $
tcGRHSsPat grhss pat_ty
; return (PatBind { pat_lhs = pat', pat_rhs = grhss', pat_rhs_ty = pat_ty,
\begin{code}
unifyCtxts :: [TcSigInfo] -> TcM [Inst]
-- Post-condition: the returned Insts are full zonked
+unifyCtxts [] = panic "unifyCtxts []"
unifyCtxts (sig1 : sigs) -- Argument is always non-empty
= do { mapM unify_ctxt sigs
; theta <- zonkTcThetaType (sig_theta sig1)
-- where F is a type function and (F a ~ [a])
-- Then unification might succeed with a coercion. But it's much
-- much simpler to require that such signatures have identical contexts
- checkTc (all isIdentityCoercion cois)
+ checkTc (all isIdentityCoI cois)
(ptext (sLit "Mutually dependent functions have syntactically distinct contexts"))
}
<+> ptext (sLit "is unified with another quantified type variable")
<+> quotes (ppr tidy_tv2)
; failWithTcM (env2, msg) }
- where
\end{code}
-- Precondition: no duplicates
mkTcSigFun sigs = lookupNameEnv env
where
- env = mkNameEnv [(name, hsExplicitTvs lhs_ty)
- | L span (TypeSig (L _ name) lhs_ty) <- sigs]
+ env = mkNameEnv (mapCatMaybes mk_pair sigs)
+ mk_pair (L _ (TypeSig (L _ name) lhs_ty)) = Just (name, hsExplicitTvs lhs_ty)
+ mk_pair (L _ (IdSig id)) = Just (idName id, [])
+ mk_pair _ = Nothing
-- 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 [More instantiated than scoped].)
= setSrcSpan span $
do { sigma_ty <- tcHsSigType (FunSigCtxt name) ty
; return (mkLocalId name sigma_ty) }
+tcTySig (L _ (IdSig id))
+ = return id
+tcTySig s = pprPanic "tcTySig" (ppr s)
-------------------
tcInstSig_maybe :: TcSigFun -> Name -> TcM (Maybe TcSigInfo)
-- this signature is part of a multi-signature group
tcInstSig_maybe sig_fn name
= case sig_fn name of
- Nothing -> return Nothing
- Just scoped_tvs -> do { tc_sig <- tcInstSig False name
- ; return (Just tc_sig) }
- -- NB: the scoped_tvs may be non-empty, but we can
+ Nothing -> return Nothing
+ Just _scoped_tvs -> do { tc_sig <- tcInstSig False name
+ ; return (Just tc_sig) }
+ -- NB: the _scoped_tvs may be non-empty, but we can
-- just ignore them. See Note [Scoped tyvars].
tcInstSig :: Bool -> Name -> TcM TcSigInfo
tcInstSig use_skols name
= do { poly_id <- tcLookupId name -- Cannot fail; the poly ids are put into
-- scope when starting the binding group
- ; let skol_info = SigSkol (FunSigCtxt name)
- inst_tyvars = tcInstSigTyVars use_skols skol_info
- ; (tvs, theta, tau) <- tcInstType inst_tyvars (idType poly_id)
+ ; let skol_info = SigSkol (FunSigCtxt name)
+ ; (tvs, theta, tau) <- tcInstSigType use_skols skol_info (idType poly_id)
; loc <- getInstLoc (SigOrigin skol_info)
; return (TcSigInfo { sig_id = poly_id,
sig_tvs = tvs, sig_theta = theta, sig_tau = tau,
= dopt Opt_MonoPatBinds dflags && any is_pat_bind binds
where
is_pat_bind (L _ (PatBind {})) = True
- is_pat_bind other = False
+ is_pat_bind _ = False
-------------------
isRestrictedGroup :: DynFlags -> [LHsBind Name] -> TcSigFun -> Bool
unrestricted (VarBind { var_id = v }) = has_sig v
unrestricted (FunBind { fun_id = v, fun_matches = matches }) = unrestricted_match matches
|| has_sig (unLoc v)
+ unrestricted (AbsBinds {})
+ = panic "isRestrictedGroup/unrestricted AbsBinds"
unrestricted_match (MatchGroup (L _ (Match [] _ _) : _) _) = False
-- No args => like a pattern binding
- unrestricted_match other = True
+ unrestricted_match _ = True
-- Some args => a function binding
\end{code}
\begin{code}
-- This one is called on LHS, when pat and grhss are both Name
-- and on RHS, when pat is TcId and grhss is still Name
+patMonoBindsCtxt :: OutputableBndr id => LPat id -> GRHSs Name -> SDoc
patMonoBindsCtxt pat grhss
= hang (ptext (sLit "In a pattern binding:")) 4 (pprPatBind pat grhss)
-----------------------------------------------
+sigContextsCtxt :: TcSigInfo -> TcSigInfo -> SDoc
sigContextsCtxt sig1 sig2
= vcat [ptext (sLit "When matching the contexts of the signatures for"),
nest 2 (vcat [ppr id1 <+> dcolon <+> ppr (idType id1),
-----------------------------------------------
+unboxedTupleErr :: Name -> Type -> SDoc
unboxedTupleErr name ty
= hang (ptext (sLit "Illegal binding of unboxed tuple"))
4 (ppr name <+> dcolon <+> ppr ty)
-----------------------------------------------
+restrictedBindCtxtErr :: [Name] -> SDoc
restrictedBindCtxtErr binder_names
= hang (ptext (sLit "Illegal overloaded type signature(s)"))
4 (vcat [ptext (sLit "in a binding group for") <+> pprBinders binder_names,
ptext (sLit "that falls under the monomorphism restriction")])
+genCtxt :: [Name] -> SDoc
genCtxt binder_names
= ptext (sLit "When generalising the type(s) for") <+> pprBinders binder_names
-missingSigWarn False name ty = return ()
+missingSigWarn :: Bool -> Name -> Type -> TcM ()
+missingSigWarn False _ _ = return ()
missingSigWarn True name ty
= do { env0 <- tcInitTidyEnv
; let (env1, tidy_ty) = tidyOpenType env0 ty