%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcBinds]{TcBinds}
\begin{code}
+module TcBinds ( tcBindsAndThen, tcTopBindsAndThen,
+ tcPragmaSigs, tcBindWithSigs ) where
+
#include "HsVersions.h"
-module TcBinds ( tcBindsAndThen, tcPragmaSigs ) where
+import {-# SOURCE #-} TcGRHSs ( tcGRHSsAndBinds )
+import {-# SOURCE #-} TcExpr ( tcExpr )
-import Ubiq
+import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), InPat(..), StmtCtxt(..),
+ collectMonoBinders, andMonoBindList, andMonoBinds
+ )
+import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds )
+import TcHsSyn ( TcHsBinds, TcMonoBinds,
+ TcIdOcc(..), TcIdBndr,
+ tcIdType, zonkId
+ )
-import HsSyn ( HsBinds(..), Bind(..), Sig(..), MonoBinds(..),
- HsExpr, Match, PolyType, InPat, OutPat(..),
- GRHSsAndBinds, ArithSeqInfo, HsLit, Fake,
- collectBinders )
-import RnHsSyn ( RenamedHsBinds(..), RenamedBind(..), RenamedSig(..),
- RenamedMonoBinds(..), RnName(..)
+import TcMonad
+import Inst ( Inst, LIE, emptyLIE, mkLIE, plusLIE, plusLIEs, InstOrigin(..),
+ newDicts, tyVarsOfInst, instToId,
+ )
+import TcEnv ( tcExtendLocalValEnv, tcExtendEnvWithPat,
+ tcLookupLocalValueOK,
+ newSpecPragmaId,
+ tcGetGlobalTyVars, tcExtendGlobalTyVars
)
-import TcHsSyn ( TcHsBinds(..), TcBind(..), TcMonoBinds(..),
- TcIdOcc(..), TcIdBndr(..) )
-
-import TcMonad
-import GenSpecEtc ( checkSigTyVars, genBinds, TcSigInfo(..) )
-import Inst ( Inst, LIE(..), emptyLIE, plusLIE, InstOrigin(..) )
-import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newMonoIds )
-import TcLoop ( tcGRHSsAndBinds )
import TcMatches ( tcMatchesFun )
-import TcMonoType ( tcPolyType )
-import TcPat ( tcPat )
+import TcSimplify ( tcSimplify, tcSimplifyAndCheck )
+import TcMonoType ( tcHsTcType, checkSigTyVars,
+ TcSigInfo(..), tcTySig, maybeSig, sigCtxt
+ )
+import TcPat ( tcVarPat, tcPat )
import TcSimplify ( bindInstsOfLocalFuns )
-import TcType ( newTcTyVar, tcInstType )
-import Unify ( unifyTauTy )
-
-import Kind ( mkBoxedTypeKind, mkTypeKind )
-import Id ( GenId, idType, mkUserId )
-import IdInfo ( noIdInfo )
-import Maybes ( assocMaybe, catMaybes, Maybe(..) )
-import Name ( pprNonSym )
-import PragmaInfo ( PragmaInfo(..) )
-import Pretty
-import RnHsSyn ( RnName ) -- instances
-import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy,
- mkSigmaTy, splitSigmaTy,
- splitRhoTy, mkForAllTy, splitForAllTy )
-import Util ( isIn, panic )
+import TcType ( TcType, TcThetaType,
+ TcTyVar,
+ newTyVarTy, newTcTyVar, tcInstTcType,
+ zonkTcType, zonkTcTypes, zonkTcThetaType )
+import TcUnify ( unifyTauTy, unifyTauTyLists )
+
+import Id ( mkUserId )
+import Var ( idType, idName, setIdInfo )
+import IdInfo ( IdInfo, noIdInfo, setInlinePragInfo, InlinePragInfo(..) )
+import Name ( Name )
+import Type ( mkTyVarTy, tyVarsOfTypes,
+ splitSigmaTy, mkForAllTys, mkFunTys, getTyVar,
+ mkDictTy, splitRhoTy, mkForAllTy, isUnLiftedType,
+ isUnboxedType, openTypeKind,
+ unboxedTypeKind, boxedTypeKind
+ )
+import Var ( TyVar, tyVarKind )
+import VarSet
+import Bag
+import Util ( isIn )
+import BasicTypes ( TopLevelFlag(..), RecFlag(..) )
+import SrcLoc ( SrcLoc )
+import Outputable
\end{code}
+
%************************************************************************
%* *
\subsection{Type-checking bindings}
@tcBindsAndThen@ also takes a "combiner" which glues together the
bindings and the "thing" to make a new "thing".
-The real work is done by @tcBindAndThen@.
+The real work is done by @tcBindWithSigsAndThen@.
Recursive and non-recursive binds are handled in essentially the same
way: because of uniques there are no scoping issues left. The only
dictionaries, which we resolve at the module level.
\begin{code}
-tcBindsAndThen
- :: (TcHsBinds s -> thing -> thing) -- Combinator
+tcTopBindsAndThen, tcBindsAndThen
+ :: (RecFlag -> TcMonoBinds s -> thing -> thing) -- Combinator
-> RenamedHsBinds
- -> TcM s (thing, LIE s, thing_ty)
- -> TcM s (thing, LIE s, thing_ty)
+ -> TcM s (thing, LIE s)
+ -> TcM s (thing, LIE s)
+
+tcTopBindsAndThen = tc_binds_and_then TopLevel
+tcBindsAndThen = tc_binds_and_then NotTopLevel
+
+tc_binds_and_then top_lvl combiner EmptyBinds do_next
+ = do_next
+tc_binds_and_then top_lvl combiner (MonoBind EmptyMonoBinds sigs is_rec) do_next
+ = do_next
-tcBindsAndThen combiner EmptyBinds do_next
- = do_next `thenTc` \ (thing, lie, thing_ty) ->
- returnTc (combiner EmptyBinds thing, lie, thing_ty)
+tc_binds_and_then top_lvl combiner (ThenBinds b1 b2) do_next
+ = tc_binds_and_then top_lvl combiner b1 $
+ tc_binds_and_then top_lvl combiner b2 $
+ do_next
-tcBindsAndThen combiner (SingleBind bind) do_next
- = tcBindAndThen combiner bind [] do_next
+tc_binds_and_then top_lvl combiner (MonoBind bind sigs is_rec) do_next
+ = fixTc (\ ~(prag_info_fn, _, _) ->
+ -- This is the usual prag_info fix; the PragmaInfo field of an Id
+ -- is not inspected till ages later in the compiler, so there
+ -- should be no black-hole problems here.
-tcBindsAndThen combiner (BindWith bind sigs) do_next
- = tcBindAndThen combiner bind sigs do_next
+ -- TYPECHECK THE SIGNATURES
+ mapTc tcTySig [sig | sig@(Sig name _ _) <- sigs] `thenTc` \ tc_ty_sigs ->
+
+ tcBindWithSigs top_lvl bind
+ tc_ty_sigs is_rec prag_info_fn `thenTc` \ (poly_binds, poly_lie, poly_ids) ->
+
+ -- Extend the environment to bind the new polymorphic Ids
+ tcExtendLocalValEnv (map idName poly_ids) poly_ids $
+
+ -- Build bindings and IdInfos corresponding to user pragmas
+ tcPragmaSigs sigs `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
+
+ -- Now do whatever happens next, in the augmented envt
+ do_next `thenTc` \ (thing, thing_lie) ->
-tcBindsAndThen combiner (ThenBinds binds1 binds2) do_next
- = tcBindsAndThen combiner binds1 (tcBindsAndThen combiner binds2 do_next)
+ -- Create specialisations of functions bound here
+ -- We want to keep non-recursive things non-recursive
+ -- so that we desugar unboxed bindings correctly
+ case (top_lvl, is_rec) of
+
+ -- For the top level don't bother will 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
+ (TopLevel, _)
+ -> returnTc (prag_info_fn,
+ combiner Recursive (poly_binds `andMonoBinds` prag_binds) thing,
+ thing_lie `plusLIE` prag_lie `plusLIE` poly_lie)
+
+ (NotTopLevel, NonRecursive)
+ -> bindInstsOfLocalFuns
+ (thing_lie `plusLIE` prag_lie)
+ poly_ids `thenTc` \ (thing_lie', lie_binds) ->
+
+ returnTc (
+ prag_info_fn,
+ combiner NonRecursive poly_binds $
+ combiner NonRecursive prag_binds $
+ combiner Recursive lie_binds $
+ -- NB: the binds returned by tcSimplify and bindInstsOfLocalFuns
+ -- aren't guaranteed in dependency order (though we could change
+ -- that); hence the Recursive marker.
+ thing,
+
+ thing_lie' `plusLIE` poly_lie
+ )
+
+ (NotTopLevel, Recursive)
+ -> bindInstsOfLocalFuns
+ (thing_lie `plusLIE` poly_lie `plusLIE` prag_lie)
+ poly_ids `thenTc` \ (final_lie, lie_binds) ->
+
+ returnTc (
+ prag_info_fn,
+ combiner Recursive (
+ poly_binds `andMonoBinds`
+ lie_binds `andMonoBinds`
+ prag_binds) thing,
+ final_lie
+ )
+ ) `thenTc` \ (_, thing, lie) ->
+ returnTc (thing, lie)
\end{code}
An aside. The original version of @tcBindsAndThen@ which lacks a
examples of this, which is why I thought it worth preserving! [SLPJ]
\begin{pseudocode}
-tcBindsAndThen
- :: RenamedHsBinds
- -> TcM s (thing, LIE s, thing_ty))
- -> TcM s ((TcHsBinds s, thing), LIE s, thing_ty)
-
-tcBindsAndThen EmptyBinds do_next
- = do_next `thenTc` \ (thing, lie, thing_ty) ->
- returnTc ((EmptyBinds, thing), lie, thing_ty)
-
-tcBindsAndThen (SingleBind bind) do_next
- = tcBindAndThen bind [] do_next
-
-tcBindsAndThen (BindWith bind sigs) do_next
- = tcBindAndThen bind sigs do_next
-
-tcBindsAndThen (ThenBinds binds1 binds2) do_next
- = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next)
- `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) ->
-
- returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty)
+% tcBindsAndThen
+% :: RenamedHsBinds
+% -> TcM s (thing, LIE s, thing_ty))
+% -> TcM s ((TcHsBinds s, thing), LIE s, thing_ty)
+%
+% tcBindsAndThen EmptyBinds do_next
+% = do_next `thenTc` \ (thing, lie, thing_ty) ->
+% returnTc ((EmptyBinds, thing), lie, thing_ty)
+%
+% tcBindsAndThen (ThenBinds binds1 binds2) do_next
+% = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next)
+% `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) ->
+%
+% returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty)
+%
+% tcBindsAndThen (MonoBind bind sigs is_rec) do_next
+% = tcBindAndThen bind sigs do_next
\end{pseudocode}
+
%************************************************************************
%* *
-\subsection{Bind}
+\subsection{tcBindWithSigs}
%* *
%************************************************************************
-\begin{code}
-tcBindAndThen
- :: (TcHsBinds s -> thing -> thing) -- Combinator
- -> RenamedBind -- The Bind to typecheck
- -> [RenamedSig] -- ...and its signatures
- -> TcM s (thing, LIE s, thing_ty) -- Thing to type check in
- -- augmented envt
- -> TcM s (thing, LIE s, thing_ty) -- Results, incl the
-
-tcBindAndThen combiner bind sigs do_next
- = fixTc (\ ~(prag_info_fn, _) ->
- -- This is the usual prag_info fix; the PragmaInfo field of an Id
- -- is not inspected till ages later in the compiler, so there
- -- should be no black-hole problems here.
-
- tcBindAndSigs binder_names bind
- sigs prag_info_fn `thenTc` \ (poly_binds, poly_lie, poly_ids) ->
+@tcBindWithSigs@ deals with a single binding group. It does generalisation,
+so all the clever stuff is in here.
- -- Extend the environment to bind the new polymorphic Ids
- tcExtendLocalValEnv binder_names poly_ids $
+* binder_names and mbind must define the same set of Names
- -- Build bindings and IdInfos corresponding to user pragmas
- tcPragmaSigs sigs `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
+* The Names in tc_ty_sigs must be a subset of binder_names
- -- Now do whatever happens next, in the augmented envt
- do_next `thenTc` \ (thing, thing_lie, thing_ty) ->
+* The Ids in tc_ty_sigs don't necessarily have to have the same name
+ as the Name in the tc_ty_sig
- -- Create specialisations of functions bound here
- bindInstsOfLocalFuns (prag_lie `plusLIE` thing_lie)
- poly_ids `thenTc` \ (lie2, inst_mbinds) ->
+\begin{code}
+tcBindWithSigs
+ :: TopLevelFlag
+ -> RenamedMonoBinds
+ -> [TcSigInfo s]
+ -> RecFlag
+ -> (Name -> IdInfo)
+ -> TcM s (TcMonoBinds s, LIE s, [TcIdBndr s])
+
+tcBindWithSigs top_lvl mbind tc_ty_sigs is_rec prag_info_fn
+ = recoverTc (
+ -- If typechecking the binds fails, then return with each
+ -- signature-less binder given type (forall a.a), to minimise subsequent
+ -- error messages
+ newTcTyVar boxedTypeKind `thenNF_Tc` \ alpha_tv ->
+ let
+ forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv)
+ binder_names = map fst (bagToList (collectMonoBinders mbind))
+ poly_ids = map mk_dummy binder_names
+ mk_dummy name = case maybeSig tc_ty_sigs name of
+ Just (TySigInfo _ poly_id _ _ _ _ _ _) -> poly_id -- Signature
+ Nothing -> mkUserId name forall_a_a -- No signature
+ in
+ returnTc (EmptyMonoBinds, emptyLIE, poly_ids)
+ ) $
+
+ -- TYPECHECK THE BINDINGS
+ tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) ->
- -- All done
let
- final_lie = lie2 `plusLIE` poly_lie
- final_binds = poly_binds `ThenBinds`
- SingleBind (NonRecBind inst_mbinds) `ThenBinds`
- prag_binds
+ mono_id_tys = map idType mono_ids
in
- returnTc (prag_info_fn, (combiner final_binds thing, final_lie, thing_ty))
- ) `thenTc` \ (_, result) ->
- returnTc result
- where
- binder_names = collectBinders bind
+ -- CHECK THAT THE SIGNATURES MATCH
+ -- (must do this before getTyVarsToGen)
+ checkSigMatch tc_ty_sigs `thenTc` \ (sig_theta, lie_avail) ->
-tcBindAndSigs binder_rn_names bind sigs prag_info_fn
- = let
- binder_names = map de_rn binder_rn_names
- de_rn (RnName n) = n
+ -- COMPUTE VARIABLES OVER WHICH TO QUANTIFY, namely tyvars_to_gen
+ -- The tyvars_not_to_gen are free in the environment, and hence
+ -- candidates for generalisation, but sometimes the monomorphism
+ -- restriction means we can't generalise them nevertheless
+ getTyVarsToGen is_unrestricted mono_id_tys lie_req `thenNF_Tc` \ (tyvars_not_to_gen, tyvars_to_gen) ->
+
+ -- DEAL WITH TYPE VARIABLE KINDS
+ -- **** This step can do unification => keep other zonking after this ****
+ mapTc defaultUncommittedTyVar (varSetElems tyvars_to_gen) `thenTc` \ real_tyvars_to_gen_list ->
+ let
+ real_tyvars_to_gen = mkVarSet real_tyvars_to_gen_list
+ -- It's important that the final list
+ -- (real_tyvars_to_gen and real_tyvars_to_gen_list) is fully
+ -- zonked, *including boxity*, because they'll be included in the forall types of
+ -- the polymorphic Ids, and instances of these Ids will be generated from them.
+ --
+ -- Also NB that tcSimplify takes zonked tyvars as its arg, hence we pass
+ -- real_tyvars_to_gen
in
- recoverTc (
- -- If typechecking the binds fails, then return with each
- -- binder given type (forall a.a), to minimise subsequent
- -- error messages
- newTcTyVar mkBoxedTypeKind `thenNF_Tc` \ alpha_tv ->
- let
- forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv)
- poly_ids = [ mkUserId name forall_a_a (prag_info_fn name)
- | name <- binder_names]
- in
- returnTc (EmptyBinds, emptyLIE, poly_ids)
- ) $
- -- Create a new identifier for each binder, with each being given
- -- a type-variable type.
- newMonoIds binder_rn_names kind (\ mono_ids ->
- tcTySigs sigs `thenTc` \ sig_info ->
- tc_bind bind `thenTc` \ (bind', lie) ->
- returnTc (mono_ids, bind', lie, sig_info)
+ -- SIMPLIFY THE LIE
+ tcExtendGlobalTyVars tyvars_not_to_gen (
+ if null real_tyvars_to_gen_list then
+ -- No polymorphism, so no need to simplify context
+ returnTc (lie_req, EmptyMonoBinds, [])
+ else
+ if null tc_ty_sigs then
+ -- No signatures, so just simplify the lie
+ -- NB: no signatures => no polymorphic recursion, so no
+ -- need to use lie_avail (which will be empty anyway)
+ tcSimplify (text "tcBinds1" <+> ppr binder_names)
+ top_lvl real_tyvars_to_gen lie_req `thenTc` \ (lie_free, dict_binds, lie_bound) ->
+ returnTc (lie_free, dict_binds, map instToId (bagToList lie_bound))
+
+ else
+ zonkTcThetaType sig_theta `thenNF_Tc` \ sig_theta' ->
+ newDicts SignatureOrigin sig_theta' `thenNF_Tc` \ (dicts_sig, dict_ids) ->
+ -- It's important that sig_theta is zonked, because
+ -- dict_id is later used to form the type of the polymorphic thing,
+ -- and forall-types must be zonked so far as their bound variables
+ -- are concerned
+
+ let
+ -- The "givens" is the stuff available. We get that from
+ -- the context of the type signature, BUT ALSO the lie_avail
+ -- so that polymorphic recursion works right (see comments at end of fn)
+ givens = dicts_sig `plusLIE` lie_avail
+ in
+
+ -- Check that the needed dicts can be expressed in
+ -- terms of the signature ones
+ tcAddErrCtxt (bindSigsCtxt tysig_names) $
+ tcSimplifyAndCheck
+ (ptext SLIT("type signature for") <+> pprQuotedList binder_names)
+ real_tyvars_to_gen givens lie_req `thenTc` \ (lie_free, dict_binds) ->
+
+ returnTc (lie_free, dict_binds, dict_ids)
+
+ ) `thenTc` \ (lie_free, dict_binds, dicts_bound) ->
+
+ -- GET THE FINAL MONO_ID_TYS
+ zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_types ->
+
+
+ -- CHECK FOR BOGUS UNPOINTED BINDINGS
+ (if any isUnLiftedType zonked_mono_id_types then
+ -- Unlifted bindings must be non-recursive,
+ -- not top level, and non-polymorphic
+ checkTc (case top_lvl of {TopLevel -> False; NotTopLevel -> True})
+ (unliftedBindErr "Top-level" mbind) `thenTc_`
+ checkTc (case is_rec of {Recursive -> False; NonRecursive -> True})
+ (unliftedBindErr "Recursive" mbind) `thenTc_`
+ checkTc (null real_tyvars_to_gen_list)
+ (unliftedBindErr "Polymorphic" mbind)
+ else
+ returnTc ()
+ ) `thenTc_`
+
+ ASSERT( not (any ((== unboxedTypeKind) . tyVarKind) real_tyvars_to_gen_list) )
+ -- The instCantBeGeneralised stuff in tcSimplify should have
+ -- already raised an error if we're trying to generalise an
+ -- unboxed tyvar (NB: unboxed tyvars are always introduced
+ -- along with a class constraint) and it's better done there
+ -- because we have more precise origin information.
+ -- That's why we just use an ASSERT here.
+
+
+ -- BUILD THE POLYMORPHIC RESULT IDs
+ mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids ->
+ let
+ exports = zipWith mk_export binder_names zonked_mono_ids
+ dict_tys = map tcIdType dicts_bound
+
+ mk_export binder_name zonked_mono_id
+ = (tyvars,
+ TcId (setIdInfo poly_id (prag_info_fn binder_name)),
+ TcId zonked_mono_id)
+ where
+ (tyvars, poly_id) =
+ case maybeSig tc_ty_sigs binder_name of
+ Just (TySigInfo _ sig_poly_id sig_tyvars _ _ _ _ _) ->
+ (sig_tyvars, sig_poly_id)
+ Nothing -> (real_tyvars_to_gen_list, new_poly_id)
+
+ new_poly_id = mkUserId binder_name poly_ty
+ poly_ty = mkForAllTys real_tyvars_to_gen_list
+ $ mkFunTys dict_tys
+ $ idType (zonked_mono_id)
+ -- It's important to build a fully-zonked poly_ty, because
+ -- we'll slurp out its free type variables when extending the
+ -- local environment (tcExtendLocalValEnv); if it's not zonked
+ -- it appears to have free tyvars that aren't actually free
+ -- at all.
+
+ pat_binders :: [Name]
+ pat_binders = map fst $ bagToList $ collectMonoBinders $
+ (justPatBindings mbind EmptyMonoBinds)
+ in
+ -- CHECK FOR UNBOXED BINDERS IN PATTERN BINDINGS
+ mapTc (\id -> checkTc (not (idName id `elem` pat_binders
+ && isUnboxedType (idType id)))
+ (unboxedPatBindErr id)) zonked_mono_ids
+ `thenTc_`
+
+ -- BUILD RESULTS
+ returnTc (
+ AbsBinds real_tyvars_to_gen_list
+ dicts_bound
+ exports
+ (dict_binds `andMonoBinds` mbind'),
+ lie_free,
+ [poly_id | (_, TcId poly_id, _) <- exports]
)
- `thenTc` \ (mono_ids, bind', lie, sig_info) ->
-
- -- Notice that genBinds gets the old (non-extended) environment
- genBinds binder_names mono_ids bind' lie sig_info prag_info_fn
where
- kind = case bind of
- NonRecBind _ -> mkBoxedTypeKind -- Recursive, so no unboxed types
- RecBind _ -> mkTypeKind -- Non-recursive, so we permit unboxed types
+ tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- tc_ty_sigs]
+ is_unrestricted = isUnRestrictedGroup tysig_names mbind
+
+justPatBindings bind@(PatMonoBind _ _ _) binds = bind `andMonoBinds` binds
+justPatBindings (AndMonoBinds b1 b2) binds =
+ justPatBindings b1 (justPatBindings b2 binds)
+justPatBindings other_bind binds = binds
\end{code}
+Polymorphic recursion
+~~~~~~~~~~~~~~~~~~~~~
+The game plan for polymorphic recursion in the code above is
-===========
-\begin{code}
-{-
+ * Bind any variable for which we have a type signature
+ to an Id with a polymorphic type. Then when type-checking
+ the RHSs we'll make a full polymorphic call.
-data SigInfo
- = SigInfo RnName
- (TcIdBndr s) -- Polymorpic version
- (TcIdBndr s) -- Monomorphic verstion
- [TcType s] [TcIdOcc s] -- Instance information for the monomorphic version
+This fine, but if you aren't a bit careful you end up with a horrendous
+amount of partial application and (worse) a huge space leak. For example:
+ f :: Eq a => [a] -> [a]
+ f xs = ...f...
+If we don't take care, after typechecking we get
- -- Deal with type signatures
- tcTySigs sigs `thenTc` \ sig_infos ->
- let
- sig_binders = [binder | SigInfo binder _ _ _ _ <- sig_infos]
- poly_sigs = [(name,poly) | SigInfo name poly _ _ _ <- sig_infos]
- mono_sigs = [(name,mono) | SigInfo name _ mono _ _ <- sig_infos]
- nosig_binders = binders `minusList` sig_binders
- in
+ f = /\a -> \d::Eq a -> let f' = f a d
+ in
+ \ys:[a] -> ...f'...
+Notice the the stupid construction of (f a d), which is of course
+identical to the function we're executing. In this case, the
+polymorphic recursion isn't being used (but that's a very common case).
+We'd prefer
- -- Typecheck the binding group
- tcExtendLocalEnv poly_sigs (
- newMonoIds nosig_binders kind (\ nosig_local_ids ->
- tcMonoBinds mono_sigs mono_binds `thenTc` \ binds_w_lies ->
- returnTc (nosig_local_ids, binds_w_lies)
- )) `thenTc` \ (nosig_local_ids, binds_w_lies) ->
+ f = /\a -> \d::Eq a -> letrec
+ fm = \ys:[a] -> ...fm...
+ in
+ fm
+This can lead to a massive space leak, from the following top-level defn
+(post-typechecking)
- -- Decide what to generalise over
- getImplicitStuffToGen sig_ids binds_w_lies
- `thenTc` \ (tyvars_not_to_gen, tyvars_to_gen, lie_to_gen) ->
+ ff :: [Int] -> [Int]
+ ff = f Int dEqInt
+Now (f dEqInt) evaluates to a lambda that has f' as a free variable; but
+f' is another thunk which evaluates to the same thing... and you end
+up with a chain of identical values all hung onto by the CAF ff.
- *** CHECK FOR UNBOXED TYVARS HERE! ***
+ ff = f Int dEqInt
+ = let f' = f Int dEqInt in \ys. ...f'...
+ = let f' = let f' = f Int dEqInt in \ys. ...f'...
+ in \ys. ...f'...
- -- Make poly_ids for all the binders that don't have type signatures
- let
- tys_to_gen = mkTyVarTys tyvars_to_gen
- dicts_to_gen = map instToId (bagToList lie_to_gen)
- dict_tys = map tcIdType dicts_to_gen
-
- mk_poly binder local_id = mkUserId (getName binder) ty noPragmaInfo
- where
- ty = mkForAllTys tyvars_to_gen $
- mkFunTys dict_tys $
- tcIdType local_id
-
- more_sig_infos = [ SigInfo binder (mk_poly binder local_id)
- local_id tys_to_gen dicts_to_gen lie_to_gen
- | (binder, local_id) <- nosig_binders `zipEqual` nosig_local_ids
- ]
-
- all_sig_infos = sig_infos ++ more_sig_infos -- Contains a "signature" for each binder
- in
+Etc.
+Solution: when typechecking the RHSs we always have in hand the
+*monomorphic* Ids for each binding. So we just need to make sure that
+if (Method f a d) shows up in the constraints emerging from (...f...)
+we just use the monomorphic Id. We achieve this by adding monomorphic Ids
+to the "givens" when simplifying constraints. That's what the "lies_avail"
+is doing.
- -- Now generalise the bindings
- let
- -- local_binds is a bunch of bindings of the form
- -- f_mono = f_poly tyvars dicts
- -- one for each binder, f, that lacks a type signature.
- -- This bunch of bindings is put at the top of the RHS of every
- -- binding in the group, so as to bind all the f_monos.
-
- local_binds = [ (local_id, mkHsDictApp (mkHsTyApp (HsVar local_id) tys_to_gen) dicts_to_gen)
- | local_id <- nosig_local_ids
- ]
-
- find_sig lid = head [ (pid, tvs, ds, lie)
- | SigInfo _ pid lid' tvs ds lie,
- lid==lid'
- ]
-
- gen_bind (bind, lie)
- = tcSimplifyWithExtraGlobals tyvars_not_to_gen tyvars_to_gen avail lie
- `thenTc` \ (lie_free, dict_binds) ->
- returnTc (AbsBind tyvars_to_gen_here
- dicts
- (local_ids `zipEqual` poly_ids)
- (dict_binds ++ local_binds)
- bind,
- lie_free)
- where
- local_ids = bindersOf bind
- local_sigs = [sig | sig@(SigInfo _ _ local_id _ _) <- all_sig_infos,
- local_id `elem` local_ids
- ]
-
- (tyvars_to_gen_here, dicts, avail)
- = case (local_ids, sigs) of
-
- ([local_id], [SigInfo _ _ _ tyvars_to_gen dicts lie])
- -> (tyvars_to_gen, dicts, lie)
-
- other -> (tyvars_to_gen, dicts, avail)
-\end{code}
+%************************************************************************
+%* *
+\subsection{getTyVarsToGen}
+%* *
+%************************************************************************
-@getImplicitStuffToGen@ decides what type variables
-and LIE to generalise over.
+@getTyVarsToGen@ decides what type variables generalise over.
For a "restricted group" -- see the monomorphism restriction
for a definition -- we bind no dictionaries, and
we'll know that the literals are all Ints, and we can just produce
Int literals!
-Find all the type variables involved in overloading, the "constrained_tyvars"
-These are the ones we *aren't* going to generalise.
-We must be careful about doing this:
+Find all the type variables involved in overloading, the
+"constrained_tyvars". These are the ones we *aren't* going to
+generalise. We must be careful about doing this:
+
(a) If we fail to generalise a tyvar which is not actually
constrained, then it will never, ever get bound, and lands
up printed out in interface files! Notorious example:
Another, more common, example is when there's a Method inst in
the LIE, whose type might very well involve non-overloaded
type variables.
+
(b) On the other hand, we mustn't generalise tyvars which are constrained,
because we are going to pass on out the unmodified LIE, with those
tyvars in it. They won't be in scope if we've generalised them.
find which tyvars are constrained.
\begin{code}
-getImplicitStuffToGen is_restricted sig_ids binds_w_lies
- | isUnRestrictedGroup tysig_vars bind
- = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, dicts_to_gen) ->
- returnNF_Tc (emptyTyVarSet, tyvars_to_gen, dicts_to_gen)
-
- | otherwise
- = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, constrained_dicts) ->
- let
+getTyVarsToGen is_unrestricted mono_id_tys lie
+ = tcGetGlobalTyVars `thenNF_Tc` \ free_tyvars ->
+ zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_tys ->
+ let
+ tyvars_to_gen = tyVarsOfTypes zonked_mono_id_tys `minusVarSet` free_tyvars
+ in
+ if is_unrestricted
+ then
+ returnNF_Tc (emptyVarSet, tyvars_to_gen)
+ else
+ -- This recover and discard-errs is to avoid duplicate error
+ -- messages; this, after all, is an "extra" call to tcSimplify
+ recoverNF_Tc (returnNF_Tc (emptyVarSet, tyvars_to_gen)) $
+ discardErrsTc $
+
+ tcSimplify (text "getTVG") NotTopLevel tyvars_to_gen lie `thenTc` \ (_, _, constrained_dicts) ->
+ let
-- ASSERT: dicts_sig is already zonked!
- constrained_tyvars = foldBag unionTyVarSets tyVarsOfInst emptyTyVarSet constrained_dicts
- reduced_tyvars_to_gen = tyvars_to_gen `minusTyVarSet` constrained_tyvars
- in
- returnTc (constrained_tyvars, reduced_tyvars_to_gen, emptyLIE)
-
- where
- sig_vars = [sig_var | (TySigInfo sig_var _ _ _ _) <- ty_sigs]
-
- (tyvars_to_gen, lie) = foldBag (\(tv1,lie2) (tv2,lie2) -> (tv1 `unionTyVarSets` tv2,
- lie1 `plusLIE` lie2))
- get
- (emptyTyVarSet, emptyLIE)
- binds_w_lies
- get (bind, lie)
- = case bindersOf bind of
- [local_id] | local_id `in` sig_ids -> -- A simple binding with
- -- a type signature
- (emptyTyVarSet, emptyLIE)
-
- local_ids -> -- Complex binding or no type sig
- (foldr (unionTyVarSets . tcIdType) emptyTyVarSet local_ids,
- lie)
--}
+ constrained_tyvars = foldrBag (unionVarSet . tyVarsOfInst) emptyVarSet constrained_dicts
+ reduced_tyvars_to_gen = tyvars_to_gen `minusVarSet` constrained_tyvars
+ in
+ returnTc (constrained_tyvars, reduced_tyvars_to_gen)
\end{code}
-
\begin{code}
-tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s)
+isUnRestrictedGroup :: [Name] -- Signatures given for these
+ -> RenamedMonoBinds
+ -> Bool
-tc_bind (NonRecBind mono_binds)
- = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
- returnTc (NonRecBind mono_binds2, lie)
+is_elem v vs = isIn "isUnResMono" v vs
-tc_bind (RecBind mono_binds)
- = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
- returnTc (RecBind mono_binds2, lie)
+isUnRestrictedGroup sigs (PatMonoBind (VarPatIn v) _ _) = v `is_elem` sigs
+isUnRestrictedGroup sigs (PatMonoBind other _ _) = False
+isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs
+isUnRestrictedGroup sigs (FunMonoBind _ _ _ _) = True
+isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 &&
+ isUnRestrictedGroup sigs mb2
+isUnRestrictedGroup sigs EmptyMonoBinds = True
\end{code}
+@defaultUncommittedTyVar@ checks for generalisation over unboxed
+types, and defaults any TypeKind TyVars to BoxedTypeKind.
+
\begin{code}
-tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s)
+defaultUncommittedTyVar tyvar
+ | tyVarKind tyvar == openTypeKind
+ = newTcTyVar boxedTypeKind `thenNF_Tc` \ boxed_tyvar ->
+ unifyTauTy (mkTyVarTy tyvar) (mkTyVarTy boxed_tyvar) `thenTc_`
+ returnTc boxed_tyvar
-tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE)
+ | otherwise
+ = returnTc tyvar
+\end{code}
-tcMonoBinds (AndMonoBinds mb1 mb2)
- = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) ->
- tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) ->
- returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2)
-tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn)
- = tcAddSrcLoc locn $
+%************************************************************************
+%* *
+\subsection{tcMonoBind}
+%* *
+%************************************************************************
- -- LEFT HAND SIDE
- tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) ->
+@tcMonoBinds@ deals with a single @MonoBind@.
+The signatures have been dealt with already.
- -- BINDINGS AND GRHSS
- tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) ->
+\begin{code}
+tcMonoBinds :: RenamedMonoBinds
+ -> [TcSigInfo s]
+ -> RecFlag
+ -> TcM s (TcMonoBinds s,
+ LIE s, -- LIE required
+ [Name], -- Bound names
+ [TcIdBndr s]) -- Corresponding monomorphic bound things
+
+tcMonoBinds mbinds tc_ty_sigs is_rec
+ = tc_mb_pats mbinds `thenTc` \ (complete_it, lie_req_pat, tvs, ids, lie_avail) ->
+ let
+ tv_list = bagToList tvs
+ (names, mono_ids) = unzip (bagToList ids)
+ in
+ -- Don't know how to deal with pattern-bound existentials yet
+ checkTc (isEmptyBag tvs && isEmptyBag lie_avail)
+ (existentialExplode mbinds) `thenTc_`
+
+ -- *Before* checking the RHSs, but *after* checking *all* the patterns,
+ -- extend the envt with bindings for all the bound ids;
+ -- and *then* override with the polymorphic Ids from the signatures
+ -- That is the whole point of the "complete_it" stuff.
+ tcExtendEnvWithPat ids (tcExtendEnvWithPat sig_ids
+ complete_it
+ ) `thenTc` \ (mbinds', lie_req_rhss) ->
+ returnTc (mbinds', lie_req_pat `plusLIE` lie_req_rhss, names, mono_ids)
+ where
+ sig_fn name = case maybeSig tc_ty_sigs name of
+ Nothing -> Nothing
+ Just (TySigInfo _ _ _ _ _ mono_id _ _) -> Just mono_id
+
+ sig_ids = listToBag [(name,poly_id) | TySigInfo name poly_id _ _ _ _ _ _ <- tc_ty_sigs]
+
+ kind = case is_rec of
+ Recursive -> boxedTypeKind -- Recursive, so no unboxed types
+ NonRecursive -> openTypeKind -- Non-recursive, so we permit unboxed types
- -- Unify the two sides
- tcAddErrCtxt (patMonoBindsCtxt bind) $
- unifyTauTy pat_ty grhss_ty `thenTc_`
+ tc_mb_pats EmptyMonoBinds
+ = returnTc (returnTc (EmptyMonoBinds, emptyLIE), emptyLIE, emptyBag, emptyBag, emptyLIE)
- -- RETURN
- returnTc (PatMonoBind pat2 grhss_and_binds2 locn,
- plusLIE lie_pat lie)
+ tc_mb_pats (AndMonoBinds mb1 mb2)
+ = tc_mb_pats mb1 `thenTc` \ (complete_it1, lie_req1, tvs1, ids1, lie_avail1) ->
+ tc_mb_pats mb2 `thenTc` \ (complete_it2, lie_req2, tvs2, ids2, lie_avail2) ->
+ let
+ complete_it = complete_it1 `thenTc` \ (mb1', lie1) ->
+ complete_it2 `thenTc` \ (mb2', lie2) ->
+ returnTc (AndMonoBinds mb1' mb2', lie1 `plusLIE` lie2)
+ in
+ returnTc (complete_it,
+ lie_req1 `plusLIE` lie_req2,
+ tvs1 `unionBags` tvs2,
+ ids1 `unionBags` ids2,
+ lie_avail1 `plusLIE` lie_avail2)
+
+ tc_mb_pats (FunMonoBind name inf matches locn)
+ = newTyVarTy boxedTypeKind `thenNF_Tc` \ pat_ty ->
+ tcVarPat sig_fn name pat_ty `thenTc` \ bndr_id ->
+ let
+ complete_it = tcAddSrcLoc locn $
+ tcMatchesFun name pat_ty matches `thenTc` \ (matches', lie) ->
+ returnTc (FunMonoBind (TcId bndr_id) inf matches' locn, lie)
+ in
+ returnTc (complete_it, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE)
-tcMonoBinds (FunMonoBind name inf matches locn)
- = tcAddSrcLoc locn $
- tcLookupLocalValueOK "tcMonoBinds" name `thenNF_Tc` \ id ->
- tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) ->
- returnTc (FunMonoBind (TcId id) inf matches' locn, lie)
+ tc_mb_pats bind@(PatMonoBind pat grhss_and_binds locn)
+ = tcAddSrcLoc locn $
+ newTyVarTy kind `thenNF_Tc` \ pat_ty ->
+ tcPat sig_fn pat pat_ty `thenTc` \ (pat', lie_req, tvs, ids, lie_avail) ->
+ let
+ complete_it = tcAddSrcLoc locn $
+ tcAddErrCtxt (patMonoBindsCtxt bind) $
+ tcGRHSsAndBinds grhss_and_binds pat_ty PatBindRhs `thenTc` \ (grhss_and_binds', lie) ->
+ returnTc (PatMonoBind pat' grhss_and_binds' locn, lie)
+ in
+ returnTc (complete_it, lie_req, tvs, ids, lie_avail)
\end{code}
%************************************************************************
%* *
%************************************************************************
-@tcSigs@ checks the signatures for validity, and returns a list of
-{\em freshly-instantiated} signatures. That is, the types are already
-split up, and have fresh type variables installed. All non-type-signature
-"RenamedSigs" are ignored.
-
-\begin{code}
-tcTySigs :: [RenamedSig] -> TcM s [TcSigInfo s]
-
-tcTySigs (Sig v ty _ src_loc : other_sigs)
- = tcAddSrcLoc src_loc (
- tcPolyType ty `thenTc` \ sigma_ty ->
- tcInstType [] sigma_ty `thenNF_Tc` \ sigma_ty' ->
- let
- (tyvars', theta', tau') = splitSigmaTy sigma_ty'
- in
-
- tcLookupLocalValueOK "tcSig1" v `thenNF_Tc` \ val ->
- unifyTauTy (idType val) tau' `thenTc_`
-
- returnTc (TySigInfo val tyvars' theta' tau' src_loc)
- ) `thenTc` \ sig_info1 ->
+@checkSigMatch@ does the next step in checking signature matching.
+The tau-type part has already been unified. What we do here is to
+check that this unification has not over-constrained the (polymorphic)
+type variables of the original signature type.
- tcTySigs other_sigs `thenTc` \ sig_infos ->
- returnTc (sig_info1 : sig_infos)
+The error message here is somewhat unsatisfactory, but it'll do for
+now (ToDo).
-tcTySigs (other : sigs) = tcTySigs sigs
-tcTySigs [] = returnTc []
+\begin{code}
+checkSigMatch []
+ = returnTc (error "checkSigMatch", emptyLIE)
+
+checkSigMatch tc_ty_sigs@( sig1@(TySigInfo _ id1 _ theta1 _ _ _ _) : all_sigs_but_first )
+ = -- CHECK THAT THE SIGNATURE TYVARS AND TAU_TYPES ARE OK
+ -- Doesn't affect substitution
+ mapTc check_one_sig tc_ty_sigs `thenTc_`
+
+ -- CHECK THAT ALL THE SIGNATURE CONTEXTS ARE UNIFIABLE
+ -- The type signatures on a mutually-recursive group of definitions
+ -- must all have the same context (or none).
+ --
+ -- We unify them because, with polymorphic recursion, their types
+ -- might not otherwise be related. This is a rather subtle issue.
+ -- ToDo: amplify
+ mapTc check_one_cxt all_sigs_but_first `thenTc_`
+
+ returnTc (theta1, sig_lie)
+ where
+ sig1_dict_tys = mk_dict_tys theta1
+ n_sig1_dict_tys = length sig1_dict_tys
+ sig_lie = mkLIE [inst | TySigInfo _ _ _ _ _ _ inst _ <- tc_ty_sigs]
+
+ check_one_cxt sig@(TySigInfo _ id _ theta _ _ _ src_loc)
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (sigContextsCtxt id1 id) $
+ checkTc (length this_sig_dict_tys == n_sig1_dict_tys)
+ sigContextsErr `thenTc_`
+ unifyTauTyLists sig1_dict_tys this_sig_dict_tys
+ where
+ this_sig_dict_tys = mk_dict_tys theta
+
+ check_one_sig (TySigInfo _ id sig_tyvars _ sig_tau _ _ src_loc)
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxtM (sigCtxt (quotes (ppr id)) sig_tau) $
+ checkSigTyVars sig_tyvars
+
+ mk_dict_tys theta = [mkDictTy c ts | (c,ts) <- theta]
\end{code}
moving them into place as is done for type signatures.
\begin{code}
-tcPragmaSigs :: [RenamedSig] -- The pragma signatures
- -> TcM s (Name -> PragmaInfo, -- Maps name to the appropriate PragmaInfo
- TcHsBinds s,
+tcPragmaSigs :: [RenamedSig] -- The pragma signatures
+ -> TcM s (Name -> IdInfo, -- Maps name to the appropriate IdInfo
+ TcMonoBinds s,
LIE s)
-tcPragmaSigs sigs = returnTc ( \name -> NoPragmaInfo, EmptyBinds, emptyLIE )
-
-{-
tcPragmaSigs sigs
- = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (names_w_id_infos, binds, lies) ->
+ = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (maybe_info_modifiers, binds, lies) ->
let
- name_to_info name = foldr ($) noIdInfo
- [info_fn | (n,info_fn) <- names_w_id_infos, n==name]
+ prag_fn name = foldr ($) noIdInfo [f | Just (n,f) <- maybe_info_modifiers, n==name]
in
- returnTc (name_to_info,
- foldr ThenBinds EmptyBinds binds,
- foldr plusLIE emptyLIE lies)
-\end{code}
-
-Here are the easy cases for tcPragmaSigs
-
-\begin{code}
-tcPragmaSig (DeforestSig name loc)
- = returnTc ((name, addInfo DoDeforest),EmptyBinds,emptyLIE)
-tcPragmaSig (InlineSig name loc)
- = returnTc ((name, addInfo_UF (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE)
-tcPragmaSig (MagicUnfoldingSig name string loc)
- = returnTc ((name, addInfo_UF (mkMagicUnfolding string)), EmptyBinds, emptyLIE)
+ returnTc (prag_fn, andMonoBindList binds, plusLIEs lies)
\end{code}
The interesting case is for SPECIALISE pragmas. There are two forms.
a bit of overkill.
\begin{code}
+tcPragmaSig :: RenamedSig -> TcM s (Maybe (Name, IdInfo -> IdInfo), TcMonoBinds s, LIE s)
+tcPragmaSig (Sig _ _ _) = returnTc (Nothing, EmptyMonoBinds, emptyLIE)
+tcPragmaSig (SpecInstSig _ _) = returnTc (Nothing, EmptyMonoBinds, emptyLIE)
+
+tcPragmaSig (InlineSig name loc)
+ = returnTc (Just (name, setInlinePragInfo IWantToBeINLINEd), EmptyMonoBinds, emptyLIE)
+
+tcPragmaSig (NoInlineSig name loc)
+ = returnTc (Just (name, setInlinePragInfo IMustNotBeINLINEd), EmptyMonoBinds, emptyLIE)
+
tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (valSpecSigCtxt name spec_ty) $
+ = -- SPECIALISE f :: forall b. theta => tau = g
+ tcAddSrcLoc src_loc $
+ tcAddErrCtxt (valSpecSigCtxt name poly_ty) $
-- Get and instantiate its alleged specialised type
- tcPolyType poly_ty `thenTc` \ sig_sigma ->
- tcInstType [] sig_sigma `thenNF_Tc` \ sig_ty ->
- let
- (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
- origin = ValSpecOrigin name
- in
+ tcHsTcType poly_ty `thenTc` \ sig_ty ->
- -- Check that the SPECIALIZE pragma had an empty context
- checkTc (null sig_theta)
- (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_`
+ -- Check that f has a more general type, and build a RHS for
+ -- the spec-pragma-id at the same time
+ tcExpr (HsVar name) sig_ty `thenTc` \ (spec_expr, spec_lie) ->
- -- Get and instantiate the type of the id mentioned
- tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id ->
- tcInstType [] (idType main_id) `thenNF_Tc` \ main_ty ->
- let
- (main_tyvars, main_rho) = splitForAllTy main_ty
- (main_theta,main_tau) = splitRhoTy main_rho
- main_arg_tys = mkTyVarTys main_tyvars
- in
+ case maybe_spec_name of
+ Nothing -> -- Just specialise "f" by building a SpecPragmaId binding
+ -- It is the thing that makes sure we don't prematurely
+ -- dead-code-eliminate the binding we are really interested in.
+ newSpecPragmaId name sig_ty `thenNF_Tc` \ spec_id ->
+ returnTc (Nothing, VarMonoBind (TcId spec_id) spec_expr, spec_lie)
- -- Check that the specialised type is indeed an instance of
- -- the type of the main function.
- unifyTauTy sig_tau main_tau `thenTc_`
- checkSigTyVars sig_tyvars sig_tau `thenTc_`
-
- -- Check that the type variables of the polymorphic function are
- -- either left polymorphic, or instantiate to ground type.
- -- Also check that the overloaded type variables are instantiated to
- -- ground type; or equivalently that all dictionaries have ground type
- mapTc zonkTcType main_arg_tys `thenNF_Tc` \ main_arg_tys' ->
- zonkTcThetaType main_theta `thenNF_Tc` \ main_theta' ->
- tcAddErrCtxt (specGroundnessCtxt main_arg_tys')
- (checkTc (all isGroundOrTyVarTy main_arg_tys')) `thenTc_`
- tcAddErrCtxt (specContextGroundnessCtxt main_theta')
- (checkTc (and [isGroundTy ty | (_,ty) <- theta'])) `thenTc_`
-
- -- Build the SpecPragmaId; it is the thing that makes sure we
- -- don't prematurely dead-code-eliminate the binding we are really interested in.
- newSpecPragmaId name sig_ty `thenNF_Tc` \ spec_pragma_id ->
-
- -- Build a suitable binding; depending on whether we were given
- -- a value (Maybe Name) to be used as the specialisation.
- case using of
- Nothing -> -- No implementation function specified
-
- -- Make a Method inst for the occurrence of the overloaded function
- newMethodWithGivenTy (OccurrenceOf name)
- (TcId main_id) main_arg_tys main_rho `thenNF_Tc` \ (lie, meth_id) ->
+ Just g_name -> -- Don't create a SpecPragmaId. Instead add some suitable IdIfo
+
+ panic "Can't handle SPECIALISE with a '= g' part"
- let
- pseudo_bind = VarMonoBind spec_pragma_id pseudo_rhs
- pseudo_rhs = mkHsTyLam sig_tyvars (HsVar (TcId meth_id))
- in
- returnTc (pseudo_bind, lie, \ info -> info)
+ {- Not yet. Because we're still in the TcType world we
+ can't really add to the SpecEnv of the Id. Instead we have to
+ record the information in a different sort of Sig, and add it to
+ the IdInfo after zonking.
- Just spec_name -> -- Use spec_name as the specialisation value ...
+ For now we just leave out this case
- -- Type check a simple occurrence of the specialised Id
- tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) ->
+ -- Get the type of f, and find out what types
+ -- f has to be instantiated at to give the signature type
+ tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ f_id ->
+ tcInstTcType (idType f_id) `thenNF_Tc` \ (f_tyvars, f_rho) ->
- -- Check that it has the correct type, and doesn't constrain the
- -- signature variables at all
- unifyTauTy sig_tau spec_tau `thenTc_`
- checkSigTyVars sig_tyvars sig_tau `thenTc_`
+ let
+ (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
+ (f_theta, f_tau) = splitRhoTy f_rho
+ sig_tyvar_set = mkVarSet sig_tyvars
+ in
+ unifyTauTy sig_tau f_tau `thenTc_`
- -- Make a local SpecId to bind to applied spec_id
- newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id ->
+ tcPolyExpr str (HsVar g_name) (mkSigmaTy sig_tyvars f_theta sig_tau) `thenTc` \ (_, _,
+ -}
- let
- spec_rhs = mkHsTyLam sig_tyvars spec_body
- spec_binds = VarMonoBind local_spec_id spec_rhs
- `AndMonoBinds`
- VarMonoBind spec_pragma_id (HsVar (TcId local_spec_id))
- spec_info = SpecInfo spec_tys (length main_theta) local_spec_id
- in
- returnTc ((name, addInfo spec_info), spec_binds, spec_lie)
--}
+tcPragmaSig other = pprTrace "tcPragmaSig: ignoring" (ppr other) $
+ returnTc (Nothing, EmptyMonoBinds, emptyLIE)
\end{code}
%************************************************************************
%* *
-\subsection[TcBinds-monomorphism]{The monomorphism restriction}
+\subsection[TcBinds-errors]{Error contexts and messages}
%* *
%************************************************************************
-Not exported:
\begin{code}
-isUnRestrictedGroup :: [TcIdBndr s] -- Signatures given for these
- -> TcBind s
- -> Bool
-
-isUnRestrictedGroup sigs EmptyBind = True
-isUnRestrictedGroup sigs (NonRecBind monobinds) = isUnResMono sigs monobinds
-isUnRestrictedGroup sigs (RecBind monobinds) = isUnResMono sigs monobinds
-
-is_elem v vs = isIn "isUnResMono" v vs
-
-isUnResMono sigs (PatMonoBind (VarPat (TcId v)) _ _) = v `is_elem` sigs
-isUnResMono sigs (PatMonoBind other _ _) = False
-isUnResMono sigs (VarMonoBind (TcId v) _) = v `is_elem` sigs
-isUnResMono sigs (FunMonoBind _ _ _ _) = True
-isUnResMono sigs (AndMonoBinds mb1 mb2) = isUnResMono sigs mb1 &&
- isUnResMono sigs mb2
-isUnResMono sigs EmptyMonoBinds = True
-\end{code}
+patMonoBindsCtxt bind
+ = hang (ptext SLIT("In a pattern binding:")) 4 (ppr bind)
+-----------------------------------------------
+valSpecSigCtxt v ty
+ = sep [ptext SLIT("In a SPECIALIZE pragma for a value:"),
+ nest 4 (ppr v <+> ptext SLIT(" ::") <+> ppr ty)]
-%************************************************************************
-%* *
-\subsection[TcBinds-errors]{Error contexts and messages}
-%* *
-%************************************************************************
+-----------------------------------------------
+notAsPolyAsSigErr sig_tau mono_tyvars
+ = hang (ptext SLIT("A type signature is more polymorphic than the inferred type"))
+ 4 (vcat [text "Can't for-all the type variable(s)" <+>
+ pprQuotedList mono_tyvars,
+ text "in the type" <+> quotes (ppr sig_tau)
+ ])
+-----------------------------------------------
+badMatchErr sig_ty inferred_ty
+ = hang (ptext SLIT("Type signature doesn't match inferred type"))
+ 4 (vcat [hang (ptext SLIT("Signature:")) 4 (ppr sig_ty),
+ hang (ptext SLIT("Inferred :")) 4 (ppr inferred_ty)
+ ])
-\begin{code}
-patMonoBindsCtxt bind sty
- = ppHang (ppPStr SLIT("In a pattern binding:")) 4 (ppr sty bind)
-
---------------------------------------------
-specContextGroundnessCtxt -- err_ctxt dicts sty
- = panic "specContextGroundnessCtxt"
-{-
- = ppHang (
- ppSep [ppBesides [ppStr "In the SPECIALIZE pragma for `", ppr sty name, ppStr "'"],
- ppBesides [ppStr " specialised to the type `", ppr sty spec_ty, ppStr "'"],
- pp_spec_id sty,
- ppStr "... not all overloaded type variables were instantiated",
- ppStr "to ground types:"])
- 4 (ppAboves [ppCat [ppr sty c, ppr sty t]
- | (c,t) <- map getDictClassAndType dicts])
- where
- (name, spec_ty, locn, pp_spec_id)
- = case err_ctxt of
- ValSpecSigCtxt n ty loc -> (n, ty, loc, \ x -> ppNil)
- ValSpecSpecIdCtxt n ty spec loc ->
- (n, ty, loc,
- \ sty -> ppBesides [ppStr "... type of explicit id `", ppr sty spec, ppStr "'"])
--}
+-----------------------------------------------
+unboxedPatBindErr id
+ = ptext SLIT("variable in a lazy pattern binding has unboxed type: ")
+ <+> quotes (ppr id)
-----------------------------------------------
-specGroundnessCtxt
- = panic "specGroundnessCtxt"
+bindSigsCtxt ids
+ = ptext SLIT("When checking the type signature(s) for") <+> pprQuotedList ids
+-----------------------------------------------
+sigContextsErr
+ = ptext SLIT("Mismatched contexts")
+sigContextsCtxt s1 s2
+ = hang (hsep [ptext SLIT("When matching the contexts of the signatures for"),
+ quotes (ppr s1), ptext SLIT("and"), quotes (ppr s2)])
+ 4 (ptext SLIT("(the signature contexts in a mutually recursive group should all be identical)"))
-valSpecSigCtxt v ty sty
- = ppHang (ppPStr SLIT("In a SPECIALIZE pragma for a value:"))
- 4 (ppSep [ppBeside (pprNonSym sty v) (ppPStr SLIT(" ::")),
- ppr sty ty])
+-----------------------------------------------
+unliftedBindErr flavour mbind
+ = hang (text flavour <+> ptext SLIT("bindings for unlifted types aren't allowed"))
+ 4 (ppr mbind)
+
+existentialExplode mbinds
+ = hang (vcat [text "My brain just exploded.",
+ text "I can't handle pattern bindings for existentially-quantified constructors.",
+ text "In the binding group"])
+ 4 (ppr mbinds)
\end{code}
-
projects / ghc-hetmet.git / blobdiff