\begin{code}
#include "HsVersions.h"
-module TcBinds ( tcBindsAndThen, tcPragmaSigs ) where
-
-import Ubiq
-
-import HsSyn ( HsBinds(..), Bind(..), Sig(..), MonoBinds(..),
- HsExpr, Match, PolyType, InPat, OutPat,
- GRHSsAndBinds, ArithSeqInfo, HsLit, Fake,
- collectBinders )
-import RnHsSyn ( RenamedHsBinds(..), RenamedBind(..), RenamedSig(..),
- RenamedMonoBinds(..) )
-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 )
+module TcBinds ( tcBindsAndThen, tcPragmaSigs, checkSigTyVars, tcBindWithSigs, TcSigInfo(..) ) where
+
+IMP_Ubiq()
+#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ <= 201
+IMPORT_DELOOPER(TcLoop) ( tcGRHSsAndBinds )
+#else
+import {-# SOURCE #-} TcGRHSs ( tcGRHSsAndBinds )
+#endif
+
+import HsSyn ( HsBinds(..), Sig(..), MonoBinds(..),
+ Match, HsType, InPat(..), OutPat(..), HsExpr(..),
+ SYN_IE(RecFlag), nonRecursive,
+ GRHSsAndBinds, ArithSeqInfo, HsLit, Fake, Stmt, DoOrListComp, Fixity,
+ collectMonoBinders )
+import RnHsSyn ( SYN_IE(RenamedHsBinds), RenamedSig(..),
+ SYN_IE(RenamedMonoBinds)
+ )
+import TcHsSyn ( SYN_IE(TcHsBinds), SYN_IE(TcMonoBinds),
+ SYN_IE(TcExpr),
+ tcIdType
+ )
+
+import TcMonad
+import Inst ( Inst, SYN_IE(LIE), emptyLIE, plusLIE, InstOrigin(..),
+ newDicts, tyVarsOfInst, instToId
+ )
+import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newMonoIds,
+ tcGetGlobalTyVars, tcExtendGlobalTyVars
+ )
+import SpecEnv ( SpecEnv )
import TcMatches ( tcMatchesFun )
-import TcMonoType ( tcPolyType )
+import TcSimplify ( tcSimplify, tcSimplifyAndCheck )
+import TcMonoType ( tcHsType )
import TcPat ( tcPat )
import TcSimplify ( bindInstsOfLocalFuns )
-import TcType ( newTcTyVar, tcInstType )
-import Unify ( unifyTauTy )
-
-import Kind ( mkBoxedTypeKind, mkTypeKind )
-import Id ( GenId, idType, mkUserId )
+import TcType ( TcIdOcc(..), SYN_IE(TcIdBndr),
+ SYN_IE(TcType), SYN_IE(TcThetaType), SYN_IE(TcTauType),
+ SYN_IE(TcTyVarSet), SYN_IE(TcTyVar),
+ newTyVarTy, zonkTcType, zonkSigTyVar,
+ newTcTyVar, tcInstSigType, newTyVarTys
+ )
+import Unify ( unifyTauTy, unifyTauTyLists )
+
+import Kind ( isUnboxedTypeKind, mkTypeKind, isTypeKind, mkBoxedTypeKind )
+import Id ( GenId, idType, mkUserLocal, mkUserId )
import IdInfo ( noIdInfo )
-import Name ( Name ) -- instances
-import Maybes ( assocMaybe, catMaybes, Maybe(..) )
-import Outputable ( pprNonOp )
+import Maybes ( maybeToBool, assocMaybe, catMaybes )
+import Name ( getOccName, getSrcLoc, Name )
import PragmaInfo ( PragmaInfo(..) )
import Pretty
-import Type ( mkTyVarTy, isTyVarTy, mkSigmaTy, splitSigmaTy,
+import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy, tyVarsOfTypes, eqSimpleTheta,
+ mkSigmaTy, splitSigmaTy, mkForAllTys, mkFunTys, getTyVar, mkDictTy,
splitRhoTy, mkForAllTy, splitForAllTy )
-import Util ( panic )
+import TyVar ( GenTyVar, SYN_IE(TyVar), tyVarKind, mkTyVarSet, minusTyVarSet, emptyTyVarSet,
+ elementOfTyVarSet, unionTyVarSets, tyVarSetToList )
+import Bag ( bagToList, foldrBag, isEmptyBag )
+import Util ( isIn, zipEqual, zipWithEqual, zipWith3Equal, hasNoDups, assoc,
+ assertPanic, panic, pprTrace )
+import PprType ( GenClass, GenType, GenTyVar )
+import Unique ( Unique )
+import SrcLoc ( SrcLoc )
+
+import Outputable --( interppSP, interpp'SP )
+
+
\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
\begin{code}
tcBindsAndThen
- :: (TcHsBinds s -> thing -> thing) -- Combinator
+ :: (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)
tcBindsAndThen combiner EmptyBinds do_next
- = do_next `thenTc` \ (thing, lie, thing_ty) ->
- returnTc (combiner EmptyBinds thing, lie, thing_ty)
-
-tcBindsAndThen combiner (SingleBind bind) do_next
- = tcBindAndThen combiner bind [] do_next
-
-tcBindsAndThen combiner (BindWith bind sigs) do_next
- = tcBindAndThen combiner bind sigs do_next
+ = do_next `thenTc` \ (thing, lie) ->
+ returnTc (combiner nonRecursive EmptyMonoBinds thing, lie)
tcBindsAndThen combiner (ThenBinds binds1 binds2) do_next
= tcBindsAndThen combiner binds1 (tcBindsAndThen combiner binds2 do_next)
+
+tcBindsAndThen 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.
+
+ -- TYPECHECK THE SIGNATURES
+ mapTc (tcTySig prag_info_fn) ty_sigs `thenTc` \ tc_ty_sigs ->
+
+ tcBindWithSigs binder_names 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 binder_names 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) ->
+
+ -- Create specialisations of functions bound here
+ bindInstsOfLocalFuns (prag_lie `plusLIE` thing_lie)
+ poly_ids `thenTc` \ (lie2, inst_mbinds) ->
+
+ -- All done
+ let
+ final_lie = lie2 `plusLIE` poly_lie
+ final_thing = combiner is_rec poly_binds $
+ combiner nonRecursive inst_mbinds $
+ combiner nonRecursive prag_binds
+ thing
+ in
+ returnTc (prag_info_fn, (final_thing, final_lie))
+ ) `thenTc` \ (_, result) ->
+ returnTc result
+ where
+ binder_names = map fst (bagToList (collectMonoBinders bind))
+ ty_sigs = [sig | sig@(Sig name _ _) <- sigs]
\end{code}
An aside. The original version of @tcBindsAndThen@ which lacks a
= 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 (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) ->
-
- -- All done
- let
- final_lie = lie2 `plusLIE` poly_lie
- final_binds = poly_binds `ThenBinds`
- SingleBind (NonRecBind inst_mbinds) `ThenBinds`
- prag_binds
- in
- returnTc (prag_info_fn, (combiner final_binds thing, final_lie, thing_ty))
- ) `thenTc` \ (_, result) ->
- returnTc result
- where
- binder_names = collectBinders bind
-
-
-tcBindAndSigs binder_names bind sigs prag_info_fn
+\begin{code}
+tcBindWithSigs
+ :: [Name]
+ -> RenamedMonoBinds
+ -> [TcSigInfo s]
+ -> RecFlag
+ -> (Name -> PragmaInfo)
+ -> TcM s (TcMonoBinds s, LIE s, [TcIdBndr s])
+
+tcBindWithSigs binder_names mbind tc_ty_sigs is_rec prag_info_fn
= recoverTc (
-- If typechecking the binds fails, then return with each
- -- binder given type (forall a.a), to minimise subsequent
+ -- signature-less binder given type (forall a.a), to minimise subsequent
-- error messages
- newTcTyVar Nothing mkBoxedTypeKind `thenNF_Tc` \ alpha_tv ->
+ 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]
+ 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 NoPragmaInfo -- No signature
in
- returnTc (EmptyBinds, emptyLIE, poly_ids)
+ returnTc (EmptyMonoBinds, emptyLIE, poly_ids)
) $
- -- Create a new identifier for each binder, with each being given
- -- a type-variable type.
- newMonoIds binder_names kind (\ mono_ids ->
- tcTySigs sigs `thenTc` \ sig_info ->
- tc_bind bind `thenTc` \ (bind', lie) ->
- returnTc (mono_ids, bind', lie, sig_info)
- )
- `thenTc` \ (mono_ids, bind', lie, sig_info) ->
+ -- Create a new identifier for each binder, with each being given
+ -- a fresh unique, and a type-variable type.
+ tcGetUniques no_of_binders `thenNF_Tc` \ uniqs ->
+ mapNF_Tc mk_mono_id_ty binder_names `thenNF_Tc` \ mono_id_tys ->
+ let
+ mono_ids = zipWith3Equal "tcBindAndSigs" mk_id binder_names uniqs mono_id_tys
+ mk_id name uniq ty = mkUserLocal (getOccName name) uniq ty (getSrcLoc name)
+ in
+
+ -- TYPECHECK THE BINDINGS
+ tcMonoBinds mbind binder_names mono_ids tc_ty_sigs `thenTc` \ (mbind', lie) ->
+
+ -- CHECK THAT THE SIGNATURES MATCH
+ -- (must do this before getTyVarsToGen)
+ checkSigMatch tc_ty_sigs `thenTc` \ sig_theta ->
+
+ -- 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 `thenTc` \ (tyvars_not_to_gen, tyvars_to_gen) ->
+
+ -- DEAL WITH TYPE VARIABLE KINDS
+ mapTc defaultUncommittedTyVar (tyVarSetToList tyvars_to_gen) `thenTc` \ real_tyvars_to_gen_list ->
+ let
+ real_tyvars_to_gen = mkTyVarSet 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
+ --
+ -- **** This step can do unification => keep other zonking after this ****
+ in
- -- Notice that genBinds gets the old (non-extended) environment
- genBinds binder_names mono_ids bind' lie sig_info prag_info_fn
+ -- SIMPLIFY THE LIE
+ tcExtendGlobalTyVars tyvars_not_to_gen (
+ if null tc_ty_sigs then
+ -- No signatures, so just simplify the lie
+ tcSimplify real_tyvars_to_gen lie `thenTc` \ (lie_free, dict_binds, lie_bound) ->
+ returnTc (lie_free, dict_binds, map instToId (bagToList lie_bound))
+
+ else
+ zonk_theta 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
+
+ -- Check that the needed dicts can be expressed in
+ -- terms of the signature ones
+ tcAddErrCtxt (sigsCtxt tysig_names) $
+ tcSimplifyAndCheck real_tyvars_to_gen dicts_sig lie `thenTc` \ (lie_free, dict_binds) ->
+ returnTc (lie_free, dict_binds, dict_ids)
+
+ ) `thenTc` \ (lie_free, dict_binds, dicts_bound) ->
+
+ ASSERT( not (any (isUnboxedTypeKind . 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 zonkTcType mono_id_tys `thenNF_Tc` \ zonked_mono_id_types ->
+ let
+ exports = zipWith3 mk_export binder_names mono_ids zonked_mono_id_types
+ dict_tys = map tcIdType dicts_bound
+
+ mk_export binder_name mono_id zonked_mono_id_ty
+ | maybeToBool maybe_sig = (sig_tyvars, TcId sig_poly_id, TcId mono_id)
+ | otherwise = (real_tyvars_to_gen_list, TcId poly_id, TcId mono_id)
+ where
+ maybe_sig = maybeSig tc_ty_sigs binder_name
+ Just (TySigInfo _ sig_poly_id sig_tyvars _ _ _) = maybe_sig
+ poly_id = mkUserId binder_name poly_ty (prag_info_fn binder_name)
+ poly_ty = mkForAllTys real_tyvars_to_gen_list $ mkFunTys dict_tys $ zonked_mono_id_ty
+ -- 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.
+ in
+
+ -- BUILD RESULTS
+ returnTc (
+ AbsBinds real_tyvars_to_gen_list
+ dicts_bound
+ exports
+ (dict_binds `AndMonoBinds` mbind'),
+ lie_free,
+ [poly_id | (_, TcId poly_id, _) <- exports]
+ )
where
- kind = case bind of
- NonRecBind _ -> mkBoxedTypeKind -- Recursive, so no unboxed types
- RecBind _ -> mkTypeKind -- Non-recursive, so we permit unboxed types
-\end{code}
+ no_of_binders = length binder_names
-\begin{code}
-tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s)
+ mk_mono_id_ty binder_name = case maybeSig tc_ty_sigs binder_name of
+ Just (TySigInfo name _ _ _ tau_ty _) -> returnNF_Tc tau_ty -- There's a signature
+ otherwise -> newTyVarTy kind -- No signature
+
+ tysig_names = [name | (TySigInfo name _ _ _ _ _) <- tc_ty_sigs]
+ is_unrestricted = isUnRestrictedGroup tysig_names mbind
-tc_bind (NonRecBind mono_binds)
- = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
- returnTc (NonRecBind mono_binds2, lie)
+ kind | is_rec = mkBoxedTypeKind -- Recursive, so no unboxed types
+ | otherwise = mkTypeKind -- Non-recursive, so we permit unboxed types
-tc_bind (RecBind mono_binds)
- = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
- returnTc (RecBind mono_binds2, lie)
+zonk_theta theta = mapNF_Tc zonk theta
+ where
+ zonk (c,t) = zonkTcType t `thenNF_Tc` \ t' ->
+ returnNF_Tc (c,t')
\end{code}
+@getImplicitStuffToGen@ decides what type variables generalise over.
+
+For a "restricted group" -- see the monomorphism restriction
+for a definition -- we bind no dictionaries, and
+remove from tyvars_to_gen any constrained type variables
+
+*Don't* simplify dicts at this point, because we aren't going
+to generalise over these dicts. By the time we do simplify them
+we may well know more. For example (this actually came up)
+ f :: Array Int Int
+ f x = array ... xs where xs = [1,2,3,4,5]
+We don't want to generate lots of (fromInt Int 1), (fromInt Int 2)
+stuff. If we simplify only at the f-binding (not the xs-binding)
+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:
+
+ (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:
+ instance Eq a => Eq (Foo a b) where ..
+ Here, b is not constrained, even though it looks as if it is.
+ 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.
+
+So we are careful, and do a complete simplification just to find the
+constrained tyvars. We don't use any of the results, except to
+find which tyvars are constrained.
+
\begin{code}
-tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s)
+getTyVarsToGen is_unrestricted mono_id_tys lie
+ = tcGetGlobalTyVars `thenNF_Tc` \ free_tyvars ->
+ mapNF_Tc zonkTcType mono_id_tys `thenNF_Tc` \ zonked_mono_id_tys ->
+ let
+ tyvars_to_gen = tyVarsOfTypes zonked_mono_id_tys `minusTyVarSet` free_tyvars
+ in
+ if is_unrestricted
+ then
+ returnTc (emptyTyVarSet, tyvars_to_gen)
+ else
+ tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, constrained_dicts) ->
+ let
+ -- ASSERT: dicts_sig is already zonked!
+ constrained_tyvars = foldrBag (unionTyVarSets . tyVarsOfInst) emptyTyVarSet constrained_dicts
+ reduced_tyvars_to_gen = tyvars_to_gen `minusTyVarSet` constrained_tyvars
+ in
+ returnTc (constrained_tyvars, reduced_tyvars_to_gen)
+\end{code}
-tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE)
-tcMonoBinds (AndMonoBinds mb1 mb2)
- = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) ->
- tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) ->
- returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2)
+\begin{code}
+isUnRestrictedGroup :: [Name] -- Signatures given for these
+ -> RenamedMonoBinds
+ -> Bool
+
+is_elem v vs = isIn "isUnResMono" v vs
+
+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}
-tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn)
- = tcAddSrcLoc locn $
+@defaultUncommittedTyVar@ checks for generalisation over unboxed
+types, and defaults any TypeKind TyVars to BoxedTypeKind.
- -- LEFT HAND SIDE
- tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) ->
+\begin{code}
+defaultUncommittedTyVar tyvar
+ | isTypeKind (tyVarKind tyvar)
+ = newTcTyVar mkBoxedTypeKind `thenNF_Tc` \ boxed_tyvar ->
+ unifyTauTy (mkTyVarTy boxed_tyvar) (mkTyVarTy tyvar) `thenTc_`
+ returnTc boxed_tyvar
+
+ | otherwise
+ = returnTc tyvar
+\end{code}
- -- BINDINGS AND GRHSS
- tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) ->
- -- Unify the two sides
- tcAddErrCtxt (patMonoBindsCtxt bind) $
- unifyTauTy pat_ty grhss_ty `thenTc_`
+%************************************************************************
+%* *
+\subsection{tcMonoBind}
+%* *
+%************************************************************************
- -- RETURN
- returnTc (PatMonoBind pat2 grhss_and_binds2 locn,
- plusLIE lie_pat lie)
+@tcMonoBinds@ deals with a single @MonoBind@.
+The signatures have been dealt with already.
-tcMonoBinds (FunMonoBind name matches locn)
- = tcAddSrcLoc locn $
- tcLookupLocalValueOK "tcMonoBinds" name `thenNF_Tc` \ id ->
- tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) ->
- returnTc (FunMonoBind (TcId id) matches' locn, lie)
+\begin{code}
+tcMonoBinds :: RenamedMonoBinds
+ -> [Name] -> [TcIdBndr s]
+ -> [TcSigInfo s]
+ -> TcM s (TcMonoBinds s, LIE s)
+
+tcMonoBinds mbind binder_names mono_ids tc_ty_sigs
+ = tcExtendLocalValEnv binder_names mono_ids (
+ tc_mono_binds mbind
+ )
+ where
+ sig_names = [name | (TySigInfo name _ _ _ _ _) <- tc_ty_sigs]
+ sig_ids = [id | (TySigInfo _ id _ _ _ _) <- tc_ty_sigs]
+
+ tc_mono_binds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE)
+
+ tc_mono_binds (AndMonoBinds mb1 mb2)
+ = tc_mono_binds mb1 `thenTc` \ (mb1a, lie1) ->
+ tc_mono_binds mb2 `thenTc` \ (mb2a, lie2) ->
+ returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2)
+
+ tc_mono_binds (FunMonoBind name inf matches locn)
+ = tcAddSrcLoc locn $
+ tcLookupLocalValueOK "tc_mono_binds" name `thenNF_Tc` \ id ->
+
+ -- Before checking the RHS, extend the envt with
+ -- bindings for the *polymorphic* Ids from any type signatures
+ tcExtendLocalValEnv sig_names sig_ids $
+ tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) ->
+
+ returnTc (FunMonoBind (TcId id) inf matches' locn, lie)
+
+ tc_mono_binds bind@(PatMonoBind pat grhss_and_binds locn)
+ = tcAddSrcLoc locn $
+ tcAddErrCtxt (patMonoBindsCtxt bind) $
+ tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) ->
+
+ -- Before checking the RHS, but after the pattern, extend the envt with
+ -- bindings for the *polymorphic* Ids from any type signatures
+ tcExtendLocalValEnv sig_names sig_ids $
+ tcGRHSsAndBinds pat_ty grhss_and_binds `thenTc` \ (grhss_and_binds2, lie) ->
+ returnTc (PatMonoBind pat2 grhss_and_binds2 locn,
+ plusLIE lie_pat lie)
\end{code}
%************************************************************************
split up, and have fresh type variables installed. All non-type-signature
"RenamedSigs" are ignored.
+The @TcSigInfo@ contains @TcTypes@ because they are unified with
+the variable's type, and after that checked to see whether they've
+been instantiated.
+
\begin{code}
-tcTySigs :: [RenamedSig] -> TcM s [TcSigInfo s]
+data TcSigInfo s
+ = TySigInfo
+ Name -- N, the Name in corresponding binding
+ (TcIdBndr s) -- *Polymorphic* binder for this value...
+ -- Usually has name = N, but doesn't have to.
+ [TcTyVar s]
+ (TcThetaType s)
+ (TcTauType s)
+ SrcLoc
+
+
+maybeSig :: [TcSigInfo s] -> Name -> Maybe (TcSigInfo s)
+ -- Search for a particular signature
+maybeSig [] name = Nothing
+maybeSig (sig@(TySigInfo sig_name _ _ _ _ _) : sigs) name
+ | name == sig_name = Just sig
+ | otherwise = maybeSig sigs name
+\end{code}
-tcTySigs (Sig v ty _ src_loc : other_sigs)
- = tcAddSrcLoc src_loc (
- tcPolyType ty `thenTc` \ sigma_ty ->
- tcInstType [] sigma_ty `thenNF_Tc` \ tc_sigma_ty ->
- let
- (tyvars, theta, tau_ty) = splitSigmaTy tc_sigma_ty
- in
- tcLookupLocalValueOK "tcSig1" v `thenNF_Tc` \ val ->
- unifyTauTy (idType val) tau_ty `thenTc_`
- returnTc (TySigInfo val tyvars theta tau_ty src_loc)
- ) `thenTc` \ sig_info1 ->
- tcTySigs other_sigs `thenTc` \ sig_infos ->
- returnTc (sig_info1 : sig_infos)
+\begin{code}
+tcTySig :: (Name -> PragmaInfo)
+ -> RenamedSig
+ -> TcM s (TcSigInfo s)
+
+tcTySig prag_info_fn (Sig v ty src_loc)
+ = tcAddSrcLoc src_loc $
+ tcHsType ty `thenTc` \ sigma_ty ->
+ tcInstSigType sigma_ty `thenNF_Tc` \ sigma_ty' ->
+ let
+ poly_id = mkUserId v sigma_ty' (prag_info_fn v)
+ (tyvars', theta', tau') = splitSigmaTy sigma_ty'
+ -- This splitSigmaTy tries hard to make sure that tau' is a type synonym
+ -- wherever possible, which can improve interface files.
+ in
+ returnTc (TySigInfo v poly_id tyvars' theta' tau' src_loc)
+\end{code}
+
+@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.
+
+The error message here is somewhat unsatisfactory, but it'll do for
+now (ToDo).
+
+\begin{code}
+checkSigMatch []
+ = returnTc (error "checkSigMatch")
+
+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
+ where
+ sig1_dict_tys = mk_dict_tys theta1
+ n_sig1_dict_tys = length sig1_dict_tys
+
+ 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 name id sig_tyvars _ sig_tau src_loc)
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (sigCtxt id) $
+ checkSigTyVars sig_tyvars sig_tau
+
+ mk_dict_tys theta = [mkDictTy c t | (c,t) <- theta]
+\end{code}
+
+
+@checkSigTyVars@ is used after the type in a type signature has been unified with
+the actual type found. It then checks that the type variables of the type signature
+are
+ (a) still all type variables
+ eg matching signature [a] against inferred type [(p,q)]
+ [then a will be unified to a non-type variable]
+
+ (b) still all distinct
+ eg matching signature [(a,b)] against inferred type [(p,p)]
+ [then a and b will be unified together]
+
+BUT ACTUALLY THESE FIRST TWO ARE FORCED BY USING DontBind TYVARS
+
+ (c) not mentioned in the environment
+ eg the signature for f in this:
+
+ g x = ... where
+ f :: a->[a]
+ f y = [x,y]
-tcTySigs (other : sigs) = tcTySigs sigs
-tcTySigs [] = returnTc []
+ Here, f is forced to be monorphic by the free occurence of x.
+
+Before doing this, the substitution is applied to the signature type variable.
+
+\begin{code}
+checkSigTyVars :: [TcTyVar s] -- The original signature type variables
+ -> TcType s -- signature type (for err msg)
+ -> TcM s ()
+
+checkSigTyVars sig_tyvars sig_tau
+ = -- Several type signatures in the same bindings group can
+ -- cause the signature type variable from the different
+ -- signatures to be unified. So we need to zonk them.
+ mapNF_Tc zonkSigTyVar sig_tyvars `thenNF_Tc` \ sig_tyvars' ->
+
+ -- Point (a) is forced by the fact that they are signature type
+ -- variables, so the unifer won't bind them to a type.
+
+ -- Check point (b)
+ checkTcM (hasNoDups sig_tyvars')
+ (zonkTcType sig_tau `thenNF_Tc` \ sig_tau' ->
+ failTc (badMatchErr sig_tau sig_tau')
+ ) `thenTc_`
+
+ -- Check point (c)
+ -- We want to report errors in terms of the original signature tyvars,
+ -- ie sig_tyvars, NOT sig_tyvars'. sig_tyvars' correspond
+ -- 1-1 with sig_tyvars, so we can just map back.
+ tcGetGlobalTyVars `thenNF_Tc` \ globals ->
+ let
+-- mono_tyvars = [sig_tv | (sig_tv, sig_tv') <- sig_tyvars `zip` sig_tyvars',
+-- sig_tv' `elementOfTyVarSet` globals
+-- ]
+ mono_tyvars' = [sig_tv' | sig_tv' <- sig_tyvars',
+ sig_tv' `elementOfTyVarSet` globals]
+ in
+ checkTcM (null mono_tyvars')
+ (zonkTcType sig_tau `thenNF_Tc` \ sig_tau' ->
+ failTc (notAsPolyAsSigErr sig_tau' mono_tyvars'))
\end{code}
\begin{code}
tcPragmaSigs :: [RenamedSig] -- The pragma signatures
-> TcM s (Name -> PragmaInfo, -- Maps name to the appropriate PragmaInfo
- TcHsBinds s,
+ TcMonoBinds s,
LIE s)
-tcPragmaSigs sigs = returnTc ( \name -> NoPragmaInfo, EmptyBinds, emptyLIE )
+-- For now we just deal with INLINE pragmas
+tcPragmaSigs sigs = returnTc (prag_fn, EmptyMonoBinds, emptyLIE )
+ where
+ prag_fn name | any has_inline sigs = IWantToBeINLINEd
+ | otherwise = NoPragmaInfo
+ where
+ has_inline (InlineSig n _) = (n == name)
+ has_inline other = False
+
{-
tcPragmaSigs sigs
\begin{code}
tcPragmaSig (DeforestSig name loc)
- = returnTc ((name, addInfo DoDeforest),EmptyBinds,emptyLIE)
+ = returnTc ((name, addDeforestInfo DoDeforest),EmptyBinds,emptyLIE)
tcPragmaSig (InlineSig name loc)
- = returnTc ((name, addInfo_UF (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE)
+ = returnTc ((name, addUnfoldInfo (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE)
tcPragmaSig (MagicUnfoldingSig name string loc)
- = returnTc ((name, addInfo_UF (mkMagicUnfolding string)), EmptyBinds, emptyLIE)
+ = returnTc ((name, addUnfoldInfo (mkMagicUnfolding string)), EmptyBinds, emptyLIE)
\end{code}
The interesting case is for SPECIALISE pragmas. There are two forms.
tcAddErrCtxt (valSpecSigCtxt name spec_ty) $
-- Get and instantiate its alleged specialised type
- tcPolyType poly_ty `thenTc` \ sig_sigma ->
- tcInstType [] (idType sig_sigma) `thenNF_Tc` \ sig_ty ->
+ tcHsType poly_ty `thenTc` \ sig_sigma ->
+ tcInstSigType sig_sigma `thenNF_Tc` \ sig_ty ->
let
(sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
origin = ValSpecOrigin name
-- Get and instantiate the type of the id mentioned
tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id ->
- tcInstType [] (idType main_id) `thenNF_Tc` \ main_ty ->
+ tcInstSigType [] (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 = map mkTyVarTy main_tyvars
+ main_arg_tys = mkTyVarTys main_tyvars
in
-- 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 main_tau `thenTc_`
+ 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.
-- 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 spec_tau `thenTc_`
+ unifyTauTy sig_tau spec_tau `thenTc_`
+ checkSigTyVars sig_tyvars sig_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 ->
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)
+ returnTc ((name, addSpecInfo spec_info), spec_binds, spec_lie)
-}
\end{code}
-Error contexts and messages
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection[TcBinds-errors]{Error contexts and messages}
+%* *
+%************************************************************************
+
+
\begin{code}
patMonoBindsCtxt bind sty
- = ppHang (ppPStr SLIT("In a pattern binding:")) 4 (ppr sty bind)
+ = hang (ptext SLIT("In a pattern binding:")) 4 (ppr sty bind)
+
+-----------------------------------------------
+valSpecSigCtxt v ty sty
+ = hang (ptext SLIT("In a SPECIALIZE pragma for a value:"))
+ 4 (sep [(<>) (ppr sty v) (ptext SLIT(" ::")),
+ ppr sty ty])
+
+
+
+-----------------------------------------------
+notAsPolyAsSigErr sig_tau mono_tyvars sty
+ = hang (ptext SLIT("A type signature is more polymorphic than the inferred type"))
+ 4 (vcat [text "Can't for-all the type variable(s)" <+> interpp'SP sty mono_tyvars,
+ text "in the inferred type" <+> ppr sty sig_tau
+ ])
+
+-----------------------------------------------
+badMatchErr sig_ty inferred_ty sty
+ = hang (ptext SLIT("Type signature doesn't match inferred type"))
+ 4 (vcat [hang (ptext SLIT("Signature:")) 4 (ppr sty sig_ty),
+ hang (ptext SLIT("Inferred :")) 4 (ppr sty inferred_ty)
+ ])
+
+-----------------------------------------------
+sigCtxt id sty
+ = sep [ptext SLIT("When checking signature for"), ppr sty id]
+sigsCtxt ids sty
+ = sep [ptext SLIT("When checking signature(s) for:"), interpp'SP sty ids]
+
+-----------------------------------------------
+sigContextsErr sty
+ = ptext SLIT("Mismatched contexts")
+sigContextsCtxt s1 s2 sty
+ = hang (hsep [ptext SLIT("When matching the contexts of the signatures for"),
+ ppr sty s1, ptext SLIT("and"), ppr sty s2])
+ 4 (ptext SLIT("(the signature contexts in a mutually recursive group should all be identical)"))
+
+-----------------------------------------------
+specGroundnessCtxt
+ = panic "specGroundnessCtxt"
--------------------------------------------
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]
+ = hang (
+ sep [hsep [ptext SLIT("In the SPECIALIZE pragma for"), ppr sty name],
+ hcat [ptext SLIT(" specialised to the type"), ppr sty spec_ty],
+ pp_spec_id sty,
+ ptext SLIT("... not all overloaded type variables were instantiated"),
+ ptext SLIT("to ground types:")])
+ 4 (vcat [hsep [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)
+ ValSpecSigCtxt n ty loc -> (n, ty, loc, \ x -> empty)
ValSpecSpecIdCtxt n ty spec loc ->
(n, ty, loc,
- \ sty -> ppBesides [ppStr "... type of explicit id `", ppr sty spec, ppStr "'"])
+ \ sty -> hsep [ptext SLIT("... type of explicit id"), ppr sty spec])
-}
+\end{code}
------------------------------------------------
-specGroundnessCtxt
- = panic "specGroundnessCtxt"
-valSpecSigCtxt v ty sty
- = ppHang (ppPStr SLIT("In a SPECIALIZE pragma for a value:"))
- 4 (ppSep [ppBeside (pprNonOp sty v) (ppPStr SLIT(" ::")),
- ppr sty ty])
-\end{code}
projects / ghc-hetmet.git / blobdiff