%
-% (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, bindInstsOfLocalFuns,
- tcPragmaSigs, checkSigTyVars, tcBindWithSigs,
- sigCtxt, TcSigInfo(..) ) where
+module TcBinds ( tcBindsAndThen, tcTopBindsAndThen,
+ tcPragmaSigs, tcBindWithSigs ) where
#include "HsVersions.h"
import {-# SOURCE #-} TcGRHSs ( tcGRHSsAndBinds )
import {-# SOURCE #-} TcExpr ( tcExpr )
-import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), InPat(..),
- collectMonoBinders, andMonoBinds
+import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), InPat(..), StmtCtxt(..),
+ collectMonoBinders, andMonoBindList, andMonoBinds
)
import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds )
import TcHsSyn ( TcHsBinds, TcMonoBinds,
TcIdOcc(..), TcIdBndr,
- tcIdType
+ tcIdType, zonkId
)
import TcMonad
-import Inst ( Inst, LIE, emptyLIE, plusLIE, plusLIEs, InstOrigin(..),
- newDicts, tyVarsOfInst, instToId, newMethodWithGivenTy,
- zonkInst, pprInsts
+import Inst ( Inst, LIE, emptyLIE, mkLIE, plusLIE, plusLIEs, InstOrigin(..),
+ newDicts, tyVarsOfInst, instToId,
)
-import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK,
- newLocalId, newSpecPragmaId,
+import TcEnv ( tcExtendLocalValEnv, tcExtendEnvWithPat,
+ tcLookupLocalValueOK,
+ newSpecPragmaId,
tcGetGlobalTyVars, tcExtendGlobalTyVars
)
import TcMatches ( tcMatchesFun )
import TcSimplify ( tcSimplify, tcSimplifyAndCheck )
-import TcMonoType ( tcHsType )
-import TcPat ( tcPat )
-import TcSimplify ( bindInstsOfLocalFuns )
-import TcType ( TcType, TcThetaType, TcTauType,
- TcTyVarSet, TcTyVar,
- newTyVarTy, newTcTyVar, tcInstSigType, tcInstSigTcType,
- zonkTcType, zonkTcTypes, zonkTcThetaType, zonkTcTyVar
+import TcMonoType ( tcHsTcType, checkSigTyVars,
+ TcSigInfo(..), tcTySig, maybeSig, sigCtxt
)
-import Unify ( unifyTauTy, unifyTauTyLists )
-
-import Kind ( isUnboxedTypeKind, mkTypeKind, isTypeKind, mkBoxedTypeKind )
-import MkId ( mkUserId )
-import Id ( idType, idName, idInfo, replaceIdInfo )
+import TcPat ( tcVarPat, tcPat )
+import TcSimplify ( bindInstsOfLocalFuns )
+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 Maybes ( maybeToBool, assocMaybe )
-import Name ( getOccName, getSrcLoc, Name )
-import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy, tyVarsOfTypes,
- splitSigmaTy, mkForAllTys, mkFunTys, getTyVar, mkDictTy,
- splitRhoTy, mkForAllTy, splitForAllTys
+import Name ( Name )
+import Type ( mkTyVarTy, tyVarsOfTypes,
+ splitSigmaTy, mkForAllTys, mkFunTys, getTyVar,
+ mkDictTy, splitRhoTy, mkForAllTy, isUnLiftedType,
+ isUnboxedType, openTypeKind,
+ unboxedTypeKind, boxedTypeKind
)
-import TyVar ( TyVar, tyVarKind, mkTyVarSet, minusTyVarSet, emptyTyVarSet,
- elementOfTyVarSet, unionTyVarSets, tyVarSetToList
- )
-import Bag ( bagToList, foldrBag, )
-import Util ( isIn, hasNoDups, assoc )
-import Unique ( Unique )
+import Var ( TyVar, tyVarKind )
+import VarSet
+import Bag
+import Util ( isIn )
import BasicTypes ( TopLevelFlag(..), RecFlag(..) )
import SrcLoc ( SrcLoc )
import Outputable
\begin{code}
tcTopBindsAndThen, tcBindsAndThen
- :: (RecFlag -> TcMonoBinds s -> this -> that) -- Combinator
+ :: (RecFlag -> TcMonoBinds s -> thing -> thing) -- Combinator
-> RenamedHsBinds
- -> TcM s (this, LIE s)
- -> TcM s (that, LIE s)
+ -> 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 binds do_next
- = tcBinds top_lvl binds `thenTc` \ (mbinds1, binds_lie, env, ids) ->
- tcSetEnv env $
-
- -- Now do whatever happens next, in the augmented envt
- do_next `thenTc` \ (thing, thing_lie) ->
+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
- -- Create specialisations of functions bound here
- -- Nota Bene: we glom the bindings all together in a single
- -- recursive group ("recursive" passed to combiner, below)
- -- so that we can do thsi bindInsts thing once for all the bindings
- -- and the thing inside. This saves a quadratic-cost algorithm
- -- when there's a long sequence of bindings.
- bindInstsOfLocalFuns (binds_lie `plusLIE` thing_lie) ids `thenTc` \ (final_lie, mbinds2) ->
-
- -- All done
- let
- final_mbinds = mbinds1 `AndMonoBinds` mbinds2
- in
- returnTc (combiner Recursive final_mbinds thing, final_lie)
+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
-tcBinds :: TopLevelFlag
- -> RenamedHsBinds
- -> TcM s (TcMonoBinds s, LIE s, TcEnv s, [TcIdBndr s])
- -- The envt is the envt with binders in scope
- -- The binders are those bound by this group of bindings
-
-tcBinds top_lvl EmptyBinds
- = tcGetEnv `thenNF_Tc` \ env ->
- returnTc (EmptyMonoBinds, emptyLIE, env, [])
-
- -- Short-cut for the rather common case of an empty bunch of bindings
-tcBinds top_lvl (MonoBind EmptyMonoBinds sigs is_rec)
- = tcGetEnv `thenNF_Tc` \ env ->
- returnTc (EmptyMonoBinds, emptyLIE, env, [])
-
-tcBinds top_lvl (ThenBinds binds1 binds2)
- = tcBinds top_lvl binds1 `thenTc` \ (mbinds1, lie1, env1, ids1) ->
- tcSetEnv env1 $
- tcBinds top_lvl binds2 `thenTc` \ (mbinds2, lie2, env2, ids2) ->
- returnTc (mbinds1 `AndMonoBinds` mbinds2, lie1 `plusLIE` lie2, env2, ids1++ids2)
-
-tcBinds top_lvl (MonoBind bind sigs is_rec)
- = fixTc (\ ~(prag_info_fn, _) ->
+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.
-- TYPECHECK THE SIGNATURES
- mapTc tcTySig ty_sigs `thenTc` \ tc_ty_sigs ->
+ mapTc tcTySig [sig | sig@(Sig name _ _) <- sigs] `thenTc` \ tc_ty_sigs ->
- tcBindWithSigs top_lvl binder_names bind
+ 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 binder_names poly_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) ->
-
- -- Catch the environment and return
- tcGetEnv `thenNF_Tc` \ env ->
- returnTc (prag_info_fn, (poly_binds `AndMonoBinds` prag_binds,
- poly_lie `plusLIE` prag_lie,
- env, poly_ids)
- ) ) `thenTc` \ (_, result) ->
- returnTc result
- where
- binder_names = map fst (bagToList (collectMonoBinders bind))
- ty_sigs = [sig | sig@(Sig name _ _) <- sigs]
+ 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
+ -- 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 (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
+% 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}
\begin{code}
tcBindWithSigs
:: TopLevelFlag
- -> [Name]
-> RenamedMonoBinds
-> [TcSigInfo s]
-> RecFlag
-> (Name -> IdInfo)
-> TcM s (TcMonoBinds s, LIE s, [TcIdBndr s])
-tcBindWithSigs top_lvl binder_names mbind tc_ty_sigs is_rec prag_info_fn
+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 mkBoxedTypeKind `thenNF_Tc` \ alpha_tv ->
+ newTcTyVar boxedTypeKind `thenNF_Tc` \ alpha_tv ->
let
- forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv)
- poly_ids = map mk_dummy binder_names
+ 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
+ Just (TySigInfo _ poly_id _ _ _ _ _ _) -> poly_id -- Signature
Nothing -> mkUserId name forall_a_a -- No signature
in
returnTc (EmptyMonoBinds, emptyLIE, poly_ids)
) $
- -- Create a new identifier for each binder, with each being given
- -- a fresh unique, and a type-variable type.
- -- For "mono_lies" see comments about polymorphic recursion at the
- -- end of the function.
- mapAndUnzipNF_Tc mk_mono_id binder_names `thenNF_Tc` \ (mono_lies, mono_ids) ->
+ -- TYPECHECK THE BINDINGS
+ tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) ->
+
let
- mono_lie = plusLIEs mono_lies
mono_id_tys = map idType mono_ids
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 ->
-
+ checkSigMatch tc_ty_sigs `thenTc` \ (sig_theta, lie_avail) ->
+
-- 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 `thenNF_Tc` \ (tyvars_not_to_gen, tyvars_to_gen) ->
+ 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 (tyVarSetToList tyvars_to_gen) `thenTc` \ real_tyvars_to_gen_list ->
+ mapTc defaultUncommittedTyVar (varSetElems tyvars_to_gen) `thenTc` \ real_tyvars_to_gen_list ->
let
- real_tyvars_to_gen = mkTyVarSet real_tyvars_to_gen_list
+ 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
in
-- SIMPLIFY THE LIE
- tcExtendGlobalTyVars (tyVarSetToList tyvars_not_to_gen) (
+ 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 mono_lies (which will be empty anyway)
+ -- need to use lie_avail (which will be empty anyway)
tcSimplify (text "tcBinds1" <+> ppr binder_names)
- top_lvl real_tyvars_to_gen lie `thenTc` \ (lie_free, dict_binds, lie_bound) ->
+ 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
let
-- The "givens" is the stuff available. We get that from
- -- the context of the type signature, BUT ALSO the mono_lie
+ -- 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` mono_lie
+ 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") <+>
- hsep (punctuate comma (map (quotes . ppr) binder_names)))
- real_tyvars_to_gen givens lie `thenTc` \ (lie_free, dict_binds) ->
+ (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) ->
- ASSERT( not (any (isUnboxedTypeKind . tyVarKind) real_tyvars_to_gen_list) )
+ -- 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.
+ -- 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
- zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_types ->
+ mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids ->
let
- exports = zipWith3 mk_export binder_names mono_ids zonked_mono_id_types
+ exports = zipWith mk_export binder_names zonked_mono_ids
dict_tys = map tcIdType dicts_bound
- mk_export binder_name mono_id zonked_mono_id_ty
- = (tyvars, TcId (replaceIdInfo poly_id (prag_info_fn binder_name)), TcId mono_id)
+ 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)
+ 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 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.
+ 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'),
+ (dict_binds `andMonoBinds` mbind'),
lie_free,
[poly_id | (_, TcId poly_id, _) <- exports]
)
where
- no_of_binders = length binder_names
-
- mk_mono_id binder_name
- | theres_a_signature -- There's a signature; and it's overloaded,
- && not (null sig_theta) -- so make a Method
- = tcAddSrcLoc sig_loc $
- newMethodWithGivenTy SignatureOrigin
- (TcId poly_id) (mkTyVarTys sig_tyvars)
- sig_theta sig_tau `thenNF_Tc` \ (mono_lie, TcId mono_id) ->
- -- A bit turgid to have to strip the TcId
- returnNF_Tc (mono_lie, mono_id)
-
- | otherwise -- No signature or not overloaded;
- = tcAddSrcLoc (getSrcLoc binder_name) $
- (if theres_a_signature then
- returnNF_Tc sig_tau -- Non-overloaded signature; use its type
- else
- newTyVarTy kind -- No signature; use a new type variable
- ) `thenNF_Tc` \ mono_id_ty ->
-
- newLocalId (getOccName binder_name) mono_id_ty `thenNF_Tc` \ mono_id ->
- returnNF_Tc (emptyLIE, mono_id)
- where
- maybe_sig = maybeSig tc_ty_sigs binder_name
- theres_a_signature = maybeToBool maybe_sig
- Just (TySigInfo name poly_id sig_tyvars sig_theta sig_tau sig_loc) = maybe_sig
-
- tysig_names = [name | (TySigInfo name _ _ _ _ _) <- tc_ty_sigs]
+ tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- tc_ty_sigs]
is_unrestricted = isUnRestrictedGroup tysig_names mbind
- kind = case is_rec of
- Recursive -> mkBoxedTypeKind -- Recursive, so no unboxed types
- NonRecursive -> mkTypeKind -- Non-recursive, so we permit unboxed types
+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
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 ins't being used (but that's a very common case).
+polymorphic recursion isn't being used (but that's a very common case).
+We'd prefer
+
+ 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:
+This can lead to a massive space leak, from the following top-level defn
+(post-typechecking)
ff :: [Int] -> [Int]
- ff = f dEqInt
+ 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.
+ 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'...
+
+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. Thats' what the "mono_lies"
+to the "givens" when simplifying constraints. That's what the "lies_avail"
is doing.
= tcGetGlobalTyVars `thenNF_Tc` \ free_tyvars ->
zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_tys ->
let
- tyvars_to_gen = tyVarsOfTypes zonked_mono_id_tys `minusTyVarSet` free_tyvars
+ tyvars_to_gen = tyVarsOfTypes zonked_mono_id_tys `minusVarSet` free_tyvars
in
if is_unrestricted
then
- returnNF_Tc (emptyTyVarSet, tyvars_to_gen)
+ 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 (emptyTyVarSet, tyvars_to_gen)) $
+ 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 = foldrBag (unionTyVarSets . tyVarsOfInst) emptyTyVarSet constrained_dicts
- reduced_tyvars_to_gen = tyvars_to_gen `minusTyVarSet` constrained_tyvars
+ 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}
defaultUncommittedTyVar tyvar
- | isTypeKind (tyVarKind tyvar)
- = newTcTyVar mkBoxedTypeKind `thenNF_Tc` \ boxed_tyvar ->
- unifyTauTy (mkTyVarTy boxed_tyvar) (mkTyVarTy tyvar) `thenTc_`
+ | tyVarKind tyvar == openTypeKind
+ = newTcTyVar boxedTypeKind `thenNF_Tc` \ boxed_tyvar ->
+ unifyTauTy (mkTyVarTy tyvar) (mkTyVarTy boxed_tyvar) `thenTc_`
returnTc boxed_tyvar
| otherwise
\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
- )
+ -> 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_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)
+ 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
+
+ tc_mb_pats EmptyMonoBinds
+ = returnTc (returnTc (EmptyMonoBinds, emptyLIE), emptyLIE, emptyBag, emptyBag, emptyLIE)
+
+ 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)
+
+ 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.
-
-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}
-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}
-
-
-\begin{code}
-tcTySig :: RenamedSig
- -> TcM s (TcSigInfo s)
-
-tcTySig (Sig v ty src_loc)
- = tcAddSrcLoc src_loc $
- tcHsType ty `thenTc` \ sigma_ty ->
-
- -- Convert from Type to TcType
- tcInstSigType sigma_ty `thenNF_Tc` \ sigma_tc_ty ->
- let
- poly_id = mkUserId v sigma_tc_ty
- in
- -- Instantiate this type
- -- It's important to do this even though in the error-free case
- -- we could just split the sigma_tc_ty (since the tyvars don't
- -- unified with anything). But in the case of an error, when
- -- the tyvars *do* get unified with something, we want to carry on
- -- typechecking the rest of the program with the function bound
- -- to a pristine type, namely sigma_tc_ty
- tcInstSigTcType sigma_tc_ty `thenNF_Tc` \ (tyvars, rho) ->
- let
- (theta, tau) = splitRhoTy rho
- -- 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)
\begin{code}
checkSigMatch []
- = returnTc (error "checkSigMatch")
+ = returnTc (error "checkSigMatch", emptyLIE)
-checkSigMatch tc_ty_sigs@( sig1@(TySigInfo _ id1 _ theta1 _ _) : all_sigs_but_first )
+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_`
-- ToDo: amplify
mapTc check_one_cxt all_sigs_but_first `thenTc_`
- returnTc theta1
+ 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)
+ 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)
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
+ 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}
-@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]
-
- (c) not mentioned in the environment
- eg the signature for f in this:
-
- g x = ... where
- f :: a->[a]
- f y = [x,y]
-
- 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.
-
-We used to have the notion of a "DontBind" type variable, which would
-only be bound to itself or nothing. Then points (a) and (b) were
-self-checking. But it gave rise to bogus consequential error messages.
-For example:
-
- f = (*) -- Monomorphic
-
- g :: Num a => a -> a
- g x = f x x
-
-Here, we get a complaint when checking the type signature for g,
-that g isn't polymorphic enough; but then we get another one when
-dealing with the (Num x) context arising from f's definition;
-we try to unify x with Int (to default it), but find that x has already
-been unified with the DontBind variable "a" from g's signature.
-This is really a problem with side-effecting unification; we'd like to
-undo g's effects when its type signature fails, but unification is done
-by side effect, so we can't (easily).
-
-So we revert to ordinary type variables for signatures, and try to
-give a helpful message in checkSigTyVars.
-
-\begin{code}
-checkSigTyVars :: [TcTyVar s] -- The original signature type variables
- -> TcType s -- signature type (for err msg)
- -> TcM s [TcTyVar s] -- Zonked signature type variables
-
-checkSigTyVars sig_tyvars sig_tau
- = mapNF_Tc zonkTcTyVar sig_tyvars `thenNF_Tc` \ sig_tys ->
- let
- sig_tyvars' = map (getTyVar "checkSigTyVars") sig_tys
- in
-
- -- Check points (a) and (b)
- checkTcM (all isTyVarTy sig_tys && hasNoDups sig_tyvars')
- (zonkTcType sig_tau `thenNF_Tc` \ sig_tau' ->
- failWithTc (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_tyvars',
- sig_tv' `elementOfTyVarSet` globals]
-
- mono_tyvars = map (assoc "checkSigTyVars" (sig_tyvars' `zip` sig_tyvars)) mono_tyvars'
- in
- checkTcM (null mono_tyvars')
- (failWithTc (notAsPolyAsSigErr sig_tau mono_tyvars)) `thenTc_`
-
- returnTc sig_tyvars'
-\end{code}
-
-
%************************************************************************
%* *
\subsection{SPECIALIZE pragmas}
let
prag_fn name = foldr ($) noIdInfo [f | Just (n,f) <- maybe_info_modifiers, n==name]
in
- returnTc (prag_fn, andMonoBinds binds, plusLIEs lies)
+ returnTc (prag_fn, andMonoBindList binds, plusLIEs lies)
\end{code}
The interesting case is for SPECIALISE pragmas. There are two forms.
= returnTc (Just (name, setInlinePragInfo IWantToBeINLINEd), EmptyMonoBinds, emptyLIE)
tcPragmaSig (NoInlineSig name loc)
- = returnTc (Just (name, setInlinePragInfo IDontWantToBeINLINEd), EmptyMonoBinds, emptyLIE)
+ = returnTc (Just (name, setInlinePragInfo IMustNotBeINLINEd), EmptyMonoBinds, emptyLIE)
tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc)
= -- SPECIALISE f :: forall b. theta => tau = g
tcAddErrCtxt (valSpecSigCtxt name poly_ty) $
-- Get and instantiate its alleged specialised type
- tcHsType poly_ty `thenTc` \ sig_sigma ->
- tcInstSigType sig_sigma `thenNF_Tc` \ sig_ty ->
+ tcHsTcType poly_ty `thenTc` \ sig_ty ->
-- Check that f has a more general type, and build a RHS for
-- the spec-pragma-id at the same time
-- 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 ->
- tcInstSigTcType (idType f_id) `thenNF_Tc` \ (f_tyvars, f_rho) ->
+ tcInstTcType (idType f_id) `thenNF_Tc` \ (f_tyvars, f_rho) ->
let
(sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
(f_theta, f_tau) = splitRhoTy f_rho
- sig_tyvar_set = mkTyVarSet sig_tyvars
+ sig_tyvar_set = mkVarSet sig_tyvars
in
unifyTauTy sig_tau f_tau `thenTc_`
])
-----------------------------------------------
-sigCtxt id
- = sep [ptext SLIT("When checking the type signature for"), quotes (ppr id)]
+unboxedPatBindErr id
+ = ptext SLIT("variable in a lazy pattern binding has unboxed type: ")
+ <+> quotes (ppr id)
+-----------------------------------------------
bindSigsCtxt ids
= ptext SLIT("When checking the type signature(s) for") <+> pprQuotedList ids
4 (ptext SLIT("(the signature contexts in a mutually recursive group should all be identical)"))
-----------------------------------------------
-specGroundnessCtxt
- = panic "specGroundnessCtxt"
-
---------------------------------------------
-specContextGroundnessCtxt -- err_ctxt dicts
- = panic "specContextGroundnessCtxt"
-{-
- = hang (
- sep [hsep [ptext SLIT("In the SPECIALIZE pragma for"), ppr name],
- hcat [ptext SLIT(" specialised to the type"), ppr spec_ty],
- pp_spec_id,
- ptext SLIT("... not all overloaded type variables were instantiated"),
- ptext SLIT("to ground types:")])
- 4 (vcat [hsep [ppr c, ppr 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 -> empty)
- ValSpecSpecIdCtxt n ty spec loc ->
- (n, ty, loc,
- hsep [ptext SLIT("... type of explicit id"), ppr spec])
--}
+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