%
-% (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, checkSigTyVars, tcBindWithSigs,
- sigCtxt, sigThetaCtxt, TcSigInfo(..) ) where
+module TcBinds ( tcBindsAndThen, tcTopBinds,
+ tcSpecSigs, tcBindWithSigs ) where
#include "HsVersions.h"
-import {-# SOURCE #-} TcGRHSs ( tcGRHSsAndBinds )
+import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun )
+import {-# SOURCE #-} TcExpr ( tcExpr )
-import HsSyn ( HsBinds(..), MonoBinds(..), Sig(..), InPat(..),
- collectMonoBinders
- )
-import RnHsSyn ( RenamedHsBinds, RenamedSig(..),
- RenamedMonoBinds
- )
-import TcHsSyn ( TcHsBinds, TcMonoBinds,
- TcIdOcc(..), TcIdBndr,
- tcIdType
+import CmdLineOpts ( opt_NoMonomorphismRestriction )
+import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..),
+ Match(..), HsMatchContext(..),
+ collectMonoBinders, andMonoBinds
)
+import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds )
+import TcHsSyn ( TcMonoBinds, TcId, zonkId, mkHsLet )
import TcMonad
-import Inst ( Inst, LIE, emptyLIE, plusLIE, plusLIEs, InstOrigin(..),
- newDicts, tyVarsOfInst, instToId, newMethodWithGivenTy,
- zonkInst, pprInsts
+import Inst ( LIE, emptyLIE, mkLIE, plusLIE, InstOrigin(..),
+ newDicts, instToId
)
-import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newLocalId,
- tcGetGlobalTyVars, tcExtendGlobalTyVars
+import TcEnv ( tcExtendLocalValEnv,
+ newSpecPragmaId, newLocalId
+ )
+import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyRestricted, tcSimplifyToDicts )
+import TcMonoType ( tcHsSigType, UserTypeCtxt(..), checkSigTyVars,
+ TcSigInfo(..), tcTySig, maybeSig, sigCtxt
)
-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,
- zonkTcType, zonkTcTypes, zonkTcThetaType, zonkTcTyVar
+import TcMType ( newTyVarTy, newTyVar,
+ zonkTcTyVarToTyVar,
+ unifyTauTy, unifyTauTyLists
+ )
+import TcType ( mkTyVarTy, mkForAllTys, mkFunTys, tyVarsOfType,
+ mkPredTy, mkForAllTy, isUnLiftedType,
+ unliftedTypeKind, liftedTypeKind, openTypeKind, eqKind
)
-import Unify ( unifyTauTy, unifyTauTyLists )
-
-import Kind ( isUnboxedTypeKind, mkTypeKind, isTypeKind, mkBoxedTypeKind )
-import Id ( GenId, idType, mkUserId )
-import IdInfo ( noIdInfo )
-import Maybes ( maybeToBool, assocMaybe )
-import Name ( getOccName, getSrcLoc, Name )
-import PragmaInfo ( PragmaInfo(..) )
-import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy, tyVarsOfTypes,
- splitSigmaTy, mkForAllTys, mkFunTys, getTyVar, mkDictTy,
- splitRhoTy, mkForAllTy, splitForAllTys )
-import TyVar ( GenTyVar, TyVar, tyVarKind, mkTyVarSet, minusTyVarSet, emptyTyVarSet,
- elementOfTyVarSet, unionTyVarSets, tyVarSetToList )
-import Bag ( bagToList, foldrBag, )
-import Util ( isIn, hasNoDups, assoc )
-import Unique ( Unique )
-import BasicTypes ( TopLevelFlag(..), RecFlag(..) )
-import SrcLoc ( SrcLoc )
+
+import CoreFVs ( idFreeTyVars )
+import Id ( mkLocalId, setInlinePragma )
+import Var ( idType, idName )
+import IdInfo ( InlinePragInfo(..) )
+import Name ( Name, getOccName, getSrcLoc )
+import NameSet
+import Var ( tyVarKind )
+import VarSet
+import Bag
+import Util ( isIn )
+import Maybes ( maybeToBool )
+import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isNotTopLevel )
+import FiniteMap ( listToFM, lookupFM )
import Outputable
\end{code}
dictionaries, which we resolve at the module level.
\begin{code}
-tcTopBindsAndThen, tcBindsAndThen
- :: (RecFlag -> TcMonoBinds s -> this -> that) -- Combinator
- -> RenamedHsBinds
- -> TcM s (this, LIE s)
- -> TcM s (that, LIE s)
+tcTopBinds :: RenamedHsBinds -> TcM ((TcMonoBinds, TcEnv), LIE)
+tcTopBinds binds
+ = tc_binds_and_then TopLevel glue binds $
+ tcGetEnv `thenNF_Tc` \ env ->
+ returnTc ((EmptyMonoBinds, env), emptyLIE)
+ where
+ glue is_rec binds1 (binds2, thing) = (binds1 `AndMonoBinds` binds2, thing)
-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 $
+tcBindsAndThen
+ :: (RecFlag -> TcMonoBinds -> thing -> thing) -- Combinator
+ -> RenamedHsBinds
+ -> TcM (thing, LIE)
+ -> TcM (thing, LIE)
- -- Now do whatever happens next, in the augmented envt
- do_next `thenTc` \ (thing, thing_lie) ->
+tcBindsAndThen = tc_binds_and_then NotTopLevel
- -- 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 EmptyBinds do_next
+ = do_next
+tc_binds_and_then top_lvl combiner (MonoBind EmptyMonoBinds sigs is_rec) do_next
+ = 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, _) ->
- -- 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 ->
+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
+
+tc_binds_and_then top_lvl combiner (MonoBind bind sigs is_rec) do_next
+ = -- TYPECHECK THE SIGNATURES
+ mapTc tcTySig [sig | sig@(Sig name _ _) <- sigs] `thenTc` \ tc_ty_sigs ->
- tcBindWithSigs top_lvl binder_names bind
- tc_ty_sigs is_rec prag_info_fn `thenTc` \ (poly_binds, poly_lie, poly_ids) ->
+ tcBindWithSigs top_lvl bind tc_ty_sigs
+ sigs is_rec `thenTc` \ (poly_binds, poly_lie, poly_ids) ->
-- Extend the environment to bind the new polymorphic Ids
- tcExtendLocalValEnv binder_names poly_ids $
+ tcExtendLocalValEnv [(idName poly_id, poly_id) | poly_id <- 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]
-\end{code}
-
-An aside. The original version of @tcBindsAndThen@ which lacks a
-combiner function, appears below. Though it is perfectly well
-behaved, it cannot be typed by Haskell, because the recursive call is
-at a different type to the definition itself. There aren't too many
-examples of this, which is why I thought it worth preserving! [SLPJ]
+ tcSpecSigs sigs `thenTc` \ (prag_binds, prag_lie) ->
-\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)
+ -- Now do whatever happens next, in the augmented envt
+ do_next `thenTc` \ (thing, thing_lie) ->
-tcBindsAndThen (MonoBind bind sigs is_rec) do_next
- = tcBindAndThen bind sigs do_next
-\end{pseudocode}
+ -- Create specialisations of functions bound here
+ -- We want to keep non-recursive things non-recursive
+ -- so that we desugar unlifted 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 (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 (
+ 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 (
+ combiner Recursive (
+ poly_binds `andMonoBinds`
+ lie_binds `andMonoBinds`
+ prag_binds) thing,
+ final_lie
+ )
+\end{code}
%************************************************************************
\begin{code}
tcBindWithSigs
:: TopLevelFlag
- -> [Name]
-> RenamedMonoBinds
- -> [TcSigInfo s]
+ -> [TcSigInfo]
+ -> [RenamedSig] -- Used solely to get INLINE, NOINLINE sigs
-> RecFlag
- -> (Name -> PragmaInfo)
- -> TcM s (TcMonoBinds s, LIE s, [TcIdBndr s])
+ -> TcM (TcMonoBinds, LIE, [TcId])
-tcBindWithSigs top_lvl binder_names mbind tc_ty_sigs is_rec prag_info_fn
+tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec
= 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 ->
+ newTyVar liftedTypeKind `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 = 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 NoPragmaInfo -- No signature
+ Just (TySigInfo _ poly_id _ _ _ _ _ _) -> poly_id -- Signature
+ Nothing -> mkLocalId 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) ->
- 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 ->
-
- -- 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
- -- **** This step can do unification => keep other zonking after this ****
- mapTc defaultUncommittedTyVar (tyVarSetToList tyvars_to_gen) `thenTc` \ real_tyvars_to_gen_list ->
+ tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) ->
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
- --
+ tau_tvs = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids
in
- -- SIMPLIFY THE LIE
- tcExtendGlobalTyVars (tyVarSetToList tyvars_not_to_gen) (
- 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)
- tcSimplify (text "tcBinds1" <+> ppr binder_names)
- top_lvl real_tyvars_to_gen lie `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 mono_lie
- -- so that polymorphic recursion works right (see comments at end of fn)
- givens = dicts_sig `plusLIE` mono_lie
- in
-
- -- Check that the needed dicts can be expressed in
- -- terms of the signature ones
- tcAddErrCtxt (bindSigsCtxt tysig_names) $
- tcAddErrCtxtM (sigThetaCtxt dicts_sig) $
- tcSimplifyAndCheck
- (text "tcBinds2" <+> ppr binder_names)
- real_tyvars_to_gen givens 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
- zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_types ->
+ -- GENERALISE
+ tcAddSrcLoc (minimum (map getSrcLoc binder_names)) $
+ tcAddErrCtxt (genCtxt binder_names) $
+ generalise binder_names mbind tau_tvs lie_req tc_ty_sigs
+ `thenTc` \ (tc_tyvars_to_gen, lie_free, dict_binds, dict_ids) ->
+
+
+ -- ZONK THE GENERALISED TYPE VARIABLES TO REAL TyVars
+ -- This commits any unbound kind variables to boxed kind, by unification
+ -- It's important that the final quanfified type variables
+ -- are fully zonked, *including boxity*, because they'll be
+ -- included in the forall types of the polymorphic Ids.
+ -- At calls of these Ids we'll instantiate fresh type variables from
+ -- them, and we use their boxity then.
+ mapNF_Tc zonkTcTyVarToTyVar tc_tyvars_to_gen `thenNF_Tc` \ real_tyvars_to_gen ->
+
+ -- ZONK THE Ids
+ -- It's important that the dict Ids are zonked, including the boxity set
+ -- in the previous step, because they are later used to form the type of
+ -- the polymorphic thing, and forall-types must be zonked so far as
+ -- their bound variables are concerned
+ mapNF_Tc zonkId dict_ids `thenNF_Tc` \ zonked_dict_ids ->
+ mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids ->
+
+ -- CHECK FOR BOGUS UNLIFTED BINDINGS
+ checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind zonked_mono_ids `thenTc_`
+
+ -- BUILD THE POLYMORPHIC RESULT IDs
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)
+ exports = zipWith mk_export binder_names zonked_mono_ids
+ dict_tys = map idType zonked_dict_ids
+
+ inlines = mkNameSet [name | InlineSig name _ loc <- inline_sigs]
+ no_inlines = listToFM ([(name, IMustNotBeINLINEd False phase) | NoInlineSig name phase loc <- inline_sigs] ++
+ [(name, IMustNotBeINLINEd True phase) | InlineSig name phase loc <- inline_sigs, maybeToBool phase])
+ -- "INLINE n foo" means inline foo, but not until at least phase n
+ -- "NOINLINE n foo" means don't inline foo until at least phase n, and even
+ -- then only if it is small enough etc.
+ -- "NOINLINE foo" means don't inline foo ever, which we signal with a (IMustNotBeINLINEd Nothing)
+ -- See comments in CoreUnfold.blackListed for the Authorised Version
+
+ mk_export binder_name zonked_mono_id
+ = (tyvars,
+ attachNoInlinePrag no_inlines poly_id,
+ zonked_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.
+ (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, new_poly_id)
+
+ new_poly_id = mkLocalId binder_name poly_ty
+ poly_ty = mkForAllTys real_tyvars_to_gen
+ $ 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.
in
+ traceTc (text "binding:" <+> ppr ((zonked_dict_ids, dict_binds),
+ exports, [idType poly_id | (_, poly_id, _) <- exports])) `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]
+ AbsBinds real_tyvars_to_gen
+ zonked_dict_ids
+ exports
+ inlines
+ (dict_binds `andMonoBinds` mbind'),
+ lie_free,
+ [poly_id | (_, poly_id, _) <- exports]
)
+
+attachNoInlinePrag no_inlines bndr
+ = case lookupFM no_inlines (idName bndr) of
+ Just prag -> bndr `setInlinePragma` prag
+ Nothing -> bndr
+
+checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind zonked_mono_ids
+ = ASSERT( not (any ((eqKind unliftedTypeKind) . tyVarKind) real_tyvars_to_gen) )
+ -- 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.
+
+ -- Check that pattern-bound variables are not unlifted
+ (if or [ (idName id `elem` pat_binders) && isUnLiftedType (idType id)
+ | id <- zonked_mono_ids ] then
+ addErrTc (unliftedBindErr "Pattern" mbind)
+ else
+ returnTc ()
+ ) `thenTc_`
+
+ -- Unlifted bindings must be non-recursive,
+ -- not top level, non-polymorphic, and not pattern bound
+ if any (isUnLiftedType . idType) zonked_mono_ids then
+ checkTc (isNotTopLevel top_lvl)
+ (unliftedBindErr "Top-level" mbind) `thenTc_`
+ checkTc (isNonRec is_rec)
+ (unliftedBindErr "Recursive" mbind) `thenTc_`
+ checkTc (null real_tyvars_to_gen)
+ (unliftedBindErr "Polymorphic" mbind)
+ else
+ returnTc ()
+
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]
- is_unrestricted = isUnRestrictedGroup tysig_names mbind
+ pat_binders :: [Name]
+ pat_binders = collectMonoBinders (justPatBindings mbind EmptyMonoBinds)
- 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
~~~~~~~~~~~~~~~~~~~~~
The game plan for polymorphic recursion in the code above is
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.
%* *
%************************************************************************
-@getTyVarsToGen@ decides what type variables generalise over.
+\begin{code}
+generalise binder_names mbind tau_tvs lie_req sigs
+ | not is_unrestricted -- RESTRICTED CASE
+ = -- Check signature contexts are empty
+ checkTc (all is_mono_sig sigs)
+ (restrictedBindCtxtErr binder_names) `thenTc_`
+
+ -- Now simplify with exactly that set of tyvars
+ -- We have to squash those Methods
+ tcSimplifyRestricted doc tau_tvs lie_req `thenTc` \ (qtvs, lie_free, binds) ->
+
+ -- Check that signature type variables are OK
+ checkSigsTyVars sigs `thenTc_`
+
+ returnTc (qtvs, lie_free, binds, [])
+
+ | null sigs -- UNRESTRICTED CASE, NO TYPE SIGS
+ = tcSimplifyInfer doc tau_tvs lie_req
+
+ | otherwise -- UNRESTRICTED CASE, WITH TYPE SIGS
+ = -- CHECKING CASE: Unrestricted group, there are type signatures
+ -- Check signature contexts are empty
+ checkSigsCtxts sigs `thenTc` \ (sig_avails, sig_dicts) ->
+
+ -- Check that the needed dicts can be
+ -- expressed in terms of the signature ones
+ tcSimplifyInferCheck doc tau_tvs sig_avails lie_req `thenTc` \ (forall_tvs, lie_free, dict_binds) ->
+
+ -- Check that signature type variables are OK
+ checkSigsTyVars sigs `thenTc_`
+
+ returnTc (forall_tvs, lie_free, dict_binds, sig_dicts)
+
+ where
+ is_unrestricted | opt_NoMonomorphismRestriction = True
+ | otherwise = isUnRestrictedGroup tysig_names mbind
+
+ tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- sigs]
+ is_mono_sig (TySigInfo _ _ _ theta _ _ _ _) = null theta
+
+ doc = ptext SLIT("type signature(s) for") <+> pprBinders binder_names
+
+-----------------------
+ -- 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
+checkSigsCtxts sigs@(TySigInfo _ id1 sig_tvs theta1 _ _ _ src_loc : other_sigs)
+ = tcAddSrcLoc src_loc $
+ mapTc_ check_one other_sigs `thenTc_`
+ if null theta1 then
+ returnTc ([], []) -- Non-overloaded type signatures
+ else
+ newDicts SignatureOrigin theta1 `thenNF_Tc` \ sig_dicts ->
+ let
+ -- The "sig_avails" 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)
+ sig_avails = sig_dicts ++ sig_meths
+ in
+ returnTc (sig_avails, map instToId sig_dicts)
+ where
+ sig1_dict_tys = map mkPredTy theta1
+ n_sig1_theta = length theta1
+ sig_meths = concat [insts | TySigInfo _ _ _ _ _ _ insts _ <- sigs]
+
+ check_one sig@(TySigInfo _ id _ theta _ _ _ src_loc)
+ = tcAddErrCtxt (sigContextsCtxt id1 id) $
+ checkTc (length theta == n_sig1_theta) sigContextsErr `thenTc_`
+ unifyTauTyLists sig1_dict_tys (map mkPredTy theta)
+
+checkSigsTyVars sigs = mapTc_ check_one sigs
+ where
+ check_one (TySigInfo _ id sig_tyvars sig_theta sig_tau _ _ src_loc)
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxtM (sigCtxt (sig_msg id) sig_tyvars sig_theta sig_tau) $
+ checkSigTyVars sig_tyvars (idFreeTyVars id)
+
+ sig_msg id = ptext SLIT("When checking the type signature for") <+> quotes (ppr id)
+\end{code}
+
+@getTyVarsToGen@ decides what type variables to generalise over.
For a "restricted group" -- see the monomorphism restriction
for a definition -- we bind no dictionaries, and
Another, more common, example is when there's a Method inst in
the LIE, whose type might very well involve non-overloaded
type variables.
+ [NOTE: Jan 2001: I don't understand the problem here so I'm doing
+ the simple thing instead]
(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
find which tyvars are constrained.
\begin{code}
-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 `minusTyVarSet` free_tyvars
- in
- if is_unrestricted
- then
- returnTc (emptyTyVarSet, tyvars_to_gen)
- else
- 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
- in
- returnTc (constrained_tyvars, reduced_tyvars_to_gen)
-\end{code}
-
-
-\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 (PatMonoBind other _ _) = False
isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs
-isUnRestrictedGroup sigs (FunMonoBind _ _ _ _) = True
+isUnRestrictedGroup sigs (FunMonoBind v _ matches _) = any isUnRestrictedMatch matches ||
+ v `is_elem` sigs
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}
-defaultUncommittedTyVar tyvar
- | isTypeKind (tyVarKind tyvar)
- = newTcTyVar mkBoxedTypeKind `thenNF_Tc` \ boxed_tyvar ->
- unifyTauTy (mkTyVarTy boxed_tyvar) (mkTyVarTy tyvar) `thenTc_`
- returnTc boxed_tyvar
-
- | otherwise
- = returnTc tyvar
+isUnRestrictedMatch (Match _ [] Nothing _) = False -- No args, no signature
+isUnRestrictedMatch other = True -- Some args or a signature
\end{code}
\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}
-
-%************************************************************************
-%* *
-\subsection{Signatures}
-%* *
-%************************************************************************
-
-@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 :: (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 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 ->
+ -> [TcSigInfo]
+ -> RecFlag
+ -> TcM (TcMonoBinds,
+ LIE, -- LIE required
+ [Name], -- Bound names
+ [TcId]) -- 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
- sig_tyvars' = map (getTyVar "checkSigTyVars") sig_tys
+ id_list = bagToList ids
+ (names, mono_ids) = unzip id_list
+
+ -- This last defn is the key one:
+ -- extend the val envt with bindings for the
+ -- things bound in this group, overriding the monomorphic
+ -- ids with the polymorphic ones from the pattern
+ extra_val_env = case is_rec of
+ Recursive -> map mk_bind id_list
+ NonRecursive -> []
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.
+ --
+ -- There's a further wrinkle: we have to delay extending the environment
+ -- until after we've dealt with any pattern-bound signature type variables
+ -- Consider f (x::a) = ...f...
+ -- We're going to check that a isn't unified with anything in the envt,
+ -- so f itself had better not be! So we pass the envt binding f into
+ -- complete_it, which extends the actual envt in TcMatches.tcMatch, after
+ -- dealing with the signature tyvars
- -- 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]
+ complete_it extra_val_env `thenTc` \ (mbinds', lie_req_rhss) ->
- 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 (mbinds', lie_req_pat `plusLIE` lie_req_rhss, names, mono_ids)
+ where
+
+ -- This function is used when dealing with a LHS binder;
+ -- we make a monomorphic version of the Id.
+ -- We check for a type signature; if there is one, we use the mono_id
+ -- from the signature. This is how we make sure the tau part of the
+ -- signature actually maatches the type of the LHS; then tc_mb_pats
+ -- ensures the LHS and RHS have the same type
+
+ tc_pat_bndr name pat_ty
+ = case maybeSig tc_ty_sigs name of
+ Nothing
+ -> newLocalId (getOccName name) pat_ty (getSrcLoc name)
+
+ Just (TySigInfo _ _ _ _ _ mono_id _ _)
+ -> tcAddSrcLoc (getSrcLoc name) $
+ unifyTauTy (idType mono_id) pat_ty `thenTc_`
+ returnTc mono_id
+
+ mk_bind (name, mono_id) = case maybeSig tc_ty_sigs name of
+ Nothing -> (name, mono_id)
+ Just (TySigInfo name poly_id _ _ _ _ _ _) -> (name, poly_id)
+
+ tc_mb_pats EmptyMonoBinds
+ = returnTc (\ xve -> 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 xve = complete_it1 xve `thenTc` \ (mb1', lie1) ->
+ complete_it2 xve `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 kind `thenNF_Tc` \ bndr_ty ->
+ tc_pat_bndr name bndr_ty `thenTc` \ bndr_id ->
+ let
+ complete_it xve = tcAddSrcLoc locn $
+ tcMatchesFun xve name bndr_ty matches `thenTc` \ (matches', lie) ->
+ returnTc (FunMonoBind bndr_id inf matches' locn, lie)
+ in
+ returnTc (complete_it, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE)
+
+ tc_mb_pats bind@(PatMonoBind pat grhss locn)
+ = tcAddSrcLoc locn $
+ newTyVarTy kind `thenNF_Tc` \ pat_ty ->
+
+ -- Now typecheck the pattern
+ -- We don't support binding fresh type variables in the
+ -- pattern of a pattern binding. For example, this is illegal:
+ -- (x::a, y::b) = e
+ -- whereas this is ok
+ -- (x::Int, y::Bool) = e
+ --
+ -- We don't check explicitly for this problem. Instead, we simply
+ -- type check the pattern with tcPat. If the pattern mentions any
+ -- fresh tyvars we simply get an out-of-scope type variable error
+ tcPat tc_pat_bndr pat pat_ty `thenTc` \ (pat', lie_req, tvs, ids, lie_avail) ->
+ let
+ complete_it xve = tcAddSrcLoc locn $
+ tcAddErrCtxt (patMonoBindsCtxt bind) $
+ tcExtendLocalValEnv xve $
+ tcGRHSs PatBindRhs grhss pat_ty `thenTc` \ (grhss', lie) ->
+ returnTc (PatMonoBind pat' grhss' locn, lie)
+ in
+ returnTc (complete_it, lie_req, tvs, ids, lie_avail)
- returnTc sig_tyvars'
+ -- Figure out the appropriate kind for the pattern,
+ -- and generate a suitable type variable
+ kind = case is_rec of
+ Recursive -> liftedTypeKind -- Recursive, so no unlifted types
+ NonRecursive -> openTypeKind -- Non-recursive, so we permit unlifted types
\end{code}
%* *
%************************************************************************
-
-@tcPragmaSigs@ munches up the "signatures" that arise through *user*
+@tcSpecSigs@ munches up the specialisation "signatures" that arise through *user*
pragmas. It is convenient for them to appear in the @[RenamedSig]@
part of a binding because then the same machinery can be used for
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
- TcMonoBinds s,
- LIE s)
-
--- 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
- = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (names_w_id_infos, binds, lies) ->
- let
- name_to_info name = foldr ($) noIdInfo
- [info_fn | (n,info_fn) <- names_w_id_infos, n==name]
- in
- returnTc (name_to_info,
- foldr ThenBinds EmptyBinds binds,
- foldr plusLIE emptyLIE lies)
-\end{code}
-
-Here are the easy cases for tcPragmaSigs
+They look like this:
-\begin{code}
-tcPragmaSig (InlineSig name loc)
- = returnTc ((name, addUnfoldInfo (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE)
-tcPragmaSig (MagicUnfoldingSig name string loc)
- = returnTc ((name, addUnfoldInfo (mkMagicUnfolding string)), EmptyBinds, emptyLIE)
-\end{code}
-
-The interesting case is for SPECIALISE pragmas. There are two forms.
-Here's the first form:
\begin{verbatim}
f :: Ord a => [a] -> b -> b
{-# SPECIALIZE f :: [Int] -> b -> b #-}
Int, and will create a specialisation for @f@. After that, the
binding for @f*@ can be discarded.
-The second form is this:
-\begin{verbatim}
- f :: Ord a => [a] -> b -> b
- {-# SPECIALIZE f :: [Int] -> b -> b = g #-}
-\end{verbatim}
-
-Here @g@ is specified as a function that implements the specialised
-version of @f@. Suppose that g has type (a->b->b); that is, g's type
-is more general than that required. For this we generate
-\begin{verbatim}
- f@Int = /\b -> g Int b
- f* = f@Int
-\end{verbatim}
-
-Here @f@@Int@ is a SpecId, the specialised version of @f@. It inherits
-f's export status etc. @f*@ is a SpecPragmaId, as before, which just serves
-to prevent @f@@Int@ from being discarded prematurely. After specialisation,
-if @f@@Int@ is going to be used at all it will be used explicitly, so the simplifier can
-discard the f* binding.
-
-Actually, there is really only point in giving a SPECIALISE pragma on exported things,
-and the simplifer won't discard SpecIds for exporte things anyway, so maybe this is
-a bit of overkill.
+We used to have a form
+ {-# SPECIALISE f :: <type> = g #-}
+which promised that g implemented f at <type>, but we do that with
+a RULE now:
+ {-# SPECIALISE (f::<type) = g #-}
\begin{code}
-tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (valSpecSigCtxt name spec_ty) $
+tcSpecSigs :: [RenamedSig] -> TcM (TcMonoBinds, LIE)
+tcSpecSigs (SpecSig name poly_ty src_loc : sigs)
+ = -- SPECIALISE f :: forall b. theta => tau = g
+ tcAddSrcLoc src_loc $
+ 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 ->
- let
- (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
- origin = ValSpecOrigin name
- in
-
- -- Check that the SPECIALIZE pragma had an empty context
- checkTc (null sig_theta)
- (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_`
+ tcHsSigType (FunSigCtxt name) poly_ty `thenTc` \ sig_ty ->
- -- Get and instantiate the type of the id mentioned
- tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id ->
- tcInstSigType [] (idType main_id) `thenNF_Tc` \ main_ty ->
- let
- (main_tyvars, main_rho) = splitForAllTys main_ty
- (main_theta,main_tau) = splitRhoTy main_rho
- main_arg_tys = mkTyVarTys main_tyvars
- in
+ -- 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) ->
- -- 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
- zonkTcTypes 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) ->
-
- 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)
+ -- Squeeze out any Methods (see comments with tcSimplifyToDicts)
+ tcSimplifyToDicts spec_lie `thenTc` \ (spec_dicts, spec_binds) ->
- Just spec_name -> -- Use spec_name as the specialisation value ...
+ -- 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 ->
- -- Type check a simple occurrence of the specialised Id
- tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) ->
+ -- Do the rest and combine
+ tcSpecSigs sigs `thenTc` \ (binds_rest, lie_rest) ->
+ returnTc (binds_rest `andMonoBinds` VarMonoBind spec_id (mkHsLet spec_binds spec_expr),
+ lie_rest `plusLIE` mkLIE spec_dicts)
- -- 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_`
-
- -- Make a local SpecId to bind to applied spec_id
- newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id ->
-
- 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, addSpecInfo spec_info), spec_binds, spec_lie)
--}
+tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs
+tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE)
\end{code}
-----------------------------------------------
valSpecSigCtxt v ty
= sep [ptext SLIT("In a SPECIALIZE pragma for a value:"),
- nest 4 (ppr v <+> ptext SLIT(" ::") <+> ppr ty)]
-
------------------------------------------------
-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)
- ])
+ nest 4 (ppr v <+> dcolon <+> ppr ty)]
-----------------------------------------------
-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)
- ])
+sigContextsErr = ptext SLIT("Mismatched contexts")
------------------------------------------------
-sigCtxt id
- = sep [ptext SLIT("When checking the type signature for"), quotes (ppr id)]
-
-sigThetaCtxt dicts_sig
- = mapNF_Tc zonkInst (bagToList dicts_sig) `thenNF_Tc` \ dicts' ->
- returnNF_Tc (ptext SLIT("Available context:") <+> pprInsts dicts')
-
-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)"))
-----------------------------------------------
-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)
+
+-----------------------------------------------
+restrictedBindCtxtErr binder_names
+ = hang (ptext SLIT("Illegal overloaded type signature(s)"))
+ 4 (vcat [ptext SLIT("in a binding group for") <+> pprBinders binder_names,
+ ptext SLIT("that falls under the monomorphism restriction")])
+
+genCtxt binder_names
+ = ptext SLIT("When generalising the type(s) for") <+> pprBinders binder_names
+
+-- Used in error messages
+pprBinders bndrs = pprWithCommas ppr bndrs
\end{code}
projects / ghc-hetmet.git / blobdiff