\section[TcBinds]{TcBinds}
\begin{code}
-module TcBinds ( tcBindsAndThen, tcTopBinds,
- tcSpecSigs, tcBindWithSigs ) where
+module TcBinds ( tcBindsAndThen, tcTopBinds, tcMonoBinds, tcSpecSigs ) where
#include "HsVersions.h"
-import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun )
-import {-# SOURCE #-} TcExpr ( tcExpr )
+import {-# SOURCE #-} TcMatches ( tcGRHSsPat, tcMatchesFun )
+import {-# SOURCE #-} TcExpr ( tcCheckSigma, tcCheckRho )
-import CmdLineOpts ( opt_NoMonomorphismRestriction )
+import CmdLineOpts ( DynFlag(Opt_NoMonomorphismRestriction) )
import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..),
- Match(..), HsMatchContext(..),
- collectMonoBinders, andMonoBinds
+ Match(..), mkMonoBind,
+ collectMonoBinders, andMonoBinds,
+ collectSigTysFromMonoBinds
)
import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds )
-import TcHsSyn ( TcMonoBinds, TcId, zonkId, mkHsLet )
-
-import TcMonad
-import Inst ( LIE, emptyLIE, mkLIE, plusLIE, InstOrigin(..),
- newDicts, instToId
- )
-import TcEnv ( tcExtendLocalValEnv,
- newSpecPragmaId, newLocalId
- )
-import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyCheck, tcSimplifyRestricted, tcSimplifyToDicts )
-import TcMonoType ( tcHsSigType, checkSigTyVars,
- TcSigInfo(..), tcTySig, maybeSig, sigCtxt
+import TcHsSyn ( TcHsBinds, TcMonoBinds, TcId, zonkId, mkHsLet )
+
+import TcRnMonad
+import Inst ( InstOrigin(..), newDicts, newIPDict, instToId )
+import TcEnv ( tcExtendLocalValEnv, tcExtendLocalValEnv2, newLocalName )
+import TcUnify ( Expected(..), newHole, unifyTauTyLists, checkSigTyVarsWrt, sigCtxt )
+import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyRestricted,
+ tcSimplifyToDicts, tcSimplifyIPs )
+import TcMonoType ( tcHsSigType, UserTypeCtxt(..), TcSigInfo(..),
+ tcTySig, maybeSig, tcSigPolyId, tcSigMonoId, tcAddScopedTyVars
)
-import TcPat ( tcPat )
+import TcPat ( tcPat, tcSubPat, tcMonoPatBndr )
import TcSimplify ( bindInstsOfLocalFuns )
-import TcType ( newTyVarTy, newTyVar,
- zonkTcTyVarToTyVar
+import TcMType ( newTyVar, newTyVarTy, zonkTcTyVarToTyVar )
+import TcType ( TcTyVar, mkTyVarTy, mkForAllTys, mkFunTys, tyVarsOfType,
+ mkPredTy, mkForAllTy, isUnLiftedType,
+ unliftedTypeKind, liftedTypeKind, openTypeKind, eqKind
)
-import TcUnify ( unifyTauTy, unifyTauTyLists )
import CoreFVs ( idFreeTyVars )
-import Id ( mkLocalId, setInlinePragma )
+import Id ( mkLocalId, mkSpecPragmaId, setInlinePragma )
import Var ( idType, idName )
-import IdInfo ( InlinePragInfo(..) )
-import Name ( Name, getOccName, getSrcLoc )
+import Name ( Name, getSrcLoc )
import NameSet
-import Type ( mkTyVarTy, tyVarsOfTypes,
- mkForAllTys, mkFunTys, tyVarsOfType,
- mkPredTy, mkForAllTy, isUnLiftedType,
- unliftedTypeKind, liftedTypeKind, openTypeKind
- )
import Var ( tyVarKind )
import VarSet
import Bag
-import Util ( isIn )
-import ListSetOps ( minusList )
-import Maybes ( maybeToBool )
-import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isNotTopLevel )
+import Util ( isIn, equalLength )
+import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isRec,
+ isNotTopLevel, isAlwaysActive )
import FiniteMap ( listToFM, lookupFM )
import Outputable
\end{code}
dictionaries, which we resolve at the module level.
\begin{code}
-tcTopBinds :: RenamedHsBinds -> TcM ((TcMonoBinds, TcEnv), LIE)
+tcTopBinds :: RenamedHsBinds -> TcM (TcMonoBinds, TcLclEnv)
+ -- Note: returning the TcLclEnv is more than we really
+ -- want. The bit we care about is the local bindings
+ -- and the free type variables thereof
tcTopBinds binds
= tc_binds_and_then TopLevel glue binds $
- tcGetEnv `thenNF_Tc` \ env ->
- returnTc ((EmptyMonoBinds, env), emptyLIE)
+ getLclEnv `thenM` \ env ->
+ returnM (EmptyMonoBinds, env)
where
- glue is_rec binds1 (binds2, thing) = (binds1 `AndMonoBinds` binds2, thing)
+ -- The top level bindings are flattened into a giant
+ -- implicitly-mutually-recursive MonoBinds
+ glue binds1 (binds2, env) = (flatten binds1 `AndMonoBinds` binds2, env)
+ flatten EmptyBinds = EmptyMonoBinds
+ flatten (b1 `ThenBinds` b2) = flatten b1 `AndMonoBinds` flatten b2
+ flatten (MonoBind b _ _) = b
+ -- Can't have a IPBinds at top level
tcBindsAndThen
- :: (RecFlag -> TcMonoBinds -> thing -> thing) -- Combinator
+ :: (TcHsBinds -> thing -> thing) -- Combinator
-> RenamedHsBinds
- -> TcM (thing, LIE)
- -> TcM (thing, LIE)
+ -> TcM thing
+ -> TcM thing
tcBindsAndThen = tc_binds_and_then NotTopLevel
tc_binds_and_then top_lvl combiner b2 $
do_next
+tc_binds_and_then top_lvl combiner (IPBinds binds is_with) do_next
+ = getLIE do_next `thenM` \ (result, expr_lie) ->
+ mapAndUnzipM tc_ip_bind binds `thenM` \ (avail_ips, binds') ->
+
+ -- If the binding binds ?x = E, we must now
+ -- discharge any ?x constraints in expr_lie
+ tcSimplifyIPs avail_ips expr_lie `thenM` \ dict_binds ->
+
+ returnM (combiner (IPBinds binds' is_with) $
+ combiner (mkMonoBind Recursive dict_binds) result)
+ where
+ -- I wonder if we should do these one at at time
+ -- Consider ?x = 4
+ -- ?y = ?x + 1
+ tc_ip_bind (ip, expr)
+ = newTyVarTy openTypeKind `thenM` \ ty ->
+ getSrcLocM `thenM` \ loc ->
+ newIPDict (IPBind ip) ip ty `thenM` \ (ip', ip_inst) ->
+ tcCheckRho expr ty `thenM` \ expr' ->
+ returnM (ip_inst, (ip', expr'))
+
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 ->
+ = -- BRING ANY SCOPED TYPE VARIABLES INTO SCOPE
+ -- Notice that they scope over
+ -- a) the type signatures in the binding group
+ -- b) the bindings in the group
+ -- c) the scope of the binding group (the "in" part)
+ tcAddScopedTyVars (collectSigTysFromMonoBinds bind) $
+
+ tcBindWithSigs top_lvl bind sigs is_rec `thenM` \ (poly_binds, 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 [(idName poly_id, poly_id) | poly_id <- poly_ids] $
-
- -- Build bindings and IdInfos corresponding to user pragmas
- tcSpecSigs sigs `thenTc` \ (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 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 $
+ case top_lvl of
+ TopLevel -- 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
+ --
+ -- Subtle (and ugly) point: furthermore at top level we
+ -- return the TcLclEnv, which contains the LIE var; we
+ -- don't want to return the wrong one!
+ -> tc_body poly_ids `thenM` \ (prag_binds, thing) ->
+ returnM (combiner (mkMonoBind Recursive (poly_binds `andMonoBinds` prag_binds))
+ thing)
+
+ NotTopLevel -- For nested bindings we must do teh bindInstsOfLocalFuns thing
+ -> getLIE (tc_body poly_ids) `thenM` \ ((prag_binds, thing), lie) ->
+
+ -- Create specialisations of functions bound here
+ bindInstsOfLocalFuns lie poly_ids `thenM` \ lie_binds ->
+
+ -- We want to keep non-recursive things non-recursive
+ -- so that we desugar unlifted bindings correctly
+ if isRec is_rec then
+ returnM (
+ combiner (mkMonoBind Recursive (
+ poly_binds `andMonoBinds`
+ lie_binds `andMonoBinds`
+ prag_binds)) thing
+ )
+ else
+ returnM (
+ combiner (mkMonoBind NonRecursive poly_binds) $
+ combiner (mkMonoBind NonRecursive prag_binds) $
+ combiner (mkMonoBind 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
- )
+ thing)
+ where
+ tc_body poly_ids -- Type check the pragmas and "thing inside"
+ = -- Extend the environment to bind the new polymorphic Ids
+ tcExtendLocalValEnv poly_ids $
+
+ -- Build bindings and IdInfos corresponding to user pragmas
+ tcSpecSigs sigs `thenM` \ prag_binds ->
- (NotTopLevel, Recursive)
- -> bindInstsOfLocalFuns
- (thing_lie `plusLIE` poly_lie `plusLIE` prag_lie)
- poly_ids `thenTc` \ (final_lie, lie_binds) ->
+ -- Now do whatever happens next, in the augmented envt
+ do_next `thenM` \ thing ->
- returnTc (
- combiner Recursive (
- poly_binds `andMonoBinds`
- lie_binds `andMonoBinds`
- prag_binds) thing,
- final_lie
- )
+ returnM (prag_binds, thing)
\end{code}
tcBindWithSigs
:: TopLevelFlag
-> RenamedMonoBinds
- -> [TcSigInfo]
-> [RenamedSig] -- Used solely to get INLINE, NOINLINE sigs
-> RecFlag
- -> TcM (TcMonoBinds, LIE, [TcId])
+ -> TcM (TcMonoBinds, [TcId])
+
+tcBindWithSigs top_lvl mbind sigs is_rec
+ = -- TYPECHECK THE SIGNATURES
+ recoverM (returnM []) (
+ mappM tcTySig [sig | sig@(Sig name _ _) <- sigs]
+ ) `thenM` \ tc_ty_sigs ->
-tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec
- = recoverTc (
+ -- SET UP THE MAIN RECOVERY; take advantage of any type sigs
+ recoverM (
-- If typechecking the binds fails, then return with each
-- signature-less binder given type (forall a.a), to minimise subsequent
-- error messages
- newTyVar liftedTypeKind `thenNF_Tc` \ alpha_tv ->
+ newTyVar liftedTypeKind `thenM` \ alpha_tv ->
let
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 -> mkLocalId name forall_a_a -- No signature
+ Just sig -> tcSigPolyId sig -- Signature
+ Nothing -> mkLocalId name forall_a_a -- No signature
in
- returnTc (EmptyMonoBinds, emptyLIE, poly_ids)
+ traceTc (text "tcBindsWithSigs: error recovery" <+> ppr binder_names) `thenM_`
+ returnM (EmptyMonoBinds, poly_ids)
) $
-- TYPECHECK THE BINDINGS
- tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) ->
+ getLIE (tcMonoBinds mbind tc_ty_sigs is_rec) `thenM` \ ((mbind', bndr_names_w_ids), lie_req) ->
let
- tau_tvs = varSetElems (foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids)
+ (binder_names, mono_ids) = unzip (bagToList bndr_names_w_ids)
+ tau_tvs = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids
in
-- GENERALISE
- generalise binder_names mbind tau_tvs lie_req tc_ty_sigs
- `thenTc` \ (tc_tyvars_to_gen, lie_free, dict_binds, dict_ids) ->
+ -- (it seems a bit crude to have to do getLIE twice,
+ -- but I can't see a better way just now)
+ addSrcLoc (minimum (map getSrcLoc binder_names)) $
+ addErrCtxt (genCtxt binder_names) $
+ getLIE (generalise binder_names mbind tau_tvs lie_req tc_ty_sigs)
+ `thenM` \ ((tc_tyvars_to_gen, dict_binds, dict_ids), lie_free) ->
-- ZONK THE GENERALISED TYPE VARIABLES TO REAL TyVars
-- 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 ->
+ mappM zonkTcTyVarToTyVar tc_tyvars_to_gen `thenM` \ 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_`
+ mappM zonkId dict_ids `thenM` \ zonked_dict_ids ->
+ mappM zonkId mono_ids `thenM` \ zonked_mono_ids ->
-- BUILD THE POLYMORPHIC RESULT IDs
let
exports = zipWith mk_export binder_names zonked_mono_ids
+ poly_ids = [poly_id | (_, poly_id, _) <- exports]
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
+ inlines = mkNameSet [name | InlineSig True name _ loc <- sigs]
+ -- Any INLINE sig (regardless of phase control)
+ -- makes the RHS look small
+ inline_phases = listToFM [(name, phase) | InlineSig _ name phase _ <- sigs,
+ not (isAlwaysActive phase)]
+ -- Set the IdInfo field to control the inline phase
+ -- AlwaysActive is the default, so don't bother with them
mk_export binder_name zonked_mono_id
= (tyvars,
- attachNoInlinePrag no_inlines poly_id,
+ attachInlinePhase inline_phases poly_id,
zonked_mono_id)
where
(tyvars, poly_id) =
case maybeSig tc_ty_sigs binder_name of
- Just (TySigInfo _ sig_poly_id sig_tyvars _ _ _ _ _) ->
+ 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
+ $ 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
in
traceTc (text "binding:" <+> ppr ((zonked_dict_ids, dict_binds),
- exports, [idType poly_id | (_, poly_id, _) <- exports])) `thenTc_`
+ exports, map idType poly_ids)) `thenM_`
- -- BUILD RESULTS
- returnTc (
+ -- Check for an unlifted, non-overloaded group
+ -- In that case we must make extra checks
+ if any (isUnLiftedType . idType) zonked_mono_ids && null zonked_dict_ids
+ then -- Some bindings are unlifted
+ checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind `thenM_`
+
+ extendLIEs lie_req `thenM_`
+ returnM (
+ AbsBinds [] [] exports inlines mbind',
+ -- Do not generate even any x=y bindings
+ poly_ids
+ )
+
+ else -- The normal case
+ extendLIEs lie_free `thenM_`
+ returnM (
AbsBinds real_tyvars_to_gen
zonked_dict_ids
exports
inlines
(dict_binds `andMonoBinds` mbind'),
- lie_free,
- [poly_id | (_, poly_id, _) <- exports]
+ poly_ids
)
-attachNoInlinePrag no_inlines bndr
- = case lookupFM no_inlines (idName bndr) of
+attachInlinePhase inline_phases bndr
+ = case lookupFM inline_phases (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 ((== unliftedTypeKind) . tyVarKind) real_tyvars_to_gen) )
+-- Check that non-overloaded unlifted bindings are
+-- a) non-recursive,
+-- b) not top level,
+-- c) non-polymorphic
+-- d) not a multiple-binding group (more or less implied by (a))
+
+checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind
+ = 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
-- 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 ()
+ checkTc (isNotTopLevel top_lvl)
+ (unliftedBindErr "Top-level" mbind) `thenM_`
+ checkTc (isNonRec is_rec)
+ (unliftedBindErr "Recursive" mbind) `thenM_`
+ checkTc (single_bind mbind)
+ (unliftedBindErr "Multiple" mbind) `thenM_`
+ checkTc (null real_tyvars_to_gen)
+ (unliftedBindErr "Polymorphic" mbind)
where
- pat_binders :: [Name]
- pat_binders = collectMonoBinders (justPatBindings mbind EmptyMonoBinds)
-
- justPatBindings bind@(PatMonoBind _ _ _) binds = bind `andMonoBinds` binds
- justPatBindings (AndMonoBinds b1 b2) binds =
- justPatBindings b1 (justPatBindings b2 binds)
- justPatBindings other_bind binds = binds
+ single_bind (PatMonoBind _ _ _) = True
+ single_bind (FunMonoBind _ _ _ _) = True
+ single_bind other = False
\end{code}
%************************************************************************
\begin{code}
-generalise_help doc tau_tvs lie_req sigs
+generalise binder_names mbind tau_tvs lie_req sigs =
------------------------
- | null sigs
- = -- INFERENCE CASE: Unrestricted group, no type signatures
- tcSimplifyInfer doc
- tau_tvs lie_req
+ -- check for -fno-monomorphism-restriction
+ doptM Opt_NoMonomorphismRestriction `thenM` \ no_MR ->
+ let is_unrestricted | no_MR = True
+ | otherwise = isUnRestrictedGroup tysig_names mbind
+ in
------------------------
- | otherwise
- = -- CHECKING CASE: Unrestricted group, there are type signatures
- -- Check signature contexts are empty
- checkSigsCtxts sigs `thenTc` \ (sig_avails, sig_dicts) ->
+ if not is_unrestricted then -- RESTRICTED CASE
+ -- Check signature contexts are empty
+ checkTc (all is_mono_sig sigs)
+ (restrictedBindCtxtErr binder_names) `thenM_`
+ -- Now simplify with exactly that set of tyvars
+ -- We have to squash those Methods
+ tcSimplifyRestricted doc tau_tvs lie_req `thenM` \ (qtvs, binds) ->
+
+ -- Check that signature type variables are OK
+ checkSigsTyVars qtvs sigs `thenM` \ final_qtvs ->
+
+ returnM (final_qtvs, binds, [])
+
+ else if null sigs then -- UNRESTRICTED CASE, NO TYPE SIGS
+ tcSimplifyInfer doc tau_tvs lie_req
+
+ else -- UNRESTRICTED CASE, WITH TYPE SIGS
+ -- CHECKING CASE: Unrestricted group, there are type signatures
+ -- Check signature contexts are identical
+ checkSigsCtxts sigs `thenM` \ (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) ->
+ tcSimplifyInferCheck doc tau_tvs sig_avails lie_req `thenM` \ (forall_tvs, dict_binds) ->
-- Check that signature type variables are OK
- checkSigsTyVars sigs `thenTc_`
-
- returnTc (forall_tvs, lie_free, dict_binds, sig_dicts)
-
-generalise binder_names mbind tau_tvs lie_req sigs
- | is_unrestricted -- UNRESTRICTED CASE
- = generalise_help doc tau_tvs lie_req sigs
-
- | otherwise -- RESTRICTED CASE
- = -- Do a simplification to decide what type variables
- -- are constrained. We can't just take the free vars
- -- of lie_req because that'll have methods that may
- -- incidentally mention entirely unconstrained variables
- -- e.g. a call to f :: Eq a => a -> b -> b
- -- Here, b is unconstrained. A good example would be
- -- foo = f (3::Int)
- -- We want to infer the polymorphic type
- -- foo :: forall b. b -> b
- generalise_help doc tau_tvs lie_req sigs `thenTc` \ (forall_tvs, lie_free, dict_binds, dict_ids) ->
-
- -- Check signature contexts are empty
- checkTc (null sigs || null dict_ids)
- (restrictedBindCtxtErr binder_names) `thenTc_`
-
- -- Identify constrained tyvars
- let
- constrained_tvs = varSetElems (tyVarsOfTypes (map idType dict_ids))
- -- The dict_ids are fully zonked
- final_forall_tvs = forall_tvs `minusList` constrained_tvs
- in
-
- -- Now simplify with exactly that set of tyvars
- -- We have to squash those Methods
- tcSimplifyRestricted doc final_forall_tvs [] lie_req `thenTc` \ (lie_free, binds) ->
+ checkSigsTyVars forall_tvs sigs `thenM` \ final_qtvs ->
- returnTc (final_forall_tvs, lie_free, binds, [])
+ returnM (final_qtvs, dict_binds, sig_dicts)
where
- is_unrestricted | opt_NoMonomorphismRestriction = True
- | otherwise = isUnRestrictedGroup tysig_names mbind
-
- tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- sigs]
+ tysig_names = map (idName . tcSigPolyId) sigs
+ is_mono_sig (TySigInfo _ _ theta _ _ _ _) = null theta
doc = ptext SLIT("type signature(s) for") <+> pprBinders binder_names
-- 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 _ _ _ _ : other_sigs)
- = mapTc_ check_one other_sigs `thenTc_`
+checkSigsCtxts sigs@(TySigInfo id1 sig_tvs theta1 _ _ _ src_loc : other_sigs)
+ = addSrcLoc src_loc $
+ mappM_ check_one other_sigs `thenM_`
if null theta1 then
- returnTc ([], []) -- Non-overloaded type signatures
+ returnM ([], []) -- Non-overloaded type signatures
else
- newDicts SignatureOrigin theta1 `thenNF_Tc` \ sig_dicts ->
+ newDicts SignatureOrigin theta1 `thenM` \ 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)
+ returnM (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]
+ sig_meths = concat [insts | TySigInfo _ _ _ _ _ insts _ <- sigs]
- check_one sig@(TySigInfo _ id _ theta _ _ _ src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (sigContextsCtxt id1 id) $
- checkTc (length theta == n_sig1_theta) sigContextsErr `thenTc_`
+ check_one sig@(TySigInfo id _ theta _ _ _ _)
+ = addErrCtxt (sigContextsCtxt id1 id) $
+ checkTc (equalLength theta theta1) sigContextsErr `thenM_`
unifyTauTyLists sig1_dict_tys (map mkPredTy theta)
-checkSigsTyVars sigs = mapTc_ check_one sigs
+checkSigsTyVars :: [TcTyVar] -> [TcSigInfo] -> TcM [TcTyVar]
+checkSigsTyVars qtvs sigs
+ = mappM check_one sigs `thenM` \ sig_tvs_s ->
+ let
+ -- Sigh. Make sure that all the tyvars in the type sigs
+ -- appear in the returned ty var list, which is what we are
+ -- going to generalise over. Reason: we occasionally get
+ -- silly types like
+ -- type T a = () -> ()
+ -- f :: T a
+ -- f () = ()
+ -- Here, 'a' won't appear in qtvs, so we have to add it
+
+ sig_tvs = foldr (unionVarSet . mkVarSet) emptyVarSet sig_tvs_s
+ all_tvs = mkVarSet qtvs `unionVarSet` sig_tvs
+ in
+ returnM (varSetElems all_tvs)
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)
+ check_one (TySigInfo id sig_tyvars sig_theta sig_tau _ _ src_loc)
+ = addSrcLoc src_loc $
+ addErrCtxt (ptext SLIT("When checking the type signature for")
+ <+> quotes (ppr id)) $
+ addErrCtxtM (sigCtxt id sig_tyvars sig_theta sig_tau) $
+ checkSigTyVarsWrt (idFreeTyVars id) sig_tyvars
\end{code}
@getTyVarsToGen@ decides what type variables to generalise over.
isUnRestrictedGroup sigs (PatMonoBind other _ _) = False
isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs
-isUnRestrictedGroup sigs (FunMonoBind v _ matches _) = any isUnRestrictedMatch matches ||
+isUnRestrictedGroup sigs (FunMonoBind v _ matches _) = isUnRestrictedMatch matches ||
v `is_elem` sigs
isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 &&
isUnRestrictedGroup sigs mb2
isUnRestrictedGroup sigs EmptyMonoBinds = True
-isUnRestrictedMatch (Match _ [] Nothing _) = False -- No args, no signature
-isUnRestrictedMatch other = True -- Some args or a signature
+isUnRestrictedMatch (Match [] _ _ : _) = False -- No args => like a pattern binding
+isUnRestrictedMatch other = True -- Some args => a function binding
\end{code}
\begin{code}
tcMonoBinds :: RenamedMonoBinds
- -> [TcSigInfo]
- -> RecFlag
+ -> [TcSigInfo] -> RecFlag
-> TcM (TcMonoBinds,
- LIE, -- LIE required
- [Name], -- Bound names
- [TcId]) -- Corresponding monomorphic bound things
+ Bag (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
- 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
-
- complete_it extra_val_env `thenTc` \ (mbinds', lie_req_rhss) ->
-
- returnTc (mbinds', lie_req_pat `plusLIE` lie_req_rhss, names, mono_ids)
+ -- Three stages:
+ -- 1. Check the patterns, building up an environment binding
+ -- the variables in this group (in the recursive case)
+ -- 2. Extend the environment
+ -- 3. Check the RHSs
+ = tc_mb_pats mbinds `thenM` \ (complete_it, xve) ->
+ tcExtendLocalValEnv2 (bagToList xve) complete_it
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 EmptyMonoBinds
+ = returnM (returnM (EmptyMonoBinds, emptyBag), emptyBag)
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) ->
+ = tc_mb_pats mb1 `thenM` \ (complete_it1, xve1) ->
+ tc_mb_pats mb2 `thenM` \ (complete_it2, xve2) ->
let
- complete_it xve = complete_it1 xve `thenTc` \ (mb1', lie1) ->
- complete_it2 xve `thenTc` \ (mb2', lie2) ->
- returnTc (AndMonoBinds mb1' mb2', lie1 `plusLIE` lie2)
+ complete_it = complete_it1 `thenM` \ (mb1', bs1) ->
+ complete_it2 `thenM` \ (mb2', bs2) ->
+ returnM (AndMonoBinds mb1' mb2', bs1 `unionBags` bs2)
in
- returnTc (complete_it,
- lie_req1 `plusLIE` lie_req2,
- tvs1 `unionBags` tvs2,
- ids1 `unionBags` ids2,
- lie_avail1 `plusLIE` lie_avail2)
+ returnM (complete_it, xve1 `unionBags` xve2)
tc_mb_pats (FunMonoBind name inf matches locn)
- = newTyVarTy kind `thenNF_Tc` \ bndr_ty ->
- tc_pat_bndr name bndr_ty `thenTc` \ bndr_id ->
+ -- Three cases:
+ -- a) Type sig supplied
+ -- b) No type sig and recursive
+ -- c) No type sig and non-recursive
+
+ | Just sig <- maybeSig tc_ty_sigs name
+ = let -- (a) There is a type signature
+ -- Use it for the environment extension, and check
+ -- the RHS has the appropriate type (with outer for-alls stripped off)
+ mono_id = tcSigMonoId sig
+ mono_ty = idType mono_id
+ complete_it = addSrcLoc locn $
+ tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' ->
+ returnM (FunMonoBind mono_id inf matches' locn,
+ unitBag (name, mono_id))
+ in
+ returnM (complete_it, if isRec is_rec then unitBag (name,tcSigPolyId sig)
+ else emptyBag)
+
+ | isRec is_rec
+ = -- (b) No type signature, and recursive
+ -- So we must use an ordinary H-M type variable
+ -- which means the variable gets an inferred tau-type
+ newLocalName name `thenM` \ mono_name ->
+ newTyVarTy openTypeKind `thenM` \ mono_ty ->
let
- complete_it xve = tcAddSrcLoc locn $
- tcMatchesFun xve name bndr_ty matches `thenTc` \ (matches', lie) ->
- returnTc (FunMonoBind bndr_id inf matches' locn, lie)
+ mono_id = mkLocalId mono_name mono_ty
+ complete_it = addSrcLoc locn $
+ tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' ->
+ returnM (FunMonoBind mono_id inf matches' locn,
+ unitBag (name, mono_id))
in
- returnTc (complete_it, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE)
-
+ returnM (complete_it, unitBag (name, mono_id))
+
+ | otherwise -- (c) No type signature, and non-recursive
+ = let -- So we can use a 'hole' type to infer a higher-rank type
+ complete_it
+ = addSrcLoc locn $
+ newHole `thenM` \ hole ->
+ tcMatchesFun name matches (Infer hole) `thenM` \ matches' ->
+ readMutVar hole `thenM` \ fun_ty ->
+ newLocalName name `thenM` \ mono_name ->
+ let
+ mono_id = mkLocalId mono_name fun_ty
+ in
+ returnM (FunMonoBind mono_id inf matches' locn,
+ unitBag (name, mono_id))
+ in
+ returnM (complete_it, emptyBag)
+
tc_mb_pats bind@(PatMonoBind pat grhss locn)
- = tcAddSrcLoc locn $
- newTyVarTy kind `thenNF_Tc` \ pat_ty ->
+ = addSrcLoc locn $
-- Now typecheck the pattern
- -- We don't support binding fresh type variables in the
- -- pattern of a pattern binding. For example, this is illegal:
+ -- We do now support binding fresh (not-already-in-scope) scoped
+ -- type variables in the pattern of a pattern binding.
+ -- For example, this is now legal:
-- (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) ->
+ -- The type variables are brought into scope in tc_binds_and_then,
+ -- so we don't have to do anything here.
+
+ newHole `thenM` \ hole ->
+ tcPat tc_pat_bndr pat (Infer hole) `thenM` \ (pat', tvs, ids, lie_avail) ->
+ readMutVar hole `thenM` \ pat_ty ->
+
+ -- Don't know how to deal with pattern-bound existentials yet
+ checkTc (isEmptyBag tvs && null lie_avail)
+ (existentialExplode bind) `thenM_`
+
let
- complete_it xve = tcAddSrcLoc locn $
- tcAddErrCtxt (patMonoBindsCtxt bind) $
- tcExtendLocalValEnv xve $
- tcGRHSs grhss pat_ty PatBindRhs `thenTc` \ (grhss', lie) ->
- returnTc (PatMonoBind pat' grhss' locn, lie)
+ complete_it = addSrcLoc locn $
+ addErrCtxt (patMonoBindsCtxt bind) $
+ tcGRHSsPat grhss (Check pat_ty) `thenM` \ grhss' ->
+ returnM (PatMonoBind pat' grhss' locn, ids)
in
- returnTc (complete_it, lie_req, tvs, ids, lie_avail)
+ returnM (complete_it, if isRec is_rec then ids else emptyBag)
- -- 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
+ -- tc_pat_bndr is used when dealing with a LHS binder in a pattern.
+ -- If there was a type sig for that Id, we want to make it much
+ -- as if that type signature had been on the binder as a SigPatIn.
+ -- 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 matches 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 -> newLocalName name `thenM` \ bndr_name ->
+ tcMonoPatBndr bndr_name pat_ty
+
+ Just sig -> addSrcLoc (getSrcLoc name) $
+ tcSubPat (idType mono_id) pat_ty `thenM` \ co_fn ->
+ returnM (co_fn, mono_id)
+ where
+ mono_id = tcSigMonoId sig
\end{code}
{-# SPECIALISE (f::<type) = g #-}
\begin{code}
-tcSpecSigs :: [RenamedSig] -> TcM (TcMonoBinds, LIE)
+tcSpecSigs :: [RenamedSig] -> TcM TcMonoBinds
tcSpecSigs (SpecSig name poly_ty src_loc : sigs)
= -- SPECIALISE f :: forall b. theta => tau = g
- tcAddSrcLoc src_loc $
- tcAddErrCtxt (valSpecSigCtxt name poly_ty) $
+ addSrcLoc src_loc $
+ addErrCtxt (valSpecSigCtxt name poly_ty) $
-- Get and instantiate its alleged specialised type
- tcHsSigType poly_ty `thenTc` \ sig_ty ->
+ tcHsSigType (FunSigCtxt name) poly_ty `thenM` \ sig_ty ->
-- 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) ->
+ getLIE (tcCheckSigma (HsVar name) sig_ty) `thenM` \ (spec_expr, spec_lie) ->
-- Squeeze out any Methods (see comments with tcSimplifyToDicts)
- tcSimplifyToDicts spec_lie `thenTc` \ (spec_dicts, spec_binds) ->
+ tcSimplifyToDicts spec_lie `thenM` \ spec_binds ->
-- 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 ->
+ newLocalName name `thenM` \ spec_name ->
+ let
+ spec_bind = VarMonoBind (mkSpecPragmaId spec_name sig_ty)
+ (mkHsLet spec_binds spec_expr)
+ in
-- 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)
+ tcSpecSigs sigs `thenM` \ binds_rest ->
+ returnM (binds_rest `andMonoBinds` spec_bind)
tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs
-tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE)
+tcSpecSigs [] = returnM EmptyMonoBinds
\end{code}
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)"))
+ = vcat [ptext SLIT("When matching the contexts of the signatures for"),
+ nest 2 (vcat [ppr s1 <+> dcolon <+> ppr (idType s1),
+ ppr s2 <+> dcolon <+> ppr (idType s2)]),
+ ptext SLIT("The signature contexts in a mutually recursive group should all be identical")]
-----------------------------------------------
unliftedBindErr flavour mbind
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
+-- Use quotes for a single one; they look a bit "busy" for several
+pprBinders [bndr] = quotes (ppr bndr)
+pprBinders bndrs = pprWithCommas ppr bndrs
\end{code}
projects / ghc-hetmet.git / blobdiff