\section[TcBinds]{TcBinds}
\begin{code}
-module TcBinds ( tcBindsAndThen, tcTopBindsAndThen,
- 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 HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), InPat(..), StmtCtxt(..),
- collectMonoBinders, andMonoBindList, andMonoBinds
+import CmdLineOpts ( DynFlag(Opt_NoMonomorphismRestriction) )
+import HsSyn ( HsExpr(..), HsBind(..), LHsBind, LHsBinds, Sig(..),
+ LSig, Match(..), HsBindGroup(..), IPBind(..),
+ collectSigTysFromHsBinds, collectHsBindBinders,
)
-import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds )
-import TcHsSyn ( TcHsBinds, TcMonoBinds, TcId, zonkId, mkHsLet )
-
-import TcMonad
-import Inst ( Inst, LIE, emptyLIE, mkLIE, plusLIE, plusLIEs, InstOrigin(..),
- newDicts, tyVarsOfInst, instToId,
- getAllFunDepsOfLIE, getIPsOfLIE, zonkFunDeps
- )
-import TcEnv ( tcExtendLocalValEnv,
- newSpecPragmaId, newLocalId,
- tcLookupTyCon,
- tcGetGlobalTyVars, tcExtendGlobalTyVars
- )
-import TcSimplify ( tcSimplify, tcSimplifyAndCheck, tcSimplifyToDicts )
-import TcImprove ( tcImprove )
-import TcMonoType ( tcHsSigType, checkSigTyVars,
- TcSigInfo(..), tcTySig, maybeSig, sigCtxt
+import TcHsSyn ( 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 TcHsType ( tcHsSigType, UserTypeCtxt(..), TcSigInfo(..),
+ tcTySig, maybeSig, tcAddScopedTyVars
)
-import TcPat ( tcPat )
+import TcPat ( tcPat, tcSubPat, tcMonoPatBndr )
import TcSimplify ( bindInstsOfLocalFuns )
-import TcType ( TcType, TcThetaType,
- TcTyVar,
- newTyVarTy, newTyVar, newTyVarTy_OpenKind, tcInstTcType,
- zonkTcType, zonkTcTypes, zonkTcThetaType, 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 PrelInfo ( main_NAME, ioTyCon_NAME )
-
-import Id ( Id, mkVanillaId, setInlinePragma )
+import CoreFVs ( idFreeTyVars )
+import Id ( mkLocalId, mkSpecPragmaId, setInlinePragma )
import Var ( idType, idName )
-import IdInfo ( setInlinePragInfo, InlinePragInfo(..) )
-import Name ( Name, getName, getOccName, getSrcLoc )
+import Name ( Name, getSrcLoc )
import NameSet
-import Type ( mkTyVarTy, tyVarsOfTypes, mkTyConApp,
- splitSigmaTy, mkForAllTys, mkFunTys, getTyVar,
- mkPredTy, splitRhoTy, mkForAllTy, isUnLiftedType,
- isUnboxedType, unboxedTypeKind, boxedTypeKind
- )
-import PprType ( {- instance Outputable Type -} )
-import FunDeps ( tyVarFunDep, oclose )
-import Var ( TyVar, tyVarKind )
+import Var ( tyVarKind )
import VarSet
+import SrcLoc ( Located(..), srcLocSpan, unLoc, noLoc )
import Bag
-import Util ( isIn )
-import Maybes ( maybeToBool )
-import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNotTopLevel )
+import Util ( isIn, equalLength )
+import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isRec,
+ isNotTopLevel, isAlwaysActive )
import FiniteMap ( listToFM, lookupFM )
-import SrcLoc ( SrcLoc )
import Outputable
\end{code}
dictionaries, which we resolve at the module level.
\begin{code}
-tcTopBindsAndThen, tcBindsAndThen
- :: (RecFlag -> TcMonoBinds -> thing -> thing) -- Combinator
- -> RenamedHsBinds
- -> TcM s (thing, LIE)
- -> TcM s (thing, LIE)
+tcTopBinds :: [HsBindGroup Name] -> TcM (LHsBinds TcId, 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 $
+ getLclEnv `thenM` \ env ->
+ returnM (emptyBag, env)
+ where
+ -- The top level bindings are flattened into a giant
+ -- implicitly-mutually-recursive MonoBinds
+ glue (HsBindGroup binds1 _ _) (binds2, env) = (binds1 `unionBags` binds2, env)
+ -- Can't have a HsIPBinds at top level
-tcTopBindsAndThen = tc_binds_and_then TopLevel
-tcBindsAndThen = tc_binds_and_then NotTopLevel
-tc_binds_and_then top_lvl combiner EmptyBinds do_next
- = do_next
-tc_binds_and_then top_lvl combiner (MonoBind EmptyMonoBinds sigs is_rec) do_next
+tcBindsAndThen
+ :: (HsBindGroup TcId -> thing -> thing) -- Combinator
+ -> [HsBindGroup Name]
+ -> TcM thing
+ -> TcM thing
+
+tcBindsAndThen = tc_binds_and_then NotTopLevel
+
+tc_binds_and_then top_lvl combiner [] do_next
= do_next
+tc_binds_and_then top_lvl combiner (group : groups) do_next
+ = tc_bind_and_then top_lvl combiner group $
+ tc_binds_and_then top_lvl combiner groups do_next
-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_bind_and_then top_lvl combiner (HsIPBinds binds) do_next
+ = getLIE do_next `thenM` \ (result, expr_lie) ->
+ mapAndUnzipM (wrapLocSndM tc_ip_bind) binds `thenM` \ (avail_ips, binds') ->
-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 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] $
+ -- 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 (HsIPBinds binds') $
+ combiner (HsBindGroup dict_binds [] Recursive) result)
+ where
+ -- I wonder if we should do these one at at time
+ -- Consider ?x = 4
+ -- ?y = ?x + 1
+ tc_ip_bind (IPBind ip expr)
+ = newTyVarTy openTypeKind `thenM` \ ty ->
+ newIPDict (IPBindOrigin ip) ip ty `thenM` \ (ip', ip_inst) ->
+ tcCheckRho expr ty `thenM` \ expr' ->
+ returnM (ip_inst, (IPBind ip' expr'))
+
+tc_bind_and_then top_lvl combiner (HsBindGroup binds sigs is_rec) do_next
+ | isEmptyBag binds
+ = do_next
+ | otherwise
+ = -- 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 (collectSigTysFromHsBinds (bagToList binds)) $
+ tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, poly_ids) ->
+
+ 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 (HsBindGroup
+ (poly_binds `unionBags` prag_binds)
+ [] -- no sigs
+ Recursive)
+ thing)
+
+ NotTopLevel -- For nested bindings we must do the
+ -- bindInstsOfLocalFuns thing. We must include
+ -- the LIE from the RHSs too -- polymorphic recursion!
+ -> 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 (HsBindGroup
+ (poly_binds `unionBags`
+ lie_binds `unionBags`
+ prag_binds)
+ [] Recursive) thing
+ )
+ else
+ returnM (
+ combiner (HsBindGroup poly_binds [] NonRecursive) $
+ combiner (HsBindGroup prag_binds [] NonRecursive) $
+ combiner (HsBindGroup lie_binds [] Recursive) $
+ -- NB: the binds returned by tcSimplify and
+ -- bindInstsOfLocalFuns aren't guaranteed in
+ -- dependency order (though we could change
+ -- that); hence the Recursive marker.
+ thing)
+
+{-
+ = -- 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 (collectSigTysFromHsBinds (bagToList binds)) $
+
+ tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, 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 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 (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 (HsBindGroup
+ (poly_binds `unionBags` prag_binds)
+ [] -- no sigs
+ Recursive)
+ 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 (HsBindGroup (
+ poly_binds `unionBags`
+ lie_binds `unionBags`
+ prag_binds)
+ [] Recursive) thing
+ )
+ else
+ returnM (
+ combiner (HsBindGroup poly_binds [] NonRecursive) $
+ combiner (HsBindGroup prag_binds [] NonRecursive) $
+ combiner (HsBindGroup lie_binds [] Recursive) $
-- 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}
+ 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 ->
+
+ -- Now do whatever happens next, in the augmented envt
+ do_next `thenM` \ thing ->
-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]
-
-\begin{pseudocode}
-% tcBindsAndThen
-% :: RenamedHsBinds
-% -> TcM s (thing, LIE, thing_ty))
-% -> TcM s ((TcHsBinds, thing), LIE, 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}
+ returnM (prag_binds, thing)
+\end{code}
%************************************************************************
as the Name in the tc_ty_sig
\begin{code}
-tcBindWithSigs
- :: TopLevelFlag
- -> RenamedMonoBinds
- -> [TcSigInfo]
- -> [RenamedSig] -- Used solely to get INLINE, NOINLINE sigs
- -> RecFlag
- -> TcM s (TcMonoBinds, LIE, [TcId])
-
-tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec
- = recoverTc (
+tcBindWithSigs :: TopLevelFlag
+ -> LHsBinds Name
+ -> [LSig Name]
+ -> RecFlag
+ -> TcM (LHsBinds TcId, [TcId])
+
+tcBindWithSigs top_lvl mbind sigs is_rec
+ = -- TYPECHECK THE SIGNATURES
+ recoverM (returnM []) (
+ mappM tcTySig [sig | sig@(L _(Sig name _)) <- sigs]
+ ) `thenM` \ tc_ty_sigs ->
+
+ -- 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 boxedTypeKind `thenNF_Tc` \ alpha_tv ->
+ newTyVar liftedTypeKind `thenM` \ alpha_tv ->
let
forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv)
- binder_names = map fst (bagToList (collectMonoBinders mbind))
+ binder_names = collectHsBindBinders 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 -> mkVanillaId name forall_a_a -- No signature
+ Just sig -> sig_poly_id 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 (emptyBag, poly_ids)
+ ) $
-- TYPECHECK THE BINDINGS
- tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) ->
-
- -- CHECK THAT THE SIGNATURES MATCH
- -- (must do this before getTyVarsToGen)
- checkSigMatch top_lvl binder_names mono_ids tc_ty_sigs `thenTc` \ maybe_sig_theta ->
-
- -- IMPROVE the LIE
- -- Force any unifications dictated by functional dependencies.
- -- Because unification may happen, it's important that this step
- -- come before:
- -- - computing vars over which to quantify
- -- - zonking the generalized type vars
- tcImprove lie_req `thenTc_`
-
- -- 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
- let
- mono_id_tys = map idType mono_ids
- in
- getTyVarsToGen is_unrestricted mono_id_tys lie_req `thenNF_Tc` \ (tyvars_not_to_gen, tyvars_to_gen) ->
-
- -- Finally, zonk the generalised type variables to real TyVars
- -- This commits any unbound kind variables to boxed kind
- -- I'm a little worried that such a kind variable might be
- -- free in the environment, but I don't think it's possible for
- -- this to happen when the type variable is not free in the envt
- -- (which it isn't). SLPJ Nov 98
- mapTc zonkTcTyVarToTyVar (varSetElems tyvars_to_gen) `thenTc` \ real_tyvars_to_gen_list ->
+ traceTc (ptext SLIT("--------------------------------------------------------")) `thenM_`
+ traceTc (ptext SLIT("Bindings for") <+> ppr (collectHsBindBinders mbind)) `thenM_`
+ getLIE (tcMonoBinds mbind tc_ty_sigs is_rec) `thenM` \ ((mbind', bndr_names_w_ids), lie_req) ->
let
- real_tyvars_to_gen = mkVarSet real_tyvars_to_gen_list
- -- It's important that the final list
- -- (real_tyvars_to_gen and real_tyvars_to_gen_list) is fully
- -- zonked, *including boxity*, because they'll be included in the forall types of
- -- the polymorphic Ids, and instances of these Ids will be generated from them.
- --
- -- Also NB that tcSimplify takes zonked tyvars as its arg, hence we pass
- -- real_tyvars_to_gen
+ (binder_names, mono_ids) = unzip (bagToList bndr_names_w_ids)
+ tau_tvs = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids
in
- -- SIMPLIFY THE LIE
- tcExtendGlobalTyVars tyvars_not_to_gen (
- let ips = getIPsOfLIE lie_req in
- if null real_tyvars_to_gen_list && (null ips || not is_unrestricted) then
- -- No polymorphism, and no IPs, so no need to simplify context
- returnTc (lie_req, EmptyMonoBinds, [])
- else
- case maybe_sig_theta of
- Nothing ->
- -- No signatures, so just simplify the lie
- -- NB: no signatures => no polymorphic recursion, so no
- -- need to use lie_avail (which will be empty anyway)
- tcSimplify (text "tcBinds1" <+> ppr binder_names)
- real_tyvars_to_gen lie_req `thenTc` \ (lie_free, dict_binds, lie_bound) ->
- returnTc (lie_free, dict_binds, map instToId (bagToList lie_bound))
-
- Just (sig_theta, lie_avail) ->
- -- There are signatures, and their context is sig_theta
- -- Furthermore, lie_avail is an LIE containing the 'method insts'
- -- for the things bound here
-
- zonkTcThetaType sig_theta `thenNF_Tc` \ sig_theta' ->
- newDicts SignatureOrigin sig_theta' `thenNF_Tc` \ (dicts_sig, dict_ids) ->
- -- It's important that sig_theta is zonked, because
- -- dict_id is later used to form the type of the polymorphic thing,
- -- and forall-types must be zonked so far as their bound variables
- -- are concerned
-
- let
- -- The "givens" is the stuff available. We get that from
- -- the context of the type signature, BUT ALSO the lie_avail
- -- so that polymorphic recursion works right (see comments at end of fn)
- givens = dicts_sig `plusLIE` lie_avail
- in
-
- -- Check that the needed dicts can be expressed in
- -- terms of the signature ones
- tcAddErrCtxt (bindSigsCtxt tysig_names) $
- tcSimplifyAndCheck
- (ptext SLIT("type signature for") <+> pprQuotedList binder_names)
- real_tyvars_to_gen givens lie_req `thenTc` \ (lie_free, dict_binds) ->
-
- returnTc (lie_free, dict_binds, dict_ids)
-
- ) `thenTc` \ (lie_free, dict_binds, dicts_bound) ->
-
- -- GET THE FINAL MONO_ID_TYS
- zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_types ->
-
-
- -- CHECK FOR BOGUS UNPOINTED BINDINGS
- (if any isUnLiftedType zonked_mono_id_types then
- -- Unlifted bindings must be non-recursive,
- -- not top level, and non-polymorphic
- checkTc (isNotTopLevel top_lvl)
- (unliftedBindErr "Top-level" mbind) `thenTc_`
- checkTc (case is_rec of {Recursive -> False; NonRecursive -> True})
- (unliftedBindErr "Recursive" mbind) `thenTc_`
- checkTc (null real_tyvars_to_gen_list)
- (unliftedBindErr "Polymorphic" mbind)
- else
- returnTc ()
- ) `thenTc_`
-
- ASSERT( not (any ((== unboxedTypeKind) . tyVarKind) real_tyvars_to_gen_list) )
- -- The instCantBeGeneralised stuff in tcSimplify should have
- -- already raised an error if we're trying to generalise an
- -- unboxed tyvar (NB: unboxed tyvars are always introduced
- -- along with a class constraint) and it's better done there
- -- because we have more precise origin information.
- -- That's why we just use an ASSERT here.
-
-
- -- BUILD THE POLYMORPHIC RESULT IDs
- mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids ->
+ -- GENERALISE
+ -- (it seems a bit crude to have to do getLIE twice,
+ -- but I can't see a better way just now)
+ addSrcSpan (srcLocSpan (minimum (map getSrcLoc binder_names))) $
+ -- TODO: location wrong
+
+ 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
+ -- 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.
+ 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
+ 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
- dict_tys = map idType dicts_bound
+ poly_ids = [poly_id | (_, poly_id, _) <- exports]
+ dict_tys = map idType zonked_dict_ids
+
+ inlines = mkNameSet [ name
+ | L _ (InlineSig True (L _ name) _) <- sigs]
+ -- Any INLINE sig (regardless of phase control)
+ -- makes the RHS look small
- 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
+ inline_phases = listToFM [ (name, phase)
+ | L _ (InlineSig _ (L _ 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 _ _ _ _ _) ->
- (sig_tyvars, sig_poly_id)
- Nothing -> (real_tyvars_to_gen_list, new_poly_id)
-
- new_poly_id = mkVanillaId binder_name poly_ty
- poly_ty = mkForAllTys real_tyvars_to_gen_list
- $ mkFunTys dict_tys
- $ idType (zonked_mono_id)
+ Just sig -> (sig_tvs sig, sig_poly_id sig)
+ 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.
-
- 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 (
- -- pprTrace "binding.." (ppr ((dicts_bound, dict_binds), exports, [idType poly_id | (_, poly_id, _) <- exports])) $
- AbsBinds real_tyvars_to_gen_list
- dicts_bound
- exports
- inlines
- (dict_binds `andMonoBinds` mbind'),
- lie_free,
- [poly_id | (_, poly_id, _) <- exports]
- )
- where
- tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- tc_ty_sigs]
- is_unrestricted = isUnRestrictedGroup tysig_names mbind
-justPatBindings bind@(PatMonoBind _ _ _) binds = bind `andMonoBinds` binds
-justPatBindings (AndMonoBinds b1 b2) binds =
- justPatBindings b1 (justPatBindings b2 binds)
-justPatBindings other_bind binds = binds
+ traceTc (text "binding:" <+> ppr ((zonked_dict_ids, dict_binds),
+ exports, map idType poly_ids)) `thenM_`
-attachNoInlinePrag no_inlines bndr
- = case lookupFM no_inlines (idName bndr) of
+ -- 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 (
+ unitBag $ noLoc $
+ AbsBinds [] [] exports inlines mbind',
+ -- Do not generate even any x=y bindings
+ poly_ids
+ )
+
+ else -- The normal case
+ extendLIEs lie_free `thenM_`
+ returnM (
+ unitBag $ noLoc $
+ AbsBinds real_tyvars_to_gen
+ zonked_dict_ids
+ exports
+ inlines
+ (dict_binds `unionBags` mbind'),
+ poly_ids
+ )
+
+attachInlinePhase inline_phases bndr
+ = case lookupFM inline_phases (idName bndr) of
Just prag -> bndr `setInlinePragma` prag
Nothing -> bndr
+
+-- 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
+ -- 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.
+
+ checkTc (isNotTopLevel top_lvl)
+ (unliftedBindErr "Top-level" mbind) `thenM_`
+ checkTc (isNonRec is_rec)
+ (unliftedBindErr "Recursive" mbind) `thenM_`
+ checkTc (isSingletonBag mbind)
+ (unliftedBindErr "Multiple" mbind) `thenM_`
+ checkTc (null real_tyvars_to_gen)
+ (unliftedBindErr "Polymorphic" mbind)
\end{code}
+
Polymorphic recursion
~~~~~~~~~~~~~~~~~~~~~
The game plan for polymorphic recursion in the code above is
%* *
%************************************************************************
+\begin{code}
+generalise binder_names mbind tau_tvs lie_req sigs =
+
+ -- check for -fno-monomorphism-restriction
+ doptM Opt_NoMonomorphismRestriction `thenM` \ no_MR ->
+ let is_unrestricted | no_MR = True
+ | otherwise = isUnRestrictedGroup tysig_names mbind
+ in
+
+ 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 `thenM` \ (forall_tvs, dict_binds) ->
+
+ -- Check that signature type variables are OK
+ checkSigsTyVars forall_tvs sigs `thenM` \ final_qtvs ->
+
+ returnM (final_qtvs, dict_binds, sig_dicts)
+
+ where
+ tysig_names = map (idName . sig_poly_id) sigs
+ is_mono_sig sig = null (sig_theta sig)
+
+ 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 { sig_poly_id = id1, sig_tvs = sig_tvs, sig_theta = theta1, sig_loc = span}
+ : other_sigs)
+ = addSrcSpan span $
+ mappM_ check_one other_sigs `thenM_`
+ if null theta1 then
+ returnM ([], []) -- Non-overloaded type signatures
+ else
+ 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
+ returnM (sig_avails, map instToId sig_dicts)
+ where
+ sig1_dict_tys = map mkPredTy theta1
+ sig_meths = concatMap sig_insts sigs
+
+ check_one (TySigInfo {sig_poly_id = id, sig_theta = theta})
+ = addErrCtxt (sigContextsCtxt id1 id) $
+ checkTc (equalLength theta theta1) sigContextsErr `thenM_`
+ unifyTauTyLists sig1_dict_tys (map mkPredTy theta)
+
+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 = foldl extendVarSetList emptyVarSet sig_tvs_s
+ all_tvs = extendVarSetList sig_tvs qtvs
+ in
+ returnM (varSetElems all_tvs)
+ where
+ check_one (TySigInfo {sig_poly_id = id, sig_tvs = tvs, sig_theta = theta, sig_tau = tau})
+ = addErrCtxt (ptext SLIT("In the type signature for")
+ <+> quotes (ppr id)) $
+ addErrCtxtM (sigCtxt id tvs theta tau) $
+ checkSigTyVarsWrt (idFreeTyVars id) tvs
+\end{code}
+
@getTyVarsToGen@ decides what type variables to generalise over.
For a "restricted group" -- see the monomorphism restriction
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
- body_tyvars = tyVarsOfTypes zonked_mono_id_tys `minusVarSet` free_tyvars
- in
- if is_unrestricted
- then
- let fds = getAllFunDepsOfLIE lie in
- zonkFunDeps fds `thenNF_Tc` \ fds' ->
- let tvFundep = tyVarFunDep fds'
- extended_tyvars = oclose tvFundep body_tyvars in
- -- pprTrace "gTVTG" (ppr (lie, body_tyvars, extended_tyvars)) $
- returnNF_Tc (emptyVarSet, extended_tyvars)
- else
- -- This recover and discard-errs is to avoid duplicate error
- -- messages; this, after all, is an "extra" call to tcSimplify
- recoverNF_Tc (returnNF_Tc (emptyVarSet, body_tyvars)) $
- discardErrsTc $
-
- tcSimplify (text "getTVG") body_tyvars lie `thenTc` \ (_, _, constrained_dicts) ->
- let
- -- ASSERT: dicts_sig is already zonked!
- constrained_tyvars = foldrBag (unionVarSet . tyVarsOfInst) emptyVarSet constrained_dicts
- reduced_tyvars_to_gen = body_tyvars `minusVarSet` constrained_tyvars
- in
- returnTc (constrained_tyvars, reduced_tyvars_to_gen)
-\end{code}
-
-
-\begin{code}
isUnRestrictedGroup :: [Name] -- Signatures given for these
- -> RenamedMonoBinds
+ -> LHsBinds Name
-> Bool
+isUnRestrictedGroup sigs binds = all (unrestricted . unLoc) (bagToList binds)
+ where
+ unrestricted (PatBind other _) = False
+ unrestricted (VarBind v _) = v `is_elem` sigs
+ unrestricted (FunBind v _ matches) = unrestricted_match matches
+ || unLoc v `is_elem` sigs
+
+ unrestricted_match (L _ (Match [] _ _) : _) = False
+ -- No args => like a pattern binding
+ unrestricted_match other = True
+ -- Some args => a function binding
is_elem v vs = isIn "isUnResMono" v vs
-
-isUnRestrictedGroup sigs (PatMonoBind (VarPatIn v) _ _) = v `is_elem` sigs
-isUnRestrictedGroup sigs (PatMonoBind other _ _) = False
-isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs
-isUnRestrictedGroup sigs (FunMonoBind _ _ _ _) = True
-isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 &&
- isUnRestrictedGroup sigs mb2
-isUnRestrictedGroup sigs EmptyMonoBinds = True
\end{code}
The signatures have been dealt with already.
\begin{code}
-tcMonoBinds :: RenamedMonoBinds
- -> [TcSigInfo]
- -> RecFlag
- -> TcM s (TcMonoBinds,
- LIE, -- LIE required
- [Name], -- Bound names
- [TcId]) -- Corresponding monomorphic bound things
+tcMonoBinds :: LHsBinds Name
+ -> [TcSigInfo] -> RecFlag
+ -> TcM (LHsBinds TcId,
+ 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) ->
+ -- 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
+ = mapBagM tc_lbind_pats mbinds `thenM` \ bag_of_pairs ->
let
- tv_list = bagToList tvs
- 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 -> []
+ (complete_it, xve)
+ = foldrBag combine
+ (returnM (emptyBag, emptyBag), emptyBag)
+ bag_of_pairs
+ combine (complete_it1, xve1) (complete_it2, xve2)
+ = (complete_it, xve1 `unionBags` xve2)
+ where
+ complete_it = complete_it1 `thenM` \ (b1, bs1) ->
+ complete_it2 `thenM` \ (b2, bs2) ->
+ returnM (b1 `consBag` b2, bs1 `unionBags` bs2)
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)
+ 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 type signatures
- 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)
+ tc_lbind_pats :: LHsBind Name
+ -> TcM (TcM (LHsBind TcId, Bag (Name,TcId)), -- Completer
+ Bag (Name,TcId))
+ -- wrapper for tc_bind_pats to deal with the location stuff
+ tc_lbind_pats (L loc bind)
+ = addSrcSpan loc $ do
+ (tc, bag) <- tc_bind_pats bind
+ return (wrap tc, bag)
+ where
+ wrap tc = addSrcSpan loc $ do
+ (bind, stuff) <- tc
+ return (L loc bind, stuff)
+
+
+ tc_bind_pats :: HsBind Name
+ -> TcM (TcM (HsBind TcId, Bag (Name,TcId)), -- Completer
+ Bag (Name,TcId))
+ tc_bind_pats (FunBind (L nm_loc name) inf matches)
+ -- 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 = sig_mono_id sig
+ mono_ty = idType mono_id
+ complete_it = tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' ->
+ returnM (FunBind (L nm_loc mono_id) inf matches',
+ unitBag (name, mono_id))
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` \ bndr_ty ->
- tc_pat_bndr name bndr_ty `thenTc` \ bndr_id ->
+ returnM (complete_it, if isRec is_rec then unitBag (name, sig_poly_id 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 = tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' ->
+ returnM (FunBind (L nm_loc mono_id) inf matches',
+ unitBag (name, mono_id))
in
- returnTc (complete_it, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE)
-
- tc_mb_pats bind@(PatMonoBind pat grhss locn)
- = tcAddSrcLoc locn $
+ 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
+ = 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 (FunBind (L nm_loc mono_id) inf matches',
+ unitBag (name, mono_id))
+ in
+ returnM (complete_it, emptyBag)
+
+ tc_bind_pats bind@(PatBind pat grhss)
+ = -- Now typecheck the pattern
+ -- 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
+ -- 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 ->
- -- Figure out the appropriate kind for the pattern,
- -- and generate a suitable type variable
- (case is_rec of
- Recursive -> newTyVarTy boxedTypeKind -- Recursive, so no unboxed types
- NonRecursive -> newTyVarTy_OpenKind -- Non-recursive, so we permit unboxed types
- ) `thenNF_Tc` \ pat_ty ->
+ -- Don't know how to deal with pattern-bound existentials yet
+ checkTc (isEmptyBag tvs && null lie_avail)
+ (existentialExplode bind) `thenM_`
- -- 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 grhss pat_ty PatBindRhs `thenTc` \ (grhss', lie) ->
- returnTc (PatMonoBind pat' grhss' locn, lie)
+ complete_it = addErrCtxt (patMonoBindsCtxt bind) $
+ tcGRHSsPat grhss (Check pat_ty) `thenM` \ grhss' ->
+ returnM (PatBind pat' grhss', ids)
in
- returnTc (complete_it, lie_req, tvs, ids, lie_avail)
-\end{code}
-
-%************************************************************************
-%* *
-\subsection{Signatures}
-%* *
-%************************************************************************
-
-@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 top_lvl binder_names mono_ids sigs
- | main_bound_here
- = -- First unify the main_id with IO t, for any old t
- tcSetErrCtxt mainTyCheckCtxt (
- tcLookupTyCon ioTyCon_NAME `thenTc` \ ioTyCon ->
- newTyVarTy boxedTypeKind `thenNF_Tc` \ t_tv ->
- unifyTauTy ((mkTyConApp ioTyCon [t_tv]))
- (idType main_mono_id)
- ) `thenTc_`
-
- -- Now check the signatures
- -- Must do this after the unification with IO t,
- -- in case of a silly signature like
- -- main :: forall a. a
- -- The unification to IO t will bind the type variable 'a',
- -- which is just waht check_one_sig looks for
- mapTc check_one_sig sigs `thenTc_`
- mapTc check_main_ctxt sigs `thenTc_`
-
- returnTc (Just ([], emptyLIE))
-
- | not (null sigs)
- = mapTc check_one_sig sigs `thenTc_`
- mapTc check_one_ctxt all_sigs_but_first `thenTc_`
- returnTc (Just (theta1, sig_lie))
-
- | otherwise
- = returnTc Nothing -- No constraints from type sigs
-
- where
- (TySigInfo _ id1 _ theta1 _ _ _ _ : all_sigs_but_first) = sigs
-
- sig1_dict_tys = mk_dict_tys theta1
- n_sig1_dict_tys = length sig1_dict_tys
- sig_lie = mkLIE [inst | TySigInfo _ _ _ _ _ _ inst _ <- sigs]
-
- maybe_main = find_main top_lvl binder_names mono_ids
- main_bound_here = maybeToBool maybe_main
- Just main_mono_id = maybe_main
-
- -- CHECK THAT THE SIGNATURE TYVARS AND TAU_TYPES ARE OK
- -- Doesn't affect substitution
- check_one_sig (TySigInfo _ id sig_tyvars _ sig_tau _ _ src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxtM (sigCtxt (sig_msg id) (idType id)) $
- checkSigTyVars sig_tyvars
-
-
- -- 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
- check_one_ctxt 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 THAT FOR A GROUP INVOLVING Main.main, all
- -- the signature contexts are empty (what a bore)
- check_main_ctxt sig@(TySigInfo _ id _ theta _ _ _ src_loc)
- = tcAddSrcLoc src_loc $
- checkTc (null theta) (mainContextsErr id)
-
- mk_dict_tys theta = map mkPredTy theta
-
- sig_msg id tidy_ty = sep [ptext SLIT("When checking the type signature"),
- nest 4 (ppr id <+> dcolon <+> ppr tidy_ty)]
-
- -- Search for Main.main in the binder_names, return corresponding mono_id
- find_main NotTopLevel binder_names mono_ids = Nothing
- find_main TopLevel binder_names mono_ids = go binder_names mono_ids
- go [] [] = Nothing
- go (n:ns) (m:ms) | n == main_NAME = Just m
- | otherwise = go ns ms
+ returnM (complete_it, if isRec is_rec then ids else emptyBag)
+
+ -- 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_bind_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 -> addSrcSpan (srcLocSpan (getSrcLoc name)) $
+ -- TODO: location wrong
+ tcSubPat (idType mono_id) pat_ty `thenM` \ co_fn ->
+ returnM (co_fn, mono_id)
+ where
+ mono_id = sig_mono_id sig
\end{code}
{-# SPECIALISE (f::<type) = g #-}
\begin{code}
-tcSpecSigs :: [RenamedSig] -> TcM s (TcMonoBinds, LIE)
-tcSpecSigs (SpecSig name poly_ty src_loc : sigs)
+tcSpecSigs :: [LSig Name] -> TcM (LHsBinds TcId)
+tcSpecSigs (L loc (SpecSig (L nm_loc name) poly_ty) : sigs)
= -- SPECIALISE f :: forall b. theta => tau = g
- tcAddSrcLoc src_loc $
- tcAddErrCtxt (valSpecSigCtxt name poly_ty) $
+ addSrcSpan 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 (L nm_loc (HsVar name)) sig_ty) `thenM` \ (spec_expr, spec_lie) ->
-- Squeeze out any Methods (see comments with tcSimplifyToDicts)
- tcSimplifyToDicts spec_lie `thenTc` \ (spec_lie1, 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 = VarBind (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` spec_lie1)
+ tcSpecSigs sigs `thenM` \ binds_rest ->
+ returnM (binds_rest `snocBag` L loc spec_bind)
tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs
-tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE)
+tcSpecSigs [] = returnM emptyBag
\end{code}
-
%************************************************************************
%* *
\subsection[TcBinds-errors]{Error contexts and messages}
nest 4 (ppr v <+> dcolon <+> 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)
- ])
-
------------------------------------------------
-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)
- ])
-
------------------------------------------------
-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
-
------------------------------------------------
-sigContextsErr
- = ptext SLIT("Mismatched contexts")
+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)"))
-
-mainContextsErr id
- | getName id == main_NAME = ptext SLIT("Main.main cannot be overloaded")
- | otherwise
- = quotes (ppr id) <+> ptext SLIT("cannot be overloaded") <> char ',' <> -- sigh; workaround for cpp's inability to deal
- ptext SLIT("because it is mutually recursive with Main.main") -- with commas inside SLIT strings.
-
-mainTyCheckCtxt
- = hsep [ptext SLIT("When checking that"), quotes (ppr main_NAME),
- ptext SLIT("has the required type")]
+ = 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
- = hang (text flavour <+> ptext SLIT("bindings for unlifted types aren't allowed"))
+ = 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
+-- 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