%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcBinds]{TcBinds}
\begin{code}
-#include "HsVersions.h"
-
-module TcBinds ( tcBindsAndThen, tcPragmaSigs ) where
-
-import Ubiq
+module TcBinds ( tcBindsAndThen, tcTopBindsAndThen,
+ tcPragmaSigs, tcBindWithSigs ) where
-import HsSyn ( HsBinds(..), Bind(..), Sig(..), MonoBinds(..),
- HsExpr, Match, PolyType, InPat, OutPat,
- GRHSsAndBinds, ArithSeqInfo, HsLit, Fake,
- collectBinders )
-import RnHsSyn ( RenamedHsBinds(..), RenamedBind(..), RenamedSig(..),
- RenamedMonoBinds(..) )
-import TcHsSyn ( TcHsBinds(..), TcBind(..), TcMonoBinds(..),
- TcIdOcc(..), TcIdBndr(..) )
+#include "HsVersions.h"
-import TcMonad
-import GenSpecEtc ( checkSigTyVars, genBinds, TcSigInfo(..) )
-import Inst ( Inst, LIE(..), emptyLIE, plusLIE, InstOrigin(..) )
-import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newMonoIds )
-import TcLoop ( tcGRHSsAndBinds )
+import {-# SOURCE #-} TcGRHSs ( tcGRHSsAndBinds )
+import {-# SOURCE #-} TcExpr ( tcExpr )
+
+import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), InPat(..), StmtCtxt(..),
+ collectMonoBinders, andMonoBindList, andMonoBinds
+ )
+import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds )
+import TcHsSyn ( TcHsBinds, TcMonoBinds,
+ TcIdOcc(..), TcIdBndr,
+ tcIdType, zonkId
+ )
+
+import TcMonad
+import Inst ( Inst, LIE, emptyLIE, mkLIE, plusLIE, plusLIEs, InstOrigin(..),
+ newDicts, tyVarsOfInst, instToId,
+ )
+import TcEnv ( tcExtendLocalValEnv, tcExtendEnvWithPat,
+ tcLookupLocalValueOK,
+ newSpecPragmaId,
+ tcGetGlobalTyVars, tcExtendGlobalTyVars
+ )
import TcMatches ( tcMatchesFun )
-import TcMonoType ( tcPolyType )
-import TcPat ( tcPat )
+import TcSimplify ( tcSimplify, tcSimplifyAndCheck )
+import TcMonoType ( tcHsTcType, checkSigTyVars,
+ TcSigInfo(..), tcTySig, maybeSig, sigCtxt
+ )
+import TcPat ( tcVarPat, tcPat )
import TcSimplify ( bindInstsOfLocalFuns )
-import TcType ( newTcTyVar, tcInstType )
-import Unify ( unifyTauTy )
-
-import Kind ( mkBoxedTypeKind, mkTypeKind )
-import Id ( GenId, idType, mkUserId )
-import IdInfo ( noIdInfo )
-import Name ( Name ) -- instances
-import Maybes ( assocMaybe, catMaybes, Maybe(..) )
-import Outputable ( pprNonOp )
-import PragmaInfo ( PragmaInfo(..) )
-import Pretty
-import Type ( mkTyVarTy, isTyVarTy, mkSigmaTy, splitSigmaTy,
- splitRhoTy, mkForAllTy, splitForAllTy )
-import Util ( panic )
+import TcType ( TcType, TcThetaType,
+ TcTyVar,
+ newTyVarTy, newTcTyVar, tcInstTcType,
+ zonkTcType, zonkTcTypes, zonkTcThetaType )
+import TcUnify ( unifyTauTy, unifyTauTyLists )
+
+import Id ( mkUserId )
+import Var ( idType, idName, setIdInfo )
+import IdInfo ( IdInfo, noIdInfo, setInlinePragInfo, InlinePragInfo(..) )
+import Name ( Name )
+import Type ( mkTyVarTy, tyVarsOfTypes,
+ splitSigmaTy, mkForAllTys, mkFunTys, getTyVar,
+ mkDictTy, splitRhoTy, mkForAllTy, isUnLiftedType,
+ isUnboxedType, openTypeKind,
+ unboxedTypeKind, boxedTypeKind
+ )
+import Var ( TyVar, tyVarKind )
+import VarSet
+import Bag
+import Util ( isIn )
+import BasicTypes ( TopLevelFlag(..), RecFlag(..) )
+import SrcLoc ( SrcLoc )
+import Outputable
\end{code}
+
%************************************************************************
%* *
\subsection{Type-checking bindings}
@tcBindsAndThen@ also takes a "combiner" which glues together the
bindings and the "thing" to make a new "thing".
-The real work is done by @tcBindAndThen@.
+The real work is done by @tcBindWithSigsAndThen@.
Recursive and non-recursive binds are handled in essentially the same
way: because of uniques there are no scoping issues left. The only
dictionaries, which we resolve at the module level.
\begin{code}
-tcBindsAndThen
- :: (TcHsBinds s -> thing -> thing) -- Combinator
+tcTopBindsAndThen, tcBindsAndThen
+ :: (RecFlag -> TcMonoBinds s -> thing -> thing) -- Combinator
-> RenamedHsBinds
- -> TcM s (thing, LIE s, thing_ty)
- -> TcM s (thing, LIE s, thing_ty)
+ -> TcM s (thing, LIE s)
+ -> TcM s (thing, LIE s)
-tcBindsAndThen combiner EmptyBinds do_next
- = do_next `thenTc` \ (thing, lie, thing_ty) ->
- returnTc (combiner EmptyBinds thing, lie, thing_ty)
+tcTopBindsAndThen = tc_binds_and_then TopLevel
+tcBindsAndThen = tc_binds_and_then NotTopLevel
-tcBindsAndThen combiner (SingleBind bind) do_next
- = tcBindAndThen combiner bind [] do_next
+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
-tcBindsAndThen combiner (BindWith bind sigs) do_next
- = tcBindAndThen combiner bind sigs 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_binds_and_then top_lvl combiner (MonoBind bind sigs is_rec) do_next
+ = fixTc (\ ~(prag_info_fn, _, _) ->
+ -- This is the usual prag_info fix; the PragmaInfo field of an Id
+ -- is not inspected till ages later in the compiler, so there
+ -- should be no black-hole problems here.
-tcBindsAndThen combiner (ThenBinds binds1 binds2) do_next
- = tcBindsAndThen combiner binds1 (tcBindsAndThen combiner binds2 do_next)
+ -- TYPECHECK THE SIGNATURES
+ mapTc tcTySig [sig | sig@(Sig name _ _) <- sigs] `thenTc` \ tc_ty_sigs ->
+
+ tcBindWithSigs top_lvl bind
+ tc_ty_sigs is_rec prag_info_fn `thenTc` \ (poly_binds, poly_lie, poly_ids) ->
+
+ -- Extend the environment to bind the new polymorphic Ids
+ tcExtendLocalValEnv (map idName poly_ids) poly_ids $
+
+ -- Build bindings and IdInfos corresponding to user pragmas
+ tcPragmaSigs sigs `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
+
+ -- Now do whatever happens next, in the augmented envt
+ do_next `thenTc` \ (thing, thing_lie) ->
+
+ -- Create specialisations of functions bound here
+ -- We want to keep non-recursive things non-recursive
+ -- so that we desugar unboxed bindings correctly
+ case (top_lvl, is_rec) of
+
+ -- For the top level don't bother will all this bindInstsOfLocalFuns stuff
+ -- All the top level things are rec'd together anyway, so it's fine to
+ -- leave them to the tcSimplifyTop, and quite a bit faster too
+ (TopLevel, _)
+ -> returnTc (prag_info_fn,
+ combiner Recursive (poly_binds `andMonoBinds` prag_binds) thing,
+ thing_lie `plusLIE` prag_lie `plusLIE` poly_lie)
+
+ (NotTopLevel, NonRecursive)
+ -> bindInstsOfLocalFuns
+ (thing_lie `plusLIE` prag_lie)
+ poly_ids `thenTc` \ (thing_lie', lie_binds) ->
+
+ returnTc (
+ prag_info_fn,
+ combiner NonRecursive poly_binds $
+ combiner NonRecursive prag_binds $
+ combiner Recursive lie_binds $
+ -- NB: the binds returned by tcSimplify and bindInstsOfLocalFuns
+ -- aren't guaranteed in dependency order (though we could change
+ -- that); hence the Recursive marker.
+ thing,
+
+ thing_lie' `plusLIE` poly_lie
+ )
+
+ (NotTopLevel, Recursive)
+ -> bindInstsOfLocalFuns
+ (thing_lie `plusLIE` poly_lie `plusLIE` prag_lie)
+ poly_ids `thenTc` \ (final_lie, lie_binds) ->
+
+ returnTc (
+ prag_info_fn,
+ combiner Recursive (
+ poly_binds `andMonoBinds`
+ lie_binds `andMonoBinds`
+ prag_binds) thing,
+ final_lie
+ )
+ ) `thenTc` \ (_, thing, lie) ->
+ returnTc (thing, lie)
\end{code}
An aside. The original version of @tcBindsAndThen@ which lacks a
examples of this, which is why I thought it worth preserving! [SLPJ]
\begin{pseudocode}
-tcBindsAndThen
- :: RenamedHsBinds
- -> TcM s (thing, LIE s, thing_ty))
- -> TcM s ((TcHsBinds s, thing), LIE s, thing_ty)
-
-tcBindsAndThen EmptyBinds do_next
- = do_next `thenTc` \ (thing, lie, thing_ty) ->
- returnTc ((EmptyBinds, thing), lie, thing_ty)
-
-tcBindsAndThen (SingleBind bind) do_next
- = tcBindAndThen bind [] do_next
-
-tcBindsAndThen (BindWith bind sigs) do_next
- = tcBindAndThen bind sigs do_next
-
-tcBindsAndThen (ThenBinds binds1 binds2) do_next
- = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next)
- `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) ->
-
- returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty)
+% tcBindsAndThen
+% :: RenamedHsBinds
+% -> TcM s (thing, LIE s, thing_ty))
+% -> TcM s ((TcHsBinds s, thing), LIE s, thing_ty)
+%
+% tcBindsAndThen EmptyBinds do_next
+% = do_next `thenTc` \ (thing, lie, thing_ty) ->
+% returnTc ((EmptyBinds, thing), lie, thing_ty)
+%
+% tcBindsAndThen (ThenBinds binds1 binds2) do_next
+% = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next)
+% `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) ->
+%
+% returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty)
+%
+% tcBindsAndThen (MonoBind bind sigs is_rec) do_next
+% = tcBindAndThen bind sigs do_next
\end{pseudocode}
+
%************************************************************************
%* *
-\subsection{Bind}
+\subsection{tcBindWithSigs}
%* *
%************************************************************************
-\begin{code}
-tcBindAndThen
- :: (TcHsBinds s -> thing -> thing) -- Combinator
- -> RenamedBind -- The Bind to typecheck
- -> [RenamedSig] -- ...and its signatures
- -> TcM s (thing, LIE s, thing_ty) -- Thing to type check in
- -- augmented envt
- -> TcM s (thing, LIE s, thing_ty) -- Results, incl the
-
-tcBindAndThen combiner bind sigs do_next
- = fixTc (\ ~(prag_info_fn, _) ->
- -- This is the usual prag_info fix; the PragmaInfo field of an Id
- -- is not inspected till ages later in the compiler, so there
- -- should be no black-hole problems here.
-
- tcBindAndSigs binder_names bind
- sigs prag_info_fn `thenTc` \ (poly_binds, poly_lie, poly_ids) ->
-
- -- Extend the environment to bind the new polymorphic Ids
- tcExtendLocalValEnv binder_names poly_ids $
-
- -- Build bindings and IdInfos corresponding to user pragmas
- tcPragmaSigs sigs `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
+@tcBindWithSigs@ deals with a single binding group. It does generalisation,
+so all the clever stuff is in here.
- -- Now do whatever happens next, in the augmented envt
- do_next `thenTc` \ (thing, thing_lie, thing_ty) ->
-
- -- Create specialisations of functions bound here
- bindInstsOfLocalFuns (prag_lie `plusLIE` thing_lie)
- poly_ids `thenTc` \ (lie2, inst_mbinds) ->
+* binder_names and mbind must define the same set of Names
- -- All done
- let
- final_lie = lie2 `plusLIE` poly_lie
- final_binds = poly_binds `ThenBinds`
- SingleBind (NonRecBind inst_mbinds) `ThenBinds`
- prag_binds
- in
- returnTc (prag_info_fn, (combiner final_binds thing, final_lie, thing_ty))
- ) `thenTc` \ (_, result) ->
- returnTc result
- where
- binder_names = collectBinders bind
+* The Names in tc_ty_sigs must be a subset of binder_names
+* The Ids in tc_ty_sigs don't necessarily have to have the same name
+ as the Name in the tc_ty_sig
-tcBindAndSigs binder_names bind sigs prag_info_fn
+\begin{code}
+tcBindWithSigs
+ :: TopLevelFlag
+ -> RenamedMonoBinds
+ -> [TcSigInfo s]
+ -> RecFlag
+ -> (Name -> IdInfo)
+ -> TcM s (TcMonoBinds s, LIE s, [TcIdBndr s])
+
+tcBindWithSigs top_lvl mbind tc_ty_sigs is_rec prag_info_fn
= recoverTc (
-- If typechecking the binds fails, then return with each
- -- binder given type (forall a.a), to minimise subsequent
+ -- signature-less binder given type (forall a.a), to minimise subsequent
-- error messages
- newTcTyVar Nothing mkBoxedTypeKind `thenNF_Tc` \ alpha_tv ->
+ newTcTyVar boxedTypeKind `thenNF_Tc` \ alpha_tv ->
let
- forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv)
- poly_ids = [ mkUserId name forall_a_a (prag_info_fn name)
- | name <- binder_names]
+ forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv)
+ binder_names = map fst (bagToList (collectMonoBinders mbind))
+ poly_ids = map mk_dummy binder_names
+ mk_dummy name = case maybeSig tc_ty_sigs name of
+ Just (TySigInfo _ poly_id _ _ _ _ _ _) -> poly_id -- Signature
+ Nothing -> mkUserId name forall_a_a -- No signature
in
- returnTc (EmptyBinds, emptyLIE, poly_ids)
+ returnTc (EmptyMonoBinds, emptyLIE, poly_ids)
) $
- -- Create a new identifier for each binder, with each being given
- -- a type-variable type.
- newMonoIds binder_names kind (\ mono_ids ->
- tcTySigs sigs `thenTc` \ sig_info ->
- tc_bind bind `thenTc` \ (bind', lie) ->
- returnTc (mono_ids, bind', lie, sig_info)
- )
- `thenTc` \ (mono_ids, bind', lie, sig_info) ->
+ -- TYPECHECK THE BINDINGS
+ tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) ->
- -- Notice that genBinds gets the old (non-extended) environment
- genBinds binder_names mono_ids bind' lie sig_info prag_info_fn
+ let
+ mono_id_tys = map idType mono_ids
+ in
+
+ -- CHECK THAT THE SIGNATURES MATCH
+ -- (must do this before getTyVarsToGen)
+ checkSigMatch tc_ty_sigs `thenTc` \ (sig_theta, lie_avail) ->
+
+ -- COMPUTE VARIABLES OVER WHICH TO QUANTIFY, namely tyvars_to_gen
+ -- The tyvars_not_to_gen are free in the environment, and hence
+ -- candidates for generalisation, but sometimes the monomorphism
+ -- restriction means we can't generalise them nevertheless
+ getTyVarsToGen is_unrestricted mono_id_tys lie_req `thenNF_Tc` \ (tyvars_not_to_gen, tyvars_to_gen) ->
+
+ -- DEAL WITH TYPE VARIABLE KINDS
+ -- **** This step can do unification => keep other zonking after this ****
+ mapTc defaultUncommittedTyVar (varSetElems tyvars_to_gen) `thenTc` \ real_tyvars_to_gen_list ->
+ 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
+ in
+
+ -- SIMPLIFY THE LIE
+ tcExtendGlobalTyVars tyvars_not_to_gen (
+ if null real_tyvars_to_gen_list then
+ -- No polymorphism, so no need to simplify context
+ returnTc (lie_req, EmptyMonoBinds, [])
+ else
+ if null tc_ty_sigs then
+ -- No signatures, so just simplify the lie
+ -- NB: no signatures => no polymorphic recursion, so no
+ -- need to use lie_avail (which will be empty anyway)
+ tcSimplify (text "tcBinds1" <+> ppr binder_names)
+ top_lvl real_tyvars_to_gen lie_req `thenTc` \ (lie_free, dict_binds, lie_bound) ->
+ returnTc (lie_free, dict_binds, map instToId (bagToList lie_bound))
+
+ else
+ 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 (case top_lvl of {TopLevel -> False; NotTopLevel -> True})
+ (unliftedBindErr "Top-level" mbind) `thenTc_`
+ checkTc (case is_rec of {Recursive -> False; NonRecursive -> True})
+ (unliftedBindErr "Recursive" mbind) `thenTc_`
+ checkTc (null real_tyvars_to_gen_list)
+ (unliftedBindErr "Polymorphic" mbind)
+ else
+ returnTc ()
+ ) `thenTc_`
+
+ ASSERT( not (any ((== unboxedTypeKind) . tyVarKind) real_tyvars_to_gen_list) )
+ -- The instCantBeGeneralised stuff in tcSimplify should have
+ -- already raised an error if we're trying to generalise an
+ -- unboxed tyvar (NB: unboxed tyvars are always introduced
+ -- along with a class constraint) and it's better done there
+ -- because we have more precise origin information.
+ -- That's why we just use an ASSERT here.
+
+
+ -- BUILD THE POLYMORPHIC RESULT IDs
+ mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids ->
+ let
+ exports = zipWith mk_export binder_names zonked_mono_ids
+ dict_tys = map tcIdType dicts_bound
+
+ mk_export binder_name zonked_mono_id
+ = (tyvars,
+ TcId (setIdInfo poly_id (prag_info_fn binder_name)),
+ TcId zonked_mono_id)
+ where
+ (tyvars, poly_id) =
+ case maybeSig tc_ty_sigs binder_name of
+ Just (TySigInfo _ sig_poly_id sig_tyvars _ _ _ _ _) ->
+ (sig_tyvars, sig_poly_id)
+ Nothing -> (real_tyvars_to_gen_list, new_poly_id)
+
+ new_poly_id = mkUserId binder_name poly_ty
+ poly_ty = mkForAllTys real_tyvars_to_gen_list
+ $ mkFunTys dict_tys
+ $ idType (zonked_mono_id)
+ -- It's important to build a fully-zonked poly_ty, because
+ -- we'll slurp out its free type variables when extending the
+ -- local environment (tcExtendLocalValEnv); if it's not zonked
+ -- it appears to have free tyvars that aren't actually free
+ -- at all.
+
+ pat_binders :: [Name]
+ pat_binders = map fst $ bagToList $ collectMonoBinders $
+ (justPatBindings mbind EmptyMonoBinds)
+ in
+ -- CHECK FOR UNBOXED BINDERS IN PATTERN BINDINGS
+ mapTc (\id -> checkTc (not (idName id `elem` pat_binders
+ && isUnboxedType (idType id)))
+ (unboxedPatBindErr id)) zonked_mono_ids
+ `thenTc_`
+
+ -- BUILD RESULTS
+ returnTc (
+ AbsBinds real_tyvars_to_gen_list
+ dicts_bound
+ exports
+ (dict_binds `andMonoBinds` mbind'),
+ lie_free,
+ [poly_id | (_, TcId poly_id, _) <- exports]
+ )
where
- kind = case bind of
- NonRecBind _ -> mkBoxedTypeKind -- Recursive, so no unboxed types
- RecBind _ -> mkTypeKind -- Non-recursive, so we permit unboxed types
+ 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
\end{code}
-\begin{code}
-tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s)
+Polymorphic recursion
+~~~~~~~~~~~~~~~~~~~~~
+The game plan for polymorphic recursion in the code above is
-tc_bind (NonRecBind mono_binds)
- = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
- returnTc (NonRecBind mono_binds2, lie)
+ * Bind any variable for which we have a type signature
+ to an Id with a polymorphic type. Then when type-checking
+ the RHSs we'll make a full polymorphic call.
-tc_bind (RecBind mono_binds)
- = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
- returnTc (RecBind mono_binds2, lie)
-\end{code}
+This fine, but if you aren't a bit careful you end up with a horrendous
+amount of partial application and (worse) a huge space leak. For example:
-\begin{code}
-tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s)
+ f :: Eq a => [a] -> [a]
+ f xs = ...f...
+
+If we don't take care, after typechecking we get
-tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE)
+ f = /\a -> \d::Eq a -> let f' = f a d
+ in
+ \ys:[a] -> ...f'...
-tcMonoBinds (AndMonoBinds mb1 mb2)
- = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) ->
- tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) ->
- returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2)
+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 isn't being used (but that's a very common case).
+We'd prefer
-tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn)
- = tcAddSrcLoc locn $
+ f = /\a -> \d::Eq a -> letrec
+ fm = \ys:[a] -> ...fm...
+ in
+ fm
- -- LEFT HAND SIDE
- tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) ->
+This can lead to a massive space leak, from the following top-level defn
+(post-typechecking)
- -- BINDINGS AND GRHSS
- tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) ->
+ ff :: [Int] -> [Int]
+ ff = f Int dEqInt
- -- Unify the two sides
- tcAddErrCtxt (patMonoBindsCtxt bind) $
- unifyTauTy pat_ty grhss_ty `thenTc_`
+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.
- -- RETURN
- returnTc (PatMonoBind pat2 grhss_and_binds2 locn,
- plusLIE lie_pat lie)
+ ff = f Int dEqInt
-tcMonoBinds (FunMonoBind name matches locn)
- = tcAddSrcLoc locn $
- tcLookupLocalValueOK "tcMonoBinds" name `thenNF_Tc` \ id ->
- tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) ->
- returnTc (FunMonoBind (TcId id) matches' locn, lie)
+ = 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. That's what the "lies_avail"
+is doing.
+
+
+%************************************************************************
+%* *
+\subsection{getTyVarsToGen}
+%* *
+%************************************************************************
+
+@getTyVarsToGen@ decides what type variables generalise over.
+
+For a "restricted group" -- see the monomorphism restriction
+for a definition -- we bind no dictionaries, and
+remove from tyvars_to_gen any constrained type variables
+
+*Don't* simplify dicts at this point, because we aren't going
+to generalise over these dicts. By the time we do simplify them
+we may well know more. For example (this actually came up)
+ f :: Array Int Int
+ f x = array ... xs where xs = [1,2,3,4,5]
+We don't want to generate lots of (fromInt Int 1), (fromInt Int 2)
+stuff. If we simplify only at the f-binding (not the xs-binding)
+we'll know that the literals are all Ints, and we can just produce
+Int literals!
+
+Find all the type variables involved in overloading, the
+"constrained_tyvars". These are the ones we *aren't* going to
+generalise. We must be careful about doing this:
+
+ (a) If we fail to generalise a tyvar which is not actually
+ constrained, then it will never, ever get bound, and lands
+ up printed out in interface files! Notorious example:
+ instance Eq a => Eq (Foo a b) where ..
+ Here, b is not constrained, even though it looks as if it is.
+ Another, more common, example is when there's a Method inst in
+ the LIE, whose type might very well involve non-overloaded
+ type variables.
+
+ (b) On the other hand, we mustn't generalise tyvars which are constrained,
+ because we are going to pass on out the unmodified LIE, with those
+ tyvars in it. They won't be in scope if we've generalised them.
+
+So we are careful, and do a complete simplification just to find the
+constrained tyvars. We don't use any of the results, except to
+find which tyvars are constrained.
+
+\begin{code}
+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 `minusVarSet` free_tyvars
+ in
+ if is_unrestricted
+ then
+ returnNF_Tc (emptyVarSet, tyvars_to_gen)
+ else
+ -- This recover and discard-errs is to avoid duplicate error
+ -- messages; this, after all, is an "extra" call to tcSimplify
+ recoverNF_Tc (returnNF_Tc (emptyVarSet, tyvars_to_gen)) $
+ discardErrsTc $
+
+ tcSimplify (text "getTVG") NotTopLevel tyvars_to_gen lie `thenTc` \ (_, _, constrained_dicts) ->
+ let
+ -- ASSERT: dicts_sig is already zonked!
+ constrained_tyvars = foldrBag (unionVarSet . tyVarsOfInst) emptyVarSet constrained_dicts
+ reduced_tyvars_to_gen = tyvars_to_gen `minusVarSet` constrained_tyvars
+ in
+ returnTc (constrained_tyvars, reduced_tyvars_to_gen)
\end{code}
+
+\begin{code}
+isUnRestrictedGroup :: [Name] -- Signatures given for these
+ -> RenamedMonoBinds
+ -> Bool
+
+is_elem v vs = isIn "isUnResMono" v vs
+
+isUnRestrictedGroup sigs (PatMonoBind (VarPatIn v) _ _) = v `is_elem` sigs
+isUnRestrictedGroup sigs (PatMonoBind other _ _) = False
+isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs
+isUnRestrictedGroup sigs (FunMonoBind _ _ _ _) = True
+isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 &&
+ isUnRestrictedGroup sigs mb2
+isUnRestrictedGroup sigs EmptyMonoBinds = True
+\end{code}
+
+@defaultUncommittedTyVar@ checks for generalisation over unboxed
+types, and defaults any TypeKind TyVars to BoxedTypeKind.
+
+\begin{code}
+defaultUncommittedTyVar tyvar
+ | tyVarKind tyvar == openTypeKind
+ = newTcTyVar boxedTypeKind `thenNF_Tc` \ boxed_tyvar ->
+ unifyTauTy (mkTyVarTy tyvar) (mkTyVarTy boxed_tyvar) `thenTc_`
+ returnTc boxed_tyvar
+
+ | otherwise
+ = returnTc tyvar
+\end{code}
+
+
%************************************************************************
%* *
-\subsection{Signatures}
+\subsection{tcMonoBind}
%* *
%************************************************************************
-@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.
+@tcMonoBinds@ deals with a single @MonoBind@.
+The signatures have been dealt with already.
\begin{code}
-tcTySigs :: [RenamedSig] -> TcM s [TcSigInfo s]
+tcMonoBinds :: RenamedMonoBinds
+ -> [TcSigInfo s]
+ -> RecFlag
+ -> TcM s (TcMonoBinds s,
+ LIE s, -- LIE required
+ [Name], -- Bound names
+ [TcIdBndr s]) -- Corresponding monomorphic bound things
+
+tcMonoBinds mbinds tc_ty_sigs is_rec
+ = tc_mb_pats mbinds `thenTc` \ (complete_it, lie_req_pat, tvs, ids, lie_avail) ->
+ let
+ tv_list = bagToList tvs
+ (names, mono_ids) = unzip (bagToList ids)
+ in
+ -- Don't know how to deal with pattern-bound existentials yet
+ checkTc (isEmptyBag tvs && isEmptyBag lie_avail)
+ (existentialExplode mbinds) `thenTc_`
+
+ -- *Before* checking the RHSs, but *after* checking *all* the patterns,
+ -- extend the envt with bindings for all the bound ids;
+ -- and *then* override with the polymorphic Ids from the signatures
+ -- That is the whole point of the "complete_it" stuff.
+ tcExtendEnvWithPat ids (tcExtendEnvWithPat sig_ids
+ complete_it
+ ) `thenTc` \ (mbinds', lie_req_rhss) ->
+ returnTc (mbinds', lie_req_pat `plusLIE` lie_req_rhss, names, mono_ids)
+ where
+ sig_fn name = case maybeSig tc_ty_sigs name of
+ Nothing -> Nothing
+ Just (TySigInfo _ _ _ _ _ mono_id _ _) -> Just mono_id
+
+ sig_ids = listToBag [(name,poly_id) | TySigInfo name poly_id _ _ _ _ _ _ <- tc_ty_sigs]
+
+ kind = case is_rec of
+ Recursive -> boxedTypeKind -- Recursive, so no unboxed types
+ NonRecursive -> openTypeKind -- Non-recursive, so we permit unboxed types
+
+ tc_mb_pats EmptyMonoBinds
+ = returnTc (returnTc (EmptyMonoBinds, emptyLIE), emptyLIE, emptyBag, emptyBag, emptyLIE)
+
+ tc_mb_pats (AndMonoBinds mb1 mb2)
+ = tc_mb_pats mb1 `thenTc` \ (complete_it1, lie_req1, tvs1, ids1, lie_avail1) ->
+ tc_mb_pats mb2 `thenTc` \ (complete_it2, lie_req2, tvs2, ids2, lie_avail2) ->
+ let
+ complete_it = complete_it1 `thenTc` \ (mb1', lie1) ->
+ complete_it2 `thenTc` \ (mb2', lie2) ->
+ returnTc (AndMonoBinds mb1' mb2', lie1 `plusLIE` lie2)
+ in
+ returnTc (complete_it,
+ lie_req1 `plusLIE` lie_req2,
+ tvs1 `unionBags` tvs2,
+ ids1 `unionBags` ids2,
+ lie_avail1 `plusLIE` lie_avail2)
+
+ tc_mb_pats (FunMonoBind name inf matches locn)
+ = newTyVarTy boxedTypeKind `thenNF_Tc` \ pat_ty ->
+ tcVarPat sig_fn name pat_ty `thenTc` \ bndr_id ->
+ let
+ complete_it = tcAddSrcLoc locn $
+ tcMatchesFun name pat_ty matches `thenTc` \ (matches', lie) ->
+ returnTc (FunMonoBind (TcId bndr_id) inf matches' locn, lie)
+ in
+ returnTc (complete_it, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE)
-tcTySigs (Sig v ty _ src_loc : other_sigs)
- = tcAddSrcLoc src_loc (
- tcPolyType ty `thenTc` \ sigma_ty ->
- tcInstType [] sigma_ty `thenNF_Tc` \ tc_sigma_ty ->
+ tc_mb_pats bind@(PatMonoBind pat grhss_and_binds locn)
+ = tcAddSrcLoc locn $
+ newTyVarTy kind `thenNF_Tc` \ pat_ty ->
+ tcPat sig_fn pat pat_ty `thenTc` \ (pat', lie_req, tvs, ids, lie_avail) ->
let
- (tyvars, theta, tau_ty) = splitSigmaTy tc_sigma_ty
+ complete_it = tcAddSrcLoc locn $
+ tcAddErrCtxt (patMonoBindsCtxt bind) $
+ tcGRHSsAndBinds grhss_and_binds pat_ty PatBindRhs `thenTc` \ (grhss_and_binds', lie) ->
+ returnTc (PatMonoBind pat' grhss_and_binds' locn, lie)
in
- tcLookupLocalValueOK "tcSig1" v `thenNF_Tc` \ val ->
- unifyTauTy (idType val) tau_ty `thenTc_`
- returnTc (TySigInfo val tyvars theta tau_ty src_loc)
- ) `thenTc` \ sig_info1 ->
+ returnTc (complete_it, lie_req, tvs, ids, lie_avail)
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{Signatures}
+%* *
+%************************************************************************
- tcTySigs other_sigs `thenTc` \ sig_infos ->
- returnTc (sig_info1 : sig_infos)
+@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.
-tcTySigs (other : sigs) = tcTySigs sigs
-tcTySigs [] = returnTc []
+The error message here is somewhat unsatisfactory, but it'll do for
+now (ToDo).
+
+\begin{code}
+checkSigMatch []
+ = returnTc (error "checkSigMatch", emptyLIE)
+
+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, sig_lie)
+ where
+ sig1_dict_tys = mk_dict_tys theta1
+ n_sig1_dict_tys = length sig1_dict_tys
+ sig_lie = mkLIE [inst | TySigInfo _ _ _ _ _ _ inst _ <- tc_ty_sigs]
+
+ check_one_cxt sig@(TySigInfo _ id _ theta _ _ _ src_loc)
+ = 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 _ id sig_tyvars _ sig_tau _ _ src_loc)
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxtM (sigCtxt (quotes (ppr id)) sig_tau) $
+ checkSigTyVars sig_tyvars
+
+ mk_dict_tys theta = [mkDictTy c ts | (c,ts) <- theta]
\end{code}
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
- TcHsBinds s,
+tcPragmaSigs :: [RenamedSig] -- The pragma signatures
+ -> TcM s (Name -> IdInfo, -- Maps name to the appropriate IdInfo
+ TcMonoBinds s,
LIE s)
-tcPragmaSigs sigs = returnTc ( \name -> NoPragmaInfo, EmptyBinds, emptyLIE )
-
-{-
tcPragmaSigs sigs
- = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (names_w_id_infos, binds, lies) ->
+ = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (maybe_info_modifiers, binds, lies) ->
let
- name_to_info name = foldr ($) noIdInfo
- [info_fn | (n,info_fn) <- names_w_id_infos, n==name]
+ prag_fn name = foldr ($) noIdInfo [f | Just (n,f) <- maybe_info_modifiers, n==name]
in
- returnTc (name_to_info,
- foldr ThenBinds EmptyBinds binds,
- foldr plusLIE emptyLIE lies)
-\end{code}
-
-Here are the easy cases for tcPragmaSigs
-
-\begin{code}
-tcPragmaSig (DeforestSig name loc)
- = returnTc ((name, addInfo DoDeforest),EmptyBinds,emptyLIE)
-tcPragmaSig (InlineSig name loc)
- = returnTc ((name, addInfo_UF (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE)
-tcPragmaSig (MagicUnfoldingSig name string loc)
- = returnTc ((name, addInfo_UF (mkMagicUnfolding string)), EmptyBinds, emptyLIE)
+ returnTc (prag_fn, andMonoBindList binds, plusLIEs lies)
\end{code}
The interesting case is for SPECIALISE pragmas. There are two forms.
a bit of overkill.
\begin{code}
-tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (valSpecSigCtxt name spec_ty) $
+tcPragmaSig :: RenamedSig -> TcM s (Maybe (Name, IdInfo -> IdInfo), TcMonoBinds s, LIE s)
+tcPragmaSig (Sig _ _ _) = returnTc (Nothing, EmptyMonoBinds, emptyLIE)
+tcPragmaSig (SpecInstSig _ _) = returnTc (Nothing, EmptyMonoBinds, emptyLIE)
- -- Get and instantiate its alleged specialised type
- tcPolyType poly_ty `thenTc` \ sig_sigma ->
- tcInstType [] (idType sig_sigma) `thenNF_Tc` \ sig_ty ->
- let
- (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
- origin = ValSpecOrigin name
- in
+tcPragmaSig (InlineSig name loc)
+ = returnTc (Just (name, setInlinePragInfo IWantToBeINLINEd), EmptyMonoBinds, emptyLIE)
- -- Check that the SPECIALIZE pragma had an empty context
- checkTc (null sig_theta)
- (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_`
+tcPragmaSig (NoInlineSig name loc)
+ = returnTc (Just (name, setInlinePragInfo IMustNotBeINLINEd), EmptyMonoBinds, emptyLIE)
- -- Get and instantiate the type of the id mentioned
- tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id ->
- tcInstType [] (idType main_id) `thenNF_Tc` \ main_ty ->
- let
- (main_tyvars, main_rho) = splitForAllTy main_ty
- (main_theta,main_tau) = splitRhoTy main_rho
- main_arg_tys = map mkTyVarTy main_tyvars
- in
+tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc)
+ = -- SPECIALISE f :: forall b. theta => tau = g
+ tcAddSrcLoc src_loc $
+ tcAddErrCtxt (valSpecSigCtxt name poly_ty) $
- -- Check that the specialised type is indeed an instance of
- -- the type of the main function.
- unifyTauTy sig_tau main_tau `thenTc_`
- checkSigTyVars sig_tyvars sig_tau main_tau `thenTc_`
-
- -- 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
- mapTc zonkTcType 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) ->
+ -- Get and instantiate its alleged specialised type
+ tcHsTcType poly_ty `thenTc` \ sig_ty ->
+
+ -- Check that f has a more general type, and build a RHS for
+ -- the spec-pragma-id at the same time
+ tcExpr (HsVar name) sig_ty `thenTc` \ (spec_expr, spec_lie) ->
+
+ case maybe_spec_name of
+ Nothing -> -- 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 ->
+ returnTc (Nothing, VarMonoBind (TcId spec_id) spec_expr, spec_lie)
+
+ Just g_name -> -- Don't create a SpecPragmaId. Instead add some suitable IdIfo
+
+ panic "Can't handle SPECIALISE with a '= g' part"
+
+ {- Not yet. Because we're still in the TcType world we
+ can't really add to the SpecEnv of the Id. Instead we have to
+ record the information in a different sort of Sig, and add it to
+ the IdInfo after zonking.
+
+ For now we just leave out this case
+
+ -- Get the type of f, and find out what types
+ -- f has to be instantiated at to give the signature type
+ tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ f_id ->
+ tcInstTcType (idType f_id) `thenNF_Tc` \ (f_tyvars, f_rho) ->
+
+ let
+ (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
+ (f_theta, f_tau) = splitRhoTy f_rho
+ sig_tyvar_set = mkVarSet sig_tyvars
+ in
+ unifyTauTy sig_tau f_tau `thenTc_`
+
+ tcPolyExpr str (HsVar g_name) (mkSigmaTy sig_tyvars f_theta sig_tau) `thenTc` \ (_, _,
+ -}
+
+tcPragmaSig other = pprTrace "tcPragmaSig: ignoring" (ppr other) $
+ returnTc (Nothing, EmptyMonoBinds, emptyLIE)
+\end{code}
- 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)
- Just spec_name -> -- Use spec_name as the specialisation value ...
+%************************************************************************
+%* *
+\subsection[TcBinds-errors]{Error contexts and messages}
+%* *
+%************************************************************************
- -- Type check a simple occurrence of the specialised Id
- tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) ->
- -- Check that it has the correct type, and doesn't constrain the
- -- signature variables at all
- unifyTauTy sig_tau spec_tau `thenTc_`
- checkSigTyVars sig_tyvars sig_tau spec_tau `thenTc_`
+\begin{code}
+patMonoBindsCtxt bind
+ = hang (ptext SLIT("In a pattern binding:")) 4 (ppr bind)
- -- Make a local SpecId to bind to applied spec_id
- newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id ->
+-----------------------------------------------
+valSpecSigCtxt v ty
+ = sep [ptext SLIT("In a SPECIALIZE pragma for a value:"),
+ nest 4 (ppr v <+> ptext SLIT(" ::") <+> ppr ty)]
- 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, addInfo spec_info), spec_binds, spec_lie)
--}
-\end{code}
+-----------------------------------------------
+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)
+ ])
-Error contexts and messages
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-patMonoBindsCtxt bind sty
- = ppHang (ppPStr SLIT("In a pattern binding:")) 4 (ppr sty bind)
-
---------------------------------------------
-specContextGroundnessCtxt -- err_ctxt dicts sty
- = panic "specContextGroundnessCtxt"
-{-
- = ppHang (
- ppSep [ppBesides [ppStr "In the SPECIALIZE pragma for `", ppr sty name, ppStr "'"],
- ppBesides [ppStr " specialised to the type `", ppr sty spec_ty, ppStr "'"],
- pp_spec_id sty,
- ppStr "... not all overloaded type variables were instantiated",
- ppStr "to ground types:"])
- 4 (ppAboves [ppCat [ppr sty c, ppr sty t]
- | (c,t) <- map getDictClassAndType dicts])
- where
- (name, spec_ty, locn, pp_spec_id)
- = case err_ctxt of
- ValSpecSigCtxt n ty loc -> (n, ty, loc, \ x -> ppNil)
- ValSpecSpecIdCtxt n ty spec loc ->
- (n, ty, loc,
- \ sty -> ppBesides [ppStr "... type of explicit id `", ppr sty spec, ppStr "'"])
--}
+-----------------------------------------------
+unboxedPatBindErr id
+ = ptext SLIT("variable in a lazy pattern binding has unboxed type: ")
+ <+> quotes (ppr id)
-----------------------------------------------
-specGroundnessCtxt
- = panic "specGroundnessCtxt"
+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)"))
-valSpecSigCtxt v ty sty
- = ppHang (ppPStr SLIT("In a SPECIALIZE pragma for a value:"))
- 4 (ppSep [ppBeside (pprNonOp sty v) (ppPStr SLIT(" ::")),
- ppr sty ty])
+-----------------------------------------------
+unliftedBindErr flavour mbind
+ = hang (text flavour <+> ptext SLIT("bindings for unlifted types aren't allowed"))
+ 4 (ppr mbind)
+
+existentialExplode mbinds
+ = hang (vcat [text "My brain just exploded.",
+ text "I can't handle pattern bindings for existentially-quantified constructors.",
+ text "In the binding group"])
+ 4 (ppr mbinds)
\end{code}
-
projects / ghc-hetmet.git / blobdiff