%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcBinds]{TcBinds}
\begin{code}
+module TcBinds ( tcBindsAndThen, tcTopBinds,
+ tcSpecSigs, tcBindWithSigs ) where
+
#include "HsVersions.h"
-module TcBinds ( tcBindsAndThen, tcPragmaSigs ) where
-
-import Ubiq
-
-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(..) )
-
-import TcMonad
-import GenSpecEtc ( checkSigTyVars, genBinds, TcSigInfo(..) )
-import Inst ( Inst, LIE(..), emptyLIE, plusLIE, InstOrigin(..) )
-import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newMonoIds )
-import TcLoop ( tcGRHSsAndBinds )
-import TcMatches ( tcMatchesFun )
-import TcMonoType ( tcPolyType )
-import TcPat ( tcPat )
+import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun )
+import {-# SOURCE #-} TcExpr ( tcExpr )
+
+import CmdLineOpts ( opt_NoMonomorphismRestriction )
+import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..),
+ Match(..), HsMatchContext(..),
+ collectMonoBinders, andMonoBinds,
+ collectSigTysFromMonoBinds
+ )
+import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds )
+import TcHsSyn ( TcMonoBinds, TcId, zonkId, mkHsLet )
+
+import TcMonad
+import Inst ( LIE, emptyLIE, mkLIE, plusLIE, InstOrigin(..),
+ newDicts, instToId
+ )
+import TcEnv ( tcExtendLocalValEnv, newLocalName )
+import TcUnify ( unifyTauTyLists, checkSigTyVars, sigCtxt )
+import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyRestricted, tcSimplifyToDicts )
+import TcMonoType ( tcHsSigType, UserTypeCtxt(..),
+ TcSigInfo(..), tcTySig, maybeSig, tcAddScopedTyVars
+ )
+import TcPat ( tcPat, tcSubPat, tcMonoPatBndr )
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 TcMType ( newTyVar, newTyVarTy, newHoleTyVarTy,
+ zonkTcTyVarToTyVar
+ )
+import TcType ( mkTyVarTy, mkForAllTys, mkFunTys, tyVarsOfType,
+ mkPredTy, mkForAllTy, isUnLiftedType,
+ unliftedTypeKind, liftedTypeKind, openTypeKind, eqKind
+ )
+
+import CoreFVs ( idFreeTyVars )
+import Id ( mkLocalId, mkSpecPragmaId, setInlinePragma )
+import Var ( idType, idName )
+import Name ( Name, getSrcLoc )
+import NameSet
+import Var ( tyVarKind )
+import VarSet
+import Bag
+import Util ( isIn, equalLength )
+import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isNotTopLevel,
+ isAlwaysActive )
+import FiniteMap ( listToFM, lookupFM )
+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
- -> RenamedHsBinds
- -> TcM s (thing, LIE s, thing_ty)
- -> TcM s (thing, LIE s, thing_ty)
-
-tcBindsAndThen combiner EmptyBinds do_next
- = do_next `thenTc` \ (thing, lie, thing_ty) ->
- returnTc (combiner EmptyBinds thing, lie, thing_ty)
-
-tcBindsAndThen combiner (SingleBind bind) do_next
- = tcBindAndThen combiner bind [] do_next
-
-tcBindsAndThen combiner (BindWith bind sigs) do_next
- = tcBindAndThen combiner bind sigs do_next
-
-tcBindsAndThen combiner (ThenBinds binds1 binds2) do_next
- = tcBindsAndThen combiner binds1 (tcBindsAndThen combiner binds2 do_next)
-\end{code}
+tcTopBinds :: RenamedHsBinds -> TcM ((TcMonoBinds, TcEnv), LIE)
+tcTopBinds binds
+ = tc_binds_and_then TopLevel glue binds $
+ tcGetEnv `thenNF_Tc` \ env ->
+ returnTc ((EmptyMonoBinds, env), emptyLIE)
+ where
+ glue is_rec binds1 (binds2, thing) = (binds1 `AndMonoBinds` binds2, thing)
-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 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
+ :: (RecFlag -> TcMonoBinds -> thing -> thing) -- Combinator
+ -> RenamedHsBinds
+ -> TcM (thing, LIE)
+ -> TcM (thing, LIE)
+
+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
+ = 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
+ = -- BRING ANY SCOPED TYPE VARIABLES INTO SCOPE
+ -- Notice that they scope over
+ -- a) the type signatures in the binding group
+ -- b) the bindings in the group
+ -- c) the scope of the binding group (the "in" part)
+ tcAddScopedTyVars (collectSigTysFromMonoBinds bind) $
+
+ -- 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] $
+
+ -- Build bindings and IdInfos corresponding to user pragmas
+ tcSpecSigs sigs `thenTc` \ (prag_binds, prag_lie) ->
-tcBindsAndThen (BindWith bind sigs) do_next
- = tcBindAndThen bind sigs do_next
+ -- Now do whatever happens next, in the augmented envt
+ do_next `thenTc` \ (thing, thing_lie) ->
-tcBindsAndThen (ThenBinds binds1 binds2) do_next
- = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next)
- `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) ->
+ -- Create specialisations of functions bound here
+ -- We want to keep non-recursive things non-recursive
+ -- so that we desugar unlifted bindings correctly
+ case (top_lvl, is_rec) of
+
+ -- For the top level don't bother will all this bindInstsOfLocalFuns stuff
+ -- All the top level things are rec'd together anyway, so it's fine to
+ -- leave them to the tcSimplifyTop, and quite a bit faster too
+ (TopLevel, _)
+ -> returnTc (combiner Recursive (poly_binds `andMonoBinds` prag_binds) thing,
+ thing_lie `plusLIE` prag_lie `plusLIE` poly_lie)
+
+ (NotTopLevel, NonRecursive)
+ -> bindInstsOfLocalFuns
+ (thing_lie `plusLIE` prag_lie)
+ poly_ids `thenTc` \ (thing_lie', lie_binds) ->
+
+ returnTc (
+ combiner NonRecursive poly_binds $
+ combiner NonRecursive prag_binds $
+ combiner Recursive lie_binds $
+ -- NB: the binds returned by tcSimplify and bindInstsOfLocalFuns
+ -- aren't guaranteed in dependency order (though we could change
+ -- that); hence the Recursive marker.
+ thing,
+
+ thing_lie' `plusLIE` poly_lie
+ )
+
+ (NotTopLevel, Recursive)
+ -> bindInstsOfLocalFuns
+ (thing_lie `plusLIE` poly_lie `plusLIE` prag_lie)
+ poly_ids `thenTc` \ (final_lie, lie_binds) ->
+
+ returnTc (
+ combiner Recursive (
+ poly_binds `andMonoBinds`
+ lie_binds `andMonoBinds`
+ prag_binds) thing,
+ final_lie
+ )
+\end{code}
- returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty)
-\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 $
+@tcBindWithSigs@ deals with a single binding group. It does generalisation,
+so all the clever stuff is in here.
- -- Build bindings and IdInfos corresponding to user pragmas
- tcPragmaSigs sigs `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
+* binder_names and mbind must define the same set of Names
- -- Now do whatever happens next, in the augmented envt
- do_next `thenTc` \ (thing, thing_lie, thing_ty) ->
+* The Names in tc_ty_sigs must be a subset of binder_names
- -- Create specialisations of functions bound here
- bindInstsOfLocalFuns (prag_lie `plusLIE` thing_lie)
- poly_ids `thenTc` \ (lie2, inst_mbinds) ->
+* The Ids in tc_ty_sigs don't necessarily have to have the same name
+ as the Name in the tc_ty_sig
- -- 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
-
-
-tcBindAndSigs binder_names bind sigs prag_info_fn
+\begin{code}
+tcBindWithSigs
+ :: TopLevelFlag
+ -> RenamedMonoBinds
+ -> [TcSigInfo]
+ -> [RenamedSig] -- Used solely to get INLINE, NOINLINE sigs
+ -> RecFlag
+ -> TcM (TcMonoBinds, LIE, [TcId])
+
+tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec
= 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 ->
+ newTyVar liftedTypeKind `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 = collectMonoBinders mbind
+ poly_ids = map mk_dummy binder_names
+ mk_dummy name = case maybeSig tc_ty_sigs name of
+ Just (TySigInfo _ poly_id _ _ _ _ _ _) -> poly_id -- Signature
+ Nothing -> mkLocalId name forall_a_a -- No signature
in
- returnTc (EmptyBinds, 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)
+ returnTc (EmptyMonoBinds, emptyLIE, poly_ids)
+ ) $
+
+ -- TYPECHECK THE BINDINGS
+ tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) ->
+ let
+ tau_tvs = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids
+ in
+
+ -- GENERALISE
+ tcAddSrcLoc (minimum (map getSrcLoc binder_names)) $
+ tcAddErrCtxt (genCtxt binder_names) $
+ generalise binder_names mbind tau_tvs lie_req tc_ty_sigs
+ `thenTc` \ (tc_tyvars_to_gen, lie_free, dict_binds, dict_ids) ->
+
+
+ -- ZONK THE GENERALISED TYPE VARIABLES TO REAL TyVars
+ -- This commits any unbound kind variables to boxed kind, by unification
+ -- It's important that the final quanfified type variables
+ -- are fully zonked, *including boxity*, because they'll be
+ -- included in the forall types of the polymorphic Ids.
+ -- At calls of these Ids we'll instantiate fresh type variables from
+ -- them, and we use their boxity then.
+ mapNF_Tc zonkTcTyVarToTyVar tc_tyvars_to_gen `thenNF_Tc` \ real_tyvars_to_gen ->
+
+ -- ZONK THE Ids
+ -- It's important that the dict Ids are zonked, including the boxity set
+ -- in the previous step, because they are later used to form the type of
+ -- the polymorphic thing, and forall-types must be zonked so far as
+ -- their bound variables are concerned
+ mapNF_Tc zonkId dict_ids `thenNF_Tc` \ zonked_dict_ids ->
+ mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids ->
+
+ -- CHECK FOR BOGUS UNLIFTED BINDINGS
+ checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind zonked_mono_ids `thenTc_`
+
+ -- BUILD THE POLYMORPHIC RESULT IDs
+ let
+ exports = zipWith mk_export binder_names zonked_mono_ids
+ dict_tys = map idType zonked_dict_ids
+
+ inlines = mkNameSet [name | InlineSig True name _ loc <- inline_sigs]
+ no_inlines = listToFM [(name, phase) | InlineSig _ name phase _ <- inline_sigs,
+ not (isAlwaysActive phase)]
+ -- AlwaysActive is the default, so don't bother with them
+
+ mk_export binder_name zonked_mono_id
+ = (tyvars,
+ attachNoInlinePrag no_inlines 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, new_poly_id)
+
+ new_poly_id = mkLocalId binder_name poly_ty
+ poly_ty = mkForAllTys real_tyvars_to_gen
+ $ mkFunTys dict_tys
+ $ idType zonked_mono_id
+ -- It's important to build a fully-zonked poly_ty, because
+ -- we'll slurp out its free type variables when extending the
+ -- local environment (tcExtendLocalValEnv); if it's not zonked
+ -- it appears to have free tyvars that aren't actually free
+ -- at all.
+ in
+
+ traceTc (text "binding:" <+> ppr ((zonked_dict_ids, dict_binds),
+ exports, [idType poly_id | (_, poly_id, _) <- exports])) `thenTc_`
+
+ -- BUILD RESULTS
+ returnTc (
+ AbsBinds real_tyvars_to_gen
+ zonked_dict_ids
+ exports
+ inlines
+ (dict_binds `andMonoBinds` mbind'),
+ lie_free,
+ [poly_id | (_, poly_id, _) <- exports]
)
- `thenTc` \ (mono_ids, bind', lie, sig_info) ->
- -- Notice that genBinds gets the old (non-extended) environment
- genBinds binder_names mono_ids bind' lie sig_info prag_info_fn
+attachNoInlinePrag no_inlines bndr
+ = case lookupFM no_inlines (idName bndr) of
+ Just prag -> bndr `setInlinePragma` prag
+ Nothing -> bndr
+
+checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind zonked_mono_ids
+ = ASSERT( not (any ((eqKind unliftedTypeKind) . tyVarKind) real_tyvars_to_gen) )
+ -- The instCantBeGeneralised stuff in tcSimplify should have
+ -- already raised an error if we're trying to generalise an
+ -- unboxed tyvar (NB: unboxed tyvars are always introduced
+ -- along with a class constraint) and it's better done there
+ -- because we have more precise origin information.
+ -- That's why we just use an ASSERT here.
+
+ -- Check that pattern-bound variables are not unlifted
+ (if or [ (idName id `elem` pat_binders) && isUnLiftedType (idType id)
+ | id <- zonked_mono_ids ] then
+ addErrTc (unliftedBindErr "Pattern" mbind)
+ else
+ returnTc ()
+ ) `thenTc_`
+
+ -- Unlifted bindings must be non-recursive,
+ -- not top level, non-polymorphic, and not pattern bound
+ if any (isUnLiftedType . idType) zonked_mono_ids then
+ checkTc (isNotTopLevel top_lvl)
+ (unliftedBindErr "Top-level" mbind) `thenTc_`
+ checkTc (isNonRec is_rec)
+ (unliftedBindErr "Recursive" mbind) `thenTc_`
+ checkTc (null real_tyvars_to_gen)
+ (unliftedBindErr "Polymorphic" mbind)
+ else
+ returnTc ()
+
where
- kind = case bind of
- NonRecBind _ -> mkBoxedTypeKind -- Recursive, so no unboxed types
- RecBind _ -> mkTypeKind -- Non-recursive, so we permit unboxed types
+ pat_binders :: [Name]
+ pat_binders = collectMonoBinders (justPatBindings mbind EmptyMonoBinds)
+
+ justPatBindings bind@(PatMonoBind _ _ _) binds = bind `andMonoBinds` binds
+ justPatBindings (AndMonoBinds b1 b2) binds =
+ justPatBindings b1 (justPatBindings b2 binds)
+ justPatBindings other_bind binds = binds
\end{code}
-\begin{code}
-tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s)
-tc_bind (NonRecBind mono_binds)
- = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
- returnTc (NonRecBind mono_binds2, lie)
+Polymorphic recursion
+~~~~~~~~~~~~~~~~~~~~~
+The game plan for polymorphic recursion in the code above is
-tc_bind (RecBind mono_binds)
- = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
- returnTc (RecBind mono_binds2, lie)
-\end{code}
+ * 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.
+
+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:
+
+ f :: Eq a => [a] -> [a]
+ f xs = ...f...
+
+If we don't take care, after typechecking we get
+
+ f = /\a -> \d::Eq a -> let f' = f a d
+ in
+ \ys:[a] -> ...f'...
+
+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
+
+ f = /\a -> \d::Eq a -> letrec
+ fm = \ys:[a] -> ...fm...
+ in
+ fm
+
+This can lead to a massive space leak, from the following top-level defn
+(post-typechecking)
+
+ ff :: [Int] -> [Int]
+ ff = f Int dEqInt
+
+Now (f dEqInt) evaluates to a lambda that has f' as a free variable; but
+f' is another thunk which evaluates to the same thing... and you end
+up with a chain of identical values all hung onto by the CAF ff.
+
+ ff = f Int dEqInt
+
+ = let f' = f Int dEqInt in \ys. ...f'...
+
+ = let f' = let f' = f Int dEqInt in \ys. ...f'...
+ in \ys. ...f'...
+
+Etc.
+Solution: when typechecking the RHSs we always have in hand the
+*monomorphic* Ids for each binding. So we just need to make sure that
+if (Method f a d) shows up in the constraints emerging from (...f...)
+we just use the monomorphic Id. We achieve this by adding monomorphic Ids
+to the "givens" when simplifying constraints. That's what the "lies_avail"
+is doing.
+
+
+%************************************************************************
+%* *
+\subsection{getTyVarsToGen}
+%* *
+%************************************************************************
\begin{code}
-tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s)
+generalise binder_names mbind tau_tvs lie_req sigs
+ | not is_unrestricted -- RESTRICTED CASE
+ = -- Check signature contexts are empty
+ checkTc (all is_mono_sig sigs)
+ (restrictedBindCtxtErr binder_names) `thenTc_`
-tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE)
+ -- Now simplify with exactly that set of tyvars
+ -- We have to squash those Methods
+ tcSimplifyRestricted doc tau_tvs lie_req `thenTc` \ (qtvs, lie_free, binds) ->
-tcMonoBinds (AndMonoBinds mb1 mb2)
- = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) ->
- tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) ->
- returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2)
+ -- Check that signature type variables are OK
+ checkSigsTyVars sigs `thenTc_`
-tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn)
- = tcAddSrcLoc locn $
+ returnTc (qtvs, lie_free, binds, [])
- -- LEFT HAND SIDE
- tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) ->
+ | null sigs -- UNRESTRICTED CASE, NO TYPE SIGS
+ = tcSimplifyInfer doc tau_tvs lie_req
- -- BINDINGS AND GRHSS
- tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) ->
+ | otherwise -- UNRESTRICTED CASE, WITH TYPE SIGS
+ = -- CHECKING CASE: Unrestricted group, there are type signatures
+ -- Check signature contexts are empty
+ checkSigsCtxts sigs `thenTc` \ (sig_avails, sig_dicts) ->
+
+ -- Check that the needed dicts can be
+ -- expressed in terms of the signature ones
+ tcSimplifyInferCheck doc tau_tvs sig_avails lie_req `thenTc` \ (forall_tvs, lie_free, dict_binds) ->
+
+ -- Check that signature type variables are OK
+ checkSigsTyVars sigs `thenTc_`
- -- Unify the two sides
- tcAddErrCtxt (patMonoBindsCtxt bind) $
- unifyTauTy pat_ty grhss_ty `thenTc_`
+ returnTc (forall_tvs, lie_free, dict_binds, sig_dicts)
- -- RETURN
- returnTc (PatMonoBind pat2 grhss_and_binds2 locn,
- plusLIE lie_pat lie)
+ where
+ is_unrestricted | opt_NoMonomorphismRestriction = True
+ | otherwise = isUnRestrictedGroup tysig_names mbind
+
+ tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- sigs]
+ is_mono_sig (TySigInfo _ _ _ theta _ _ _ _) = null theta
+
+ doc = ptext SLIT("type signature(s) for") <+> pprBinders binder_names
+
+-----------------------
+ -- CHECK THAT ALL THE SIGNATURE CONTEXTS ARE UNIFIABLE
+ -- The type signatures on a mutually-recursive group of definitions
+ -- must all have the same context (or none).
+ --
+ -- We unify them because, with polymorphic recursion, their types
+ -- might not otherwise be related. This is a rather subtle issue.
+ -- ToDo: amplify
+checkSigsCtxts sigs@(TySigInfo _ id1 sig_tvs theta1 _ _ _ src_loc : other_sigs)
+ = tcAddSrcLoc src_loc $
+ mapTc_ check_one other_sigs `thenTc_`
+ if null theta1 then
+ returnTc ([], []) -- Non-overloaded type signatures
+ else
+ newDicts SignatureOrigin theta1 `thenNF_Tc` \ sig_dicts ->
+ let
+ -- The "sig_avails" is the stuff available. We get that from
+ -- the context of the type signature, BUT ALSO the lie_avail
+ -- so that polymorphic recursion works right (see comments at end of fn)
+ sig_avails = sig_dicts ++ sig_meths
+ in
+ returnTc (sig_avails, map instToId sig_dicts)
+ where
+ sig1_dict_tys = map mkPredTy theta1
+ sig_meths = concat [insts | TySigInfo _ _ _ _ _ _ insts _ <- sigs]
+
+ check_one sig@(TySigInfo _ id _ theta _ _ _ src_loc)
+ = tcAddErrCtxt (sigContextsCtxt id1 id) $
+ checkTc (equalLength theta theta1) sigContextsErr `thenTc_`
+ unifyTauTyLists sig1_dict_tys (map mkPredTy theta)
+
+checkSigsTyVars sigs = mapTc_ check_one sigs
+ where
+ check_one (TySigInfo _ id sig_tyvars sig_theta sig_tau _ _ src_loc)
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (ptext SLIT("When checking the type signature for")
+ <+> quotes (ppr id)) $
+ tcAddErrCtxtM (sigCtxt sig_tyvars sig_theta sig_tau) $
+ checkSigTyVars sig_tyvars (idFreeTyVars id)
+\end{code}
-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)
+@getTyVarsToGen@ decides what type variables to 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.
+ [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
+ 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}
+isUnRestrictedGroup :: [Name] -- Signatures given for these
+ -> RenamedMonoBinds
+ -> Bool
+
+is_elem v vs = isIn "isUnResMono" v vs
+
+isUnRestrictedGroup sigs (PatMonoBind other _ _) = False
+isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs
+isUnRestrictedGroup sigs (FunMonoBind v _ matches _) = isUnRestrictedMatch matches ||
+ v `is_elem` sigs
+isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 &&
+ isUnRestrictedGroup sigs mb2
+isUnRestrictedGroup sigs EmptyMonoBinds = True
+
+isUnRestrictedMatch (Match [] _ _ : _) = False -- No args => like a pattern binding
+isUnRestrictedMatch other = True -- Some args => a function binding
\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]
+ -> RecFlag
+ -> TcM (TcMonoBinds,
+ LIE, -- LIE required
+ [Name], -- Bound names
+ [TcId]) -- Corresponding monomorphic bound things
+
+tcMonoBinds mbinds tc_ty_sigs is_rec
+ = tc_mb_pats mbinds `thenTc` \ (complete_it, lie_req_pat, tvs, ids, lie_avail) ->
+ let
+ id_list = bagToList ids
+ (names, mono_ids) = unzip id_list
+
+ -- This last defn is the key one:
+ -- extend the val envt with bindings for the
+ -- things bound in this group, overriding the monomorphic
+ -- ids with the polymorphic ones from the pattern
+ extra_val_env = case is_rec of
+ Recursive -> map mk_bind id_list
+ NonRecursive -> []
+ in
+ -- Don't know how to deal with pattern-bound existentials yet
+ checkTc (isEmptyBag tvs && isEmptyBag lie_avail)
+ (existentialExplode mbinds) `thenTc_`
+
+ -- *Before* checking the RHSs, but *after* checking *all* the patterns,
+ -- extend the envt with bindings for all the bound ids;
+ -- and *then* override with the polymorphic Ids from the signatures
+ -- That is the whole point of the "complete_it" stuff.
+ --
+ -- There's a further wrinkle: we have to delay extending the environment
+ -- until after we've dealt with any pattern-bound signature type variables
+ -- Consider f (x::a) = ...f...
+ -- We're going to check that a isn't unified with anything in the envt,
+ -- so f itself had better not be! So we pass the envt binding f into
+ -- complete_it, which extends the actual envt in TcMatches.tcMatch, after
+ -- dealing with the signature tyvars
+
+ complete_it extra_val_env `thenTc` \ (mbinds', lie_req_rhss) ->
+
+ returnTc (mbinds', lie_req_pat `plusLIE` lie_req_rhss, names, mono_ids)
+ where
-tcTySigs (Sig v ty _ src_loc : other_sigs)
- = tcAddSrcLoc src_loc (
- tcPolyType ty `thenTc` \ sigma_ty ->
- tcInstType [] sigma_ty `thenNF_Tc` \ tc_sigma_ty ->
+ mk_bind (name, mono_id) = case maybeSig tc_ty_sigs name of
+ Nothing -> (name, mono_id)
+ Just (TySigInfo name poly_id _ _ _ _ _ _) -> (name, poly_id)
+
+ tc_mb_pats EmptyMonoBinds
+ = returnTc (\ xve -> returnTc (EmptyMonoBinds, emptyLIE), emptyLIE, emptyBag, emptyBag, emptyLIE)
+
+ tc_mb_pats (AndMonoBinds mb1 mb2)
+ = tc_mb_pats mb1 `thenTc` \ (complete_it1, lie_req1, tvs1, ids1, lie_avail1) ->
+ tc_mb_pats mb2 `thenTc` \ (complete_it2, lie_req2, tvs2, ids2, lie_avail2) ->
+ let
+ complete_it xve = complete_it1 xve `thenTc` \ (mb1', lie1) ->
+ complete_it2 xve `thenTc` \ (mb2', lie2) ->
+ returnTc (AndMonoBinds mb1' mb2', lie1 `plusLIE` lie2)
+ in
+ returnTc (complete_it,
+ lie_req1 `plusLIE` lie_req2,
+ tvs1 `unionBags` tvs2,
+ ids1 `unionBags` ids2,
+ lie_avail1 `plusLIE` lie_avail2)
+
+ tc_mb_pats (FunMonoBind name inf matches locn)
+ = (case maybeSig tc_ty_sigs name of
+ Just (TySigInfo _ _ _ _ _ mono_id _ _)
+ -> returnNF_Tc mono_id
+ Nothing -> newLocalName name `thenNF_Tc` \ bndr_name ->
+ newTyVarTy openTypeKind `thenNF_Tc` \ bndr_ty ->
+ -- NB: not a 'hole' tyvar; since there is no type
+ -- signature, we revert to ordinary H-M typechecking
+ -- which means the variable gets an inferred tau-type
+ returnNF_Tc (mkLocalId bndr_name bndr_ty)
+ ) `thenNF_Tc` \ bndr_id ->
let
- (tyvars, theta, tau_ty) = splitSigmaTy tc_sigma_ty
+ bndr_ty = idType bndr_id
+ complete_it xve = tcAddSrcLoc locn $
+ tcMatchesFun xve name bndr_ty matches `thenTc` \ (matches', lie) ->
+ returnTc (FunMonoBind bndr_id inf matches' 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, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE)
+
+ tc_mb_pats bind@(PatMonoBind pat grhss locn)
+ = tcAddSrcLoc locn $
+ newHoleTyVarTy `thenNF_Tc` \ pat_ty ->
- tcTySigs other_sigs `thenTc` \ sig_infos ->
- returnTc (sig_info1 : sig_infos)
+ -- 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.
-tcTySigs (other : sigs) = tcTySigs sigs
-tcTySigs [] = returnTc []
+ tcPat tc_pat_bndr pat pat_ty `thenTc` \ (pat', lie_req, tvs, ids, lie_avail) ->
+ let
+ complete_it xve = tcAddSrcLoc locn $
+ tcAddErrCtxt (patMonoBindsCtxt bind) $
+ tcExtendLocalValEnv xve $
+ tcGRHSs PatBindRhs grhss pat_ty `thenTc` \ (grhss', lie) ->
+ returnTc (PatMonoBind pat' grhss' locn, lie)
+ in
+ returnTc (complete_it, lie_req, tvs, ids, lie_avail)
+
+ -- tc_pat_bndr is used when dealing with a LHS binder in a pattern.
+ -- If there was a type sig for that Id, we want to make it much
+ -- as if that type signature had been on the binder as a SigPatIn.
+ -- We check for a type signature; if there is one, we use the mono_id
+ -- from the signature. This is how we make sure the tau part of the
+ -- signature actually matches the type of the LHS; then tc_mb_pats
+ -- ensures the LHS and RHS have the same type
+
+ tc_pat_bndr name pat_ty
+ = case maybeSig tc_ty_sigs name of
+ Nothing
+ -> newLocalName name `thenNF_Tc` \ bndr_name ->
+ tcMonoPatBndr bndr_name pat_ty
+
+ Just (TySigInfo _ _ _ _ _ mono_id _ _)
+ -> tcAddSrcLoc (getSrcLoc name) $
+ tcSubPat pat_ty (idType mono_id) `thenTc` \ (co_fn, lie) ->
+ returnTc (co_fn, lie, mono_id)
\end{code}
%* *
%************************************************************************
-
-@tcPragmaSigs@ munches up the "signatures" that arise through *user*
+@tcSpecSigs@ munches up the specialisation "signatures" that arise through *user*
pragmas. It is convenient for them to appear in the @[RenamedSig]@
part of a binding because then the same machinery can be used for
moving them into place as is done for type signatures.
-\begin{code}
-tcPragmaSigs :: [RenamedSig] -- The pragma signatures
- -> TcM s (Name -> PragmaInfo, -- Maps name to the appropriate PragmaInfo
- TcHsBinds s,
- LIE s)
-
-tcPragmaSigs sigs = returnTc ( \name -> NoPragmaInfo, EmptyBinds, emptyLIE )
-
-{-
-tcPragmaSigs sigs
- = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (names_w_id_infos, binds, lies) ->
- let
- name_to_info name = foldr ($) noIdInfo
- [info_fn | (n,info_fn) <- names_w_id_infos, n==name]
- in
- returnTc (name_to_info,
- foldr ThenBinds EmptyBinds binds,
- foldr plusLIE emptyLIE lies)
-\end{code}
-
-Here are the easy cases for tcPragmaSigs
-
-\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)
-\end{code}
+They look like this:
-The interesting case is for SPECIALISE pragmas. There are two forms.
-Here's the first form:
\begin{verbatim}
f :: Ord a => [a] -> b -> b
{-# SPECIALIZE f :: [Int] -> b -> b #-}
Int, and will create a specialisation for @f@. After that, the
binding for @f*@ can be discarded.
-The second form is this:
-\begin{verbatim}
- f :: Ord a => [a] -> b -> b
- {-# SPECIALIZE f :: [Int] -> b -> b = g #-}
-\end{verbatim}
-
-Here @g@ is specified as a function that implements the specialised
-version of @f@. Suppose that g has type (a->b->b); that is, g's type
-is more general than that required. For this we generate
-\begin{verbatim}
- f@Int = /\b -> g Int b
- f* = f@Int
-\end{verbatim}
-
-Here @f@@Int@ is a SpecId, the specialised version of @f@. It inherits
-f's export status etc. @f*@ is a SpecPragmaId, as before, which just serves
-to prevent @f@@Int@ from being discarded prematurely. After specialisation,
-if @f@@Int@ is going to be used at all it will be used explicitly, so the simplifier can
-discard the f* binding.
-
-Actually, there is really only point in giving a SPECIALISE pragma on exported things,
-and the simplifer won't discard SpecIds for exporte things anyway, so maybe this is
-a bit of overkill.
+We used to have a form
+ {-# SPECIALISE f :: <type> = g #-}
+which promised that g implemented f at <type>, but we do that with
+a RULE now:
+ {-# SPECIALISE (f::<type) = g #-}
\begin{code}
-tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (valSpecSigCtxt name spec_ty) $
+tcSpecSigs :: [RenamedSig] -> TcM (TcMonoBinds, LIE)
+tcSpecSigs (SpecSig name poly_ty src_loc : sigs)
+ = -- SPECIALISE f :: forall b. theta => tau = g
+ tcAddSrcLoc src_loc $
+ tcAddErrCtxt (valSpecSigCtxt name poly_ty) $
-- Get and instantiate its alleged specialised type
- 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
+ tcHsSigType (FunSigCtxt name) poly_ty `thenTc` \ sig_ty ->
- -- Check that the SPECIALIZE pragma had an empty context
- checkTc (null sig_theta)
- (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_`
+ -- 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) ->
- -- Get and instantiate the type of the id mentioned
- tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id ->
- tcInstType [] (idType main_id) `thenNF_Tc` \ main_ty ->
+ -- Squeeze out any Methods (see comments with tcSimplifyToDicts)
+ tcSimplifyToDicts spec_lie `thenTc` \ (spec_dicts, 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.
+ newLocalName name `thenNF_Tc` \ spec_name ->
let
- (main_tyvars, main_rho) = splitForAllTy main_ty
- (main_theta,main_tau) = splitRhoTy main_rho
- main_arg_tys = map mkTyVarTy main_tyvars
+ spec_bind = VarMonoBind (mkSpecPragmaId spec_name sig_ty)
+ (mkHsLet spec_binds spec_expr)
in
- -- 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) ->
+ -- Do the rest and combine
+ tcSpecSigs sigs `thenTc` \ (binds_rest, lie_rest) ->
+ returnTc (binds_rest `andMonoBinds` spec_bind,
+ lie_rest `plusLIE` mkLIE spec_dicts)
- 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)
+tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs
+tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE)
+\end{code}
- Just spec_name -> -- Use spec_name as the specialisation value ...
- -- Type check a simple occurrence of the specialised Id
- tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) ->
+%************************************************************************
+%* *
+\subsection[TcBinds-errors]{Error contexts and messages}
+%* *
+%************************************************************************
- -- 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_`
- -- Make a local SpecId to bind to applied spec_id
- newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id ->
+\begin{code}
+patMonoBindsCtxt bind
+ = hang (ptext SLIT("In a pattern binding:")) 4 (ppr bind)
- 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}
+-----------------------------------------------
+valSpecSigCtxt v ty
+ = sep [ptext SLIT("In a SPECIALIZE pragma for a value:"),
+ nest 4 (ppr v <+> dcolon <+> ppr ty)]
+-----------------------------------------------
+sigContextsErr = ptext SLIT("Mismatched contexts")
-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 "'"])
--}
+sigContextsCtxt s1 s2
+ = 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")]
-----------------------------------------------
-specGroundnessCtxt
- = panic "specGroundnessCtxt"
+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)
-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])
+-----------------------------------------------
+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