%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcInstDecls]{Typechecking instance declarations}
\begin{code}
-#include "HsVersions.h"
-
module TcInstDcls (
tcInstDecls1,
- tcInstDecls2,
- processInstBinds
+ tcInstDecls2
) where
+#include "HsVersions.h"
-IMP_Ubiq()
-
-import HsSyn ( HsDecl(..), InstDecl(..), TyDecl, ClassDecl, DefaultDecl,
- FixityDecl, IfaceSig, Sig(..),
- SpecInstSig(..), HsBinds(..), Bind(..),
- MonoBinds(..), GRHSsAndBinds, Match,
- InPat(..), OutPat(..), HsExpr(..), HsLit(..),
- Stmt, Qualifier, ArithSeqInfo, Fake,
- HsType(..), HsTyVar )
-import RnHsSyn ( SYN_IE(RenamedHsBinds), SYN_IE(RenamedMonoBinds),
- SYN_IE(RenamedInstDecl), SYN_IE(RenamedFixityDecl),
- SYN_IE(RenamedSig), SYN_IE(RenamedSpecInstSig), SYN_IE(RenamedHsDecl)
+import HsSyn ( HsDecl(..), InstDecl(..),
+ HsBinds(..), MonoBinds(..),
+ HsExpr(..), InPat(..), HsLit(..), Sig(..),
+ collectMonoBinders, andMonoBindList
+ )
+import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl )
+import TcHsSyn ( TcMonoBinds,
+ maybeBoxedPrimType
)
-import TcHsSyn ( TcIdOcc(..), SYN_IE(TcHsBinds),
- SYN_IE(TcMonoBinds), SYN_IE(TcExpr), tcIdType,
- mkHsTyLam, mkHsTyApp,
- mkHsDictLam, mkHsDictApp )
-
-import TcMonad
-import RnMonad ( SYN_IE(RnNameSupply) )
-import GenSpecEtc ( checkSigTyVars )
-import Inst ( Inst, InstOrigin(..), SYN_IE(InstanceMapper),
- newDicts, newMethod, SYN_IE(LIE), emptyLIE, plusLIE )
import TcBinds ( tcPragmaSigs )
+import TcClassDcl ( tcMethodBind, badMethodErr )
+import TcMonad
+import RnMonad ( RnNameSupply )
+import Inst ( Inst, InstOrigin(..),
+ newDicts, LIE, emptyLIE, plusLIE, plusLIEs )
import TcDeriv ( tcDeriving )
-import TcEnv ( tcLookupClass, newLocalId, tcExtendGlobalTyVars )
-import SpecEnv ( SpecEnv )
-import TcGRHSs ( tcGRHSsAndBinds )
-import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs )
-import TcKind ( TcKind, unifyKind )
-import TcMatches ( tcMatchesFun )
-import TcMonoType ( tcTyVarScope, tcContext, tcHsTypeKind )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( SYN_IE(TcType), SYN_IE(TcTyVar), SYN_IE(TcTyVarSet),
- tcInstSigTyVars, tcInstType, tcInstTheta, tcInstTcType
+import TcEnv ( ValueEnv, tcExtendGlobalValEnv, tcExtendTyVarEnvForMeths,
+ tcAddImportedIdInfo, tcInstId
)
-import Unify ( unifyTauTy, unifyTauTyLists )
-
+import TcInstUtil ( InstInfo(..), classDataCon )
+import TcMonoType ( tcHsTopType )
+import TcSimplify ( tcSimplifyAndCheck )
+import TcType ( TcTyVar, zonkTcTyVarBndr )
import Bag ( emptyBag, unitBag, unionBags, unionManyBags,
- concatBag, foldBag, bagToList )
-import CmdLineOpts ( opt_GlasgowExts, opt_CompilingGhcInternals,
- opt_OmitDefaultInstanceMethods,
- opt_SpecialiseOverloaded
+ foldBag, bagToList, Bag
)
-import Class ( GenClass, GenClassOp,
- classBigSig, classOps, classOpLocalType,
- classOpTagByOccName_maybe
- )
-import Id ( GenId, idType, isDefaultMethodId_maybe, isNullaryDataCon, dataConArgTys )
-import PrelInfo ( isCcallishClass )
-import ListSetOps ( minusList )
-import Maybes ( maybeToBool, expectJust )
-import Name ( getOccString, occNameString, moduleString, isLocallyDefined, OccName, Name{--O only-} )
-import PrelVals ( nO_EXPLICIT_METHOD_ERROR_ID )
-import PprType ( GenType, GenTyVar, GenClass, GenClassOp, TyCon,
- pprParendGenType
+import CmdLineOpts ( opt_GlasgowExts, opt_AllowUndecidableInstances )
+import Class ( classBigSig, Class )
+import Var ( setIdInfo, idName, idType, Id, TyVar )
+import DataCon ( isNullaryDataCon, dataConArgTys, dataConId )
+import Maybes ( maybeToBool, catMaybes, expectJust )
+import MkId ( mkDictFunId )
+import Name ( nameOccName, isLocallyDefined, Module,
+ NamedThing(..)
)
-import PprStyle
+import PrelVals ( eRROR_ID )
+import PprType ( pprConstraint )
import SrcLoc ( SrcLoc )
-import Pretty
-import TyCon ( isSynTyCon, derivedFor )
-import Type ( GenType(..), SYN_IE(ThetaType), mkTyVarTys,
- splitSigmaTy, splitAppTy, isTyVarTy, matchTy, mkSigmaTy,
- getTyCon_maybe, maybeAppTyCon,
- maybeBoxedPrimType, maybeAppDataTyCon, splitRhoTy, eqTy
+import TyCon ( isSynTyCon, isDataTyCon, tyConDerivings )
+import Type ( Type, isUnLiftedType, mkTyVarTys,
+ splitSigmaTy, isTyVarTy,
+ splitTyConApp_maybe, splitDictTy_maybe,
+ splitAlgTyConApp_maybe,
+ tyVarsOfTypes, substTopTheta
)
-import TyVar ( GenTyVar, SYN_IE(GenTyVarSet), mkTyVarSet, unionTyVarSets )
+import VarEnv ( zipVarEnv )
+import VarSet ( mkVarSet, varSetElems )
import TysPrim ( byteArrayPrimTyCon, mutableByteArrayPrimTyCon )
import TysWiredIn ( stringTy )
-import Unique ( Unique, cCallableClassKey, cReturnableClassKey )
-import Util ( zipEqual, panic, pprPanic, pprTrace )
+import Unique ( Unique, cCallableClassKey, cReturnableClassKey, Uniquable(..) )
+import Outputable
\end{code}
Typechecking instance declarations is done in two passes. The first
\end{enumerate}
\begin{code}
-tcInstDecls1 :: [RenamedHsDecl]
+tcInstDecls1 :: ValueEnv -- Contains IdInfo for dfun ids
+ -> [RenamedHsDecl]
-> Module -- module name for deriving
-> RnNameSupply -- for renaming derivings
-> TcM s (Bag InstInfo,
- RenamedHsBinds,
- PprStyle -> Pretty)
+ RenamedHsBinds)
-tcInstDecls1 decls mod_name rn_name_supply
+tcInstDecls1 unf_env decls mod_name rn_name_supply
= -- Do the ordinary instance declarations
- mapNF_Tc (tcInstDecl1 mod_name)
+ mapNF_Tc (tcInstDecl1 unf_env mod_name)
[inst_decl | InstD inst_decl <- decls] `thenNF_Tc` \ inst_info_bags ->
let
decl_inst_info = unionManyBags inst_info_bags
in
-- Handle "derived" instances; note that we only do derivings
-- for things in this module; we ignore deriving decls from
- -- interfaces! We pass fixities, because they may be used
- -- in deriving Read and Show.
+ -- interfaces!
tcDeriving mod_name rn_name_supply decl_inst_info
- `thenTc` \ (deriv_inst_info, deriv_binds, ddump_deriv) ->
+ `thenTc` \ (deriv_inst_info, deriv_binds) ->
let
full_inst_info = deriv_inst_info `unionBags` decl_inst_info
in
- returnTc (full_inst_info, deriv_binds, ddump_deriv)
+ returnTc (full_inst_info, deriv_binds)
-tcInstDecl1 :: Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo)
+tcInstDecl1 :: ValueEnv -> Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo)
-tcInstDecl1 mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src_loc)
+tcInstDecl1 unf_env mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src_loc)
= -- Prime error recovery, set source location
recoverNF_Tc (returnNF_Tc emptyBag) $
tcAddSrcLoc src_loc $
- -- Look things up
- tcLookupClass class_name `thenTc` \ (clas_kind, clas) ->
-
- -- Typecheck the context and instance type
- tcTyVarScope tyvar_names (\ tyvars ->
- tcContext context `thenTc` \ theta ->
- tcHsTypeKind inst_ty `thenTc` \ (tau_kind, tau) ->
- unifyKind clas_kind tau_kind `thenTc_`
- returnTc (tyvars, theta, tau)
- ) `thenTc` \ (inst_tyvars, inst_theta, inst_tau) ->
+ -- Type-check all the stuff before the "where"
+ tcHsTopType poly_ty `thenTc` \ poly_ty' ->
+ let
+ (tyvars, theta, dict_ty) = splitSigmaTy poly_ty'
+ (clas, inst_tys) = case splitDictTy_maybe dict_ty of
+ Nothing -> pprPanic "tcInstDecl1" (ppr poly_ty)
+ Just pair -> pair
+ in
- -- Check for respectable instance type
- scrutiniseInstanceType dfun_name clas inst_tau
- `thenTc` \ (inst_tycon,arg_tys) ->
+ -- Check for respectable instance type, and context
+ scrutiniseInstanceHead clas inst_tys `thenNF_Tc_`
+ mapNF_Tc scrutiniseInstanceConstraint theta `thenNF_Tc_`
-- Make the dfun id and constant-method ids
- mkInstanceRelatedIds dfun_name
- clas inst_tyvars inst_tau inst_theta
- `thenNF_Tc` \ (dfun_id, dfun_theta) ->
+ let
+ dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta
- returnTc (unitBag (InstInfo clas inst_tyvars inst_tau inst_theta
- dfun_theta dfun_id
+ -- Add info from interface file
+ final_dfun_id = tcAddImportedIdInfo unf_env dfun_id
+ in
+ returnTc (unitBag (InstInfo clas tyvars inst_tys theta
+ final_dfun_id
binds src_loc uprags))
- where
- (tyvar_names, context, dict_ty) = case poly_ty of
- HsForAllTy tvs cxt dict_ty -> (tvs, cxt, dict_ty)
- other -> ([], [], poly_ty)
- (class_name, inst_ty) = case dict_ty of
- MonoDictTy cls ty -> (cls,ty)
- other -> pprPanic "Malformed intance decl" (ppr PprDebug poly_ty)
\end{code}
\begin{code}
tcInstDecls2 :: Bag InstInfo
- -> NF_TcM s (LIE s, TcHsBinds s)
+ -> NF_TcM s (LIE, TcMonoBinds)
tcInstDecls2 inst_decls
- = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyBinds)) inst_decls
+ = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyMonoBinds)) inst_decls
where
combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) ->
tc2 `thenNF_Tc` \ (lie2, binds2) ->
returnNF_Tc (lie1 `plusLIE` lie2,
- binds1 `ThenBinds` binds2)
+ binds1 `AndMonoBinds` binds2)
\end{code}
First comes the easy case of a non-local instance decl.
\begin{code}
-tcInstDecl2 :: InstInfo
- -> NF_TcM s (LIE s, TcHsBinds s)
+tcInstDecl2 :: InstInfo -> NF_TcM s (LIE, TcMonoBinds)
-tcInstDecl2 (InstInfo clas inst_tyvars inst_ty
- inst_decl_theta dfun_theta
+tcInstDecl2 (InstInfo clas inst_tyvars inst_tys
+ inst_decl_theta
dfun_id monobinds
locn uprags)
| not (isLocallyDefined dfun_id)
+ = returnNF_Tc (emptyLIE, EmptyMonoBinds)
+
+{-
+ -- I deleted this "optimisation" because when importing these
+ -- instance decls the renamer would look for the dfun bindings and they weren't there.
+ -- This would be fixable, but it seems simpler just to produce a tiny void binding instead,
+ -- even though it's never used.
+
+ -- This case deals with CCallable etc, which don't need any bindings
+ | isNoDictClass clas
= returnNF_Tc (emptyLIE, EmptyBinds)
+-}
| otherwise
= -- Prime error recovery
- recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyBinds)) $
- tcAddSrcLoc locn $
-
- -- Get the class signature
- tcInstSigTyVars inst_tyvars `thenNF_Tc` \ (inst_tyvars', _, tenv) ->
- let
- (class_tyvar,
- super_classes, sc_sel_ids,
- class_ops, op_sel_ids, defm_ids) = classBigSig clas
- in
- tcInstType tenv inst_ty `thenNF_Tc` \ inst_ty' ->
- tcInstTheta tenv dfun_theta `thenNF_Tc` \ dfun_theta' ->
- tcInstTheta tenv inst_decl_theta `thenNF_Tc` \ inst_decl_theta' ->
+ recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
+ tcAddSrcLoc locn $
+
+ -- Instantiate the instance decl with tc-style type variables
+ tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') ->
let
- sc_theta' = super_classes `zip` repeat inst_ty'
- origin = InstanceDeclOrigin
- mk_method sel_id = newMethod origin (RealId sel_id) [inst_ty']
+ (clas, inst_tys') = expectJust "tcInstDecl2" (splitDictTy_maybe dict_ty')
+
+ origin = InstanceDeclOrigin
+
+ (class_tyvars,
+ sc_theta, sc_sel_ids,
+ op_sel_ids, defm_ids) = classBigSig clas
+
+ -- Instantiate the theta found in the original instance decl
+ inst_decl_theta' = substTopTheta (zipVarEnv inst_tyvars (mkTyVarTys inst_tyvars'))
+ inst_decl_theta
+
+ -- Instantiate the super-class context with inst_tys
+ sc_theta' = substTopTheta (zipVarEnv class_tyvars inst_tys') sc_theta
in
-- Create dictionary Ids from the specified instance contexts.
newDicts origin sc_theta' `thenNF_Tc` \ (sc_dicts, sc_dict_ids) ->
newDicts origin dfun_theta' `thenNF_Tc` \ (dfun_arg_dicts, dfun_arg_dicts_ids) ->
newDicts origin inst_decl_theta' `thenNF_Tc` \ (inst_decl_dicts, _) ->
- newDicts origin [(clas,inst_ty')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
-
- -- Create method variables
- mapAndUnzipNF_Tc mk_method op_sel_ids `thenNF_Tc` \ (meth_insts_s, meth_ids) ->
+ newDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
- -- Collect available Insts
+ -- Check that all the method bindings come from this class
let
- inst_tyvars_set' = mkTyVarSet inst_tyvars'
+ check_from_this_class (bndr, loc)
+ | nameOccName bndr `elem` sel_names = returnNF_Tc ()
+ | otherwise = tcAddSrcLoc loc $
+ addErrTc (badMethodErr bndr clas)
+ sel_names = map getOccName op_sel_ids
+ bndrs = bagToList (collectMonoBinders monobinds)
+ in
+ mapNF_Tc check_from_this_class bndrs `thenNF_Tc_`
+
+ tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' (
+ tcExtendGlobalValEnv (catMaybes defm_ids) (
+ -- Default-method Ids may be mentioned in synthesised RHSs
- avail_insts -- These insts are in scope; quite a few, eh?
- = unionManyBags (this_dict : dfun_arg_dicts : meth_insts_s)
+ mapAndUnzip3Tc (tcMethodBind clas origin inst_tyvars' inst_tys' inst_decl_theta'
+ monobinds uprags True)
+ (op_sel_ids `zip` defm_ids)
+ )) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) ->
- mk_method_expr
- = makeInstanceDeclDefaultMethodExpr locn clas meth_ids defm_ids inst_ty' this_dict_id
+ -- Deal with SPECIALISE instance pragmas
+ let
+ dfun_prags = [Sig (idName dfun_id) ty loc | SpecInstSig ty loc <- uprags]
in
- tcExtendGlobalTyVars inst_tyvars_set' (
- processInstBinds clas mk_method_expr avail_insts meth_ids monobinds
- ) `thenTc` \ (insts_needed, method_mbinds) ->
+ tcExtendGlobalValEnv [dfun_id] (
+ tcPragmaSigs dfun_prags
+ ) `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
+
+ -- Check the overloading constraints of the methods and superclasses
+
+ -- tcMethodBind has checked that the class_tyvars havn't
+ -- been unified with each other or another type, but we must
+ -- still zonk them
+ mapNF_Tc zonkTcTyVarBndr inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars ->
let
- -- Create the dict and method binds
- dict_bind
- = VarMonoBind this_dict_id (Dictionary sc_dict_ids meth_ids)
+ inst_tyvars_set = mkVarSet zonked_inst_tyvars
- dict_and_method_binds
- = dict_bind `AndMonoBinds` method_mbinds
+ (meth_lies, meth_ids) = unzip meth_lies_w_ids
+ -- These insts are in scope; quite a few, eh?
+ avail_insts = this_dict `plusLIE`
+ dfun_arg_dicts `plusLIE`
+ sc_dicts `plusLIE`
+ unionManyBags meth_lies
+
+ methods_lie = plusLIEs insts_needed_s
in
- -- Check the overloading constraints of the methods and superclasses
- tcAddErrCtxt (bindSigCtxt meth_ids) (
- tcSimplifyAndCheck
- inst_tyvars_set' -- Local tyvars
- avail_insts
- (sc_dicts `unionBags` insts_needed) -- Need to get defns for all these
- ) `thenTc` \ (const_lie, super_binds) ->
+ -- Ditto method bindings
+ tcAddErrCtxt methodCtxt (
+ tcSimplifyAndCheck
+ (ptext SLIT("instance declaration context"))
+ inst_tyvars_set -- Local tyvars
+ avail_insts
+ methods_lie
+ ) `thenTc` \ (const_lie1, lie_binds1) ->
+
-- Check that we *could* construct the superclass dictionaries,
-- even though we are *actually* going to pass the superclass dicts in;
- -- the check ensures that the caller will never have a problem building
- -- them.
- tcAddErrCtxt superClassSigCtxt (
- tcSimplifyAndCheck
- inst_tyvars_set' -- Local tyvars
+ -- the check ensures that the caller will never have
+ --a problem building them.
+ tcAddErrCtxt superClassCtxt (
+ tcSimplifyAndCheck
+ (ptext SLIT("instance declaration context"))
+ inst_tyvars_set -- Local tyvars
inst_decl_dicts -- The instance dictionaries available
sc_dicts -- The superclass dicationaries reqd
- ) `thenTc_`
- -- Ignore the result; we're only doing
+ ) `thenTc` \ _ ->
+ -- Ignore the result; we're only doing
-- this to make sure it can be done.
- -- Now process any SPECIALIZE pragmas for the methods
- let
- spec_sigs = [ s | s@(SpecSig _ _ _ _) <- uprags ]
- in
- tcPragmaSigs spec_sigs `thenTc` \ (_, spec_binds, spec_lie) ->
+ -- Now do the simplification again, this time to get the
+ -- bindings; this time we use an enhanced "avails"
+ -- Ignore errors because they come from the *previous* tcSimplify
+ discardErrsTc (
+ tcSimplifyAndCheck
+ (ptext SLIT("instance declaration context"))
+ inst_tyvars_set
+ dfun_arg_dicts -- NB! Don't include this_dict here, else the sc_dicts
+ -- get bound by just selecting from this_dict!!
+ sc_dicts
+ ) `thenTc` \ (const_lie2, lie_binds2) ->
+
+
+ -- Create the result bindings
let
- -- Complete the binding group, adding any spec_binds
- inst_binds
+ dict_constr = classDataCon clas
+ scs_and_meths = sc_dict_ids ++ meth_ids
+
+ dict_rhs
+ | null scs_and_meths
+ = -- Blatant special case for CCallable, CReturnable
+ -- If the dictionary is empty then we should never
+ -- select anything from it, so we make its RHS just
+ -- emit an error message. This in turn means that we don't
+ -- mention the constructor, which doesn't exist for CCallable, CReturnable
+ -- Hardly beautiful, but only three extra lines.
+ HsApp (TyApp (HsVar eRROR_ID) [idType this_dict_id])
+ (HsLitOut (HsString msg) stringTy)
+
+ | otherwise -- The common case
+ = foldl HsApp (TyApp (HsVar (dataConId dict_constr)) inst_tys')
+ (map HsVar (sc_dict_ids ++ meth_ids))
+ -- We don't produce a binding for the dict_constr; instead we
+ -- rely on the simplifier to unfold this saturated application
+ -- We do this rather than generate an HsCon directly, because
+ -- it means that the special cases (e.g. dictionary with only one
+ -- member) are dealt with by the common MkId.mkDataConId code rather
+ -- than needing to be repeated here.
+
+ where
+ msg = _PK_ ("Compiler error: bad dictionary " ++ showSDoc (ppr clas))
+
+ dict_bind = VarMonoBind this_dict_id dict_rhs
+ method_binds = andMonoBindList method_binds_s
+
+ final_dfun_id = setIdInfo dfun_id (prag_info_fn (idName dfun_id))
+ -- Pretty truesome
+ main_bind
= AbsBinds
- inst_tyvars'
+ zonked_inst_tyvars
dfun_arg_dicts_ids
- [(this_dict_id, RealId dfun_id)]
- super_binds
- (RecBind dict_and_method_binds)
-
- `ThenBinds`
- spec_binds
+ [(inst_tyvars', final_dfun_id, this_dict_id)]
+ (lie_binds1 `AndMonoBinds`
+ lie_binds2 `AndMonoBinds`
+ method_binds `AndMonoBinds`
+ dict_bind)
in
-
- returnTc (const_lie `plusLIE` spec_lie, inst_binds)
-\end{code}
-
-The next function makes a default method which calls the global default method, at
-the appropriate instance type.
-
-See the notes under default decls in TcClassDcl.lhs.
-
-\begin{code}
-makeInstanceDeclDefaultMethodExpr
- :: SrcLoc
- -> Class
- -> [TcIdOcc s]
- -> [Id]
- -> TcType s
- -> TcIdOcc s
- -> Int
- -> NF_TcM s (TcExpr s)
-
-makeInstanceDeclDefaultMethodExpr src_loc clas meth_ids defm_ids inst_ty this_dict tag
- | not defm_is_err -- Not sure that the default method is just error message
- = -- def_op_id = defm_id inst_ty this_dict
- returnNF_Tc (mkHsDictApp (mkHsTyApp (HsVar (RealId defm_id)) [inst_ty]) [this_dict])
-
- | otherwise -- There's definitely no default decl in the class,
- -- so we produce a warning, and a better run=time error message too
- = warnTc True (omitDefaultMethodWarn clas_op clas_name inst_ty)
- `thenNF_Tc_`
-
- returnNF_Tc (HsApp (mkHsTyApp (HsVar (RealId nO_EXPLICIT_METHOD_ERROR_ID)) [tcIdType meth_id])
- (HsLitOut (HsString (_PK_ error_msg)) stringTy))
- where
- idx = tag - 1
- meth_id = meth_ids !! idx
- defm_id = defm_ids !! idx
-
- Just (_, _, defm_is_err) = isDefaultMethodId_maybe defm_id
-
- error_msg = ppShow 80 (ppSep [ppr PprForUser clas_op, ppStr "at", ppr PprForUser src_loc])
-
- clas_op = (classOps clas) !! idx
- clas_name = getOccString clas
+ returnTc (const_lie1 `plusLIE` const_lie2 `plusLIE` prag_lie,
+ main_bind `AndMonoBinds` prag_binds)
\end{code}
-
%************************************************************************
%* *
-\subsection{Processing each method}
+\subsection{Checking for a decent instance type}
%* *
%************************************************************************
-@processInstBinds@ returns a @MonoBinds@ which binds
-all the method ids (which are passed in). It is used
- - both for instance decls,
- - and to compile the default-method declarations in a class decl.
-
-Any method ids which don't have a binding have a suitable default
-binding created for them. The actual right-hand side used is
-created using a function which is passed in, because the right thing to
-do differs between instance and class decls.
-
-\begin{code}
-processInstBinds
- :: Class
- -> (Int -> NF_TcM s (TcExpr s)) -- Function to make default method
- -> LIE s -- available Insts
- -> [TcIdOcc s] -- Local method ids in tag order
- -- (instance tyvars are free in their types)
- -> RenamedMonoBinds
- -> TcM s (LIE s, -- These are required
- TcMonoBinds s)
-
-processInstBinds clas mk_default_method_rhs avail_insts method_ids monobinds
- =
- -- Process the explicitly-given method bindings
- processInstBinds1 clas avail_insts method_ids monobinds
- `thenTc` \ (tags, insts_needed_in_methods, method_binds) ->
-
- -- Find the methods not handled, and make default method bindings for them.
- let
- unmentioned_tags = [1.. length method_ids] `minusList` tags
- in
- mapNF_Tc mk_default_method unmentioned_tags
- `thenNF_Tc` \ default_bind_list ->
-
- returnTc (insts_needed_in_methods,
- foldr AndMonoBinds method_binds default_bind_list)
- where
- -- From a tag construct us the passed-in function to construct
- -- the binding for the default method
- mk_default_method tag = mk_default_method_rhs tag `thenNF_Tc` \ rhs ->
- returnNF_Tc (VarMonoBind (method_ids !! (tag-1)) rhs)
-\end{code}
-
-\begin{code}
-processInstBinds1
- :: Class
- -> LIE s -- available Insts
- -> [TcIdOcc s] -- Local method ids in tag order (instance tyvars are free),
- -> RenamedMonoBinds
- -> TcM s ([Int], -- Class-op tags accounted for
- LIE s, -- These are required
- TcMonoBinds s)
-
-processInstBinds1 clas avail_insts method_ids EmptyMonoBinds
- = returnTc ([], emptyLIE, EmptyMonoBinds)
-
-processInstBinds1 clas avail_insts method_ids (AndMonoBinds mb1 mb2)
- = processInstBinds1 clas avail_insts method_ids mb1
- `thenTc` \ (op_tags1,dicts1,method_binds1) ->
- processInstBinds1 clas avail_insts method_ids mb2
- `thenTc` \ (op_tags2,dicts2,method_binds2) ->
- returnTc (op_tags1 ++ op_tags2,
- dicts1 `unionBags` dicts2,
- AndMonoBinds method_binds1 method_binds2)
-\end{code}
-
-\begin{code}
-processInstBinds1 clas avail_insts method_ids mbind
- =
- -- Find what class op is being defined here. The complication is
- -- that we could have a PatMonoBind or a FunMonoBind. If the
- -- former, it should only bind a single variable, or else we're in
- -- trouble (I'm not sure what the static semantics of methods
- -- defined in a pattern binding with multiple patterns is!)
- -- Renamer has reduced us to these two cases.
- let
- (op,locn) = case mbind of
- FunMonoBind op _ _ locn -> (op, locn)
- PatMonoBind (VarPatIn op) _ locn -> (op, locn)
-
- occ = getOccName op
- origin = InstanceDeclOrigin
- in
- tcAddSrcLoc locn $
-
- -- Make a method id for the method
- let
- maybe_tag = classOpTagByOccName_maybe clas occ
- (Just tag) = maybe_tag
- method_id = method_ids !! (tag-1)
- method_ty = tcIdType method_id
- in
- -- check that the method mentioned is actually in the class:
- checkMaybeTc maybe_tag (instMethodNotInClassErr occ clas) `thenTc_`
-
- tcInstTcType method_ty `thenNF_Tc` \ (method_tyvars, method_rho) ->
- let
- (method_theta, method_tau) = splitRhoTy method_rho
- in
- newDicts origin method_theta `thenNF_Tc` \ (method_dicts,method_dict_ids) ->
-
- case (method_tyvars, method_dict_ids) of
-
- ([],[]) -> -- The simple case; no local polymorphism or overloading in the method
-
- -- Type check the method itself
- tcMethodBind method_id method_tau mbind `thenTc` \ (mbind', lieIop) ->
- returnTc ([tag], lieIop, mbind')
-
- other -> -- It's a locally-polymorphic and/or overloaded method; UGH!
-
- -- Make a new id for (a) the local, non-overloaded method
- -- and (b) the locally-overloaded method
- -- The latter is needed just so we can return an AbsBinds wrapped
- -- up inside a MonoBinds.
-
-
- -- Make the method_tyvars into signature tyvars so they
- -- won't get unified with anything.
- tcInstSigTyVars method_tyvars `thenNF_Tc` \ (sig_tyvars, sig_tyvar_tys, _) ->
- unifyTauTyLists sig_tyvar_tys (mkTyVarTys method_tyvars) `thenTc_`
-
- newLocalId occ method_tau `thenNF_Tc` \ local_id ->
- newLocalId occ method_ty `thenNF_Tc` \ copy_id ->
- let
- tc_local_id = TcId local_id
- tc_copy_id = TcId copy_id
- sig_tyvar_set = mkTyVarSet sig_tyvars
- in
- -- Typecheck the method
- tcMethodBind tc_local_id method_tau mbind `thenTc` \ (mbind', lieIop) ->
-
- -- Check the overloading part of the signature.
-
- -- =========== POSSIBLE BUT NOT DONE =================
- -- Simplify everything fully, even though some
- -- constraints could "really" be left to the next
- -- level out. The case which forces this is
- --
- -- class Foo a where { op :: Bar a => a -> a }
- --
- -- Here we must simplify constraints on "a" to catch all
- -- the Bar-ish things.
-
- -- We don't do this because it's currently illegal Haskell (not sure why),
- -- and because the local type of the method would have a context at
- -- the front with no for-all, which confuses the hell out of everything!
- -- ====================================================
-
- tcAddErrCtxt (methodSigCtxt op method_ty) (
- checkSigTyVars
- sig_tyvars method_tau `thenTc_`
-
- tcSimplifyAndCheck
- sig_tyvar_set
- (method_dicts `plusLIE` avail_insts)
- lieIop
- ) `thenTc` \ (f_dicts, dict_binds) ->
-
-
- returnTc ([tag],
- f_dicts,
- VarMonoBind method_id
- (HsLet
- (AbsBinds
- method_tyvars
- method_dict_ids
- [(tc_local_id, tc_copy_id)]
- dict_binds
- (NonRecBind mbind'))
- (HsVar tc_copy_id)))
-\end{code}
-
-\begin{code}
-tcMethodBind :: TcIdOcc s -> TcType s -> RenamedMonoBinds
- -> TcM s (TcMonoBinds s, LIE s)
-
-tcMethodBind meth_id meth_ty (FunMonoBind name inf matches locn)
- = tcMatchesFun name meth_ty matches `thenTc` \ (rhs', lie) ->
- returnTc (FunMonoBind meth_id inf rhs' locn, lie)
-
-tcMethodBind meth_id meth_ty pbind@(PatMonoBind pat grhss_and_binds locn)
- -- pat is sure to be a (VarPatIn op)
- = tcAddErrCtxt (patMonoBindsCtxt pbind) $
- tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds', lie, rhs_ty) ->
- unifyTauTy meth_ty rhs_ty `thenTc_`
- returnTc (PatMonoBind (VarPat meth_id) grhss_and_binds' locn, lie)
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Type-checking specialise instance pragmas}
-%* *
-%************************************************************************
-
-\begin{code}
-{- LATER
-tcSpecInstSigs :: E -> CE -> TCE
- -> Bag InstInfo -- inst decls seen (declared and derived)
- -> [RenamedSpecInstSig] -- specialise instance upragmas
- -> TcM (Bag InstInfo) -- new, overlapped, inst decls
-
-tcSpecInstSigs e ce tce inst_infos []
- = returnTc emptyBag
-
-tcSpecInstSigs e ce tce inst_infos sigs
- = buildInstanceEnvs inst_infos `thenTc` \ inst_mapper ->
- tc_inst_spec_sigs inst_mapper sigs `thenNF_Tc` \ spec_inst_infos ->
- returnTc spec_inst_infos
- where
- tc_inst_spec_sigs inst_mapper []
- = returnNF_Tc emptyBag
- tc_inst_spec_sigs inst_mapper (sig:sigs)
- = tcSpecInstSig e ce tce inst_infos inst_mapper sig `thenNF_Tc` \ info_sig ->
- tc_inst_spec_sigs inst_mapper sigs `thenNF_Tc` \ info_sigs ->
- returnNF_Tc (info_sig `unionBags` info_sigs)
-
-tcSpecInstSig :: E -> CE -> TCE
- -> Bag InstInfo
- -> InstanceMapper
- -> RenamedSpecInstSig
- -> NF_TcM (Bag InstInfo)
-
-tcSpecInstSig e ce tce inst_infos inst_mapper (SpecInstSig class_name ty src_loc)
- = recoverTc emptyBag (
- tcAddSrcLoc src_loc (
- let
- clas = lookupCE ce class_name -- Renamer ensures this can't fail
-
- -- Make some new type variables, named as in the specialised instance type
- ty_names = extractHsTyNames ???is_tyvarish_name??? ty
- (tmpl_e,inst_tmpls,inst_tmpl_tys) = mkTVE ty_names
- in
- babyTcMtoTcM (tcInstanceType ce tce tmpl_e True src_loc ty)
- `thenTc` \ inst_ty ->
- let
- maybe_tycon = case maybeAppDataTyCon inst_ty of
- Just (tc,_,_) -> Just tc
- Nothing -> Nothing
-
- maybe_unspec_inst = lookup_unspec_inst clas maybe_tycon inst_infos
- in
- -- Check that we have a local instance declaration to specialise
- checkMaybeTc maybe_unspec_inst
- (specInstUnspecInstNotFoundErr clas inst_ty src_loc) `thenTc_`
-
- -- Create tvs to substitute for tmpls while simplifying the context
- copyTyVars inst_tmpls `thenNF_Tc` \ (tv_e, inst_tvs, inst_tv_tys) ->
- let
- Just (InstInfo _ unspec_tyvars unspec_inst_ty unspec_theta
- _ _ binds _ uprag) = maybe_unspec_inst
-
- subst = case matchTy unspec_inst_ty inst_ty of
- Just subst -> subst
- Nothing -> panic "tcSpecInstSig:matchTy"
-
- subst_theta = instantiateThetaTy subst unspec_theta
- subst_tv_theta = instantiateThetaTy tv_e subst_theta
-
- mk_spec_origin clas ty
- = InstanceSpecOrigin inst_mapper clas ty src_loc
- -- I'm VERY SUSPICIOUS ABOUT THIS
- -- the inst-mapper is in a knot at this point so it's no good
- -- looking at it in tcSimplify...
- in
- tcSimplifyThetas mk_spec_origin subst_tv_theta
- `thenTc` \ simpl_tv_theta ->
- let
- simpl_theta = [ (clas, tv_to_tmpl tv) | (clas, tv) <- simpl_tv_theta ]
-
- tv_tmpl_map = zipEqual "tcSpecInstSig" inst_tv_tys inst_tmpl_tys
- tv_to_tmpl tv = assoc "tcSpecInstSig" tv_tmpl_map tv
- in
- mkInstanceRelatedIds
- clas inst_tmpls inst_ty simpl_theta uprag
- `thenNF_Tc` \ (dfun_id, dfun_theta, const_meth_ids) ->
-
- getSwitchCheckerTc `thenNF_Tc` \ sw_chkr ->
- (if sw_chkr SpecialiseTrace then
- pprTrace "Specialised Instance: "
- (ppAboves [ppCat [if null simpl_theta then ppNil else ppr PprDebug simpl_theta,
- if null simpl_theta then ppNil else ppStr "=>",
- ppr PprDebug clas,
- pprParendGenType PprDebug inst_ty],
- ppCat [ppStr " derived from:",
- if null unspec_theta then ppNil else ppr PprDebug unspec_theta,
- if null unspec_theta then ppNil else ppStr "=>",
- ppr PprDebug clas,
- pprParendGenType PprDebug unspec_inst_ty]])
- else id) (
-
- returnTc (unitBag (InstInfo clas inst_tmpls inst_ty simpl_theta
- dfun_theta dfun_id
- binds src_loc uprag))
- )))
-
-
-lookup_unspec_inst clas maybe_tycon inst_infos
- = case filter (match_info match_inst_ty) (bagToList inst_infos) of
- [] -> Nothing
- (info:_) -> Just info
- where
- match_info match_ty (InstInfo inst_clas _ inst_ty _ _ _ _ _ from_here _ _ _)
- = from_here && clas == inst_clas &&
- match_ty inst_ty && is_plain_instance inst_ty
-
- match_inst_ty = case maybe_tycon of
- Just tycon -> match_tycon tycon
- Nothing -> match_fun
-
- match_tycon tycon inst_ty = case (maybeAppDataTyCon inst_ty) of
- Just (inst_tc,_,_) -> tycon == inst_tc
- Nothing -> False
-
- match_fun inst_ty = isFunType inst_ty
-
-
-is_plain_instance inst_ty
- = case (maybeAppDataTyCon inst_ty) of
- Just (_,tys,_) -> all isTyVarTemplateTy tys
- Nothing -> case maybeUnpackFunTy inst_ty of
- Just (arg, res) -> isTyVarTemplateTy arg && isTyVarTemplateTy res
- Nothing -> error "TcInstDecls:is_plain_instance"
--}
-\end{code}
-
-
-Checking for a decent instance type
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-@scrutiniseInstanceType@ checks the type {\em and} its syntactic constraints:
+@scrutiniseInstanceHead@ checks the type {\em and} its syntactic constraints:
it must normally look like: @instance Foo (Tycon a b c ...) ...@
The exceptions to this syntactic checking: (1)~if the @GlasgowExts@
We can also have instances for functions: @instance Foo (a -> b) ...@.
\begin{code}
-scrutiniseInstanceType dfun_name clas inst_tau
- -- TYCON CHECK
- | not (maybeToBool inst_tycon_maybe) || isSynTyCon inst_tycon
- = failTc (instTypeErr inst_tau)
-
- -- IMPORTED INSTANCES ARE OK (but see tcInstDecl1)
- | not (isLocallyDefined dfun_name)
- = returnTc (inst_tycon,arg_tys)
-
- -- TYVARS CHECK
- | not (all isTyVarTy arg_tys ||
- opt_GlasgowExts)
- = failTc (instTypeErr inst_tau)
+scrutiniseInstanceConstraint (clas, tys)
+ | all isTyVarTy tys
+ || opt_AllowUndecidableInstances = returnNF_Tc ()
+ | otherwise = addErrTc (instConstraintErr clas tys)
+
+scrutiniseInstanceHead clas inst_taus
+ | -- CCALL CHECK (a).... urgh!
+ -- To verify that a user declaration of a CCallable/CReturnable
+ -- instance is OK, we must be able to see the constructor(s)
+ -- of the instance type (see next guard.)
+ --
+ -- We flag this separately to give a more precise error msg.
+ --
+ (getUnique clas == cCallableClassKey || getUnique clas == cReturnableClassKey)
+ && is_alg_tycon_app && not constructors_visible
+ = addErrTc (invisibleDataConPrimCCallErr clas first_inst_tau)
+
+ | -- CCALL CHECK (b)
+ -- A user declaration of a CCallable/CReturnable instance
+ -- must be for a "boxed primitive" type.
+ (getUnique clas == cCallableClassKey && not (ccallable_type first_inst_tau)) ||
+ (getUnique clas == cReturnableClassKey && not (creturnable_type first_inst_tau))
+ = addErrTc (nonBoxedPrimCCallErr clas first_inst_tau)
-- DERIVING CHECK
-- It is obviously illegal to have an explicit instance
-- for something that we are also planning to `derive'
- -- Though we can have an explicit instance which is more
- -- specific than the derived instance
- | clas `derivedFor` inst_tycon
- && all isTyVarTy arg_tys
- = failTc (derivingWhenInstanceExistsErr clas inst_tycon)
-
- | -- CCALL CHECK
- -- A user declaration of a CCallable/CReturnable instance
- -- must be for a "boxed primitive" type.
- (uniqueOf clas == cCallableClassKey && not (ccallable_type inst_tau)) ||
- (uniqueOf clas == cReturnableClassKey && not (creturnable_type inst_tau))
- = failTc (nonBoxedPrimCCallErr clas inst_tau)
+ | maybeToBool alg_tycon_app_maybe && clas `elem` (tyConDerivings alg_tycon)
+ = addErrTc (derivingWhenInstanceExistsErr clas first_inst_tau)
+ -- Kind check will have ensured inst_taus is of length 1
+
+ -- Allow anything for AllowUndecidableInstances
+ | opt_AllowUndecidableInstances
+ = returnNF_Tc ()
+
+ -- If GlasgowExts then check at least one isn't a type variable
+ | opt_GlasgowExts
+ = if all isTyVarTy inst_taus then
+ addErrTc (instTypeErr clas inst_taus (text "There must be at least one non-type-variable in the instance head"))
+ else
+ returnNF_Tc ()
+
+ -- WITH HASKELL 1.4, MUST HAVE C (T a b c)
+ | not (length inst_taus == 1 &&
+ maybeToBool maybe_tycon_app && -- Yes, there's a type constuctor
+ not (isSynTyCon tycon) && -- ...but not a synonym
+ all isTyVarTy arg_tys && -- Applied to type variables
+ length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys
+ -- This last condition checks that all the type variables are distinct
+ )
+ = addErrTc (instTypeErr clas inst_taus
+ (text "the instance type must be of form (T a b c)" $$
+ text "where T is not a synonym, and a,b,c are distinct type variables")
+ )
| otherwise
- = returnTc (inst_tycon,arg_tys)
+ = returnNF_Tc ()
where
- (possible_tycon, arg_tys) = splitAppTy inst_tau
- inst_tycon_maybe = getTyCon_maybe possible_tycon
- inst_tycon = expectJust "tcInstDecls1:inst_tycon" inst_tycon_maybe
+ (first_inst_tau : _) = inst_taus
+
+ -- Stuff for algebraic or -> type
+ maybe_tycon_app = splitTyConApp_maybe first_inst_tau
+ Just (tycon, arg_tys) = maybe_tycon_app
+
+ -- Stuff for an *algebraic* data type
+ alg_tycon_app_maybe = splitAlgTyConApp_maybe first_inst_tau
+ -- The "Alg" part looks through synonyms
+ is_alg_tycon_app = maybeToBool alg_tycon_app_maybe
+ Just (alg_tycon, _, data_cons) = alg_tycon_app_maybe
+
+ constructors_visible = not (null data_cons)
+
-- These conditions come directly from what the DsCCall is capable of.
-- Totally grotesque. Green card should solve this.
-ccallable_type ty = maybeToBool (maybeBoxedPrimType ty) ||
- ty `eqTy` stringTy ||
+ccallable_type ty = isUnLiftedType ty || -- Allow CCallable Int# etc
+ maybeToBool (maybeBoxedPrimType ty) || -- Ditto Int etc
+ ty == stringTy ||
byte_arr_thing
where
- byte_arr_thing = case maybeAppDataTyCon ty of
- Just (tycon, ty_args, [data_con]) ->
--- pprTrace "cc1" (ppSep [ppr PprDebug tycon, ppr PprDebug data_con,
--- ppSep (map (ppr PprDebug) data_con_arg_tys)])(
+ byte_arr_thing = case splitAlgTyConApp_maybe ty of
+ Just (tycon, ty_args, [data_con]) | isDataTyCon tycon ->
length data_con_arg_tys == 2 &&
maybeToBool maybe_arg2_tycon &&
--- pprTrace "cc2" (ppSep [ppr PprDebug arg2_tycon]) (
(arg2_tycon == byteArrayPrimTyCon ||
arg2_tycon == mutableByteArrayPrimTyCon)
--- ))
where
data_con_arg_tys = dataConArgTys data_con ty_args
(data_con_arg_ty1 : data_con_arg_ty2 : _) = data_con_arg_tys
- maybe_arg2_tycon = maybeAppTyCon data_con_arg_ty2
+ maybe_arg2_tycon = splitTyConApp_maybe data_con_arg_ty2
Just (arg2_tycon,_) = maybe_arg2_tycon
other -> False
creturnable_type ty = maybeToBool (maybeBoxedPrimType ty) ||
-- Or, a data type with a single nullary constructor
- case (maybeAppDataTyCon ty) of
+ case (splitAlgTyConApp_maybe ty) of
Just (tycon, tys_applied, [data_con])
-> isNullaryDataCon data_con
other -> False
\end{code}
\begin{code}
-
-instTypeErr ty sty
- = case ty of
- SynTy tc _ _ -> ppBesides [ppStr "The type synonym `", ppr sty tc, rest_of_msg]
- TyVarTy tv -> ppBesides [ppStr "The type variable `", ppr sty tv, rest_of_msg]
- other -> ppBesides [ppStr "The type `", ppr sty ty, rest_of_msg]
- where
- rest_of_msg = ppStr "' cannot be used as an instance type."
-
-derivingWhenInstanceExistsErr clas tycon sty
- = ppHang (ppBesides [ppStr "Deriving class `", ppr sty clas, ppStr "' type `", ppr sty tycon, ppStr "'"])
- 4 (ppStr "when an explicit instance exists")
-
-derivingWhenInstanceImportedErr inst_mod clas tycon sty
- = ppHang (ppBesides [ppStr "Deriving class `", ppr sty clas, ppStr "' type `", ppr sty tycon, ppStr "'"])
- 4 (ppBesides [ppStr "when an instance declared in module `", pp_mod, ppStr "' has been imported"])
- where
- pp_mod = ppBesides [ppStr "module `", ppPStr inst_mod, ppStr "'"]
-
-nonBoxedPrimCCallErr clas inst_ty sty
- = ppHang (ppStr "Unacceptable instance type for ccall-ish class")
- 4 (ppBesides [ ppStr "class `", ppr sty clas, ppStr "' type `",
- ppr sty inst_ty, ppStr "'"])
-
-omitDefaultMethodWarn clas_op clas_name inst_ty sty
- = ppCat [ppStr "Warning: Omitted default method for",
- ppr sty clas_op, ppStr "in instance",
- ppStr clas_name, pprParendGenType sty inst_ty]
-
-instMethodNotInClassErr occ clas sty
- = ppHang (ppStr "Instance mentions a method not in the class")
- 4 (ppBesides [ppStr "class `", ppr sty clas, ppStr "' method `",
- ppr sty occ, ppStr "'"])
-
-patMonoBindsCtxt pbind sty
- = ppHang (ppStr "In a pattern binding:")
- 4 (ppr sty pbind)
-
-methodSigCtxt name ty sty
- = ppHang (ppBesides [ppStr "When matching the definition of class method `",
- ppr sty name, ppStr "' to its signature :" ])
- 4 (ppr sty ty)
-
-bindSigCtxt method_ids sty
- = ppHang (ppStr "When checking type signatures for: ")
- 4 (ppInterleave (ppStr ", ") (map (ppr sty) method_ids))
-
-superClassSigCtxt sty
- = ppStr "When checking superclass constraints on instance declaration"
-
+instConstraintErr clas tys
+ = hang (ptext SLIT("Illegal constaint") <+>
+ quotes (pprConstraint clas tys) <+>
+ ptext SLIT("in instance context"))
+ 4 (ptext SLIT("(Instance contexts must constrain only type variables)"))
+
+instTypeErr clas tys msg
+ = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys),
+ nest 4 (parens msg)
+ ]
+
+derivingWhenInstanceExistsErr clas tycon
+ = hang (hsep [ptext SLIT("Deriving class"),
+ quotes (ppr clas),
+ ptext SLIT("type"), quotes (ppr tycon)])
+ 4 (ptext SLIT("when an explicit instance exists"))
+
+nonBoxedPrimCCallErr clas inst_ty
+ = hang (ptext SLIT("Unacceptable instance type for ccall-ish class"))
+ 4 (hsep [ ptext SLIT("class"), ppr clas, ptext SLIT("type"),
+ ppr inst_ty])
+
+{-
+ Declaring CCallable & CReturnable instances in a module different
+ from where the type was defined. Caused by importing data type
+ abstractly (either programmatically or by the renamer being over-eager
+ in its pruning.)
+-}
+invisibleDataConPrimCCallErr clas inst_ty
+ = hang (hsep [ptext SLIT("Constructors for"), quotes (ppr inst_ty),
+ ptext SLIT("not visible when checking"),
+ quotes (ppr clas), ptext SLIT("instance")])
+ 4 (hsep [text "(Try either importing", ppr inst_ty,
+ text "non-abstractly or compile using -fno-prune-tydecls ..)"])
+
+methodCtxt = ptext SLIT("When checking the methods of an instance declaration")
+superClassCtxt = ptext SLIT("When checking the superclasses of an instance declaration")
\end{code}
projects / ghc-hetmet.git / blobdiff