%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
%
\section[TcInstDecls]{Typechecking instance declarations}
#include "HsVersions.h"
module TcInstDcls (
- tcInstDecls1, tcInstDecls2,
- tcSpecInstSigs,
- buildInstanceEnvs, processInstBinds,
- mkInstanceRelatedIds,
- InstInfo(..)
+ tcInstDecls1,
+ tcInstDecls2,
+ processInstBinds
) where
-IMPORT_Trace -- ToDo:rm debugging
-import Outputable
-import Pretty
-import TcMonad -- typechecking monad machinery
-import TcMonadFns ( newDicts, newMethod, newLocalWithGivenTy,
- newClassOpLocals, copyTyVars,
- applyTcSubstAndCollectTyVars
- )
-import AbsSyn -- the stuff being typechecked
-import AbsPrel ( pAT_ERROR_ID )
-import AbsUniType
-import BackSubst ( applyTcSubstToBinds )
-import Bag ( emptyBag, unitBag, unionBags, bagToList )
-import CE ( lookupCE, CE(..) )
-import CmdLineOpts ( GlobalSwitch(..) )
-import GenSpecEtc ( checkSigTyVars, SignatureInfo )
-import E ( mkE, getE_CE, getE_TCE, growE_LVE, tvOfE, LVE(..), E )
-import Errors ( dupInstErr, derivingWhenInstanceExistsErr,
- preludeInstanceErr, nonBoxedPrimCCallErr,
- specInstUnspecInstNotFoundErr,
- Error(..), UnifyErrContext(..)
+IMP_Ubiq()
+
+import HsSyn ( InstDecl(..), FixityDecl, Sig(..),
+ SpecInstSig(..), HsBinds(..), Bind(..),
+ MonoBinds(..), GRHSsAndBinds, Match,
+ InPat(..), OutPat(..), HsExpr(..), HsLit(..),
+ Stmt, Qualifier, ArithSeqInfo, Fake,
+ PolyType(..), MonoType )
+import RnHsSyn ( SYN_IE(RenamedHsBinds), SYN_IE(RenamedMonoBinds),
+ RenamedInstDecl(..), RenamedFixityDecl(..),
+ RenamedSig(..), RenamedSpecInstSig(..),
+ RnName(..){-incl instance Outputable-}
)
-import HsPragmas -- ****** NEED TO SEE CONSTRUCTORS ******
-import Id -- lots of things
-import IdInfo -- ditto
-import Inst ( Inst, InstOrigin(..) )
-import InstEnv
-import Maybes ( catMaybes, mkLookupFun, maybeToBool, Maybe(..) )
-import Name ( getTagFromClassOpName )
-import NameTypes ( fromPrelude )
-import PlainCore ( escErrorMsg )
-import LIE ( nullLIE, mkLIE, unMkLIE, plusLIE, LIE )
-import ListSetOps ( minusList )
-import TCE ( TCE(..), UniqFM )
-import TVE ( mkTVE, TVE(..) )
-import Spec ( specTy )
-import TcContext ( tcContext )
-import TcBinds ( tcSigs, doSpecPragma )
+import TcHsSyn ( TcIdOcc(..), SYN_IE(TcHsBinds),
+ SYN_IE(TcMonoBinds), SYN_IE(TcExpr), tcIdType,
+ mkHsTyLam, mkHsTyApp,
+ mkHsDictLam, mkHsDictApp )
+
+
+import TcMonad hiding ( rnMtoTcM )
+import GenSpecEtc ( checkSigTyVars )
+import Inst ( Inst, InstOrigin(..), SYN_IE(InstanceMapper),
+ newDicts, newMethod, SYN_IE(LIE), emptyLIE, plusLIE )
+import TcBinds ( tcPragmaSigs )
+import TcDeriv ( tcDeriving )
+import TcEnv ( tcLookupClass, tcTyVarScope, newLocalId, tcExtendGlobalTyVars )
+import SpecEnv ( SpecEnv )
import TcGRHSs ( tcGRHSsAndBinds )
+import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs )
+import TcKind ( TcKind, unifyKind )
import TcMatches ( tcMatchesFun )
-import TcMonoType ( tcInstanceType )
-import TcPragmas ( tcDictFunPragmas, tcGenPragmas )
-import TcSimplify ( tcSimplifyAndCheck, tcSimplifyThetas )
-import Unify ( unifyTauTy )
-import Unique ( cCallableClassKey, cReturnableClassKey )
-import Util
+import TcMonoType ( tcContext, tcMonoTypeKind )
+import TcSimplify ( tcSimplifyAndCheck )
+import TcType ( SYN_IE(TcType), SYN_IE(TcTyVar), SYN_IE(TcTyVarSet),
+ tcInstSigTyVars, tcInstType, tcInstTheta, tcInstTcType
+ )
+import Unify ( unifyTauTy, unifyTauTyLists )
+
+
+import Bag ( emptyBag, unitBag, unionBags, unionManyBags,
+ concatBag, foldBag, bagToList )
+import CmdLineOpts ( opt_GlasgowExts, opt_CompilingGhcInternals,
+ opt_OmitDefaultInstanceMethods,
+ opt_SpecialiseOverloaded
+ )
+import Class ( GenClass, GenClassOp,
+ isCcallishClass, classBigSig,
+ classOps, classOpLocalType,
+ classOpTagByString_maybe
+ )
+import Id ( GenId, idType, isDefaultMethodId_maybe )
+import ListSetOps ( minusList )
+import Maybes ( maybeToBool, expectJust )
+import Name ( getLocalName, origName, nameOf, Name{--O only-} )
+import PrelVals ( nO_EXPLICIT_METHOD_ERROR_ID )
+import PrelMods ( pRELUDE )
+import PprType ( GenType, GenTyVar, GenClass, GenClassOp, TyCon,
+ pprParendGenType
+ )
+import PprStyle
+import Pretty
+import RnUtils ( SYN_IE(RnEnv) )
+import TyCon ( isSynTyCon, derivedFor )
+import Type ( GenType(..), SYN_IE(ThetaType), mkTyVarTys,
+ splitSigmaTy, splitAppTy, isTyVarTy, matchTy, mkSigmaTy,
+ getTyCon_maybe, maybeBoxedPrimType, splitRhoTy, eqTy
+ )
+import TyVar ( GenTyVar, SYN_IE(GenTyVarSet), mkTyVarSet, unionTyVarSets )
+import TysWiredIn ( stringTy )
+import Unique ( Unique )
+import Util ( zipEqual, panic )
\end{code}
Typechecking instance declarations is done in two passes. The first
-pass, made by @tcInstDecls1@,
-collects information to be used in the second pass.
+pass, made by @tcInstDecls1@, collects information to be used in the
+second pass.
This pre-processed info includes the as-yet-unprocessed bindings
inside the instance declaration. These are type-checked in the second
all the instance and value decls. Indeed that's the reason we need
two passes over the instance decls.
- instance c => k (t tvs) where b
-
-\begin{code}
-data InstInfo
- = InstInfo
- Class -- Class, k
- [TyVarTemplate] -- Type variables, tvs
- UniType -- The type at which the class is being
- -- instantiated
- ThetaType -- inst_decl_theta: the original context from the
- -- instance declaration. It constrains (some of)
- -- the TyVarTemplates above
- ThetaType -- dfun_theta: the inst_decl_theta, plus one
- -- element for each superclass; the "Mark
- -- Jones optimisation"
- Id -- The dfun id
- [Id] -- Constant methods (either all or none)
- RenamedMonoBinds -- Bindings, b
- Bool -- True <=> local instance decl
- FAST_STRING -- Name of module where this instance was
- -- defined.
- SrcLoc -- Source location assoc'd with this instance's defn
- [RenamedSig] -- User pragmas recorded for generating specialised methods
-\end{code}
+Here is the overall algorithm.
+Assume that we have an instance declaration
-Here is the overall algorithm. Assume that
+ instance c => k (t tvs) where b
\begin{enumerate}
\item
\end{enumerate}
\begin{code}
-tcInstDecls1 :: E -> CE -> TCE -> [RenamedInstDecl] -> NF_TcM (Bag InstInfo)
-
-tcInstDecls1 e ce tce [] = returnNF_Tc emptyBag
-
-tcInstDecls1 e ce tce (inst_decl : rest)
- = tc_inst_1 inst_decl `thenNF_Tc` \ infos1 ->
- tcInstDecls1 e ce tce rest `thenNF_Tc` \ infos2 ->
- returnNF_Tc (infos1 `unionBags` infos2)
- where
- tc_inst_1 (InstDecl context class_name ty binds from_here modname imod uprags pragmas src_loc)
- =
- -- Prime error recovery and substitution pruning
- recoverTc emptyBag (
- addSrcLocTc src_loc (
-
- let
- clas = lookupCE ce class_name -- Renamer ensures this can't fail
-
- for_ccallable_or_creturnable
- = class_name == cCallableClass || class_name == cReturnableClass
- where
- cCallableClass = PreludeClass cCallableClassKey bottom
- cReturnableClass = PreludeClass cReturnableClassKey bottom
- bottom = panic "for_ccallable_etc"
-
- -- Make some new type variables, named as in the instance type
- ty_names = extractMonoTyNames (==) ty
- (tve,inst_tyvars,_) = mkTVE ty_names
- in
- -- Check the instance type, including its syntactic constraints
- babyTcMtoTcM (tcInstanceType ce tce tve from_here src_loc ty)
- `thenTc` \ inst_ty ->
-
- -- DEAL WITH THE INSTANCE CONTEXT
- babyTcMtoTcM (tcContext ce tce tve context) `thenTc` \ theta ->
-
- -- SOME BORING AND TURGID CHECKING:
- let
- inst_for_function_type = isFunType inst_ty
- -- sigh; it happens; must avoid tickling inst_tycon
-
- inst_tycon_maybe = getUniDataTyCon_maybe inst_ty
-
- inst_tycon = case inst_tycon_maybe of
- Just (xx,_,_) -> xx
- Nothing -> panic "tcInstDecls1:inst_tycon"
- in
- -------------------------------------------------------------
- -- It is illegal for a normal user's module to declare an
- -- instance for a Prelude-class/Prelude-type instance:
- checkTc (from_here -- really an inst decl in this module
- && fromPreludeCore clas -- prelude class
- && (inst_for_function_type -- prelude type
- || fromPreludeCore inst_tycon)
- && not (fromPrelude modname) -- we aren't compiling a Prelude mod
- )
- (preludeInstanceErr clas inst_ty src_loc) `thenTc_`
-
- -------------------------------------------------------------
- -- It is obviously illegal to have an explicit instance
- -- for something that we are also planning to `derive'.
- -- Note that an instance decl coming in from outside
- -- is probably just telling us about the derived instance
- -- (ToDo: actually check, if possible), so we mustn't flag
- -- it as an error.
- checkTc (from_here
- && not inst_for_function_type
- && clas `derivedFor` inst_tycon)
- (derivingWhenInstanceExistsErr clas inst_tycon) `thenTc_`
-
- -------------------------------------------------------------
- -- A user declaration of a _CCallable/_CReturnable instance
- -- must be for a "boxed primitive" type.
- getSwitchCheckerTc `thenNF_Tc` \ sw_chkr ->
- checkTc (for_ccallable_or_creturnable
- && from_here -- instance defined here
- && not (sw_chkr CompilingPrelude) -- which allows anything
- && (inst_for_function_type || -- a *function*??? hah!
- not (maybeToBool (maybeBoxedPrimType inst_ty)))) -- naughty, naughty
- (nonBoxedPrimCCallErr clas inst_ty src_loc) `thenTc_`
-
- -- END OF TURGIDITY; back to real fun
- -------------------------------------------------------------
-
- if (not inst_for_function_type && clas `derivedFor` inst_tycon) then
- -- Don't use this InstDecl; tcDeriv will make the
- -- InstInfo to be used in later processing.
- returnTc emptyBag
-
- else
- -- Make the dfun id and constant-method ids
- mkInstanceRelatedIds e
- from_here modname pragmas src_loc
- clas inst_tyvars inst_ty theta uprags
- `thenTc` \ (dfun_id, dfun_theta, const_meth_ids) ->
-
- returnTc ( unitBag (
- InstInfo clas inst_tyvars inst_ty theta
- dfun_theta dfun_id const_meth_ids
- binds from_here modname src_loc uprags
- ))
- ))
-\end{code}
-
-
-Common bit of code shared with @tcDeriving@:
-\begin{code}
-mkInstanceRelatedIds e
- from_here modname inst_pragmas locn
- clas
- inst_tyvars inst_ty inst_decl_theta uprags
- = getUniqueTc `thenNF_Tc` \ uniq ->
- let
- (class_tyvar, super_classes, _, class_ops, _, _) = getClassBigSig clas
-
- super_class_theta = super_classes `zip` (repeat inst_ty)
-
-
- dfun_theta = case inst_decl_theta of
-
- [] -> [] -- If inst_decl_theta is empty, then we don't
- -- want to have any dict arguments, so that we can
- -- expose the constant methods.
-
- other -> inst_decl_theta ++ super_class_theta
- -- Otherwise we pass the superclass dictionaries to
- -- the dictionary function; the Mark Jones optimisation.
-
- dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_ty)
+tcInstDecls1 :: Bag RenamedInstDecl
+ -> [RenamedSpecInstSig]
+ -> Module -- module name for deriving
+ -> RnEnv -- for renaming derivings
+ -> [RenamedFixityDecl] -- fixities for deriving
+ -> TcM s (Bag InstInfo,
+ RenamedHsBinds,
+ PprStyle -> Pretty)
+
+tcInstDecls1 inst_decls specinst_sigs mod_name rn_env fixities
+ = -- Do the ordinary instance declarations
+ mapBagNF_Tc (tcInstDecl1 mod_name) inst_decls
+ `thenNF_Tc` \ inst_info_bags ->
+ let
+ decl_inst_info = concatBag inst_info_bags
in
- fixNF_Tc ( \ rec_dfun_id ->
- babyTcMtoNF_TcM (
- tcDictFunPragmas e dfun_ty rec_dfun_id inst_pragmas
- ) `thenNF_Tc` \ dfun_pragma_info ->
- let
- dfun_specenv = mkInstSpecEnv clas inst_ty inst_tyvars dfun_theta
- dfun_info = dfun_pragma_info `addInfo` dfun_specenv
- in
- returnNF_Tc (mkDictFunId uniq clas inst_ty dfun_ty from_here modname dfun_info)
- ) `thenNF_Tc` \ dfun_id ->
-
- -- Make the constant-method ids, if there are no type variables involved
- (if not (null inst_tyvars) -- ToDo: could also do this if theta is null...
- then
- returnNF_Tc []
- else
- let
- inline_mes = [ getTagFromClassOpName v | (InlineSig v _ _) <- uprags ]
-
- mk_const_meth op uniq
- = mkConstMethodId
- uniq
- clas op inst_ty
- meth_ty from_here modname info
- where
- is_elem = isIn "mkInstanceRelatedIds"
-
- info = if tag `is_elem` inline_mes
- then noIdInfo `addInfo_UF` (iWantToBeINLINEd UnfoldAlways)
- else noIdInfo
-
- tenv = [(class_tyvar, inst_ty)]
- tag = getClassOpTag op
- op_ty = getClassOpLocalType op
- meth_ty = instantiateTy tenv op_ty
- -- If you move to a null-theta version, you need a
- -- mkForallTy inst_tyvars here
-
- mk_constm_w_info (op, u, (name, prags)) -- ToDo: chk name?
- = fixNF_Tc ( \ rec_constm_id ->
-
- babyTcMtoNF_TcM (tcGenPragmas e (Just meth_ty) rec_constm_id prags)
- `thenNF_Tc` \ id_info ->
-
- returnNF_Tc (mkConstMethodId u clas op inst_ty meth_ty
- from_here modname id_info)
- )
- where
- tenv = [(class_tyvar, inst_ty)]
- op_ty = getClassOpLocalType op
- meth_ty = instantiateTy tenv op_ty
-
- in
- getUniquesTc (length class_ops) `thenNF_Tc` \ constm_uniqs ->
- (case inst_pragmas of
- ConstantInstancePragma _ name_pragma_pairs ->
- mapNF_Tc mk_constm_w_info (zip3 class_ops constm_uniqs name_pragma_pairs)
-
- other_inst_pragmas ->
- returnNF_Tc (zipWith mk_const_meth class_ops constm_uniqs)
- )
- ) `thenNF_Tc` \ const_meth_ids ->
-
- returnTc (dfun_id, dfun_theta, const_meth_ids)
-\end{code}
+ -- 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.
+ tcDeriving mod_name rn_env decl_inst_info fixities
+ `thenTc` \ (deriv_inst_info, deriv_binds, ddump_deriv) ->
+ let
+ inst_info = deriv_inst_info `unionBags` decl_inst_info
+ in
+{- LATER
+ -- Handle specialise instance pragmas
+ tcSpecInstSigs inst_info specinst_sigs
+ `thenTc` \ spec_inst_info ->
+-}
+ let
+ spec_inst_info = emptyBag -- For now
-%************************************************************************
-%* *
-\subsection{Converting instance info into suitable InstEnvs}
-%* *
-%************************************************************************
+ full_inst_info = inst_info `unionBags` spec_inst_info
+ in
+ returnTc (full_inst_info, deriv_binds, ddump_deriv)
-\begin{code}
-buildInstanceEnvs :: Bag InstInfo
- -> TcM InstanceMapper
-buildInstanceEnvs info
- = let
- cmp :: InstInfo -> InstInfo -> TAG_
- (InstInfo c1 _ _ _ _ _ _ _ _ _ _ _) `cmp` (InstInfo c2 _ _ _ _ _ _ _ _ _ _ _)
- = if c1 == c2 then EQ_ else if c1 < c2 then LT_ else GT_
+tcInstDecl1 :: FAST_STRING -> RenamedInstDecl -> NF_TcM s (Bag InstInfo)
- info_by_class = equivClasses cmp (bagToList info)
- in
- mapTc buildInstanceEnv info_by_class `thenTc` \ inst_env_entries ->
- let
- class_lookup_maybe_fn
- :: Class
- -> Maybe (ClassInstEnv, (ClassOp -> SpecEnv))
- class_lookup_fn
- :: InstanceMapper
-
- class_lookup_maybe_fn = mkLookupFun (==) inst_env_entries
-
- class_lookup_fn c
- = case class_lookup_maybe_fn c of
- Nothing -> (nullMEnv, \ o -> nullSpecEnv)
- Just xx -> xx
- in
- returnTc class_lookup_fn
-\end{code}
+tcInstDecl1 mod_name
+ (InstDecl class_name
+ poly_ty@(HsForAllTy tyvar_names context inst_ty)
+ binds
+ from_here inst_mod uprags pragmas src_loc)
+ = -- Prime error recovery, set source location
+ recoverNF_Tc (returnNF_Tc emptyBag) $
+ tcAddSrcLoc src_loc $
-\begin{code}
-buildInstanceEnv :: [InstInfo] -- Non-empty, and all for same class
- -> TcM (Class, (ClassInstEnv, (ClassOp -> SpecEnv)))
+ -- Look things up
+ tcLookupClass class_name `thenNF_Tc` \ (clas_kind, clas) ->
-buildInstanceEnv inst_infos@(info_for_one@(InstInfo clas _ _ _ _ _ _ _ _ _ _ _) : rest)
- = let
- ops = getClassOps clas
- no_of_ops = length ops
- in
- foldlTc addClassInstance
- (nullMEnv, nOfThem no_of_ops nullSpecEnv)
- inst_infos `thenTc` \ (class_inst_env, op_inst_envs) ->
let
- class_op_maybe_fn :: ClassOp -> Maybe SpecEnv
- class_op_fn :: ClassOp -> SpecEnv
-
- class_op_maybe_fn = mkLookupFun (==) (ops `zip` op_inst_envs)
- -- They compare by ClassOp tags
- class_op_fn op
- = case class_op_maybe_fn op of
- Nothing -> nullSpecEnv
- Just xx -> xx
+ de_rn (RnName n) = n
in
- returnTc (clas, (class_inst_env, class_op_fn))
+ -- Typecheck the context and instance type
+ tcTyVarScope (map de_rn tyvar_names) (\ tyvars ->
+ tcContext context `thenTc` \ theta ->
+ tcMonoTypeKind inst_ty `thenTc` \ (tau_kind, tau) ->
+ unifyKind clas_kind tau_kind `thenTc_`
+ returnTc (tyvars, theta, tau)
+ ) `thenTc` \ (inst_tyvars, inst_theta, inst_tau) ->
+
+ -- Check for respectable instance type
+ scrutiniseInstanceType from_here clas inst_tau
+ `thenTc` \ (inst_tycon,arg_tys) ->
+
+ -- Deal with the case where we are deriving
+ -- and importing the same instance
+ if (not from_here && (clas `derivedFor` inst_tycon)
+ && all isTyVarTy arg_tys)
+ then
+ if mod_name == inst_mod
+ then
+ -- Imported instance came from this module;
+ -- discard and derive fresh instance
+ returnTc emptyBag
+ else
+ -- Imported instance declared in another module;
+ -- report duplicate instance error
+ failTc (derivingWhenInstanceImportedErr inst_mod clas inst_tycon)
+ else
+
+ -- Make the dfun id and constant-method ids
+ mkInstanceRelatedIds from_here src_loc inst_mod pragmas
+ clas inst_tyvars inst_tau inst_theta uprags
+ `thenTc` \ (dfun_id, dfun_theta, const_meth_ids) ->
+
+ returnTc (unitBag (InstInfo clas inst_tyvars inst_tau inst_theta
+ dfun_theta dfun_id const_meth_ids
+ binds from_here inst_mod src_loc uprags))
\end{code}
-\begin{code}
-addClassInstance
- :: (ClassInstEnv, [SpecEnv])
- -> InstInfo
- -> TcM (ClassInstEnv, [SpecEnv]) -- One SpecEnv for each class op
-
-addClassInstance
- (class_inst_env, op_spec_envs)
- (InstInfo clas inst_tyvars inst_ty inst_decl_theta dfun_theta dfun_id const_meth_ids _ _ _ src_loc _)
- = getSwitchCheckerTc `thenNF_Tc` \ sw_chkr ->
- -- We anly add specialised/overlapped instances
- -- if we are specialising the overloading
---
--- ToDo ... This causes getConstMethodId errors!
---
--- if is_plain_instance inst_ty || sw_chkr SpecialiseOverloaded
--- then
-
- -- Insert into the class_inst_env first
- checkMaybeErrTc (addClassInst clas class_inst_env inst_ty dfun_id inst_tyvars dfun_theta src_loc)
- dupInstErr `thenTc` \ class_inst_env' ->
- let
- -- Adding the classop instances can't fail if the class instance itself didn't
- op_spec_envs' = case const_meth_ids of
- [] -> op_spec_envs
- other -> zipWith add_const_meth op_spec_envs const_meth_ids
- in
- returnTc (class_inst_env', op_spec_envs')
-
--- else
--- -- Drop this specialised/overlapped instance
--- returnTc (class_inst_env, op_spec_envs)
-
- where
- add_const_meth spec_env meth_id
- = addOneToSpecEnv spec_env (SpecInfo (Just inst_ty:nothings) 1 meth_id)
- where
- (const_meth_tyvars,_) = splitForalls (getIdUniType meth_id)
- nothings = [Nothing | _ <- const_meth_tyvars]
- -- This only works if the constant method id only has its local polymorphism.
- -- If you want to have constant methods for
- -- instance Foo (a,b,c) where
- -- op x = ...
- -- then the constant method will be polymorphic in a,b,c, and
- -- the SpecInfo will need to be elaborated.
-
-\end{code}
%************************************************************************
%* *
%************************************************************************
\begin{code}
-tcInstDecls2 :: E
- -> Bag InstInfo
- -> NF_TcM (LIE, TypecheckedBinds)
-
-tcInstDecls2 e inst_decls
- = let
- -- Get type variables free in environment. Sadly, there may be
- -- some, because of the dreaded monomorphism restriction
- free_tyvars = tvOfE e
- in
- tcInstDecls2_help e free_tyvars (bagToList inst_decls)
-
-tcInstDecls2_help e free_tyvars [] = returnNF_Tc (nullLIE, EmptyBinds)
+tcInstDecls2 :: Bag InstInfo
+ -> NF_TcM s (LIE s, TcHsBinds s)
-tcInstDecls2_help e free_tyvars (inst_decl:inst_decls)
- = tcInstDecl2 e free_tyvars inst_decl `thenNF_Tc` \ (lie1, binds1) ->
- tcInstDecls2_help e free_tyvars inst_decls `thenNF_Tc` \ (lie2, binds2) ->
- returnNF_Tc (lie1 `plusLIE` lie2, binds1 `ThenBinds` binds2)
+tcInstDecls2 inst_decls
+ = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyBinds)) inst_decls
+ where
+ combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) ->
+ tc2 `thenNF_Tc` \ (lie2, binds2) ->
+ returnNF_Tc (lie1 `plusLIE` lie2,
+ binds1 `ThenBinds` binds2)
\end{code}
======= New documentation starts here (Sept 92) ==============
-The main purpose of @tcInstDecl2@ is to return a @Binds@ which defines
+The main purpose of @tcInstDecl2@ is to return a @HsBinds@ which defines
the dictionary function for this instance declaration. For example
\begin{verbatim}
instance Foo a => Foo [a] where
Dict [op1, op2]
\end{verbatim}
-HOWEVER, if the instance decl has no type variables, then it returns a
-bigger @Binds@ with declarations for each method. For example
+HOWEVER, if the instance decl has no context, then it returns a
+bigger @HsBinds@ with declarations for each method. For example
\begin{verbatim}
- instance Foo Int where
+ instance Foo [a] where
op1 x = ...
op2 y = ...
\end{verbatim}
might produce
\begin{verbatim}
- dfun.Foo.Int = Dict [Foo.op1.Int, Foo.op2.Int]
- Foo.op1.Int x = ...
- Foo.op2.Int y = ...
+ dfun.Foo.List a = Dict [Foo.op1.List a, Foo.op2.List a]
+ const.Foo.op1.List a x = ...
+ const.Foo.op2.List a y = ...
\end{verbatim}
This group may be mutually recursive, because (for example) there may
be no method supplied for op2 in which case we'll get
\begin{verbatim}
- Foo.op2.Int = default.Foo.op2 dfun.Foo.Int
+ const.Foo.op2.List a = default.Foo.op2 (dfun.Foo.List a)
\end{verbatim}
that is, the default method applied to the dictionary at this type.
-\begin{code}
-tcInstDecl2 :: E
- -> [TyVar] -- Free in the environment
- -> InstInfo
- -> NF_TcM (LIE, TypecheckedBinds)
-\end{code}
+What we actually produce in either case is:
-First comes the easy case of a non-local instance decl.
+ AbsBinds [a] [dfun_theta_dicts]
+ [(dfun.Foo.List, d)] ++ (maybe) [(const.Foo.op1.List, op1), ...]
+ { d = (sd1,sd2, ..., op1, op2, ...)
+ op1 = ...
+ op2 = ...
+ }
-\begin{code}
-tcInstDecl2 e free_tyvars (InstInfo _ _ _ _ _ _ _ _ False{-not this module-} _ _ _)
- = returnNF_Tc (nullLIE, EmptyBinds)
-\end{code}
+The "maybe" says that we only ask AbsBinds to make global constant methods
+if the dfun_theta is empty.
-Now the case of a general local instance. For an instance declaration, say,
+
+For an instance declaration, say,
instance (C1 a, C2 b) => C (T a b) where
...
is the ``Mark Jones optimisation''. The stuff before the "=>" here
is the @dfun_theta@ below.
+First comes the easy case of a non-local instance decl.
+
\begin{code}
-tcInstDecl2
- e free_tyvars
- (InstInfo clas template_tyvars inst_ty_tmpl inst_decl_theta dfun_theta
- dfun_id const_meth_ids monobinds True{-from here-} inst_mod locn uprags)
- = let
- origin = InstanceDeclOrigin locn
- in
- recoverTc (nullLIE, EmptyBinds) (
- addSrcLocTc locn (
- pruneSubstTc free_tyvars (
+tcInstDecl2 :: InstInfo
+ -> NF_TcM s (LIE s, TcHsBinds s)
+
+tcInstDecl2 (InstInfo _ _ _ _ _ _ _ _ False{-import-} _ _ _)
+ = returnNF_Tc (emptyLIE, EmptyBinds)
+
+tcInstDecl2 (InstInfo clas inst_tyvars inst_ty
+ inst_decl_theta dfun_theta
+ dfun_id const_meth_ids monobinds
+ True{-here-} inst_mod locn uprags)
+ = -- Prime error recovery
+ recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyBinds)) $
+ tcAddSrcLoc locn $
-- Get the class signature
- let (class_tyvar,
- super_classes, sc_sel_ids,
- class_ops, op_sel_ids, defm_ids) = getClassBigSig clas
- in
- -- Prime error recovery and substitution pruning. Instantiate
- -- dictionaries from the specified instance context. These
- -- dicts will be passed into the dictionary-construction
- -- function.
- copyTyVars template_tyvars `thenNF_Tc` \ (inst_env, inst_tyvars, inst_tyvar_tys) ->
+ tcInstSigTyVars inst_tyvars `thenNF_Tc` \ (inst_tyvars', _, tenv) ->
let
- inst_ty = instantiateTy inst_env inst_ty_tmpl
-
- inst_decl_theta' = instantiateThetaTy inst_env inst_decl_theta
- dfun_theta' = instantiateThetaTy inst_env dfun_theta
- sc_theta' = super_classes `zip` (repeat inst_ty)
- in
- newDicts origin sc_theta' `thenNF_Tc` \ sc_dicts' ->
- newDicts origin dfun_theta' `thenNF_Tc` \ dfun_arg_dicts' ->
- newDicts origin inst_decl_theta' `thenNF_Tc` \ inst_decl_dicts' ->
- let
- sc_dicts'_ids = map mkInstId sc_dicts'
- dfun_arg_dicts'_ids = map mkInstId dfun_arg_dicts'
+ (class_tyvar,
+ super_classes, sc_sel_ids,
+ class_ops, op_sel_ids, defm_ids) = classBigSig clas
in
- -- Instantiate the dictionary being constructed
- -- and the dictionary-construction function
- newDicts origin [(clas,inst_ty)] `thenNF_Tc` \ [this_dict] ->
+ 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' ->
let
- this_dict_id = mkInstId this_dict
- in
- -- Instantiate method variables
- listNF_Tc [ newMethodId sel_id inst_ty origin locn
- | sel_id <- op_sel_ids
- ] `thenNF_Tc` \ method_ids ->
- let
- method_insts = catMaybes (map isInstId_maybe method_ids)
- -- Extract Insts from those method ids which have them (most do)
- -- See notes on newMethodId
+ sc_theta' = super_classes `zip` repeat inst_ty'
+ origin = InstanceDeclOrigin
+ mk_method sel_id = newMethod origin (RealId sel_id) [inst_ty']
in
- -- Collect available dictionaries
- let avail_insts = -- These insts are in scope; quite a few, eh?
- [this_dict] ++
- method_insts ++
- dfun_arg_dicts'
- in
- getSwitchCheckerTc `thenNF_Tc` \ sw_chkr ->
+ -- 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) ->
+
+ -- Collect available Insts
let
+ inst_tyvars_set' = mkTyVarSet inst_tyvars'
+
+ avail_insts -- These insts are in scope; quite a few, eh?
+ = unionManyBags (this_dict : dfun_arg_dicts : meth_insts_s)
+
mk_method_expr
- = if sw_chkr OmitDefaultInstanceMethods then
- makeInstanceDeclNoDefaultExpr origin clas method_ids defm_ids inst_mod inst_ty
+ = if opt_OmitDefaultInstanceMethods then
+ makeInstanceDeclNoDefaultExpr origin meth_ids defm_ids inst_ty' clas inst_mod
else
- makeInstanceDeclDefaultMethodExpr origin this_dict_id class_ops defm_ids inst_ty
+ makeInstanceDeclDefaultMethodExpr origin meth_ids defm_ids inst_ty' this_dict_id
in
- processInstBinds e free_tyvars mk_method_expr
- inst_tyvars avail_insts method_ids monobinds
- `thenTc` \ (insts_needed, method_mbinds) ->
+ tcExtendGlobalTyVars inst_tyvars_set' (
+ processInstBinds clas mk_method_expr avail_insts meth_ids monobinds
+ ) `thenTc` \ (insts_needed, method_mbinds) ->
let
-- Create the dict and method binds
dict_bind
- = VarMonoBind this_dict_id (Dictionary sc_dicts'_ids method_ids)
+ = VarMonoBind this_dict_id (Dictionary sc_dict_ids meth_ids)
dict_and_method_binds
= dict_bind `AndMonoBinds` method_mbinds
+
in
-- Check the overloading constraints of the methods and superclasses
- -- The global tyvars must be a fixed point of the substitution
- applyTcSubstAndCollectTyVars free_tyvars `thenNF_Tc` \ real_free_tyvars ->
- tcSimplifyAndCheck
- True -- Top level
- real_free_tyvars -- Global tyvars
- inst_tyvars -- Local tyvars
+ tcAddErrCtxt (bindSigCtxt meth_ids) (
+ tcSimplifyAndCheck
+ inst_tyvars_set' -- Local tyvars
avail_insts
- (sc_dicts' ++ insts_needed) -- Need to get defns for all these
- (BindSigCtxt method_ids)
- `thenTc` \ (const_insts, super_binds) ->
+ (sc_dicts `unionBags` insts_needed) -- Need to get defns for all these
+ ) `thenTc` \ (const_lie, super_binds) ->
-- 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
- False -- Doesn't matter; more efficient this way
- real_free_tyvars -- Global tyvars
- inst_tyvars -- Local tyvars
- inst_decl_dicts' -- The instance dictionaries available
- sc_dicts' -- The superclass dicationaries reqd
- SuperClassSigCtxt
- `thenTc_`
+ 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
-- this to make sure it can be done.
-- Now process any SPECIALIZE pragmas for the methods
let
spec_sigs = [ s | s@(SpecSig _ _ _ _) <- uprags ]
-
- get_const_method_id name
- = const_meth_ids !! ((getTagFromClassOpName name) - 1)
in
- tcSigs e [] spec_sigs `thenTc` \ sig_info ->
-
- mapAndUnzipTc (doSpecPragma e get_const_method_id) sig_info
- `thenTc` \ (spec_binds_s, spec_lie_s) ->
- let
- spec_lie = foldr plusLIE nullLIE spec_lie_s
- spec_binds = foldr AndMonoBinds EmptyMonoBinds spec_binds_s
-
+ tcPragmaSigs spec_sigs `thenTc` \ (_, spec_binds, spec_lie) ->
+ let
-- Complete the binding group, adding any spec_binds
- inst_binds
- = AbsBinds
- inst_tyvars
- dfun_arg_dicts'_ids
- ((this_dict_id,dfun_id) : (method_ids `zip` const_meth_ids))
- -- const_meth_ids will often be empty
+ inst_binds
+ = AbsBinds
+ inst_tyvars'
+ dfun_arg_dicts_ids
+ ((this_dict_id, RealId dfun_id)
+ : (meth_ids `zip` map RealId const_meth_ids))
+ -- NB: const_meth_ids will often be empty
super_binds
(RecBind dict_and_method_binds)
-
+
`ThenBinds`
- SingleBind (NonRecBind spec_binds)
+ spec_binds
in
- -- Back-substitute
- applyTcSubstToBinds inst_binds `thenNF_Tc` \ final_inst_binds ->
- returnTc (mkLIE const_insts `plusLIE` spec_lie,
- final_inst_binds)
- )))
+ returnTc (const_lie `plusLIE` spec_lie, inst_binds)
\end{code}
-@mkMethodId@ manufactures an id for a local method.
-It's rather turgid stuff, because there are two cases:
-
- (a) For methods with no local polymorphism, we can make an Inst of the
- class-op selector function and a corresp InstId;
- which is good because then other methods which call
- this one will do so directly.
-
- (b) For methods with local polymorphism, we can't do this. For example,
-
- class Foo a where
- op :: (Num b) => a -> b -> a
-
- Here the type of the class-op-selector is
-
- forall a b. (Foo a, Num b) => a -> b -> a
-
- The locally defined method at (say) type Float will have type
-
- forall b. (Num b) => Float -> b -> Float
-
- and the one is not an instance of the other.
-
- So for these we just make a local (non-Inst) id with a suitable type.
-
-How disgusting.
-
-\begin{code}
-newMethodId sel_id inst_ty origin loc
- = let (sel_tyvars,sel_theta,sel_tau) = splitType (getIdUniType sel_id)
- (_:meth_theta) = sel_theta -- The local theta is all except the
- -- first element of the context
- in
- case sel_tyvars of
- -- Ah! a selector for a class op with no local polymorphism
- -- Build an Inst for this
- [clas_tyvar] -> newMethod origin sel_id [inst_ty] `thenNF_Tc` \ inst ->
- returnNF_Tc (mkInstId inst)
-
- -- Ho! a selector for a class op with local polymorphism.
- -- Just make a suitably typed local id for this
- (clas_tyvar:local_tyvars) ->
- let
- method_ty = instantiateTy [(clas_tyvar,inst_ty)]
- (mkSigmaTy local_tyvars meth_theta sel_tau)
- in
- getUniqueTc `thenNF_Tc` \ uniq ->
- returnNF_Tc (mkUserLocal (getOccurrenceName sel_id) uniq method_ty loc)
-\end{code}
-
-This function makes a default method which calls the global default method, at
+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
- :: InstOrigin
- -> Id
- -> [ClassOp]
+ :: InstOrigin s
+ -> [TcIdOcc s]
-> [Id]
- -> UniType
+ -> TcType s
+ -> TcIdOcc s
-> Int
- -> NF_TcM TypecheckedExpr
-
-makeInstanceDeclDefaultMethodExpr origin this_dict_id class_ops defm_ids inst_ty tag
- = let
- (tyvar_tmpls, local_theta, _) = splitType (getClassOpLocalType class_op)
- in
- copyTyVars tyvar_tmpls `thenNF_Tc` \ (inst_env, tyvars, tys) ->
- let
- inst_theta = instantiateThetaTy inst_env local_theta
- in
- newDicts origin inst_theta `thenNF_Tc` \ local_dict_insts ->
- let
- local_dicts = map mkInstId local_dict_insts
- in
- returnNF_Tc (
- mkTyLam tyvars (
- mkDictLam local_dicts (
- mkDictApp (mkTyApp (Var defm_id)
- (inst_ty : tys))
- (this_dict_id:local_dicts)))
- )
- where
- idx = tag - 1
- class_op = class_ops !! idx
- defm_id = defm_ids !! idx
+ -> NF_TcM s (TcExpr s)
+makeInstanceDeclDefaultMethodExpr origin meth_ids defm_ids inst_ty this_dict tag
+ =
+ -- def_op_id = defm_id inst_ty this_dict
+ returnNF_Tc (mkHsDictApp (mkHsTyApp (HsVar (RealId defm_id)) [inst_ty]) [this_dict])
+ where
+ idx = tag - 1
+ meth_id = meth_ids !! idx
+ defm_id = defm_ids !! idx
makeInstanceDeclNoDefaultExpr
- :: InstOrigin
- -> Class
+ :: InstOrigin s
+ -> [TcIdOcc s]
-> [Id]
- -> [Id]
- -> FAST_STRING
- -> UniType
+ -> TcType s
+ -> Class
+ -> Module
-> Int
- -> NF_TcM TypecheckedExpr
-
-makeInstanceDeclNoDefaultExpr origin clas method_ids defm_ids inst_mod inst_ty tag
- = specTy origin (getIdUniType method_id) `thenNF_Tc` \ (tyvars, dicts, tau) ->
-
- (if not err_defm then
- pprTrace "Warning: "
- (ppCat [ppStr "Omitted default method for",
- ppr PprForUser clas_op, ppStr "in instance",
- ppPStr clas_name, pprParendUniType PprForUser inst_ty])
- else id) (
+ -> NF_TcM s (TcExpr s)
- returnNF_Tc (mkTyLam tyvars (
- mkDictLam (map mkInstId dicts) (
- App (mkTyApp (Var pAT_ERROR_ID) [tau])
- (Lit (StringLit (_PK_ error_msg))))))
- )
+makeInstanceDeclNoDefaultExpr origin meth_ids defm_ids inst_ty clas inst_mod tag
+ =
+ -- Produce a warning if the default instance method
+ -- has been omitted when one exists in the class
+ warnTc (not err_defm_ok)
+ (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
- clas_op = (getClassOps clas) !! idx
- method_id = method_ids !! idx
- defm_id = defm_ids !! idx
-
- Just (_, _, err_defm) = isDefaultMethodId_maybe defm_id
+ idx = tag - 1
+ meth_id = meth_ids !! idx
+ clas_op = (classOps clas) !! idx
+ defm_id = defm_ids !! idx
- error_msg = "%E" -- => No explicit method for \"
- ++ escErrorMsg error_str
+ Just (_, _, err_defm_ok) = isDefaultMethodId_maybe defm_id
- error_str = _UNPK_ inst_mod ++ "." ++ _UNPK_ clas_name ++ "."
+ error_msg = _UNPK_ inst_mod ++ "." ++ _UNPK_ clas_name ++ "."
++ (ppShow 80 (ppr PprForUser inst_ty)) ++ "."
++ (ppShow 80 (ppr PprForUser clas_op)) ++ "\""
- (_, clas_name) = getOrigName clas
+ clas_name = nameOf (origName "makeInstanceDeclNoDefaultExpr" clas)
\end{code}
%* *
%************************************************************************
-@processInstBinds@ returns a @MonoBinds@ which binds
+@processInstBinds@ returns a @MonoBinds@ which binds
all the method ids (which are passed in). It is used
- - both for instance decls,
+ - 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
+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
- :: E
- -> [TyVar] -- Free in envt
-
- -> (Int -> NF_TcM TypecheckedExpr) -- Function to make
- -- default method
-
- -> [TyVar] -- Tyvars for this instance decl
-
- -> [Inst] -- available Insts
-
- -> [Id] -- Local method ids
- -- (instance tyvars are free
- -- in their types),
- -- in tag order
+ :: 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)
- -> TcM ([Inst], -- These are required
- TypecheckedMonoBinds)
-
-processInstBinds e free_tyvars mk_method_expr inst_tyvars
- avail_insts method_ids monobinds
- =
+processInstBinds clas mk_default_method_rhs avail_insts method_ids monobinds
+ =
-- Process the explicitly-given method bindings
- processInstBinds1 e free_tyvars inst_tyvars avail_insts method_ids monobinds
- `thenTc` (\ (tags, insts_needed_in_methods, method_binds) ->
+ 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
+ let
+ unmentioned_tags = [1.. length method_ids] `minusList` tags
in
- makeDefaultMethods mk_method_expr unmentioned_tags method_ids
- `thenNF_Tc` (\ default_monobinds ->
+ mapNF_Tc mk_default_method unmentioned_tags
+ `thenNF_Tc` \ default_bind_list ->
- returnTc (insts_needed_in_methods,
- method_binds `AndMonoBinds` default_monobinds)
- ))
+ 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
- :: E
- -> [TyVar] -- Global free tyvars
- -> [TyVar] -- Tyvars for this instance decl
- -> [Inst] -- available Insts
- -> [Id] -- Local method ids (instance tyvars are free),
- -- in tag order
- -> RenamedMonoBinds
- -> TcM ([Int], -- Class-op tags accounted for
- [Inst], -- These are required
- TypecheckedMonoBinds)
-
-processInstBinds1 e free_tyvars inst_tyvars avail_insts method_ids EmptyMonoBinds
- = returnTc ([], [], EmptyMonoBinds)
-
-processInstBinds1 e free_tyvars inst_tyvars avail_insts method_ids (AndMonoBinds mb1 mb2)
- = processInstBinds1 e free_tyvars inst_tyvars avail_insts method_ids mb1
+ :: 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 e free_tyvars inst_tyvars avail_insts method_ids mb2
+ processInstBinds1 clas avail_insts method_ids mb2
`thenTc` \ (op_tags2,dicts2,method_binds2) ->
returnTc (op_tags1 ++ op_tags2,
- dicts1 ++ dicts2,
+ dicts1 `unionBags` dicts2,
AndMonoBinds method_binds1 method_binds2)
\end{code}
\begin{code}
-processInstBinds1 e free_tyvars inst_tyvars avail_insts method_ids mbind
- =
+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
-- Renamer has reduced us to these two cases.
let
(op,locn) = case mbind of
- FunMonoBind op _ locn -> (op, locn)
+ FunMonoBind op _ _ locn -> (op, locn)
PatMonoBind (VarPatIn op) _ locn -> (op, locn)
-
- origin = InstanceDeclOrigin locn
+
+ occ = getLocalName op
+ origin = InstanceDeclOrigin
in
- addSrcLocTc locn (
+ tcAddSrcLoc locn $
-- Make a method id for the method
- let tag = getTagFromClassOpName op
- method_id = method_ids !! (tag-1)
- method_ty = getIdUniType method_id
+ let
+ maybe_tag = classOpTagByString_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
- specTy origin method_ty `thenNF_Tc` \ (method_tyvars, method_dicts, method_tau) ->
+ newDicts origin method_theta `thenNF_Tc` \ (method_dicts,method_dict_ids) ->
- -- Build the result
- case (method_tyvars, method_dicts) of
+ case (method_tyvars, method_dict_ids) of
([],[]) -> -- The simple case; no local polymorphism or overloading in the method
-- Type check the method itself
- tcMethodBind e method_id method_tau mbind `thenTc` \ (mbind', lieIop) ->
+ tcMethodBind method_id method_tau mbind `thenTc` \ (mbind', lieIop) ->
+ returnTc ([tag], lieIop, mbind')
- -- Make sure that the instance tyvars havn't been
- -- unified with each other or with the method tyvars.
- -- The global tyvars must be a fixed point of the substitution
- applyTcSubstAndCollectTyVars free_tyvars `thenNF_Tc` \ real_free_tyvars ->
- checkSigTyVars real_free_tyvars inst_tyvars method_tau method_tau
- (MethodSigCtxt op method_tau) `thenTc_`
+ other -> -- It's a locally-polymorphic and/or overloaded method; UGH!
- returnTc ([tag], unMkLIE lieIop, mbind')
+ -- 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.
- 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.
- newLocalWithGivenTy op method_tau `thenNF_Tc` \ local_meth_id ->
- newLocalWithGivenTy op method_ty `thenNF_Tc` \ copy_meth_id ->
+ -- 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
+ sig_tyvar_set = mkTyVarSet sig_tyvars
+ in
-- Typecheck the method
- tcMethodBind e local_meth_id method_tau mbind `thenTc` \ (mbind', lieIop) ->
-
- -- Make sure that the instance tyvars haven't been
- -- unified with each other or with the method tyvars.
- -- The global tyvars must be a fixed point of the substitution
- applyTcSubstAndCollectTyVars free_tyvars `thenNF_Tc` \ real_free_tyvars ->
- checkSigTyVars real_free_tyvars (method_tyvars ++ inst_tyvars) method_tau method_tau
- (MethodSigCtxt op method_tau) `thenTc_`
+ tcMethodBind 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
--
-- Here we must simplify constraints on "a" to catch all
-- the Bar-ish things.
- tcSimplifyAndCheck
- False -- Not top level
- real_free_tyvars
- (inst_tyvars ++ method_tyvars)
- (method_dicts ++ avail_insts)
- (unMkLIE lieIop)
- (MethodSigCtxt op method_ty) `thenTc` \ (f_dicts, dict_binds) ->
+
+ -- 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
- (Let
+ (HsLet
(AbsBinds
method_tyvars
- (map mkInstId method_dicts)
- [(local_meth_id, copy_meth_id)]
+ method_dict_ids
+ [(local_id, copy_id)]
dict_binds
(NonRecBind mbind'))
- (Var copy_meth_id)))
- )
+ (HsVar copy_id)))
\end{code}
\begin{code}
-tcMethodBind :: E -> Id -> UniType -> RenamedMonoBinds
- -> TcM (TypecheckedMonoBinds, LIE)
+tcMethodBind :: TcIdOcc s -> TcType s -> RenamedMonoBinds
+ -> TcM s (TcMonoBinds s, LIE s)
-tcMethodBind e meth_id meth_ty (FunMonoBind name matches locn)
- = addSrcLocTc locn (
- tcMatchesFun e name meth_ty matches `thenTc` \ (rhs', lie) ->
- returnTc (FunMonoBind meth_id rhs' locn, lie)
- )
+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 e meth_id meth_ty (PatMonoBind pat grhss_and_binds locn)
+tcMethodBind meth_id meth_ty pbind@(PatMonoBind pat grhss_and_binds locn)
-- pat is sure to be a (VarPatIn op)
- = addSrcLocTc locn (
- tcGRHSsAndBinds e grhss_and_binds `thenTc` \ (grhss_and_binds', lie, rhs_ty) ->
- unifyTauTy meth_ty rhs_ty (PatMonoBindsCtxt pat grhss_and_binds) `thenTc_`
+ = 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}
-Creates bindings for the default methods, being the application of the
-appropriate global default method to the type of this instance decl.
-
-\begin{code}
-makeDefaultMethods
- :: (Int -> NF_TcM TypecheckedExpr) -- Function to make
- -- default method
- -> [Int] -- Tags for methods required
- -> [Id] -- Method names to bind, in tag order
- -> NF_TcM TypecheckedMonoBinds
-
-
-makeDefaultMethods mk_method_expr [] method_ids
- = returnNF_Tc EmptyMonoBinds
-
-makeDefaultMethods mk_method_expr (tag:tags) method_ids
- = mk_method_expr tag `thenNF_Tc` \ rhs ->
- makeDefaultMethods mk_method_expr tags method_ids `thenNF_Tc` \ meth_binds ->
-
- returnNF_Tc ((VarMonoBind method_id rhs) `AndMonoBinds` meth_binds)
- where
- method_id = method_ids !! (tag-1)
-\end{code}
-
%************************************************************************
%* *
\subsection{Type-checking specialise instance pragmas}
%************************************************************************
\begin{code}
+{- LATER
tcSpecInstSigs :: E -> CE -> TCE
- -> Bag InstInfo -- inst decls seen (declared and derived)
- -> [RenamedSpecialisedInstanceSig] -- specialise instance upragmas
- -> TcM (Bag InstInfo) -- new, overlapped, inst decls
+ -> 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
= 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)
+ 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
- -> RenamedSpecialisedInstanceSig
+ -> RenamedSpecInstSig
-> NF_TcM (Bag InstInfo)
-tcSpecInstSig e ce tce inst_infos inst_mapper (InstSpecSig class_name ty src_loc)
+tcSpecInstSig e ce tce inst_infos inst_mapper (SpecInstSig class_name ty src_loc)
= recoverTc emptyBag (
- addSrcLocTc src_loc (
+ 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 = extractMonoTyNames (==) ty
+ ty_names = extractMonoTyNames ???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 getUniDataTyCon_maybe inst_ty of
- Just (tc,_,_) -> Just tc
- Nothing -> Nothing
+ maybe_tycon = case maybeAppDataTyCon inst_ty of
+ Just (tc,_,_) -> Just tc
+ Nothing -> Nothing
- maybe_unspec_inst = lookup_unspec_inst clas maybe_tycon inst_infos
+ 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
copyTyVars inst_tmpls `thenNF_Tc` \ (tv_e, inst_tvs, inst_tv_tys) ->
let
Just (InstInfo _ unspec_tyvars unspec_inst_ty unspec_theta
- _ _ _ binds True{-from here-} mod _ uprag) = maybe_unspec_inst
+ _ _ _ binds True{-from here-} mod _ 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
+ subst_tv_theta = instantiateThetaTy tv_e subst_theta
mk_spec_origin clas ty
- = InstanceSpecOrigin inst_mapper clas ty src_loc
+ = 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 = inst_tv_tys `zipEqual` inst_tmpl_tys
+ tv_tmpl_map = zipEqual "tcSpecInstSig" inst_tv_tys inst_tmpl_tys
tv_to_tmpl tv = assoc "tcSpecInstSig" tv_tmpl_map tv
in
- mkInstanceRelatedIds e True{-from here-} mod NoInstancePragmas src_loc
+ mkInstanceRelatedIds e True{-from here-} src_loc mod NoInstancePragmas
clas inst_tmpls inst_ty simpl_theta uprag
`thenTc` \ (dfun_id, dfun_theta, const_meth_ids) ->
(ppAboves [ppCat [if null simpl_theta then ppNil else ppr PprDebug simpl_theta,
if null simpl_theta then ppNil else ppStr "=>",
ppr PprDebug clas,
- pprParendUniType PprDebug inst_ty],
+ 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,
- pprParendUniType PprDebug unspec_inst_ty]])
+ pprParendGenType PprDebug unspec_inst_ty]])
else id) (
returnTc (unitBag (InstInfo clas inst_tmpls inst_ty simpl_theta
- dfun_theta dfun_id const_meth_ids
- binds True{-from here-} mod src_loc uprag))
+ dfun_theta dfun_id const_meth_ids
+ binds True{-from here-} mod src_loc uprag))
)))
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_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 (getUniDataTyCon_maybe inst_ty) of
+ match_tycon tycon inst_ty = case (maybeAppDataTyCon inst_ty) of
Just (inst_tc,_,_) -> tycon == inst_tc
Nothing -> False
is_plain_instance inst_ty
- = case (getUniDataTyCon_maybe inst_ty) of
+ = 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:
+it must normally look like: @instance Foo (Tycon a b c ...) ...@
+
+The exceptions to this syntactic checking: (1)~if the @GlasgowExts@
+flag is on, or (2)~the instance is imported (they must have been
+compiled elsewhere). In these cases, we let them go through anyway.
+
+We can also have instances for functions: @instance Foo (a -> b) ...@.
+
+\begin{code}
+scrutiniseInstanceType from_here 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 from_here
+ = returnTc (inst_tycon,arg_tys)
+
+ -- TYVARS CHECK
+ | not (all isTyVarTy arg_tys ||
+ opt_GlasgowExts)
+ = failTc (instTypeErr 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.
+ isCcallishClass clas
+ && not (maybeToBool (maybeBoxedPrimType inst_tau)
+ || opt_CompilingGhcInternals) -- this lets us get up to mischief;
+ -- e.g., instance CCallable ()
+ = failTc (nonBoxedPrimCCallErr clas inst_tau)
+
+ | otherwise
+ = returnTc (inst_tycon,arg_tys)
+
+ where
+ (possible_tycon, arg_tys) = splitAppTy inst_tau
+ inst_tycon_maybe = getTyCon_maybe possible_tycon
+ inst_tycon = expectJust "tcInstDecls1:inst_tycon" inst_tycon_maybe
+\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 "Instance isn't for a `boxed-primitive' type")
+ 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",
+ ppPStr 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 `",
+ ppPStr 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"
+
\end{code}
projects / ghc-hetmet.git / blobdiff