\section[Inst]{The @Inst@ type: dictionaries or method instances}
\begin{code}
-#include "HsVersions.h"
-
module Inst (
- Inst(..), -- Visible only to TcSimplify
+ LIE, emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE, plusLIEs, mkLIE,
+ pprInsts, pprInstsInFull,
- InstOrigin(..), OverloadedLit(..),
- SYN_IE(LIE), emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE, plusLIEs,
- pprLIE, pprLIEInFull,
+ Inst, OverloadedLit(..), pprInst,
- SYN_IE(InstanceMapper),
+ InstanceMapper,
- newDicts, newDictsAtLoc, newMethod, newMethodWithGivenTy, newOverloadedLit,
+ newDictFromOld, newDicts, newDictsAtLoc,
+ newMethod, newMethodWithGivenTy, newOverloadedLit,
- instType, tyVarsOfInst, lookupInst, lookupSimpleInst,
+ tyVarsOfInst, instLoc, getDictClassTys,
- isDict, isTyVarDict,
+ lookupInst, lookupSimpleInst, LookupInstResult(..),
+
+ isDict, isTyVarDict, isStdClassTyVarDict, isMethodFor,
+ instBindingRequired, instCanBeGeneralised,
zonkInst, instToId,
- matchesInst,
- instBindingRequired, instCanBeGeneralised,
-
- pprInst
+ InstOrigin(..), pprOrigin
) where
-IMP_Ubiq()
-IMPORT_1_3(Ratio(Rational))
-
-import HsSyn ( HsLit(..), HsExpr(..), HsBinds, Fixity, MonoBinds(..),
- InPat, OutPat, Stmt, DoOrListComp, Match, GRHSsAndBinds,
- ArithSeqInfo, HsType, Fake )
-import RnHsSyn ( SYN_IE(RenamedArithSeqInfo), SYN_IE(RenamedHsExpr) )
-import TcHsSyn ( SYN_IE(TcExpr),
- SYN_IE(TcDictBinds), SYN_IE(TcMonoBinds),
- mkHsTyApp, mkHsDictApp, tcIdTyVars )
+#include "HsVersions.h"
+import CmdLineOpts ( opt_AllowOverlappingInstances )
+import HsSyn ( HsLit(..), HsExpr(..), MonoBinds )
+import RnHsSyn ( RenamedArithSeqInfo, RenamedHsExpr )
+import TcHsSyn ( TcExpr, TcIdOcc(..), TcIdBndr,
+ mkHsTyApp, mkHsDictApp, tcIdTyVars, zonkTcId
+ )
import TcMonad
import TcEnv ( tcLookupGlobalValueByKey, tcLookupTyConByKey )
-import TcType ( TcIdOcc(..), SYN_IE(TcIdBndr),
- SYN_IE(TcType), SYN_IE(TcRhoType), TcMaybe, SYN_IE(TcTyVarSet),
- tcInstType, zonkTcType, tcSplitForAllTy, tcSplitRhoTy )
-
-import Bag ( emptyBag, unitBag, unionBags, unionManyBags, bagToList,
+import TcType ( TcThetaType,
+ TcType, TcTauType, TcMaybe, TcTyVarSet,
+ tcInstType, zonkTcType, zonkTcTypes, tcSplitForAllTy,
+ zonkTcThetaType
+ )
+import Bag ( emptyBag, unitBag, unionBags, unionManyBags,
listToBag, consBag, Bag )
import Class ( classInstEnv,
- SYN_IE(Class), GenClass, SYN_IE(ClassInstEnv)
+ Class, ClassInstEnv
)
-import ErrUtils ( addErrLoc, SYN_IE(Error) )
-import Id ( GenId, idType, mkInstId, SYN_IE(Id) )
-import PrelInfo ( isCcallishClass, isNoDictClass )
-import MatchEnv ( lookupMEnv, insertMEnv )
-import Name ( OccName(..), Name, mkLocalName,
- mkSysLocalName, occNameString, getOccName )
-import Outputable
-import PprType ( GenClass, TyCon, GenType, GenTyVar, pprParendGenType )
-import Pretty
-import SpecEnv ( SpecEnv )
-import SrcLoc ( SrcLoc, noSrcLoc )
-import Type ( GenType, eqSimpleTy, instantiateTy,
- isTyVarTy, mkDictTy, splitForAllTy, splitSigmaTy,
- splitRhoTy, matchTy, tyVarsOfType, tyVarsOfTypes,
- mkSynTy, SYN_IE(Type)
+import MkId ( mkUserLocal, mkSysLocal )
+import Id ( Id, idType, mkId,
+ GenIdSet, elementOfIdSet
)
-import TyVar ( unionTyVarSets, GenTyVar )
+import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
+import Name ( OccName(..), Name, occNameString, getOccName )
+import PprType ( TyCon, pprConstraint )
+import SpecEnv ( SpecEnv, lookupSpecEnv )
+import SrcLoc ( SrcLoc )
+import Type ( Type, ThetaType, instantiateTy, instantiateThetaTy,
+ isTyVarTy, mkDictTy, splitForAllTys, splitSigmaTy,
+ splitRhoTy, tyVarsOfType, tyVarsOfTypes,
+ mkSynTy
+ )
+import TyVar ( zipTyVarEnv, lookupTyVarEnv, unionTyVarSets )
import TysPrim ( intPrimTy )
import TysWiredIn ( intDataCon, integerTy, isIntTy, isIntegerTy, inIntRange )
import Unique ( fromRationalClassOpKey, rationalTyConKey,
fromIntClassOpKey, fromIntegerClassOpKey, Unique
)
-import Util ( panic, zipEqual, zipWithEqual, assoc, assertPanic, pprTrace{-ToDo:rm-} )
-#if __GLASGOW_HASKELL__ >= 202
-import Maybes
-#endif
+import Maybes ( MaybeErr, expectJust )
+import Util ( thenCmp, zipWithEqual )
+import Outputable
\end{code}
%************************************************************************
emptyLIE = emptyBag
unitLIE inst = unitBag inst
+mkLIE insts = listToBag insts
plusLIE lie1 lie2 = lie1 `unionBags` lie2
consLIE inst lie = inst `consBag` lie
plusLIEs lies = unionManyBags lies
zonkLIE :: LIE s -> NF_TcM s (LIE s)
zonkLIE lie = mapBagNF_Tc zonkInst lie
-pprLIE :: PprStyle -> LIE s -> Doc
-pprLIE sty lie = pprQuote sty $ \ sty ->
- braces (hsep (punctuate comma (map (pprInst sty) (bagToList lie))))
+pprInsts :: [Inst s] -> SDoc
+pprInsts insts = parens (hsep (punctuate comma (map pprInst insts)))
-pprLIEInFull sty insts
- = vcat (map go (bagToList insts))
+pprInstsInFull insts
+ = vcat (map go insts)
where
- go inst = ppr sty inst <+> pprOrigin sty inst
+ go inst = quotes (ppr inst) <+> pprOrigin inst
\end{code}
%************************************************************************
data Inst s
= Dict
Unique
- Class -- The type of the dict is (c t), where
- (TcType s) -- c is the class and t the type;
+ Class -- The type of the dict is (c ts), where
+ [TcType s] -- c is the class and ts the types;
(InstOrigin s)
SrcLoc
-- should be instantiated.
-- These types must saturate the Id's foralls.
- (TcRhoType s) -- Cached: (type-of-id applied to inst_tys)
- -- If this type is (theta => tau) then the type of the Method
- -- is tau, and the method can be built by saying
- -- id inst_tys dicts
- -- where dicts are constructed from theta
+ (TcThetaType s) -- The (types of the) dictionaries to which the function
+ -- must be applied to get the method
+
+ (TcTauType s) -- The type of the method
(InstOrigin s)
SrcLoc
+ -- INVARIANT: in (Method u f tys theta tau loc)
+ -- type of (f tys dicts(from theta)) = tau
+
| LitInst
Unique
OverloadedLit
data OverloadedLit
= OverloadedIntegral Integer -- The number
| OverloadedFractional Rational -- The number
+\end{code}
+
+Ordering
+~~~~~~~~
+@Insts@ are ordered by their class/type info, rather than by their
+unique. This allows the context-reduction mechanism to use standard finite
+maps to do their stuff.
+
+\begin{code}
+instance Ord (Inst s) where
+ compare = cmpInst
+
+instance Eq (Inst s) where
+ (==) i1 i2 = case i1 `cmpInst` i2 of
+ EQ -> True
+ other -> False
+
+cmpInst (Dict _ clas1 tys1 _ _) (Dict _ clas2 tys2 _ _)
+ = (clas1 `compare` clas2) `thenCmp` (tys1 `compare` tys2)
+cmpInst (Dict _ _ _ _ _) other
+ = LT
+
+
+cmpInst (Method _ _ _ _ _ _ _) (Dict _ _ _ _ _)
+ = GT
+cmpInst (Method _ id1 tys1 _ _ _ _) (Method _ id2 tys2 _ _ _ _)
+ = (id1 `compare` id2) `thenCmp` (tys1 `compare` tys2)
+cmpInst (Method _ _ _ _ _ _ _) other
+ = LT
+
+cmpInst (LitInst _ lit1 ty1 _ _) (LitInst _ lit2 ty2 _ _)
+ = (lit1 `cmpOverLit` lit2) `thenCmp` (ty1 `compare` ty2)
+cmpInst (LitInst _ _ _ _ _) other
+ = GT
+
+cmpOverLit (OverloadedIntegral i1) (OverloadedIntegral i2) = i1 `compare` i2
+cmpOverLit (OverloadedFractional f1) (OverloadedFractional f2) = f1 `compare` f2
+cmpOverLit (OverloadedIntegral _) (OverloadedFractional _) = LT
+cmpOverLit (OverloadedFractional _) (OverloadedIntegral _) = GT
+\end{code}
+
+
+Selection
+~~~~~~~~~
+\begin{code}
+instOrigin (Dict u clas tys origin loc) = origin
+instOrigin (Method u clas ty _ _ origin loc) = origin
+instOrigin (LitInst u lit ty origin loc) = origin
+
+instLoc (Dict u clas tys origin loc) = loc
+instLoc (Method u clas ty _ _ origin loc) = loc
+instLoc (LitInst u lit ty origin loc) = loc
+
+getDictClassTys (Dict u clas tys _ _) = (clas, tys)
+
+tyVarsOfInst :: Inst s -> TcTyVarSet s
+tyVarsOfInst (Dict _ _ tys _ _) = tyVarsOfTypes tys
+tyVarsOfInst (Method _ id tys _ _ _ _) = tyVarsOfTypes tys `unionTyVarSets` tcIdTyVars id
+ -- The id might not be a RealId; in the case of
+ -- locally-overloaded class methods, for example
+tyVarsOfInst (LitInst _ _ ty _ _) = tyVarsOfType ty
+\end{code}
+
+Predicates
+~~~~~~~~~~
+\begin{code}
+isDict :: Inst s -> Bool
+isDict (Dict _ _ _ _ _) = True
+isDict other = False
+
+isMethodFor :: GenIdSet (TcType s) -> Inst s -> Bool
+isMethodFor ids (Method uniq (TcId id) tys _ _ orig loc)
+ = id `elementOfIdSet` ids
+isMethodFor ids inst
+ = False
+
+isTyVarDict :: Inst s -> Bool
+isTyVarDict (Dict _ _ tys _ _) = all isTyVarTy tys
+isTyVarDict other = False
-getInstOrigin (Dict u clas ty origin loc) = origin
-getInstOrigin (Method u clas ty rho origin loc) = origin
-getInstOrigin (LitInst u lit ty origin loc) = origin
+isStdClassTyVarDict (Dict _ clas [ty] _ _) = isStandardClass clas && isTyVarTy ty
+isStdClassTyVarDict other = False
\end{code}
+Two predicates which deal with the case where class constraints don't
+necessarily result in bindings. The first tells whether an @Inst@
+must be witnessed by an actual binding; the second tells whether an
+@Inst@ can be generalised over.
+
+\begin{code}
+instBindingRequired :: Inst s -> Bool
+instBindingRequired (Dict _ clas _ _ _) = not (isNoDictClass clas)
+instBindingRequired other = True
+
+instCanBeGeneralised :: Inst s -> Bool
+instCanBeGeneralised (Dict _ clas _ _ _) = not (isCcallishClass clas)
+instCanBeGeneralised other = True
+\end{code}
+
+
Construction
~~~~~~~~~~~~
\begin{code}
newDicts :: InstOrigin s
- -> [(Class, TcType s)]
+ -> TcThetaType s
-> NF_TcM s (LIE s, [TcIdOcc s])
newDicts orig theta
= tcGetSrcLoc `thenNF_Tc` \ loc ->
newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, ids) ->
returnNF_Tc (listToBag dicts, ids)
-{-
- tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
- let
- mk_dict u (clas, ty) = Dict u clas ty orig loc
- dicts = zipWithEqual "newDicts" mk_dict new_uniqs theta
- in
- returnNF_Tc (listToBag dicts, map instToId dicts)
--}
-- Local function, similar to newDicts,
-- but with slightly different interface
newDictsAtLoc :: InstOrigin s
-> SrcLoc
- -> [(Class, TcType s)]
+ -> TcThetaType s
-> NF_TcM s ([Inst s], [TcIdOcc s])
newDictsAtLoc orig loc theta =
tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
let
- mk_dict u (clas, ty) = Dict u clas ty orig loc
+ mk_dict u (clas, tys) = Dict u clas tys orig loc
dicts = zipWithEqual "newDictsAtLoc" mk_dict new_uniqs theta
in
returnNF_Tc (dicts, map instToId dicts)
+newDictFromOld :: Inst s -> Class -> [TcType s] -> NF_TcM s (Inst s)
+newDictFromOld (Dict _ _ _ orig loc) clas tys
+ = tcGetUnique `thenNF_Tc` \ uniq ->
+ returnNF_Tc (Dict uniq clas tys orig loc)
+
+
newMethod :: InstOrigin s
-> TcIdOcc s
-> [TcType s]
newMethod orig id tys
= -- Get the Id type and instantiate it at the specified types
(case id of
- RealId id -> let (tyvars, rho) = splitForAllTy (idType id)
+ RealId id -> let (tyvars, rho) = splitForAllTys (idType id)
in
- (if length tyvars /= length tys then pprTrace "newMethod" (ppr PprDebug (idType id)) else \x->x) $
- tcInstType (zip{-Equal "newMethod"-} tyvars tys) rho
+ ASSERT( length tyvars == length tys)
+ tcInstType (zipTyVarEnv tyvars tys) rho
+
TcId id -> tcSplitForAllTy (idType id) `thenNF_Tc` \ (tyvars, rho) ->
- returnNF_Tc (instantiateTy (zipEqual "newMethod(2)" tyvars tys) rho)
+ returnNF_Tc (instantiateTy (zipTyVarEnv tyvars tys) rho)
) `thenNF_Tc` \ rho_ty ->
+ let
+ (theta, tau) = splitRhoTy rho_ty
+ in
-- Our friend does the rest
- newMethodWithGivenTy orig id tys rho_ty
+ newMethodWithGivenTy orig id tys theta tau
-newMethodWithGivenTy orig id tys rho_ty
+newMethodWithGivenTy orig id tys theta tau
= tcGetSrcLoc `thenNF_Tc` \ loc ->
tcGetUnique `thenNF_Tc` \ new_uniq ->
let
- meth_inst = Method new_uniq id tys rho_ty orig loc
+ meth_inst = Method new_uniq id tys theta tau orig loc
in
returnNF_Tc (unitLIE meth_inst, instToId meth_inst)
-newMethodAtLoc :: InstOrigin s -> SrcLoc -> Id -> [TcType s] -> NF_TcM s (Inst s, TcIdOcc s)
+newMethodAtLoc :: InstOrigin s -> SrcLoc
+ -> Id -> [TcType s]
+ -> NF_TcM s (Inst s, TcIdOcc s)
newMethodAtLoc orig loc real_id tys -- Local function, similar to newMethod but with
-- slightly different interface
= -- Get the Id type and instantiate it at the specified types
let
- (tyvars,rho) = splitForAllTy (idType real_id)
+ (tyvars,rho) = splitForAllTys (idType real_id)
in
- tcInstType (zipEqual "newMethodAtLoc" tyvars tys) rho `thenNF_Tc` \ rho_ty ->
- tcGetUnique `thenNF_Tc` \ new_uniq ->
+ tcInstType (zipTyVarEnv tyvars tys) rho `thenNF_Tc` \ rho_ty ->
+ tcGetUnique `thenNF_Tc` \ new_uniq ->
let
- meth_inst = Method new_uniq (RealId real_id) tys rho_ty orig loc
+ (theta, tau) = splitRhoTy rho_ty
+ meth_inst = Method new_uniq (RealId real_id) tys theta tau orig loc
in
returnNF_Tc (meth_inst, instToId meth_inst)
\begin{code}
instToId :: Inst s -> TcIdOcc s
instToId (Dict u clas ty orig loc)
- = TcId (mkInstId u (mkDictTy clas ty) (mkLocalName u str loc))
+ = TcId (mkUserLocal occ u (mkDictTy clas ty) loc)
where
- str = VarOcc (SLIT("d.") _APPEND_ (occNameString (getOccName clas)))
+ occ = VarOcc (SLIT("d.") _APPEND_ (occNameString (getOccName clas)))
-instToId (Method u id tys rho_ty orig loc)
- = TcId (mkInstId u tau_ty (mkLocalName u occ loc))
- where
- occ = getOccName id
- (_, tau_ty) = splitRhoTy rho_ty
- -- I hope we don't need tcSplitRhoTy...
- -- NB The method Id has just the tau type
+instToId (Method u id tys theta tau orig loc)
+ = TcId (mkUserLocal (getOccName id) u tau loc)
instToId (LitInst u list ty orig loc)
- = TcId (mkInstId u ty (mkSysLocalName u SLIT("lit") loc))
-\end{code}
-
-\begin{code}
-instType :: Inst s -> TcType s
-instType (Dict _ clas ty _ _) = mkDictTy clas ty
-instType (LitInst _ _ ty _ _) = ty
-instType (Method _ id tys ty _ _) = ty
+ = TcId (mkSysLocal SLIT("lit") u ty loc)
\end{code}
\begin{code}
zonkInst :: Inst s -> NF_TcM s (Inst s)
-zonkInst (Dict u clas ty orig loc)
- = zonkTcType ty `thenNF_Tc` \ new_ty ->
- returnNF_Tc (Dict u clas new_ty orig loc)
-
-zonkInst (Method u id tys rho orig loc) -- Doesn't zonk the id!
- = mapNF_Tc zonkTcType tys `thenNF_Tc` \ new_tys ->
- zonkTcType rho `thenNF_Tc` \ new_rho ->
- returnNF_Tc (Method u id new_tys new_rho orig loc)
+zonkInst (Dict u clas tys orig loc)
+ = zonkTcTypes tys `thenNF_Tc` \ new_tys ->
+ returnNF_Tc (Dict u clas new_tys orig loc)
+
+zonkInst (Method u id tys theta tau orig loc)
+ = zonkTcId id `thenNF_Tc` \ new_id ->
+ -- Essential to zonk the id in case it's a local variable
+ zonkTcTypes tys `thenNF_Tc` \ new_tys ->
+ zonkTcThetaType theta `thenNF_Tc` \ new_theta ->
+ zonkTcType tau `thenNF_Tc` \ new_tau ->
+ returnNF_Tc (Method u new_id new_tys new_theta new_tau orig loc)
zonkInst (LitInst u lit ty orig loc)
= zonkTcType ty `thenNF_Tc` \ new_ty ->
\end{code}
-\begin{code}
-tyVarsOfInst :: Inst s -> TcTyVarSet s
-tyVarsOfInst (Dict _ _ ty _ _) = tyVarsOfType ty
-tyVarsOfInst (Method _ id tys rho _ _) = tyVarsOfTypes tys `unionTyVarSets` tcIdTyVars id
- -- The id might not be a RealId; in the case of
- -- locally-overloaded class methods, for example
-tyVarsOfInst (LitInst _ _ ty _ _) = tyVarsOfType ty
-\end{code}
-
-@matchesInst@ checks when two @Inst@s are instances of the same
-thing at the same type, even if their uniques differ.
-
-\begin{code}
-matchesInst :: Inst s -> Inst s -> Bool
-
-matchesInst (Dict _ clas1 ty1 _ _) (Dict _ clas2 ty2 _ _)
- = clas1 == clas2 && ty1 `eqSimpleTy` ty2
-
-matchesInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _)
- = id1 == id2
- && and (zipWith eqSimpleTy tys1 tys2)
- && length tys1 == length tys2
-
-matchesInst (LitInst _ lit1 ty1 _ _) (LitInst _ lit2 ty2 _ _)
- = lit1 `eq` lit2 && ty1 `eqSimpleTy` ty2
- where
- (OverloadedIntegral i1) `eq` (OverloadedIntegral i2) = i1 == i2
- (OverloadedFractional f1) `eq` (OverloadedFractional f2) = f1 == f2
- _ `eq` _ = False
-
-matchesInst other1 other2 = False
-\end{code}
-
-
-Predicates
-~~~~~~~~~~
-\begin{code}
-isDict :: Inst s -> Bool
-isDict (Dict _ _ _ _ _) = True
-isDict other = False
-
-isTyVarDict :: Inst s -> Bool
-isTyVarDict (Dict _ _ ty _ _) = isTyVarTy ty
-isTyVarDict other = False
-\end{code}
-
-Two predicates which deal with the case where class constraints don't
-necessarily result in bindings. The first tells whether an @Inst@
-must be witnessed by an actual binding; the second tells whether an
-@Inst@ can be generalised over.
-
-\begin{code}
-instBindingRequired :: Inst s -> Bool
-instBindingRequired (Dict _ clas _ _ _) = not (isNoDictClass clas)
-instBindingRequired other = True
-
-instCanBeGeneralised :: Inst s -> Bool
-instCanBeGeneralised (Dict _ clas _ _ _) = not (isCcallishClass clas)
-instCanBeGeneralised other = True
-\end{code}
-
-
Printing
~~~~~~~~
ToDo: improve these pretty-printing things. The ``origin'' is really only
\begin{code}
instance Outputable (Inst s) where
- ppr sty inst = pprQuote sty (\ sty -> pprInst sty inst)
+ ppr inst = pprInst inst
-pprInst sty (LitInst u lit ty orig loc)
+pprInst (LitInst u lit ty orig loc)
= hsep [case lit of
OverloadedIntegral i -> integer i
OverloadedFractional f -> rational f,
ptext SLIT("at"),
- ppr sty ty,
- show_uniq sty u]
+ ppr ty,
+ show_uniq u]
-pprInst sty (Dict u clas ty orig loc)
- = hsep [ppr sty clas, pprParendGenType sty ty, show_uniq sty u]
+pprInst (Dict u clas tys orig loc) = pprConstraint clas tys <+> show_uniq u
-pprInst sty (Method u id tys rho orig loc)
- = hsep [ppr sty id, ptext SLIT("at"),
- interppSP sty tys,
- show_uniq sty u]
+pprInst (Method u id tys _ _ orig loc)
+ = hsep [ppr id, ptext SLIT("at"),
+ interppSP tys,
+ show_uniq u]
-show_uniq PprDebug u = ppr PprDebug u
-show_uniq sty u = empty
+show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
\end{code}
-Printing in error messages. These two must look the same.
-
-\begin{code}
-noInstanceErr inst sty = ptext SLIT("No instance for:") <+> ppr sty inst
-
-noSimpleInst clas ty sty
- = ptext SLIT("No instance for:") <+>
- (pprQuote sty (\ sty -> ppr sty clas <+> pprParendGenType sty ty))
-\end{code}
%************************************************************************
%* *
the dfun type.
\begin{code}
+data LookupInstResult s
+ = NoInstance
+ | SimpleInst (TcExpr s) -- Just a variable, type application, or literal
+ | GenInst [Inst s] (TcExpr s) -- The expression and its needed insts
lookupInst :: Inst s
- -> TcM s ([Inst s],
- TcDictBinds s) -- The new binding
+ -> NF_TcM s (LookupInstResult s)
-- Dictionaries
-lookupInst dict@(Dict _ clas ty orig loc)
- = case lookupMEnv matchTy (get_inst_env clas orig) ty of
- Nothing -> tcAddSrcLoc loc $
- tcAddErrCtxt (\sty -> pprOrigin sty dict) $
- failTc (noInstanceErr dict)
+lookupInst dict@(Dict _ clas tys orig loc)
+ = case lookupSpecEnv (classInstEnv clas) tys of
- Just (dfun_id, tenv)
+ Just (tenv, dfun_id)
-> let
- (tyvars, rho) = splitForAllTy (idType dfun_id)
- ty_args = map (assoc "lookupInst" tenv) tyvars
- -- tenv should bind all the tyvars
+ (tyvars, rho) = splitForAllTys (idType dfun_id)
+ ty_args = map (expectJust "Inst" . lookupTyVarEnv tenv) tyvars
+ -- tenv should bind all the tyvars
in
tcInstType tenv rho `thenNF_Tc` \ dfun_rho ->
let
(theta, tau) = splitRhoTy dfun_rho
+ ty_app = mkHsTyApp (HsVar (RealId dfun_id)) ty_args
in
+ if null theta then
+ returnNF_Tc (SimpleInst ty_app)
+ else
newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
let
- rhs = mkHsDictApp (mkHsTyApp (HsVar (RealId dfun_id)) ty_args) dict_ids
+ rhs = mkHsDictApp ty_app dict_ids
in
- returnTc (dicts, VarMonoBind (instToId dict) rhs)
+ returnNF_Tc (GenInst dicts rhs)
+ Nothing -> returnNF_Tc NoInstance
-- Methods
-lookupInst inst@(Method _ id tys rho orig loc)
- = tcSplitRhoTy rho `thenNF_Tc` \ (theta, _) ->
- newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
- returnTc (dicts, VarMonoBind (instToId inst) (mkHsDictApp (mkHsTyApp (HsVar id) tys) dict_ids))
+lookupInst inst@(Method _ id tys theta _ orig loc)
+ = newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
+ returnNF_Tc (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) dict_ids))
-- Literals
lookupInst inst@(LitInst u (OverloadedIntegral i) ty orig loc)
| isIntTy ty && in_int_range -- Short cut for Int
- = returnTc ([], VarMonoBind inst_id int_lit)
+ = returnNF_Tc (GenInst [] int_lit)
+ -- GenInst, not SimpleInst, because int_lit is actually a constructor application
| isIntegerTy ty -- Short cut for Integer
- = returnTc ([], VarMonoBind inst_id integer_lit)
+ = returnNF_Tc (GenInst [] integer_lit)
| in_int_range -- It's overloaded but small enough to fit into an Int
= tcLookupGlobalValueByKey fromIntClassOpKey `thenNF_Tc` \ from_int ->
newMethodAtLoc orig loc from_int [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnTc ([method_inst], VarMonoBind inst_id (HsApp (HsVar method_id) int_lit))
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) int_lit))
| otherwise -- Alas, it is overloaded and a big literal!
= tcLookupGlobalValueByKey fromIntegerClassOpKey `thenNF_Tc` \ from_integer ->
newMethodAtLoc orig loc from_integer [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnTc ([method_inst], VarMonoBind inst_id (HsApp (HsVar method_id) integer_lit))
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) integer_lit))
where
in_int_range = inIntRange i
intprim_lit = HsLitOut (HsIntPrim i) intPrimTy
integer_lit = HsLitOut (HsInt i) integerTy
int_lit = HsApp (HsVar (RealId intDataCon)) intprim_lit
- inst_id = instToId inst
lookupInst inst@(LitInst u (OverloadedFractional f) ty orig loc)
= tcLookupGlobalValueByKey fromRationalClassOpKey `thenNF_Tc` \ from_rational ->
rational_lit = HsLitOut (HsFrac f) rational_ty
in
newMethodAtLoc orig loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnTc ([method_inst], VarMonoBind (instToId inst) (HsApp (HsVar method_id) rational_lit))
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rational_lit))
\end{code}
There is a second, simpler interface, when you want an instance of a
\begin{code}
lookupSimpleInst :: ClassInstEnv
-> Class
- -> Type -- Look up (c,t)
- -> TcM s [(Class,Type)] -- Here are the needed (c,t)s
-
-lookupSimpleInst class_inst_env clas ty
- = case (lookupMEnv matchTy class_inst_env ty) of
- Nothing -> failTc (noSimpleInst clas ty)
- Just (dfun,tenv) -> returnTc [(c,instantiateTy tenv t) | (c,t) <- theta]
- where
- (_, theta, _) = splitSigmaTy (idType dfun)
-\end{code}
-
-
-@mkInstSpecEnv@ is used to construct the @SpecEnv@ for a dfun.
-It does it by filtering the class's @InstEnv@. All pretty shady stuff.
-
-\begin{code}
-mkInstSpecEnv clas inst_ty inst_tvs inst_theta = panic "mkInstSpecEnv"
-\end{code}
-
-\begin{pseudocode}
-mkInstSpecEnv :: Class -- class
- -> Type -- instance type
- -> [TyVarTemplate] -- instance tyvars
- -> ThetaType -- superclasses dicts
- -> SpecEnv -- specenv for dfun of instance
+ -> [Type] -- Look up (c,t)
+ -> NF_TcM s (Maybe ThetaType) -- Here are the needed (c,t)s
-mkInstSpecEnv clas inst_ty inst_tvs inst_theta
- = mkSpecEnv (catMaybes (map maybe_spec_info matches))
- where
- matches = matchMEnv matchTy (classInstEnv clas) inst_ty
-
- maybe_spec_info (_, match_info, MkInstTemplate dfun _ [])
- = Just (SpecInfo (map (assocMaybe match_info) inst_tvs) (length inst_theta) dfun)
- maybe_spec_info (_, match_info, _)
- = Nothing
-\end{pseudocode}
+lookupSimpleInst class_inst_env clas tys
+ = case lookupSpecEnv class_inst_env tys of
+ Nothing -> returnNF_Tc Nothing
-
-\begin{code}
-addClassInst
- :: ClassInstEnv -- Incoming envt
- -> Type -- The instance type: inst_ty
- -> Id -- Dict fun id to apply. Free tyvars of inst_ty must
- -- be the same as the forall'd tyvars of the dfun id.
- -> MaybeErr
- ClassInstEnv -- Success
- (Type, Id) -- Offending overlap
-
-addClassInst inst_env inst_ty dfun_id = insertMEnv matchTy inst_env inst_ty dfun_id
+ Just (tenv, dfun)
+ -> returnNF_Tc (Just (instantiateThetaTy tenv theta))
+ where
+ (_, theta, _) = splitSigmaTy (idType dfun)
\end{code}
| ClassDeclOrigin -- Manufactured during a class decl
--- NO MORE!
--- | DerivingOrigin InstanceMapper
--- Class
--- TyCon
-
- -- During "deriving" operations we have an ever changing
- -- mapping of classes to instances, so we record it inside the
- -- origin information. This is a bit of a hack, but it works
- -- fine. (Simon is to blame [WDP].)
-
- | InstanceSpecOrigin InstanceMapper
- Class -- in a SPECIALIZE instance pragma
+ | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
Type
-- When specialising instances the instance info attached to
-- origin information. This is a bit of a hack, but it works
-- fine. (Patrick is to blame [WDP].)
--- | DefaultDeclOrigin -- Related to a `default' declaration
-
| ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
-- Argument or result of a ccall
\end{code}
\begin{code}
--- During deriving and instance specialisation operations
--- we can't get the instances of the class from inside the
--- class, because the latter ain't ready yet. Instead we
--- find a mapping from classes to envts inside the dict origin.
-
-get_inst_env :: Class -> InstOrigin s -> ClassInstEnv
--- get_inst_env clas (DerivingOrigin inst_mapper _ _)
--- = fst (inst_mapper clas)
-get_inst_env clas (InstanceSpecOrigin inst_mapper _ _)
- = inst_mapper clas
-get_inst_env clas other_orig = classInstEnv clas
-
-
-pprOrigin :: PprStyle -> Inst s -> Doc
-pprOrigin sty inst
- = hsep [text "arising from", pp_orig orig, text "at", ppr sty locn]
+pprOrigin :: Inst s -> SDoc
+pprOrigin inst
+ = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
where
(orig, locn) = case inst of
- Dict _ _ _ orig loc -> (orig,loc)
- Method _ _ _ _ orig loc -> (orig,loc)
- LitInst _ _ _ orig loc -> (orig,loc)
+ Dict _ _ _ orig loc -> (orig,loc)
+ Method _ _ _ _ _ orig loc -> (orig,loc)
+ LitInst _ _ _ orig loc -> (orig,loc)
pp_orig (OccurrenceOf id)
- = hsep [ptext SLIT("use of"), ppr sty id]
+ = hsep [ptext SLIT("use of"), quotes (ppr id)]
pp_orig (OccurrenceOfCon id)
- = hsep [ptext SLIT("use of"), ppr sty id]
+ = hsep [ptext SLIT("use of"), quotes (ppr id)]
pp_orig (LiteralOrigin lit)
- = hsep [ptext SLIT("the literal"), ppr sty lit]
+ = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
pp_orig (InstanceDeclOrigin)
= ptext SLIT("an instance declaration")
pp_orig (ArithSeqOrigin seq)
- = hsep [ptext SLIT("the arithmetic sequence:"), ppr sty seq]
+ = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
pp_orig (SignatureOrigin)
= ptext SLIT("a type signature")
pp_orig (Rank2Origin)
= ptext SLIT("a do statement")
pp_orig (ClassDeclOrigin)
= ptext SLIT("a class declaration")
- pp_orig (InstanceSpecOrigin _ clas ty)
+ pp_orig (InstanceSpecOrigin clas ty)
= hsep [text "a SPECIALIZE instance pragma; class",
- ppr sty clas, text "type:", ppr sty ty]
+ quotes (ppr clas), text "type:", ppr ty]
pp_orig (ValSpecOrigin name)
- = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), ppr sty name]
+ = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), quotes (ppr name)]
pp_orig (CCallOrigin clabel Nothing{-ccall result-})
- = hsep [ptext SLIT("the result of the _ccall_ to"), text clabel]
+ = hsep [ptext SLIT("the result of the _ccall_ to"), quotes (text clabel)]
pp_orig (CCallOrigin clabel (Just arg_expr))
- = hsep [ptext SLIT("an argument in the _ccall_ to"), text clabel <> comma, text "namely", ppr sty arg_expr]
+ = hsep [ptext SLIT("an argument in the _ccall_ to"), quotes (text clabel) <> comma,
+ text "namely", quotes (ppr arg_expr)]
pp_orig (LitLitOrigin s)
- = hsep [ptext SLIT("the ``literal-literal''"), text s]
+ = hsep [ptext SLIT("the ``literal-literal''"), quotes (text s)]
pp_orig (UnknownOrigin)
= ptext SLIT("...oops -- I don't know where the overloading came from!")
\end{code}
projects / ghc-hetmet.git / blobdiff