%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[Inst]{The @Inst@ type: dictionaries or method instances}
\begin{code}
-#include "HsVersions.h"
-
-module Inst (
- Inst(..), -- Visible only to TcSimplify
+module Inst (
+ LIE, emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE,
+ plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE,
- InstOrigin(..), OverloadedLit(..),
- LIE(..), emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE, plusLIEs,
+ Inst, OverloadedLit(..),
+ pprInst, pprInsts, pprInstsInFull, tidyInst, tidyInsts,
- InstanceMapper(..),
+ InstanceMapper,
- newDicts, newDictsAtLoc, newMethod, newMethodWithGivenTy, newOverloadedLit,
+ newDictFromOld, newDicts, newClassDicts, newDictsAtLoc,
+ newMethod, newMethodWithGivenTy, newOverloadedLit,
+ newIPDict, instOverloadedFun,
- instType, tyVarsOfInst, lookupInst,
+ tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, instLoc, getDictClassTys,
+ getDictPred_maybe, getMethodTheta_maybe,
+ getFunDeps, getFunDepsOfLIE,
+ getIPs, getIPsOfLIE,
+ getAllFunDeps, getAllFunDepsOfLIE,
- isDict, isTyVarDict,
+ lookupInst, lookupSimpleInst, LookupInstResult(..),
- zonkInst, instToId,
+ isDict, isClassDict, isTyVarDict, isStdClassTyVarDict, isMethodFor, notFunDep,
+ instBindingRequired, instCanBeGeneralised,
- matchesInst,
- instBindingRequired, instCanBeGeneralised
+ zonkInst, zonkInsts, zonkFunDeps, zonkTvFunDeps,
+ instToId, instToIdBndr, ipToId,
+ InstOrigin(..), InstLoc, pprInstLoc
) where
-import Ubiq
-
-import HsSyn ( HsLit(..), HsExpr(..), HsBinds,
- InPat, OutPat, Stmt, Qual, Match,
- ArithSeqInfo, PolyType, Fake )
-import RnHsSyn ( RenamedArithSeqInfo(..), RenamedHsExpr(..) )
-import TcHsSyn ( TcIdOcc(..), TcExpr(..), TcIdBndr(..),
- mkHsTyApp, mkHsDictApp )
+#include "HsVersions.h"
+import HsSyn ( HsLit(..), HsExpr(..) )
+import RnHsSyn ( RenamedArithSeqInfo, RenamedHsExpr, RenamedPat )
+import TcHsSyn ( TcExpr, TcId,
+ mkHsTyApp, mkHsDictApp, mkHsDictLam, zonkId
+ )
import TcMonad
-import TcEnv ( tcLookupGlobalValueByKey )
-import TcType ( TcType(..), TcRhoType(..), TcMaybe, TcTyVarSet(..),
- tcInstType, tcInstTcType, zonkTcType )
-
-import Bag ( emptyBag, unitBag, unionBags, unionManyBags, listToBag, consBag )
-import Class ( Class(..), GenClass, ClassInstEnv(..), classInstEnv )
-import Id ( GenId, idType, mkInstId )
-import MatchEnv ( lookupMEnv, insertMEnv )
-import Name ( mkLocalName, getLocalName, Name )
+import TcEnv ( TcIdSet, tcLookupValueByKey, tcLookupTyConByKey )
+import TcType ( TcThetaType,
+ TcType, TcTauType, TcTyVarSet,
+ zonkTcTyVars, zonkTcType, zonkTcTypes,
+ zonkTcThetaType
+ )
+import Bag
+import Class ( classInstEnv, Class )
+import FunDeps ( instantiateFdClassTys )
+import Id ( Id, idFreeTyVars, idType, mkUserLocal, mkSysLocal )
+import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
+import Name ( OccName, Name, mkDictOcc, mkMethodOcc, mkIPOcc,
+ getOccName, nameUnique )
+import PprType ( pprPred )
+import InstEnv ( InstEnv, lookupInstEnv )
+import SrcLoc ( SrcLoc )
+import Type ( Type, PredType(..), ThetaType,
+ mkTyVarTy, isTyVarTy, mkDictTy, mkPredTy,
+ splitForAllTys, splitSigmaTy,
+ splitRhoTy, tyVarsOfType, tyVarsOfTypes, tyVarsOfPred,
+ mkSynTy, tidyOpenType, tidyOpenTypes
+ )
+import InstEnv ( InstEnv )
+import Subst ( emptyInScopeSet, mkSubst,
+ substTy, substClasses, mkTyVarSubst, mkTopTyVarSubst
+ )
+import TyCon ( TyCon )
+import Var ( TyVar )
+import VarEnv ( lookupVarEnv, TidyEnv,
+ lookupSubstEnv, SubstResult(..)
+ )
+import VarSet ( elemVarSet, emptyVarSet, unionVarSet )
+import TysPrim ( intPrimTy, floatPrimTy, doublePrimTy )
+import TysWiredIn ( intDataCon, isIntTy, inIntRange,
+ floatDataCon, isFloatTy,
+ doubleDataCon, isDoubleTy,
+ integerTy, isIntegerTy
+ )
+import Unique ( fromRationalClassOpKey, rationalTyConKey,
+ fromIntClassOpKey, fromIntegerClassOpKey, Unique
+ )
+import Maybes ( expectJust )
+import Maybe ( catMaybes )
+import Util ( thenCmp, zipWithEqual, mapAccumL )
import Outputable
-import PprType ( GenClass, TyCon, GenType, GenTyVar )
-import PprStyle ( PprStyle(..) )
-import Pretty
-import RnHsSyn ( RnName{-instance NamedThing-} )
-import SpecEnv ( SpecEnv(..) )
-import SrcLoc ( SrcLoc, mkUnknownSrcLoc )
-import Type ( GenType, eqSimpleTy,
- isTyVarTy, mkDictTy, splitForAllTy, splitSigmaTy,
- splitRhoTy, matchTy, tyVarsOfType, tyVarsOfTypes )
-import TyVar ( GenTyVar )
-import TysPrim ( intPrimTy )
-import TysWiredIn ( intDataCon )
-import Unique ( Unique, showUnique,
- fromRationalClassOpKey, fromIntClassOpKey, fromIntegerClassOpKey )
-import Util ( panic, zipEqual, zipWithEqual, assoc, assertPanic )
-
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-type LIE s = Bag (Inst s)
+type LIE = Bag Inst
+isEmptyLIE = isEmptyBag
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
+lieToList = bagToList
+listToLIE = listToBag
-zonkLIE :: LIE s -> NF_TcM s (LIE s)
+zonkLIE :: LIE -> NF_TcM s LIE
zonkLIE lie = mapBagNF_Tc zonkInst lie
+
+pprInsts :: [Inst] -> SDoc
+pprInsts insts = parens (sep (punctuate comma (map pprInst insts)))
+
+
+pprInstsInFull insts
+ = vcat (map go insts)
+ where
+ go inst = quotes (ppr inst) <+> pprInstLoc (instLoc inst)
\end{code}
%************************************************************************
Method 34 doubleId [Int] origin
\begin{code}
-data Inst s
+data Inst
= Dict
Unique
- Class -- The type of the dict is (c t), where
- (TcType s) -- c is the class and t the type;
- (InstOrigin s)
- SrcLoc
+ TcPredType
+ InstLoc
| Method
Unique
- (TcIdOcc s) -- The overloaded function
+ TcId -- The overloaded function
-- This function will be a global, local, or ClassOpId;
-- inside instance decls (only) it can also be an InstId!
-- The id needn't be completely polymorphic.
-- You'll probably find its name (for documentation purposes)
-- inside the InstOrigin
- [TcType s] -- The types to which its polymorphic tyvars
+ [TcType] -- The types to which its polymorphic tyvars
-- 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 -- The (types of the) dictionaries to which the function
+ -- must be applied to get the method
+
+ TcTauType -- The type of the method
+
+ InstLoc
- (InstOrigin s)
- SrcLoc
+ -- INVARIANT: in (Method u f tys theta tau loc)
+ -- type of (f tys dicts(from theta)) = tau
| LitInst
Unique
OverloadedLit
- (TcType s) -- The type at which the literal is used
- (InstOrigin s) -- Always a literal; but more convenient to carry this around
- SrcLoc
+ TcType -- The type at which the literal is used
+ InstLoc
+
+ | FunDep
+ Class -- the class from which this arises
+ [([TcType], [TcType])]
+ InstLoc
data OverloadedLit
= OverloadedIntegral Integer -- The number
| OverloadedFractional Rational -- The number
+\end{code}
-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
+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 where
+ compare = cmpInst
+instance Ord PredType where
+ compare = cmpPred
+
+instance Eq Inst where
+ (==) i1 i2 = case i1 `cmpInst` i2 of
+ EQ -> True
+ other -> False
+instance Eq PredType where
+ (==) p1 p2 = case p1 `cmpPred` p2 of
+ EQ -> True
+ other -> False
+
+cmpInst (Dict _ pred1 _) (Dict _ pred2 _)
+ = (pred1 `cmpPred` pred2)
+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 _ _ _ _) (FunDep _ _ _)
+ = LT
+cmpInst (LitInst _ _ _ _) other
+ = GT
+
+cmpInst (FunDep clas1 fds1 _) (FunDep clas2 fds2 _)
+ = (clas1 `compare` clas2) `thenCmp` (fds1 `compare` fds2)
+cmpInst (FunDep _ _ _) other
+ = GT
+
+cmpPred (Class c1 tys1) (Class c2 tys2)
+ = (c1 `compare` c2) `thenCmp` (tys1 `compare` tys2)
+cmpPred (IParam n1 ty1) (IParam n2 ty2)
+ = (n1 `compare` n2) `thenCmp` (ty1 `compare` ty2)
+cmpPred (Class _ _) (IParam _ _) = LT
+cmpPred _ _ = 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}
+instLoc (Dict u pred loc) = loc
+instLoc (Method u _ _ _ _ loc) = loc
+instLoc (LitInst u lit ty loc) = loc
+instLoc (FunDep _ _ loc) = loc
+
+getDictPred_maybe (Dict _ p _) = Just p
+getDictPred_maybe _ = Nothing
+
+getMethodTheta_maybe (Method _ _ _ theta _ _) = Just theta
+getMethodTheta_maybe _ = Nothing
+
+getDictClassTys (Dict u (Class clas tys) _) = (clas, tys)
+
+getFunDeps (FunDep clas fds _) = Just (clas, fds)
+getFunDeps _ = Nothing
+
+getFunDepsOfLIE lie = catMaybes (map getFunDeps (lieToList lie))
+
+getIPsOfPred (IParam n ty) = [(n, ty)]
+getIPsOfPred _ = []
+getIPsOfTheta theta = concatMap getIPsOfPred theta
+
+getIPs (Dict u (IParam n ty) loc) = [(n, ty)]
+getIPs (Method u id _ theta t loc) = getIPsOfTheta theta
+getIPs _ = []
+
+getIPsOfLIE lie = concatMap getIPs (lieToList lie)
+
+getAllFunDeps (FunDep clas fds _) = fds
+getAllFunDeps inst = map (\(n,ty) -> ([], [ty])) (getIPs inst)
+
+getAllFunDepsOfLIE lie = concat (map getAllFunDeps (lieToList lie))
+
+tyVarsOfInst :: Inst -> TcTyVarSet
+tyVarsOfInst (Dict _ pred _) = tyVarsOfPred pred
+tyVarsOfInst (Method _ id tys _ _ _) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id
+ -- The id might have free type variables; in the case of
+ -- locally-overloaded class methods, for example
+tyVarsOfInst (LitInst _ _ ty _) = tyVarsOfType ty
+tyVarsOfInst (FunDep _ fds _)
+ = foldr unionVarSet emptyVarSet (map tyVarsOfFd fds)
+ where tyVarsOfFd (ts1, ts2) =
+ tyVarsOfTypes ts1 `unionVarSet` tyVarsOfTypes ts2
+
+tyVarsOfInsts insts
+ = foldr unionVarSet emptyVarSet (map tyVarsOfInst insts)
+
+tyVarsOfLIE lie
+ = foldr unionVarSet emptyVarSet (map tyVarsOfInst insts)
+ where insts = lieToList lie
+\end{code}
+
+Predicates
+~~~~~~~~~~
+\begin{code}
+isDict :: Inst -> Bool
+isDict (Dict _ _ _) = True
+isDict other = False
+isClassDict :: Inst -> Bool
+isClassDict (Dict _ (Class _ _) _) = True
+isClassDict other = False
+
+isMethodFor :: TcIdSet -> Inst -> Bool
+isMethodFor ids (Method uniq id tys _ _ loc)
+ = id `elemVarSet` ids
+isMethodFor ids inst
+ = False
+
+isTyVarDict :: Inst -> Bool
+isTyVarDict (Dict _ (Class _ tys) _) = all isTyVarTy tys
+isTyVarDict other = False
+
+isStdClassTyVarDict (Dict _ (Class clas [ty]) _)
+ = isStandardClass clas && isTyVarTy ty
+isStdClassTyVarDict other
+ = False
+
+notFunDep :: Inst -> Bool
+notFunDep (FunDep _ _ _) = False
+notFunDep other = True
+\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 -> Bool
+instBindingRequired (Dict _ (Class clas _) _) = not (isNoDictClass clas)
+instBindingRequired (Dict _ (IParam _ _) _) = False
+instBindingRequired other = True
+
+instCanBeGeneralised :: Inst -> Bool
+instCanBeGeneralised (Dict _ (Class clas _) _) = not (isCcallishClass clas)
+instCanBeGeneralised other = True
+\end{code}
+
+
Construction
~~~~~~~~~~~~
\begin{code}
-newDicts :: InstOrigin s
- -> [(Class, TcType s)]
- -> NF_TcM s (LIE s, [TcIdOcc s])
+newDicts :: InstOrigin
+ -> TcThetaType
+ -> NF_TcM s (LIE, [TcId])
newDicts orig theta
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
- tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
- let
- mk_dict u (clas, ty) = Dict u clas ty orig loc
- dicts = zipWithEqual mk_dict new_uniqs theta
- in
- returnNF_Tc (listToBag dicts, map instToId dicts)
-
-newDictsAtLoc orig loc theta -- Local function, similar to newDicts,
- -- but with slightly different interface
- = tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
- let
- mk_dict u (clas, ty) = Dict u clas ty orig loc
- dicts = zipWithEqual mk_dict new_uniqs theta
- in
- returnNF_Tc (dicts, map instToId dicts)
-
-newMethod :: InstOrigin s
- -> TcIdOcc s
- -> [TcType s]
- -> NF_TcM s (LIE s, TcIdOcc s)
+ = tcGetInstLoc orig `thenNF_Tc` \ loc ->
+ newDictsAtLoc loc theta `thenNF_Tc` \ (dicts, ids) ->
+ returnNF_Tc (listToBag dicts, ids)
+
+newClassDicts :: InstOrigin
+ -> [(Class,[TcType])]
+ -> NF_TcM s (LIE, [TcId])
+newClassDicts orig theta
+ = newDicts orig (map (uncurry Class) theta)
+
+-- Local function, similar to newDicts,
+-- but with slightly different interface
+newDictsAtLoc :: InstLoc
+ -> TcThetaType
+ -> NF_TcM s ([Inst], [TcId])
+newDictsAtLoc loc theta =
+ tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
+ let
+ mk_dict u pred = Dict u pred loc
+ dicts = zipWithEqual "newDictsAtLoc" mk_dict new_uniqs theta
+ in
+ returnNF_Tc (dicts, map instToId dicts)
+
+newDictFromOld :: Inst -> Class -> [TcType] -> NF_TcM s Inst
+newDictFromOld (Dict _ _ loc) clas tys
+ = tcGetUnique `thenNF_Tc` \ uniq ->
+ returnNF_Tc (Dict uniq (Class clas tys) loc)
+
+
+newMethod :: InstOrigin
+ -> TcId
+ -> [TcType]
+ -> NF_TcM s (LIE, TcId)
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)
- in tcInstType (tyvars `zipEqual` tys) rho
- TcId id -> let (tyvars, rho) = splitForAllTy (idType id)
- in tcInstTcType (tyvars `zipEqual` tys) rho
- ) `thenNF_Tc` \ rho_ty ->
- -- Our friend does the rest
- newMethodWithGivenTy orig id tys rho_ty
-
-
-newMethodWithGivenTy orig id tys rho_ty
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
- tcGetUnique `thenNF_Tc` \ new_uniq ->
let
- meth_inst = Method new_uniq id tys rho_ty orig loc
+ (tyvars, rho) = splitForAllTys (idType id)
+ rho_ty = substTy (mkTyVarSubst tyvars tys) rho
+ (theta, tau) = splitRhoTy rho_ty
in
+ newMethodWithGivenTy orig id tys theta tau `thenNF_Tc` \ meth_inst ->
returnNF_Tc (unitLIE meth_inst, instToId meth_inst)
-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
+instOverloadedFun orig (HsVar v) arg_tys theta tau
+ = newMethodWithGivenTy orig v arg_tys theta tau `thenNF_Tc` \ inst ->
+ instFunDeps orig theta `thenNF_Tc` \ fds ->
+ returnNF_Tc (HsVar (instToId inst), mkLIE (inst : fds))
+
+instFunDeps orig theta
+ = tcGetInstLoc orig `thenNF_Tc` \ loc ->
+ let ifd (Class clas tys) =
+ let fds = instantiateFdClassTys clas tys in
+ if null fds then Nothing else Just (FunDep clas fds loc)
+ ifd _ = Nothing
+ in returnNF_Tc (catMaybes (map ifd theta))
+
+newMethodWithGivenTy orig id tys theta tau
+ = tcGetInstLoc orig `thenNF_Tc` \ loc ->
+ newMethodWith id tys theta tau loc
+
+newMethodWith id tys theta tau loc
+ = tcGetUnique `thenNF_Tc` \ new_uniq ->
+ returnNF_Tc (Method new_uniq id tys theta tau loc)
+
+newMethodAtLoc :: InstLoc
+ -> Id -> [TcType]
+ -> NF_TcM s (Inst, TcId)
+newMethodAtLoc 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)
- in
- tcInstType (tyvars `zipEqual` 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
+ (tyvars,rho) = splitForAllTys (idType real_id)
+ rho_ty = ASSERT( length tyvars == length tys )
+ substTy (mkTopTyVarSubst tyvars tys) rho
+ (theta, tau) = splitRhoTy rho_ty
+ meth_inst = Method new_uniq real_id tys theta tau loc
in
returnNF_Tc (meth_inst, instToId meth_inst)
+\end{code}
-newOverloadedLit :: InstOrigin s
+In newOverloadedLit we convert directly to an Int or Integer if we
+know that's what we want. This may save some time, by not
+temporarily generating overloaded literals, but it won't catch all
+cases (the rest are caught in lookupInst).
+
+\begin{code}
+newOverloadedLit :: InstOrigin
-> OverloadedLit
- -> TcType s
- -> NF_TcM s (LIE s, TcIdOcc s)
-newOverloadedLit orig lit ty
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
+ -> TcType
+ -> NF_TcM s (TcExpr, LIE)
+newOverloadedLit orig (OverloadedIntegral i) ty
+ | isIntTy ty && inIntRange i -- Short cut for Int
+ = returnNF_Tc (int_lit, emptyLIE)
+
+ | isIntegerTy ty -- Short cut for Integer
+ = returnNF_Tc (integer_lit, emptyLIE)
+
+ where
+ intprim_lit = HsLitOut (HsIntPrim i) intPrimTy
+ integer_lit = HsLitOut (HsInt i) integerTy
+ int_lit = HsCon intDataCon [] [intprim_lit]
+
+newOverloadedLit orig lit ty -- The general case
+ = tcGetInstLoc orig `thenNF_Tc` \ loc ->
tcGetUnique `thenNF_Tc` \ new_uniq ->
let
- lit_inst = LitInst new_uniq lit ty orig loc
+ lit_inst = LitInst new_uniq lit ty loc
in
- returnNF_Tc (unitLIE lit_inst, instToId lit_inst)
+ returnNF_Tc (HsVar (instToId lit_inst), unitLIE lit_inst)
\end{code}
-
\begin{code}
-instToId :: Inst s -> TcIdOcc s
-instToId (Dict u clas ty orig loc)
- = TcId (mkInstId u (mkDictTy clas ty) (mkLocalName u SLIT("dict") loc))
-instToId (Method u id tys rho_ty orig loc)
- = TcId (mkInstId u tau_ty (mkLocalName u (getLocalName id) loc))
- where
- (_, tau_ty) = splitRhoTy rho_ty -- NB The method Id has just the tau type
-instToId (LitInst u list ty orig loc)
- = TcId (mkInstId u ty (mkLocalName u SLIT("lit") loc))
+newIPDict name ty loc
+ = tcGetUnique `thenNF_Tc` \ new_uniq ->
+ let d = Dict new_uniq (IParam name ty) loc in
+ returnNF_Tc d
\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
+instToId :: Inst -> TcId
+instToId inst = instToIdBndr inst
+
+instToIdBndr :: Inst -> TcId
+instToIdBndr (Dict u (Class clas ty) (_,loc,_))
+ = mkUserLocal (mkDictOcc (getOccName clas)) u (mkDictTy clas ty) loc
+instToIdBndr (Dict u (IParam n ty) (_,loc,_))
+ = ipToId n ty loc
+
+instToIdBndr (Method u id tys theta tau (_,loc,_))
+ = mkUserLocal (mkMethodOcc (getOccName id)) u tau loc
+
+instToIdBndr (LitInst u list ty loc)
+ = mkSysLocal SLIT("lit") u ty
+
+instToIdBndr (FunDep clas fds _)
+ = panic "FunDep escaped!!!"
+
+ipToId n ty loc
+ = mkUserLocal (mkIPOcc (getOccName n)) (nameUnique n) (mkPredTy (IParam n ty)) loc
\end{code}
need, and it's a lot of extra work.
\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 (LitInst u lit ty orig loc)
+zonkPred :: TcPredType -> NF_TcM s TcPredType
+zonkPred (Class clas tys)
+ = zonkTcTypes tys `thenNF_Tc` \ new_tys ->
+ returnNF_Tc (Class clas new_tys)
+zonkPred (IParam n ty)
= zonkTcType ty `thenNF_Tc` \ new_ty ->
- returnNF_Tc (LitInst u lit new_ty orig loc)
-\end{code}
+ returnNF_Tc (IParam n new_ty)
+zonkInst :: Inst -> NF_TcM s Inst
+zonkInst (Dict u pred loc)
+ = zonkPred pred `thenNF_Tc` \ new_pred ->
+ returnNF_Tc (Dict u new_pred loc)
-\begin{code}
-tyVarsOfInst :: Inst s -> TcTyVarSet s
-tyVarsOfInst (Dict _ _ ty _ _) = tyVarsOfType ty
-tyVarsOfInst (Method _ _ tys rho _ _) = tyVarsOfTypes tys
-tyVarsOfInst (LitInst _ _ ty _ _) = tyVarsOfType ty
-\end{code}
+zonkInst (Method u id tys theta tau loc)
+ = zonkId id `thenNF_Tc` \ new_id ->
+ -- Essential to zonk the id in case it's a local variable
+ -- Can't use zonkIdOcc because the id might itself be
+ -- an InstId, in which case it won't be in scope
-@matchesInst@ checks when two @Inst@s are instances of the same
-thing at the same type, even if their uniques differ.
+ 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 loc)
-\begin{code}
-matchesInst :: Inst s -> Inst s -> Bool
+zonkInst (LitInst u lit ty loc)
+ = zonkTcType ty `thenNF_Tc` \ new_ty ->
+ returnNF_Tc (LitInst u lit new_ty loc)
-matchesInst (Dict _ clas1 ty1 _ _) (Dict _ clas2 ty2 _ _)
- = clas1 == clas2 && ty1 `eqSimpleTy` ty2
+zonkInst (FunDep clas fds loc)
+ = zonkFunDeps fds `thenNF_Tc` \ fds' ->
+ returnNF_Tc (FunDep clas fds' loc)
-matchesInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _)
- = id1 == id2
- && and (zipWith eqSimpleTy tys1 tys2)
- && length tys1 == length tys2
+zonkPreds preds = mapNF_Tc zonkPred preds
+zonkInsts insts = mapNF_Tc zonkInst insts
-matchesInst (LitInst _ lit1 ty1 _ _) (LitInst _ lit2 ty2 _ _)
- = lit1 `eq` lit2 && ty1 `eqSimpleTy` ty2
+zonkFunDeps fds = mapNF_Tc zonkFd fds
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
+ zonkFd (ts1, ts2)
+ = zonkTcTypes ts1 `thenNF_Tc` \ ts1' ->
+ zonkTcTypes ts2 `thenNF_Tc` \ ts2' ->
+ returnNF_Tc (ts1', ts2')
-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 inst
- = case getInstOrigin inst of
- CCallOrigin _ _ -> False -- No binding required
- LitLitOrigin _ -> False
- OccurrenceOfCon _ -> False
- other -> True
-
-instCanBeGeneralised :: Inst s -> Bool
-instCanBeGeneralised inst
- = case getInstOrigin inst of
- CCallOrigin _ _ -> False -- Can't be generalised
- LitLitOrigin _ -> False -- Can't be generalised
- other -> True
+zonkTvFunDeps fds = mapNF_Tc zonkFd fds
+ where
+ zonkFd (tvs1, tvs2)
+ = zonkTcTyVars tvs1 `thenNF_Tc` \ tvs1' ->
+ zonkTcTyVars tvs2 `thenNF_Tc` \ tvs2' ->
+ returnNF_Tc (tvs1', tvs2')
\end{code}
relevant in error messages.
\begin{code}
-instance Outputable (Inst s) where
- ppr sty (LitInst uniq lit ty orig loc)
- = ppSep [case lit of
- OverloadedIntegral i -> ppInteger i
- OverloadedFractional f -> ppRational f,
- ppStr "at",
- ppr sty ty,
- show_uniq sty uniq
- ]
-
- ppr sty (Dict uniq clas ty orig loc)
- = ppSep [ppr sty clas,
- ppStr "at",
- ppr sty ty,
- show_uniq sty uniq
- ]
-
- ppr sty (Method uniq id tys rho orig loc)
- = ppSep [ppr sty id,
- ppStr "at",
- ppr sty tys,
- show_uniq sty uniq
- ]
-
-show_uniq PprDebug uniq = ppr PprDebug uniq
-show_uniq sty uniq = ppNil
+instance Outputable Inst where
+ ppr inst = pprInst inst
+
+pprInst (LitInst u lit ty loc)
+ = hsep [case lit of
+ OverloadedIntegral i -> integer i
+ OverloadedFractional f -> rational f,
+ ptext SLIT("at"),
+ ppr ty,
+ show_uniq u]
+
+pprInst (Dict u pred loc) = pprPred pred <+> show_uniq u
+
+pprInst m@(Method u id tys theta tau loc)
+ = hsep [ppr id, ptext SLIT("at"),
+ brackets (interppSP tys),
+ ppr theta, ppr tau,
+ show_uniq u,
+ ppr (instToId m)]
+
+pprInst (FunDep clas fds loc)
+ = hsep [ppr clas, ppr fds]
+
+tidyPred :: TidyEnv -> TcPredType -> (TidyEnv, TcPredType)
+tidyPred env (Class clas tys)
+ = (env', Class clas tys')
+ where
+ (env', tys') = tidyOpenTypes env tys
+tidyPred env (IParam n ty)
+ = (env', IParam n ty')
+ where
+ (env', ty') = tidyOpenType env ty
-\end{code}
+tidyInst :: TidyEnv -> Inst -> (TidyEnv, Inst)
+tidyInst env (LitInst u lit ty loc)
+ = (env', LitInst u lit ty' loc)
+ where
+ (env', ty') = tidyOpenType env ty
-Printing in error messages
+tidyInst env (Dict u pred loc)
+ = (env', Dict u pred' loc)
+ where
+ (env', pred') = tidyPred env pred
-\begin{code}
-noInstanceErr inst sty = ppHang (ppPStr SLIT("No instance for:")) 4 (ppr sty inst)
+tidyInst env (Method u id tys theta tau loc)
+ = (env', Method u id tys' theta tau loc)
+ -- Leave theta, tau alone cos we don't print them
+ where
+ (env', tys') = tidyOpenTypes env tys
+
+-- this case shouldn't arise... (we never print fundeps)
+tidyInst env fd@(FunDep clas fds loc)
+ = (env, fd)
+
+tidyInsts env insts = mapAccumL tidyInst env insts
+
+show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
\end{code}
+
%************************************************************************
%* *
\subsection[InstEnv-types]{Type declarations}
%************************************************************************
\begin{code}
-type InstanceMapper = Class -> (ClassInstEnv, ClassOp -> SpecEnv)
+type InstanceMapper = Class -> InstEnv
\end{code}
A @ClassInstEnv@ lives inside a class, and identifies all the instances
the dfun type.
\begin{code}
-lookupInst :: Inst s
- -> TcM s ([Inst s],
- (TcIdOcc s, TcExpr s)) -- The new binding
+data LookupInstResult s
+ = NoInstance
+ | SimpleInst TcExpr -- Just a variable, type application, or literal
+ | GenInst [Inst] TcExpr -- The expression and its needed insts
+
+lookupInst :: Inst
+ -> 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 (pprOrigin orig) $
- failTc (noInstanceErr dict)
+lookupInst dict@(Dict _ (Class clas tys) loc)
+ = case lookupInstEnv (ppr clas) (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
+ subst = mkSubst (tyVarsOfTypes tys) tenv
+ (tyvars, rho) = splitForAllTys (idType dfun_id)
+ ty_args = map subst_tv tyvars
+ dfun_rho = substTy subst rho
+ (theta, tau) = splitRhoTy dfun_rho
+ ty_app = mkHsTyApp (HsVar dfun_id) ty_args
+ subst_tv tv = case lookupSubstEnv tenv tv of
+ Just (DoneTy ty) -> ty
+ -- tenv should bind all the tyvars
in
- tcInstType tenv rho `thenNF_Tc` \ dfun_rho ->
- let
- (theta, tau) = splitRhoTy dfun_rho
- in
- newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
+ if null theta then
+ returnNF_Tc (SimpleInst ty_app)
+ else
+ newDictsAtLoc 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, (instToId dict, rhs))
-
+ returnNF_Tc (GenInst dicts rhs)
+
+ Nothing -> returnNF_Tc NoInstance
+lookupInst dict@(Dict _ _ loc) = returnNF_Tc NoInstance
-- Methods
-lookupInst inst@(Method _ id tys rho orig loc)
- = newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
- returnTc (dicts, (instToId inst, mkHsDictApp (mkHsTyApp (HsVar id) tys) dict_ids))
- where
- (theta,_) = splitRhoTy rho
+lookupInst inst@(Method _ id tys theta _ loc)
+ = newDictsAtLoc 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)
- | i >= toInteger minInt && i <= toInteger maxInt
- = -- 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], (instToId 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], (instToId inst, HsApp (HsVar method_id) (HsLitOut (HsInt i) ty)))
- where
- intprim_lit = HsLitOut (HsIntPrim i) intPrimTy
- int_lit = HsApp (HsVar (RealId intDataCon)) intprim_lit
+lookupInst inst@(LitInst u (OverloadedIntegral i) ty loc)
+ | isIntTy ty && in_int_range -- Short cut for Int
+ = returnNF_Tc (GenInst [] int_lit)
+ -- GenInst, not SimpleInst, because int_lit is actually a constructor application
-lookupInst inst@(LitInst u (OverloadedFractional f) ty orig loc)
- = tcLookupGlobalValueByKey fromRationalClassOpKey `thenNF_Tc` \ from_rational ->
- newMethodAtLoc orig loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnTc ([method_inst], (instToId inst, HsApp (HsVar method_id) (HsLitOut (HsFrac f) ty)))
-\end{code}
+ | isIntegerTy ty -- Short cut for Integer
+ = returnNF_Tc (GenInst [] integer_lit)
-There is a second, simpler interface, when you want an instance of a
-class at a given nullary type constructor. It just returns the
-appropriate dictionary if it exists. It is used only when resolving
-ambiguous dictionaries.
+ | in_int_range -- It's overloaded but small enough to fit into an Int
+ = tcLookupValueByKey fromIntClassOpKey `thenNF_Tc` \ from_int ->
+ newMethodAtLoc loc from_int [ty] `thenNF_Tc` \ (method_inst, method_id) ->
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) int_lit))
-\begin{code}
-lookupClassInstAtSimpleType :: Class -> Type -> Maybe Id
-
-lookupClassInstAtSimpleType clas ty
- = case (lookupMEnv matchTy (classInstEnv clas) ty) of
- Nothing -> Nothing
- Just (dfun,_) -> ASSERT( null tyvars && null theta )
- Just dfun
- where
- (tyvars, theta, _) = splitSigmaTy (idType dfun)
-\end{code}
+ | otherwise -- Alas, it is overloaded and a big literal!
+ = tcLookupValueByKey fromIntegerClassOpKey `thenNF_Tc` \ from_integer ->
+ newMethodAtLoc loc from_integer [ty] `thenNF_Tc` \ (method_inst, method_id) ->
+ 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 = HsCon intDataCon [] [intprim_lit]
+-- similar idea for overloaded floating point literals: if the literal is
+-- *definitely* a float or a double, generate the real thing here.
+-- This is essential (see nofib/spectral/nucleic).
-@mkInstSpecEnv@ is used to construct the @SpecEnv@ for a dfun.
-It does it by filtering the class's @InstEnv@. All pretty shady stuff.
+lookupInst inst@(LitInst u (OverloadedFractional f) ty loc)
+ | isFloatTy ty = returnNF_Tc (GenInst [] float_lit)
+ | isDoubleTy ty = returnNF_Tc (GenInst [] double_lit)
-\begin{code}
-mkInstSpecEnv clas inst_ty inst_tvs inst_theta = panic "mkInstSpecEnv"
-\end{code}
+ | otherwise
+ = tcLookupValueByKey fromRationalClassOpKey `thenNF_Tc` \ from_rational ->
-\begin{pseudocode}
-mkInstSpecEnv :: Class -- class
- -> Type -- instance type
- -> [TyVarTemplate] -- instance tyvars
- -> ThetaType -- superclasses dicts
- -> SpecEnv -- specenv for dfun of instance
+ -- The type Rational isn't wired in so we have to conjure it up
+ tcLookupTyConByKey rationalTyConKey `thenNF_Tc` \ rational_tycon ->
+ let
+ rational_ty = mkSynTy rational_tycon []
+ rational_lit = HsLitOut (HsFrac f) rational_ty
+ in
+ newMethodAtLoc loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rational_lit))
-mkInstSpecEnv clas inst_ty inst_tvs inst_theta
- = mkSpecEnv (catMaybes (map maybe_spec_info matches))
where
- matches = matchMEnv matchTy (classInstEnv clas) inst_ty
+ floatprim_lit = HsLitOut (HsFloatPrim f) floatPrimTy
+ float_lit = HsCon floatDataCon [] [floatprim_lit]
+ doubleprim_lit = HsLitOut (HsDoublePrim f) doublePrimTy
+ double_lit = HsCon doubleDataCon [] [doubleprim_lit]
- 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}
+-- there are no `instances' of functional dependencies or implicit params
+lookupInst _ = returnNF_Tc NoInstance
-\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
\end{code}
-
-
-%************************************************************************
-%* *
-\subsection[Inst-origin]{The @InstOrigin@ type}
-%* *
-%************************************************************************
-
-The @InstOrigin@ type gives information about where a dictionary came from.
-This is important for decent error message reporting because dictionaries
-don't appear in the original source code. Doubtless this type will evolve...
-
-\begin{code}
-data InstOrigin s
- = OccurrenceOf (TcIdOcc s) -- Occurrence of an overloaded identifier
- | OccurrenceOfCon Id -- Occurrence of a data constructor
-
- | RecordUpdOrigin
-
- | DataDeclOrigin -- Typechecking a data declaration
-
- | InstanceDeclOrigin -- Typechecking an instance decl
-
- | LiteralOrigin HsLit -- Occurrence of a literal
-
- | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
-
- | SignatureOrigin -- A dict created from a type signature
-
- | DoOrigin -- The monad for a do expression
-
- | ClassDeclOrigin -- Manufactured during a class decl
-
- | 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
- Type
-
- -- When specialising instances the instance info attached to
- -- each class is not yet ready, so we record it inside the
- -- 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
- -- Dictionaries with this origin aren't actually mentioned in the
- -- translated term, and so need not be bound. Nor should they
- -- be abstracted over.
-
- | CCallOrigin String -- CCall label
- (Maybe RenamedHsExpr) -- Nothing if it's the result
- -- Just arg, for an argument
-
- | LitLitOrigin String -- the litlit
-
- | UnknownOrigin -- Help! I give up...
-\end{code}
+There is a second, simpler interface, when you want an instance of a
+class at a given nullary type constructor. It just returns the
+appropriate dictionary if it exists. It is used only when resolving
+ambiguous dictionaries.
\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 _ _)
- = fst (inst_mapper clas)
-get_inst_env clas other_orig = classInstEnv clas
-
-
-pprOrigin :: InstOrigin s -> PprStyle -> Pretty
-
-pprOrigin (OccurrenceOf id) sty
- = ppBesides [ppPStr SLIT("at a use of an overloaded identifier: `"),
- ppr sty id, ppChar '\'']
-pprOrigin (OccurrenceOfCon id) sty
- = ppBesides [ppPStr SLIT("at a use of an overloaded constructor: `"),
- ppr sty id, ppChar '\'']
-pprOrigin (InstanceDeclOrigin) sty
- = ppStr "in an instance declaration"
-pprOrigin (LiteralOrigin lit) sty
- = ppCat [ppStr "at an overloaded literal:", ppr sty lit]
-pprOrigin (ArithSeqOrigin seq) sty
- = ppCat [ppStr "at an arithmetic sequence:", ppr sty seq]
-pprOrigin (SignatureOrigin) sty
- = ppStr "in a type signature"
-pprOrigin (DoOrigin) sty
- = ppStr "in a do statement"
-pprOrigin (ClassDeclOrigin) sty
- = ppStr "in a class declaration"
-pprOrigin (DerivingOrigin _ clas tycon) sty
- = ppBesides [ppStr "in a `deriving' clause; class `",
- ppr sty clas,
- ppStr "'; offending type `",
- ppr sty tycon,
- ppStr "'"]
-pprOrigin (InstanceSpecOrigin _ clas ty) sty
- = ppBesides [ppStr "in a SPECIALIZE instance pragma; class \"",
- ppr sty clas, ppStr "\" type: ", ppr sty ty]
-pprOrigin (DefaultDeclOrigin) sty
- = ppStr "in a `default' declaration"
-pprOrigin (ValSpecOrigin name) sty
- = ppBesides [ppStr "in a SPECIALIZE user-pragma for `",
- ppr sty name, ppStr "'"]
-pprOrigin (CCallOrigin clabel Nothing{-ccall result-}) sty
- = ppBesides [ppStr "in the result of the _ccall_ to `",
- ppStr clabel, ppStr "'"]
-pprOrigin (CCallOrigin clabel (Just arg_expr)) sty
- = ppBesides [ppStr "in an argument in the _ccall_ to `",
- ppStr clabel, ppStr "', namely: ", ppr sty arg_expr]
-pprOrigin (LitLitOrigin s) sty
- = ppBesides [ppStr "in this ``literal-literal'': ", ppStr s]
-pprOrigin UnknownOrigin sty
- = ppStr "in... oops -- I don't know where the overloading came from!"
+lookupSimpleInst :: InstEnv
+ -> Class
+ -> [Type] -- Look up (c,t)
+ -> NF_TcM s (Maybe [(Class,[Type])]) -- Here are the needed (c,t)s
+
+lookupSimpleInst class_inst_env clas tys
+ = case lookupInstEnv (ppr clas) class_inst_env tys of
+ Nothing -> returnNF_Tc Nothing
+
+ Just (tenv, dfun)
+ -> returnNF_Tc (Just (substClasses (mkSubst emptyInScopeSet tenv) theta'))
+ where
+ (_, theta, _) = splitSigmaTy (idType dfun)
+ theta' = map (\(Class clas tys) -> (clas,tys)) theta
\end{code}
-
-
-
projects / ghc-hetmet.git / blobdiff