%
-% (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
+ LIE, emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE,
+ plusLIEs, mkLIE, isEmptyLIE,
- 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, newDictsAtLoc,
+ newMethod, newMethodWithGivenTy, newOverloadedLit, instOverloadedFun,
- instType, tyVarsOfInst, lookupInst,
+ tyVarsOfInst, instLoc, getDictClassTys,
- isDict, isTyVarDict,
+ lookupInst, lookupSimpleInst, LookupInstResult(..),
- zonkInst, instToId,
+ isDict, isTyVarDict, isStdClassTyVarDict, isMethodFor,
+ instBindingRequired, instCanBeGeneralised,
- matchesInst,
- instBindingRequired, instCanBeGeneralised
+ zonkInst, instToId, instToIdBndr,
+ InstOrigin(..), pprOrigin
) 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, 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(..), getClassInstEnv )
-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,
+ zonkTcType, zonkTcTypes,
+ zonkTcThetaType
+ )
+import Bag
+import Class ( classInstEnv, Class )
+import Id ( Id, idFreeTyVars, idType, mkUserLocal, mkSysLocal )
+import VarSet ( elemVarSet )
+import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
+import Name ( OccName, Name, mkDictOcc, mkMethodOcc, getOccName )
+import PprType ( pprConstraint )
+import InstEnv ( InstEnv, lookupInstEnv )
+import SrcLoc ( SrcLoc )
+import Type ( Type, ThetaType,
+ mkTyVarTy, isTyVarTy, mkDictTy, splitForAllTys, splitSigmaTy,
+ splitRhoTy, tyVarsOfType, tyVarsOfTypes,
+ mkSynTy, tidyOpenType, tidyOpenTypes
+ )
+import InstEnv ( InstEnv )
+import Subst ( emptyInScopeSet, mkSubst,
+ substTy, substTheta, mkTyVarSubst, mkTopTyVarSubst
+ )
+import TyCon ( TyCon )
+import Subst ( mkTyVarSubst )
+import VarEnv ( lookupVarEnv, TidyEnv,
+ lookupSubstEnv, SubstResult(..)
+ )
+import VarSet ( 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 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
-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) <+> pprOrigin 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)
+ Class -- The type of the dict is (c ts), where
+ [TcType] -- c is the class and ts the types;
+ InstOrigin
SrcLoc
| 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
- (InstOrigin s)
+ InstOrigin
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
+ TcType -- The type at which the literal is used
+ InstOrigin -- Always a literal; but more convenient to carry this around
SrcLoc
data OverloadedLit
= OverloadedIntegral Integer -- The number
| OverloadedFractional Rational -- The number
-
-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
\end{code}
-Construction
-~~~~~~~~~~~~
+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}
-newDicts :: InstOrigin s
- -> [(Class, TcType s)]
- -> NF_TcM s (LIE s, [TcIdOcc s])
-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)
-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
- in
- 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
- -- 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
- in
- returnNF_Tc (meth_inst, instToId meth_inst)
-
-newOverloadedLit :: InstOrigin s
- -> OverloadedLit
- -> TcType s
- -> NF_TcM s (LIE s, TcIdOcc s)
-newOverloadedLit orig lit ty
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
- tcGetUnique `thenNF_Tc` \ new_uniq ->
- let
- lit_inst = LitInst new_uniq lit ty orig loc
- in
- returnNF_Tc (unitLIE lit_inst, instToId lit_inst)
+instance Ord Inst where
+ compare = cmpInst
+
+instance Eq Inst 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}
-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))
-\end{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
-\begin{code}
-instType :: Inst s -> TcType s
-instType (Dict _ clas ty _ _) = mkDictTy clas ty
-instType (LitInst _ _ ty _ _) = ty
-instType (Method _ id tys ty _ _) = ty
-\end{code}
+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)
-Zonking
-~~~~~~~
-Zonking makes sure that the instance types are fully zonked,
-but doesn't do the same for the Id in a Method. There's no
-need, and it's a lot of extra work.
+tyVarsOfInst :: Inst -> TcTyVarSet
+tyVarsOfInst (Dict _ _ tys _ _) = tyVarsOfTypes tys
+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
+\end{code}
+Predicates
+~~~~~~~~~~
\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)
+isDict :: Inst -> Bool
+isDict (Dict _ _ _ _ _) = True
+isDict other = False
-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)
+isMethodFor :: TcIdSet -> Inst -> Bool
+isMethodFor ids (Method uniq id tys _ _ orig loc)
+ = id `elemVarSet` ids
+isMethodFor ids inst
+ = False
-zonkInst (LitInst u lit ty orig loc)
- = zonkTcType ty `thenNF_Tc` \ new_ty ->
- returnNF_Tc (LitInst u lit new_ty orig loc)
+isTyVarDict :: Inst -> Bool
+isTyVarDict (Dict _ _ tys _ _) = all isTyVarTy tys
+isTyVarDict other = False
+
+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}
-tyVarsOfInst :: Inst s -> TcTyVarSet s
-tyVarsOfInst (Dict _ _ ty _ _) = tyVarsOfType ty
-tyVarsOfInst (Method _ _ tys rho _ _) = tyVarsOfTypes tys
-tyVarsOfInst (LitInst _ _ ty _ _) = tyVarsOfType ty
+instBindingRequired :: Inst -> Bool
+instBindingRequired (Dict _ clas _ _ _) = not (isNoDictClass clas)
+instBindingRequired other = True
+
+instCanBeGeneralised :: Inst -> Bool
+instCanBeGeneralised (Dict _ clas _ _ _) = not (isCcallishClass clas)
+instCanBeGeneralised other = True
\end{code}
-@matchesInst@ checks when two @Inst@s are instances of the same
-thing at the same type, even if their uniques differ.
+
+Construction
+~~~~~~~~~~~~
\begin{code}
-matchesInst :: Inst s -> Inst s -> Bool
+newDicts :: InstOrigin
+ -> TcThetaType
+ -> NF_TcM s (LIE, [TcId])
+newDicts orig theta
+ = tcGetSrcLoc `thenNF_Tc` \ loc ->
+ newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, ids) ->
+ returnNF_Tc (listToBag dicts, ids)
+
+-- Local function, similar to newDicts,
+-- but with slightly different interface
+newDictsAtLoc :: InstOrigin
+ -> SrcLoc
+ -> TcThetaType
+ -> NF_TcM s ([Inst], [TcId])
+newDictsAtLoc orig loc theta =
+ tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs ->
+ let
+ 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 -> Class -> [TcType] -> NF_TcM s Inst
+newDictFromOld (Dict _ _ _ orig loc) clas tys
+ = tcGetUnique `thenNF_Tc` \ uniq ->
+ returnNF_Tc (Dict uniq clas tys orig 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
+ let
+ (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)
+
+instOverloadedFun orig (HsVar v) arg_tys theta tau
+ = newMethodWithGivenTy orig v arg_tys theta tau `thenNF_Tc` \ inst ->
+ returnNF_Tc (HsVar (instToId inst), unitLIE inst)
+
+newMethodWithGivenTy orig id tys theta tau
+ = tcGetSrcLoc `thenNF_Tc` \ loc ->
+ tcGetUnique `thenNF_Tc` \ new_uniq ->
+ let
+ meth_inst = Method new_uniq id tys theta tau orig loc
+ in
+ returnNF_Tc meth_inst
+
+newMethodAtLoc :: InstOrigin -> SrcLoc
+ -> Id -> [TcType]
+ -> NF_TcM s (Inst, TcId)
+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
+ tcGetUnique `thenNF_Tc` \ new_uniq ->
+ let
+ (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 orig loc
+ in
+ returnNF_Tc (meth_inst, instToId meth_inst)
+\end{code}
+
+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).
-matchesInst (Dict _ clas1 ty1 _ _) (Dict _ clas2 ty2 _ _)
- = clas1 == clas2 && ty1 `eqSimpleTy` ty2
+\begin{code}
+newOverloadedLit :: InstOrigin
+ -> OverloadedLit
+ -> TcType
+ -> NF_TcM s (TcExpr, LIE)
+newOverloadedLit orig (OverloadedIntegral i) ty
+ | isIntTy ty && inIntRange i -- Short cut for Int
+ = returnNF_Tc (int_lit, emptyLIE)
-matchesInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _)
- = id1 == id2
- && and (zipWith eqSimpleTy tys1 tys2)
- && length tys1 == length tys2
+ | isIntegerTy ty -- Short cut for Integer
+ = returnNF_Tc (integer_lit, emptyLIE)
-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
+ intprim_lit = HsLitOut (HsIntPrim i) intPrimTy
+ integer_lit = HsLitOut (HsInt i) integerTy
+ int_lit = HsCon intDataCon [] [intprim_lit]
-matchesInst other1 other2 = False
+newOverloadedLit orig lit ty -- The general case
+ = tcGetSrcLoc `thenNF_Tc` \ loc ->
+ tcGetUnique `thenNF_Tc` \ new_uniq ->
+ let
+ lit_inst = LitInst new_uniq lit ty orig loc
+ in
+ returnNF_Tc (HsVar (instToId lit_inst), unitLIE lit_inst)
\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
+instToId :: Inst -> TcId
+instToId inst = instToIdBndr inst
+
+instToIdBndr :: Inst -> TcId
+instToIdBndr (Dict u clas ty orig loc)
+ = mkUserLocal (mkDictOcc (getOccName clas)) u (mkDictTy clas ty) loc
+
+instToIdBndr (Method u id tys theta tau orig loc)
+ = mkUserLocal (mkMethodOcc (getOccName id)) u tau loc
+
+instToIdBndr (LitInst u list ty orig loc)
+ = mkSysLocal SLIT("lit") u ty
\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.
+
+Zonking
+~~~~~~~
+Zonking makes sure that the instance types are fully zonked,
+but doesn't do the same for the Id in a Method. There's no
+need, and it's a lot of extra work.
\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
+zonkInst :: Inst -> NF_TcM s Inst
+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)
+ = 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
+
+ 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 ->
+ returnNF_Tc (LitInst u lit new_ty orig loc)
\end{code}
relevant in error messages.
\begin{code}
-instance Outputable (Inst s) where
- ppr sty (LitInst uniq lit ty orig loc)
- = ppHang (ppSep [case lit of
- OverloadedIntegral i -> ppInteger i
- OverloadedFractional f -> ppRational f,
- ppStr "at",
- ppr sty ty,
- show_uniq sty uniq
- ])
- 4 (show_origin sty orig)
-
- ppr sty (Dict uniq clas ty orig loc)
- = ppHang (ppSep [ppr sty clas,
- ppStr "at",
- ppr sty ty,
- show_uniq sty uniq
- ])
- 4 (show_origin sty orig)
-
- ppr sty (Method uniq id tys rho orig loc)
- = ppHang (ppSep [ppr sty id,
- ppStr "at",
- ppr sty tys,
- show_uniq sty uniq
- ])
- 4 (show_origin sty orig)
-
-show_uniq PprDebug uniq = ppr PprDebug uniq
-show_uniq sty uniq = ppNil
-
-show_origin sty orig = ppBesides [ppLparen, pprOrigin sty orig, ppRparen]
-\end{code}
+instance Outputable Inst where
+ ppr inst = pprInst inst
+
+pprInst (LitInst u lit ty orig loc)
+ = hsep [case lit of
+ OverloadedIntegral i -> integer i
+ OverloadedFractional f -> rational f,
+ ptext SLIT("at"),
+ ppr ty,
+ show_uniq u]
+
+pprInst (Dict u clas tys orig loc) = pprConstraint clas tys <+> show_uniq u
+
+pprInst (Method u id tys _ _ orig loc)
+ = hsep [ppr id, ptext SLIT("at"),
+ brackets (interppSP tys),
+ show_uniq u]
+
+tidyInst :: TidyEnv -> Inst -> (TidyEnv, Inst)
+tidyInst env (LitInst u lit ty orig loc)
+ = (env', LitInst u lit ty' orig loc)
+ where
+ (env', ty') = tidyOpenType env ty
-Printing in error messages
+tidyInst env (Dict u clas tys orig loc)
+ = (env', Dict u clas tys' orig loc)
+ where
+ (env', tys') = tidyOpenTypes env tys
-\begin{code}
-noInstanceErr inst sty = ppHang (ppPStr SLIT("No instance for:")) 4 (ppr sty inst)
+tidyInst env (Method u id tys theta tau orig loc)
+ = (env', Method u id tys' theta tau orig loc)
+ -- Leave theta, tau alone cos we don't print them
+ where
+ (env', tys') = tidyOpenTypes env tys
+
+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 -> failTc (noInstanceErr dict)
+lookupInst dict@(Dict _ clas tys orig 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
- in
- tcInstType tenv rho `thenNF_Tc` \ dfun_rho ->
- let
- (theta, tau) = splitRhoTy dfun_rho
+ 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
+ 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, (instToId dict, rhs))
+ returnNF_Tc (GenInst dicts rhs)
+ Nothing -> returnNF_Tc NoInstance
-- Methods
-lookupInst inst@(Method _ id tys rho orig loc)
+lookupInst inst@(Method _ id tys theta _ 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
+ 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))
+ | 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
- | otherwise
- = -- Alas, it is overloaded and a big literal!
- tcLookupGlobalValueByKey fromIntegerClassOpKey `thenNF_Tc` \ from_integer ->
+ | isIntegerTy ty -- Short cut for Integer
+ = returnNF_Tc (GenInst [] integer_lit)
+
+ | in_int_range -- It's overloaded but small enough to fit into an Int
+ = tcLookupValueByKey fromIntClassOpKey `thenNF_Tc` \ from_int ->
+ newMethodAtLoc orig loc from_int [ty] `thenNF_Tc` \ (method_inst, method_id) ->
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) int_lit))
+
+ | otherwise -- Alas, it is overloaded and a big literal!
+ = tcLookupValueByKey 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)))
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) integer_lit))
where
+ in_int_range = inIntRange i
intprim_lit = HsLitOut (HsIntPrim i) intPrimTy
- int_lit = HsApp (HsVar (RealId intDataCon)) intprim_lit
+ 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).
lookupInst inst@(LitInst u (OverloadedFractional f) ty orig loc)
- = tcLookupGlobalValueByKey fromRationalClassOpKey `thenNF_Tc` \ from_rational ->
+ | isFloatTy ty = returnNF_Tc (GenInst [] float_lit)
+ | isDoubleTy ty = returnNF_Tc (GenInst [] double_lit)
+
+ | otherwise
+ = tcLookupValueByKey fromRationalClassOpKey `thenNF_Tc` \ from_rational ->
+
+ -- 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 orig loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
- returnTc ([method_inst], (instToId inst, HsApp (HsVar method_id) (HsLitOut (HsFrac f) ty)))
+ returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rational_lit))
+
+ where
+ floatprim_lit = HsLitOut (HsFloatPrim f) floatPrimTy
+ float_lit = HsCon floatDataCon [] [floatprim_lit]
+ doubleprim_lit = HsLitOut (HsDoublePrim f) doublePrimTy
+ double_lit = HsCon doubleDataCon [] [doubleprim_lit]
+
\end{code}
There is a second, simpler interface, when you want an instance of a
ambiguous dictionaries.
\begin{code}
-lookupClassInstAtSimpleType :: Class -> Type -> Maybe Id
-
-lookupClassInstAtSimpleType clas ty
- = case (lookupMEnv matchTy (getClassInstEnv clas) ty) of
- Nothing -> Nothing
- Just (dfun,_) -> ASSERT( null tyvars && null theta )
- Just dfun
- where
- (tyvars, 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
-
-mkInstSpecEnv clas inst_ty inst_tvs inst_theta
- = mkSpecEnv (catMaybes (map maybe_spec_info matches))
- where
- matches = matchMEnv matchTy (getClassInstEnv 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}
-
-
-\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
+lookupSimpleInst :: InstEnv
+ -> Class
+ -> [Type] -- Look up (c,t)
+ -> NF_TcM s (Maybe ThetaType) -- 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 (substTheta (mkSubst emptyInScopeSet tenv) theta))
+ where
+ (_, theta, _) = splitSigmaTy (idType dfun)
\end{code}
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
+data InstOrigin
+ = OccurrenceOf TcId -- Occurrence of an overloaded identifier
| OccurrenceOfCon Id -- Occurrence of a data constructor
| RecordUpdOrigin
| LiteralOrigin HsLit -- Occurrence of a literal
+ | PatOrigin RenamedPat
+
| ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
| SignatureOrigin -- A dict created from a type signature
+ | Rank2Origin -- A dict created when typechecking the argument
+ -- of a rank-2 typed function
| 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
+ | 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 _ _)
- = fst (inst_mapper clas)
-get_inst_env clas other_orig = getClassInstEnv clas
-
-
-pprOrigin :: PprStyle -> InstOrigin s -> Pretty
-
-pprOrigin sty (OccurrenceOf id)
- = ppBesides [ppPStr SLIT("at a use of an overloaded identifier: `"),
- ppr sty id, ppChar '\'']
-pprOrigin sty (OccurrenceOfCon id)
- = ppBesides [ppPStr SLIT("at a use of an overloaded constructor: `"),
- ppr sty id, ppChar '\'']
-pprOrigin sty (InstanceDeclOrigin)
- = ppStr "in an instance declaration"
-pprOrigin sty (LiteralOrigin lit)
- = ppCat [ppStr "at an overloaded literal:", ppr sty lit]
-pprOrigin sty (ArithSeqOrigin seq)
- = ppCat [ppStr "at an arithmetic sequence:", ppr sty seq]
-pprOrigin sty (SignatureOrigin)
- = ppStr "in a type signature"
-pprOrigin sty (DoOrigin)
- = ppStr "in a do statement"
-pprOrigin sty (ClassDeclOrigin)
- = ppStr "in a class declaration"
-pprOrigin sty (DerivingOrigin _ clas tycon)
- = ppBesides [ppStr "in a `deriving' clause; class `",
- ppr sty clas,
- ppStr "'; offending type `",
- ppr sty tycon,
- ppStr "'"]
-pprOrigin sty (InstanceSpecOrigin _ clas ty)
- = ppBesides [ppStr "in a SPECIALIZE instance pragma; class \"",
- ppr sty clas, ppStr "\" type: ", ppr sty ty]
-pprOrigin sty (DefaultDeclOrigin)
- = ppStr "in a `default' declaration"
-pprOrigin sty (ValSpecOrigin name)
- = ppBesides [ppStr "in a SPECIALIZE user-pragma for `",
- ppr sty name, ppStr "'"]
-pprOrigin sty (CCallOrigin clabel Nothing{-ccall result-})
- = ppBesides [ppStr "in the result of the _ccall_ to `",
- ppStr clabel, ppStr "'"]
-pprOrigin sty (CCallOrigin clabel (Just arg_expr))
- = ppBesides [ppStr "in an argument in the _ccall_ to `",
- ppStr clabel, ppStr "', namely: ", ppr sty arg_expr]
-pprOrigin sty (LitLitOrigin s)
- = ppBesides [ppStr "in this ``literal-literal'': ", ppStr s]
-pprOrigin sty UnknownOrigin
- = ppStr "in... oops -- I don't know where the overloading came from!"
+pprOrigin :: Inst -> 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)
+
+ pp_orig (OccurrenceOf id)
+ = hsep [ptext SLIT("use of"), quotes (ppr id)]
+ pp_orig (OccurrenceOfCon id)
+ = hsep [ptext SLIT("use of"), quotes (ppr id)]
+ pp_orig (LiteralOrigin lit)
+ = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
+ pp_orig (PatOrigin pat)
+ = hsep [ptext SLIT("the pattern"), quotes (ppr pat)]
+ pp_orig (InstanceDeclOrigin)
+ = ptext SLIT("an instance declaration")
+ pp_orig (ArithSeqOrigin seq)
+ = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
+ pp_orig (SignatureOrigin)
+ = ptext SLIT("a type signature")
+ pp_orig (Rank2Origin)
+ = ptext SLIT("a function with an overloaded argument type")
+ pp_orig (DoOrigin)
+ = ptext SLIT("a do statement")
+ pp_orig (ClassDeclOrigin)
+ = ptext SLIT("a class declaration")
+ pp_orig (InstanceSpecOrigin clas ty)
+ = hsep [text "a SPECIALIZE instance pragma; class",
+ quotes (ppr clas), text "type:", ppr ty]
+ pp_orig (ValSpecOrigin 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"), quotes (text clabel)]
+ pp_orig (CCallOrigin clabel (Just 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''"), 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