\section[Inst]{The @Inst@ type: dictionaries or method instances}
\begin{code}
-module Inst (
+module Inst (
LIE, emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE,
- plusLIEs, mkLIE, isEmptyLIE,
+ plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE,
- Inst, OverloadedLit(..),
- pprInst, pprInsts, pprInstsInFull, tidyInst, tidyInsts,
+ Inst,
+ pprInst, pprInsts, pprInstsInFull, tidyInsts, tidyMoreInsts,
- InstanceMapper,
-
- newDictFromOld, newDicts, newDictsAtLoc,
+ newDictsFromOld, newDicts,
newMethod, newMethodWithGivenTy, newOverloadedLit,
+ newIPDict, tcInstId,
- tyVarsOfInst, instLoc, getDictClassTys,
+ tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, instLoc, getDictClassTys,
+ getIPs,
+ predsOfInsts, predsOfInst,
lookupInst, lookupSimpleInst, LookupInstResult(..),
- isDict, isTyVarDict, isStdClassTyVarDict, isMethodFor,
+ isDict, isClassDict, isMethod, instMentionsIPs,
+ isTyVarDict, isStdClassTyVarDict, isMethodFor,
instBindingRequired, instCanBeGeneralised,
- zonkInst, instToId, instToIdBndr,
+ zonkInst, zonkInsts,
+ instToId, instName,
- InstOrigin(..), pprOrigin
+ InstOrigin(..), InstLoc, pprInstLoc
) where
#include "HsVersions.h"
-import HsSyn ( HsLit(..), HsExpr(..) )
-import RnHsSyn ( RenamedArithSeqInfo, RenamedHsExpr, RenamedPat )
+import CmdLineOpts ( opt_NoMethodSharing )
+import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) )
import TcHsSyn ( TcExpr, TcId,
- mkHsTyApp, mkHsDictApp, zonkId
+ mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId
)
import TcMonad
-import TcEnv ( TcIdSet, tcLookupValueByKey, tcLookupTyConByKey )
-import TcType ( TcThetaType,
- TcType, TcTauType, TcTyVarSet,
- zonkTcType, zonkTcTypes,
- zonkTcThetaType
+import TcEnv ( TcIdSet, tcGetInstEnv, tcLookupId )
+import InstEnv ( InstLookupResult(..), lookupInstEnv )
+import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType,
+ zonkTcThetaType, tcInstTyVar, tcInstType,
)
-import Bag
-import Class ( classInstEnv,
- Class, ClassInstEnv
+import TcType ( Type,
+ SourceType(..), PredType, ThetaType,
+ tcSplitForAllTys, tcSplitForAllTys,
+ tcSplitMethodTy, tcSplitRhoTy, tcFunArgTy,
+ isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
+ tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys,
+ tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred,
+ predMentionsIPs, isClassPred, isTyVarClassPred,
+ getClassPredTys, getClassPredTys_maybe, mkPredName,
+ tidyType, tidyTypes, tidyFreeTyVars,
+ tcCmpType, tcCmpTypes, tcCmpPred
)
-import Id ( Id, idFreeTyVars, idType, mkUserLocal, mkSysLocal )
-import VarSet ( elemVarSet )
+import CoreFVs ( idFreeTyVars )
+import Class ( Class )
+import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId )
import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
-import Name ( OccName, Name, mkDictOcc, mkMethodOcc, getOccName )
-import PprType ( pprConstraint )
-import SpecEnv ( SpecEnv, lookupSpecEnv )
-import SrcLoc ( SrcLoc )
-import Type ( Type, ThetaType, substTy,
- isTyVarTy, mkDictTy, splitForAllTys, splitSigmaTy,
- splitRhoTy, tyVarsOfType, tyVarsOfTypes,
- mkSynTy, substTopTy, substTopTheta,
- tidyOpenType, tidyOpenTypes
+import Name ( Name, mkMethodOcc, getOccName )
+import NameSet ( NameSet )
+import PprType ( pprPred )
+import Subst ( emptyInScopeSet, mkSubst,
+ substTy, substTyWith, substTheta, mkTyVarSubst, mkTopTyVarSubst
)
-import TyCon ( TyCon )
-import VarEnv ( zipVarEnv, lookupVarEnv, TidyEnv )
-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 Literal ( inIntRange )
+import VarEnv ( TidyEnv, lookupSubstEnv, SubstResult(..) )
+import VarSet ( elemVarSet, emptyVarSet, unionVarSet )
+import TysWiredIn ( floatDataCon, doubleDataCon )
+import PrelNames( fromIntegerName, fromRationalName )
+import Util ( thenCmp )
+import Bag
import Outputable
\end{code}
plusLIE lie1 lie2 = lie1 `unionBags` lie2
consLIE inst lie = inst `consBag` lie
plusLIEs lies = unionManyBags lies
+lieToList = bagToList
+listToLIE = listToBag
-zonkLIE :: LIE -> NF_TcM s LIE
+zonkLIE :: LIE -> NF_TcM LIE
zonkLIE lie = mapBagNF_Tc zonkInst lie
pprInsts :: [Inst] -> SDoc
-pprInsts insts = parens (hsep (punctuate comma (map pprInst insts)))
+pprInsts insts = parens (sep (punctuate comma (map pprInst insts)))
pprInstsInFull insts
= vcat (map go insts)
where
- go inst = quotes (ppr inst) <+> pprOrigin inst
+ go inst = quotes (ppr inst) <+> pprInstLoc (instLoc inst)
\end{code}
%************************************************************************
\begin{code}
data Inst
= Dict
- Unique
- Class -- The type of the dict is (c ts), where
- [TcType] -- c is the class and ts the types;
- InstOrigin
- SrcLoc
+ Id
+ TcPredType
+ InstLoc
| Method
- Unique
+ Id
TcId -- The overloaded function
-- This function will be a global, local, or ClassOpId;
TcTauType -- The type of the method
- InstOrigin
- SrcLoc
+ InstLoc
-- INVARIANT: in (Method u f tys theta tau loc)
-- type of (f tys dicts(from theta)) = tau
| LitInst
- Unique
- OverloadedLit
+ Id
+ HsOverLit -- The literal from the occurrence site
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
+ InstLoc
\end{code}
Ordering
EQ -> True
other -> False
-cmpInst (Dict _ clas1 tys1 _ _) (Dict _ clas2 tys2 _ _)
- = (clas1 `compare` clas2) `thenCmp` (tys1 `compare` tys2)
-cmpInst (Dict _ _ _ _ _) other
- = LT
-
+cmpInst (Dict _ pred1 _) (Dict _ pred2 _) = pred1 `tcCmpPred` 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 (Method _ _ _ _ _ _) (Dict _ _ _) = GT
+cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `tcCmpTypes` tys2)
+cmpInst (Method _ _ _ _ _ _) other = LT
-cmpInst (LitInst _ lit1 ty1 _ _) (LitInst _ lit2 ty2 _ _)
- = (lit1 `cmpOverLit` lit2) `thenCmp` (ty1 `compare` ty2)
-cmpInst (LitInst _ _ _ _ _) other
- = GT
+cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `tcCmpType` 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
+-- and they can only have HsInt or HsFracs in them.
\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
+instName :: Inst -> Name
+instName inst = idName (instToId inst)
+
+instToId :: Inst -> TcId
+instToId (Dict id _ _) = id
+instToId (Method id _ _ _ _ _) = id
+instToId (LitInst id _ _ _) = id
+
+instLoc (Dict _ _ loc) = loc
+instLoc (Method _ _ _ _ _ loc) = loc
+instLoc (LitInst _ _ _ loc) = loc
+
+getDictClassTys (Dict _ pred _) = getClassPredTys pred
+
+predsOfInsts :: [Inst] -> [PredType]
+predsOfInsts insts = concatMap predsOfInst insts
-instLoc (Dict u clas tys origin loc) = loc
-instLoc (Method u clas ty _ _ origin loc) = loc
-instLoc (LitInst u lit ty origin loc) = loc
+predsOfInst (Dict _ pred _) = [pred]
+predsOfInst (Method _ _ _ theta _ _) = theta
+predsOfInst (LitInst _ _ _ _) = []
+ -- The last case is is really a big cheat
+ -- LitInsts to give rise to a (Num a) or (Fractional a) predicate
+ -- But Num and Fractional have only one parameter and no functional
+ -- dependencies, so I think no caller of predsOfInst will care.
-getDictClassTys (Dict u clas tys _ _) = (clas, tys)
+ipsOfPreds theta = [(n,ty) | IParam n ty <- theta]
+
+getIPs inst = ipsOfPreds (predsOfInst inst)
tyVarsOfInst :: Inst -> TcTyVarSet
-tyVarsOfInst (Dict _ _ tys _ _) = tyVarsOfTypes tys
-tyVarsOfInst (Method _ id tys _ _ _ _) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id
+tyVarsOfInst (LitInst _ _ ty _) = tyVarsOfType ty
+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
+
+tyVarsOfInsts insts = foldr (unionVarSet . tyVarsOfInst) emptyVarSet insts
+tyVarsOfLIE lie = tyVarsOfInsts (lieToList lie)
\end{code}
Predicates
~~~~~~~~~~
\begin{code}
isDict :: Inst -> Bool
-isDict (Dict _ _ _ _ _) = True
-isDict other = False
+isDict (Dict _ _ _) = True
+isDict other = False
-isMethodFor :: TcIdSet -> Inst -> Bool
-isMethodFor ids (Method uniq id tys _ _ orig loc)
- = id `elemVarSet` ids
-isMethodFor ids inst
- = False
+isClassDict :: Inst -> Bool
+isClassDict (Dict _ pred _) = isClassPred pred
+isClassDict other = False
isTyVarDict :: Inst -> Bool
-isTyVarDict (Dict _ _ tys _ _) = all isTyVarTy tys
-isTyVarDict other = False
+isTyVarDict (Dict _ pred _) = isTyVarClassPred pred
+isTyVarDict other = False
-isStdClassTyVarDict (Dict _ clas [ty] _ _) = isStandardClass clas && isTyVarTy ty
-isStdClassTyVarDict other = False
+isMethod :: Inst -> Bool
+isMethod (Method _ _ _ _ _ _) = True
+isMethod other = False
+
+isMethodFor :: TcIdSet -> Inst -> Bool
+isMethodFor ids (Method uniq id tys _ _ loc) = id `elemVarSet` ids
+isMethodFor ids inst = False
+
+instMentionsIPs :: Inst -> NameSet -> Bool
+ -- True if the Inst mentions any of the implicit
+ -- parameters in the supplied set of names
+instMentionsIPs (Dict _ pred _) ip_names = pred `predMentionsIPs` ip_names
+instMentionsIPs (Method _ _ _ theta _ _) ip_names = any (`predMentionsIPs` ip_names) theta
+instMentionsIPs other ip_names = False
+
+isStdClassTyVarDict (Dict _ pred _) = case getClassPredTys_maybe pred of
+ Just (clas, [ty]) -> isStandardClass clas && tcIsTyVarTy ty
+ other -> False
\end{code}
Two predicates which deal with the case where class constraints don't
\begin{code}
instBindingRequired :: Inst -> Bool
-instBindingRequired (Dict _ clas _ _ _) = not (isNoDictClass clas)
-instBindingRequired other = True
+instBindingRequired (Dict _ (ClassP clas _) _) = not (isNoDictClass clas)
+instBindingRequired (Dict _ (IParam _ _) _) = False
+instBindingRequired other = True
instCanBeGeneralised :: Inst -> Bool
-instCanBeGeneralised (Dict _ clas _ _ _) = not (isCcallishClass clas)
-instCanBeGeneralised other = True
+instCanBeGeneralised (Dict _ (ClassP clas _) _) = not (isCcallishClass clas)
+instCanBeGeneralised other = True
\end{code}
-Construction
-~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Building dictionaries}
+%* *
+%************************************************************************
\begin{code}
newDicts :: InstOrigin
-> TcThetaType
- -> NF_TcM s (LIE, [TcId])
+ -> NF_TcM [Inst]
newDicts orig theta
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
- newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, ids) ->
- returnNF_Tc (listToBag dicts, ids)
+ = tcGetInstLoc orig `thenNF_Tc` \ loc ->
+ newDictsAtLoc loc theta
+
+newDictsFromOld :: Inst -> TcThetaType -> NF_TcM [Inst]
+newDictsFromOld (Dict _ _ loc) theta = newDictsAtLoc loc theta
-- Local function, similar to newDicts,
-- but with slightly different interface
-newDictsAtLoc :: InstOrigin
- -> SrcLoc
+newDictsAtLoc :: InstLoc
-> 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)
+ -> NF_TcM [Inst]
+newDictsAtLoc inst_loc@(_,loc,_) theta
+ = tcGetUniques `thenNF_Tc` \ new_uniqs ->
+ returnNF_Tc (zipWith mk_dict new_uniqs theta)
+ where
+ mk_dict uniq pred = Dict (mkLocalId (mkPredName uniq loc pred) (mkPredTy pred)) pred inst_loc
+
+-- For implicit parameters, since there is only one in scope
+-- at any time, we use the name of the implicit parameter itself
+newIPDict orig name ty
+ = tcGetInstLoc orig `thenNF_Tc` \ inst_loc ->
+ returnNF_Tc (Dict (mkLocalId name (mkPredTy pred)) pred inst_loc)
+ where pred = IParam name ty
+\end{code}
-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)
+
+%************************************************************************
+%* *
+\subsection{Building methods (calls of overloaded functions)}
+%* *
+%************************************************************************
+
+tcInstId instantiates an occurrence of an Id.
+The instantiate_it loop runs round instantiating the Id.
+It has to be a loop because we are now prepared to entertain
+types like
+ f:: forall a. Eq a => forall b. Baz b => tau
+We want to instantiate this to
+ f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)}
+
+The -fno-method-sharing flag controls what happens so far as the LIE
+is concerned. The default case is that for an overloaded function we
+generate a "method" Id, and add the Method Inst to the LIE. So you get
+something like
+ f :: Num a => a -> a
+ f = /\a (d:Num a) -> let m = (+) a d in \ (x:a) -> m x x
+If you specify -fno-method-sharing, the dictionary application
+isn't shared, so we get
+ f :: Num a => a -> a
+ f = /\a (d:Num a) (x:a) -> (+) a d x x
+This gets a bit less sharing, but
+ a) it's better for RULEs involving overloaded functions
+ b) perhaps fewer separated lambdas
+
+
+\begin{code}
+tcInstId :: Id -> NF_TcM (TcExpr, LIE, TcType)
+tcInstId fun
+ | opt_NoMethodSharing = loop_noshare (HsVar fun) (idType fun)
+ | otherwise = loop_share fun
+ where
+ orig = OccurrenceOf fun
+ loop_noshare fun fun_ty
+ = tcInstType fun_ty `thenNF_Tc` \ (tyvars, theta, tau) ->
+ let
+ ty_app = mkHsTyApp fun (mkTyVarTys tyvars)
+ in
+ if null theta then -- Is it overloaded?
+ returnNF_Tc (ty_app, emptyLIE, tau)
+ else
+ newDicts orig theta `thenNF_Tc` \ dicts ->
+ loop_noshare (mkHsDictApp ty_app (map instToId dicts)) tau `thenNF_Tc` \ (expr, lie, final_tau) ->
+ returnNF_Tc (expr, mkLIE dicts `plusLIE` lie, final_tau)
+
+ loop_share fun
+ = tcInstType (idType fun) `thenNF_Tc` \ (tyvars, theta, tau) ->
+ let
+ arg_tys = mkTyVarTys tyvars
+ in
+ if null theta then -- Is it overloaded?
+ returnNF_Tc (mkHsTyApp (HsVar fun) arg_tys, emptyLIE, tau)
+ else
+ -- Yes, it's overloaded
+ newMethodWithGivenTy orig fun arg_tys theta tau `thenNF_Tc` \ meth ->
+ loop_share (instToId meth) `thenNF_Tc` \ (expr, lie, final_tau) ->
+ returnNF_Tc (expr, unitLIE meth `plusLIE` lie, final_tau)
newMethod :: InstOrigin
-> TcId
-> [TcType]
- -> NF_TcM s (LIE, TcId)
+ -> NF_TcM Inst
newMethod orig id tys
= -- Get the Id type and instantiate it at the specified types
let
- (tyvars, rho) = splitForAllTys (idType id)
- rho_ty = substTy (zipVarEnv tyvars tys) rho
- (theta, tau) = splitRhoTy rho_ty
+ (tyvars, rho) = tcSplitForAllTys (idType id)
+ rho_ty = substTyWith tyvars tys rho
+ (pred, tau) = tcSplitMethodTy rho_ty
in
- newMethodWithGivenTy orig id tys theta tau `thenNF_Tc` \ meth_inst ->
- returnNF_Tc (unitLIE meth_inst, instToId meth_inst)
-
+ newMethodWithGivenTy orig id tys [pred] tau
newMethodWithGivenTy orig id tys theta tau
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
- tcGetUnique `thenNF_Tc` \ new_uniq ->
+ = tcGetInstLoc orig `thenNF_Tc` \ loc ->
+ newMethodWith loc id tys theta tau
+
+newMethodWith inst_loc@(_,loc,_) id tys theta tau
+ = tcGetUnique `thenNF_Tc` \ new_uniq ->
let
- meth_inst = Method new_uniq id tys theta tau orig loc
+ meth_id = mkUserLocal (mkMethodOcc (getOccName id)) new_uniq tau loc
in
- returnNF_Tc meth_inst
+ returnNF_Tc (Method meth_id id tys theta tau inst_loc)
-newMethodAtLoc :: InstOrigin -> SrcLoc
+newMethodAtLoc :: InstLoc
-> Id -> [TcType]
- -> NF_TcM s (Inst, TcId)
-newMethodAtLoc orig loc real_id tys -- Local function, similar to newMethod but with
- -- slightly different interface
+ -> NF_TcM (Inst, TcId)
+newMethodAtLoc inst_loc real_id tys
+ -- This actually builds the Inst
= -- Get the Id type and instantiate it at the specified types
- tcGetUnique `thenNF_Tc` \ new_uniq ->
let
- (tyvars,rho) = splitForAllTys (idType real_id)
+ (tyvars,rho) = tcSplitForAllTys (idType real_id)
rho_ty = ASSERT( length tyvars == length tys )
- substTopTy (zipVarEnv tyvars tys) rho
- (theta, tau) = splitRhoTy rho_ty
- meth_inst = Method new_uniq real_id tys theta tau orig loc
+ substTy (mkTopTyVarSubst tyvars tys) rho
+ (theta, tau) = tcSplitRhoTy rho_ty
in
+ newMethodWith inst_loc real_id tys theta tau `thenNF_Tc` \ meth_inst ->
returnNF_Tc (meth_inst, instToId meth_inst)
\end{code}
\begin{code}
newOverloadedLit :: InstOrigin
- -> OverloadedLit
+ -> HsOverLit
-> 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]
+ -> NF_TcM (TcExpr, LIE)
+newOverloadedLit orig lit ty
+ | Just expr <- shortCutLit lit ty
+ = returnNF_Tc (expr, emptyLIE)
-newOverloadedLit orig lit ty -- The general case
- = tcGetSrcLoc `thenNF_Tc` \ loc ->
+ | otherwise
+ = tcGetInstLoc orig `thenNF_Tc` \ loc ->
tcGetUnique `thenNF_Tc` \ new_uniq ->
let
- lit_inst = LitInst new_uniq lit ty orig loc
+ lit_inst = LitInst lit_id lit ty loc
+ lit_id = mkSysLocal SLIT("lit") new_uniq ty
in
returnNF_Tc (HsVar (instToId lit_inst), unitLIE lit_inst)
-\end{code}
-
-\begin{code}
-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 (getOccName id) u tau loc
- -- We used to call mkMethodOcc here, but that gives rise to bad
- -- error messages when we print the function name or pattern
- -- of an instance-decl binding. Why? Because the binding is zapped
- -- to use the method name in place of the selector name.
- -- The way it is now, -ddump-xx output may look confusing, but
- -- you can always say -dppr-debug to get the uniques
-
-instToIdBndr (LitInst u list ty orig loc)
- = mkSysLocal SLIT("lit") u ty
+shortCutLit :: HsOverLit -> TcType -> Maybe TcExpr
+shortCutLit (HsIntegral i fi) ty
+ | isIntTy ty && inIntRange i && fi == fromIntegerName -- Short cut for Int
+ = Just (HsLit (HsInt i))
+ | isIntegerTy ty && fi == fromIntegerName -- Short cut for Integer
+ = Just (HsLit (HsInteger i))
+
+shortCutLit (HsFractional f fr) ty
+ | isFloatTy ty && fr == fromRationalName
+ = Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)])
+ | isDoubleTy ty && fr == fromRationalName
+ = Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)])
+
+shortCutLit lit ty
+ = Nothing
\end{code}
-Zonking
-~~~~~~~
+%************************************************************************
+%* *
+\subsection{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
+but doesn't do the same for any of the Ids in an Inst. There's no
need, and it's a lot of extra work.
\begin{code}
-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 :: Inst -> NF_TcM Inst
+zonkInst (Dict id pred loc)
+ = zonkTcPredType pred `thenNF_Tc` \ new_pred ->
+ returnNF_Tc (Dict id new_pred loc)
-zonkInst (Method u id tys theta tau orig loc)
+zonkInst (Method m 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
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)
+ returnNF_Tc (Method m new_id new_tys new_theta new_tau loc)
-zonkInst (LitInst u lit ty orig loc)
+zonkInst (LitInst id lit ty loc)
= zonkTcType ty `thenNF_Tc` \ new_ty ->
- returnNF_Tc (LitInst u lit new_ty orig loc)
+ returnNF_Tc (LitInst id lit new_ty loc)
+
+zonkInsts insts = mapNF_Tc zonkInst insts
\end{code}
-Printing
-~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Printing}
+%* *
+%************************************************************************
+
ToDo: improve these pretty-printing things. The ``origin'' is really only
relevant in error messages.
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 (LitInst u lit ty loc)
+ = hsep [ppr lit, ptext SLIT("at"), ppr ty, show_uniq u]
-pprInst (Dict u clas tys orig loc) = pprConstraint clas tys <+> show_uniq u
+pprInst (Dict u pred loc) = pprPred pred <+> show_uniq u
-pprInst (Method u id tys _ _ orig loc)
+pprInst m@(Method u id tys theta tau loc)
= hsep [ppr id, ptext SLIT("at"),
- brackets (interppSP tys),
- show_uniq u]
+ brackets (interppSP tys) {- ,
+ ptext SLIT("theta"), ppr theta,
+ ptext SLIT("tau"), ppr tau
+ show_uniq u,
+ ppr (instToId m) -}]
-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
+show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
-tidyInst env (Dict u clas tys orig loc)
- = (env', Dict u clas tys' orig loc)
- where
- (env', tys') = tidyOpenTypes env tys
+tidyInst :: TidyEnv -> Inst -> Inst
+tidyInst env (LitInst u lit ty loc) = LitInst u lit (tidyType env ty) loc
+tidyInst env (Dict u pred loc) = Dict u (tidyPred env pred) loc
+tidyInst env (Method u id tys theta tau loc) = Method u id (tidyTypes env tys) theta tau loc
-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
+tidyMoreInsts :: TidyEnv -> [Inst] -> (TidyEnv, [Inst])
+-- This function doesn't assume that the tyvars are in scope
+-- so it works like tidyOpenType, returning a TidyEnv
+tidyMoreInsts env insts
+ = (env', map (tidyInst env') insts)
where
- (env', tys') = tidyOpenTypes env tys
-
-tidyInsts env insts = mapAccumL tidyInst env insts
+ env' = tidyFreeTyVars env (tyVarsOfInsts insts)
-show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
+tidyInsts :: [Inst] -> (TidyEnv, [Inst])
+tidyInsts insts = tidyMoreInsts emptyTidyEnv insts
\end{code}
%************************************************************************
%* *
-\subsection[InstEnv-types]{Type declarations}
+\subsection{Looking up Insts}
%* *
%************************************************************************
\begin{code}
-type InstanceMapper = Class -> ClassInstEnv
-\end{code}
-
-A @ClassInstEnv@ lives inside a class, and identifies all the instances
-of that class. The @Id@ inside a ClassInstEnv mapping is the dfun for
-that instance.
-
-There is an important consistency constraint between the @MatchEnv@s
-in and the dfun @Id@s inside them: the free type variables of the
-@Type@ key in the @MatchEnv@ must be a subset of the universally-quantified
-type variables of the dfun. Thus, the @ClassInstEnv@ for @Eq@ might
-contain the following entry:
-@
- [a] ===> dfun_Eq_List :: forall a. Eq a => Eq [a]
-@
-The "a" in the pattern must be one of the forall'd variables in
-the dfun type.
-
-\begin{code}
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)
+ -> NF_TcM (LookupInstResult s)
-- Dictionaries
-lookupInst dict@(Dict _ clas tys orig loc)
- = case lookupSpecEnv (ppr clas) (classInstEnv clas) tys of
+lookupInst dict@(Dict _ (ClassP clas tys) loc)
+ = tcGetInstEnv `thenNF_Tc` \ inst_env ->
+ case lookupInstEnv inst_env clas tys of
- Just (tenv, dfun_id)
+ FoundInst tenv dfun_id
-> let
- (tyvars, rho) = splitForAllTys (idType dfun_id)
- ty_args = map (expectJust "Inst" . lookupVarEnv tenv) tyvars
- -- tenv should bind all the tyvars
- dfun_rho = substTopTy tenv rho
- (theta, tau) = splitRhoTy dfun_rho
+ (tyvars, rho) = tcSplitForAllTys (idType dfun_id)
+ mk_ty_arg tv = case lookupSubstEnv tenv tv of
+ Just (DoneTy ty) -> returnNF_Tc ty
+ Nothing -> tcInstTyVar tv `thenNF_Tc` \ tc_tv ->
+ returnTc (mkTyVarTy tc_tv)
+ in
+ mapNF_Tc mk_ty_arg tyvars `thenNF_Tc` \ ty_args ->
+ let
+ subst = mkTyVarSubst tyvars ty_args
+ dfun_rho = substTy subst rho
+ (theta, _) = tcSplitRhoTy dfun_rho
ty_app = mkHsTyApp (HsVar dfun_id) ty_args
in
if null theta then
returnNF_Tc (SimpleInst ty_app)
else
- newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) ->
+ newDictsAtLoc loc theta `thenNF_Tc` \ dicts ->
let
- rhs = mkHsDictApp ty_app dict_ids
+ rhs = mkHsDictApp ty_app (map instToId dicts)
in
returnNF_Tc (GenInst dicts rhs)
-
- Nothing -> returnNF_Tc NoInstance
-
--- Methods
-
-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
+ other -> returnNF_Tc NoInstance
-lookupInst inst@(LitInst u (OverloadedIntegral i) ty orig 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 dict@(Dict _ _ loc) = returnNF_Tc NoInstance
- | isIntegerTy ty -- Short cut for Integer
- = returnNF_Tc (GenInst [] integer_lit)
+-- Methods
- | 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))
+lookupInst inst@(Method _ id tys theta _ loc)
+ = newDictsAtLoc loc theta `thenNF_Tc` \ dicts ->
+ returnNF_Tc (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) (map instToId dicts)))
- | 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) ->
- 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]
+-- Literals
--- similar idea for overloaded floating point literals: if the literal is
--- *definitely* a float or a double, generate the real thing here.
+-- Look for short cuts first: if the literal is *definitely* a
+-- int, integer, float or a double, generate the real thing here.
-- This is essential (see nofib/spectral/nucleic).
+-- [Same shortcut as in newOverloadedLit, but we
+-- may have done some unification by now]
-lookupInst inst@(LitInst u (OverloadedFractional f) ty orig loc)
- | isFloatTy ty = returnNF_Tc (GenInst [] float_lit)
- | isDoubleTy ty = returnNF_Tc (GenInst [] double_lit)
+lookupInst inst@(LitInst u lit ty loc)
+ | Just expr <- shortCutLit lit ty
+ = returnNF_Tc (GenInst [] expr) -- GenInst, not SimpleInst, because
+ -- expr may be a constructor application
- | otherwise
- = tcLookupValueByKey fromRationalClassOpKey `thenNF_Tc` \ from_rational ->
+lookupInst inst@(LitInst u (HsIntegral i from_integer_name) ty loc)
+ = tcLookupId from_integer_name `thenNF_Tc` \ from_integer ->
+ newMethodAtLoc loc from_integer [ty] `thenNF_Tc` \ (method_inst, method_id) ->
+ returnNF_Tc (GenInst [method_inst]
+ (HsApp (HsVar method_id) (HsLit (HsInteger i))))
- -- The type Rational isn't wired in so we have to conjure it up
- tcLookupTyConByKey rationalTyConKey `thenNF_Tc` \ rational_tycon ->
+
+lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc)
+ = tcLookupId from_rat_name `thenNF_Tc` \ from_rational ->
+ newMethodAtLoc loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
let
- rational_ty = mkSynTy rational_tycon []
- rational_lit = HsLitOut (HsFrac f) rational_ty
+ rational_ty = tcFunArgTy (idType method_id)
+ rational_lit = HsLit (HsRat f rational_ty)
in
- newMethodAtLoc orig loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) ->
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}
-lookupSimpleInst :: ClassInstEnv
- -> Class
+lookupSimpleInst :: 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 lookupSpecEnv (ppr clas) class_inst_env tys of
- Nothing -> returnNF_Tc Nothing
+ -> NF_TcM (Maybe ThetaType) -- Here are the needed (c,t)s
- Just (tenv, dfun)
- -> returnNF_Tc (Just (substTopTheta tenv theta))
+lookupSimpleInst clas tys
+ = tcGetInstEnv `thenNF_Tc` \ inst_env ->
+ case lookupInstEnv inst_env clas tys of
+ FoundInst tenv dfun
+ -> returnNF_Tc (Just (substTheta (mkSubst emptyInScopeSet tenv) theta))
where
- (_, theta, _) = splitSigmaTy (idType dfun)
-\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
- = OccurrenceOf TcId -- 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
-
- | PatOrigin RenamedPat
-
- | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
+ (_, rho) = tcSplitForAllTys (idType dfun)
+ (theta,_) = tcSplitRhoTy rho
- | 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
-
- | InstanceSpecOrigin 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].)
-
- | 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}
-
-\begin{code}
-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!")
+ other -> returnNF_Tc Nothing
\end{code}
projects / ghc-hetmet.git / blobdiff