%
+% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
-\section[Inst]{The @Inst@ type: dictionaries or method instances}
+
+The @Inst@ type: dictionaries or method instances
\begin{code}
module Inst (
tidyInsts, tidyMoreInsts,
- newDicts, newDictsAtLoc, cloneDict,
+ newDictBndr, newDictBndrs, newDictBndrsO,
+ instCall, instStupidTheta,
+ cloneDict,
shortCutFracLit, shortCutIntLit, newIPDict,
newMethod, newMethodFromName, newMethodWithGivenTy,
- tcInstClassOp, tcInstStupidTheta,
+ tcInstClassOp,
tcSyntaxName, isHsVar,
tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE,
ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts,
instLoc, getDictClassTys, dictPred,
- mkInstCoFn,
lookupInst, LookupInstResult(..), lookupPred,
tcExtendLocalInstEnv, tcGetInstEnvs, getOverlapFlag,
isDict, isClassDict, isMethod,
- isLinearInst, linearInstType, isIPDict, isInheritableInst,
+ isIPDict, isInheritableInst,
isTyVarDict, isMethodFor,
zonkInst, zonkInsts,
#include "HsVersions.h"
import {-# SOURCE #-} TcExpr( tcPolyExpr )
+import {-# SOURCE #-} TcUnify( unifyType )
-import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..), LHsExpr, mkHsApp,
- ExprCoFn(..), (<.>), nlHsLit, nlHsVar )
-import TcHsSyn ( zonkId )
+import HsSyn
+import TcHsSyn
import TcRnMonad
-import TcEnv ( tcLookupId, checkWellStaged, topIdLvl, tcMetaTy )
-import InstEnv ( DFunId, InstEnv, Instance(..), OverlapFlag(..),
- lookupInstEnv, extendInstEnv, pprInstances,
- instanceHead, instanceDFunId, setInstanceDFunId )
-import FunDeps ( checkFunDeps )
-import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zonkTcThetaType,
- tcInstTyVar, tcInstSkolType
- )
-import TcType ( Type, TcType, TcThetaType, TcTyVarSet, TcPredType,
- BoxyRhoType,
- PredType(..), SkolemInfo(..), typeKind, mkSigmaTy,
- tcSplitForAllTys, applyTys,
- tcSplitPhiTy, tcSplitDFunHead,
- isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
- mkPredTy, mkTyVarTys,
- tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred,
- isClassPred, isTyVarClassPred, isLinearPred,
- getClassPredTys, mkPredName,
- isInheritablePred, isIPPred,
- tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy,
- pprPred, pprParendType, pprTheta
- )
-import Type ( TvSubst, substTy, substTyVar, substTyWith, substTheta, zipTopTvSubst,
- notElemTvSubst, extendTvSubstList )
-import Unify ( tcMatchTys )
-import Module ( modulePackageId )
-import {- Kind parts of -} Type ( isSubKind )
-import Coercion ( isEqPred )
-import HscTypes ( ExternalPackageState(..), HscEnv(..) )
-import CoreFVs ( idFreeTyVars )
-import DataCon ( DataCon, dataConStupidTheta, dataConName,
- dataConWrapId, dataConUnivTyVars )
-import Id ( Id, idName, idType, mkUserLocal, mkLocalId )
-import Name ( Name, mkMethodOcc, getOccName, getSrcLoc, nameModule,
- isInternalName, setNameUnique )
-import NameSet ( addOneToNameSet )
-import Literal ( inIntRange )
-import Var ( Var, TyVar, tyVarKind, setIdType, mkTyVar )
-import VarEnv ( TidyEnv, emptyTidyEnv )
-import VarSet ( elemVarSet, emptyVarSet, unionVarSet, mkVarSet )
-import TysWiredIn ( floatDataCon, doubleDataCon )
-import PrelNames ( integerTyConName, fromIntegerName, fromRationalName, rationalTyConName )
-import BasicTypes( IPName(..), mapIPName, ipNameName )
-import UniqSupply( uniqsFromSupply )
-import SrcLoc ( mkSrcSpan, noLoc, unLoc, Located(..) )
-import DynFlags ( DynFlag(..), DynFlags(..), dopt )
-import Maybes ( isJust )
+import TcEnv
+import InstEnv
+import FunDeps
+import TcMType
+import TcType
+import Type
+import Unify
+import Module
+import Coercion
+import HscTypes
+import CoreFVs
+import DataCon
+import Id
+import Name
+import NameSet
+import Literal
+import Var ( Var, TyVar )
+import qualified Var
+import VarEnv
+import VarSet
+import TysWiredIn
+import PrelNames
+import BasicTypes
+import SrcLoc
+import DynFlags
+import Maybes
import Outputable
\end{code}
Selection
~~~~~~~~~
\begin{code}
-mkInstCoFn :: [TcType] -> [Inst] -> ExprCoFn
-mkInstCoFn tys dicts = CoApps (map instToId dicts) <.> CoTyApps tys
-
instName :: Inst -> Name
instName inst = idName (instToId inst)
id = instToVar inst
instToVar :: Inst -> Var
-instToVar (LitInst nm _ ty _) = mkLocalId nm ty
-instToVar (Method id _ _ _ _) = id
-instToVar (Dict nm pred _)
- | isEqPred pred = mkTyVar nm (mkPredTy pred)
+instToVar (LitInst {tci_name = nm, tci_ty = ty})
+ = mkLocalId nm ty
+instToVar (Method {tci_id = id})
+ = id
+instToVar (Dict {tci_name = nm, tci_pred = pred})
+ | isEqPred pred = Var.mkCoVar nm (mkPredTy pred)
| otherwise = mkLocalId nm (mkPredTy pred)
-instLoc (Dict _ _ loc) = loc
-instLoc (Method _ _ _ _ loc) = loc
-instLoc (LitInst _ _ _ loc) = loc
+instLoc inst = tci_loc inst
-dictPred (Dict _ pred _ ) = pred
-dictPred inst = pprPanic "dictPred" (ppr inst)
+dictPred (Dict {tci_pred = pred}) = pred
+dictPred inst = pprPanic "dictPred" (ppr inst)
-getDictClassTys (Dict _ pred _) = getClassPredTys pred
+getDictClassTys (Dict {tci_pred = pred}) = getClassPredTys pred
+getDictClassTys inst = pprPanic "getDictClassTys" (ppr inst)
-- fdPredsOfInst is used to get predicates that contain functional
-- dependencies *or* might do so. The "might do" part is because
-- Leaving these in is really important for the call to fdPredsOfInsts
-- in TcSimplify.inferLoop, because the result is fed to 'grow',
-- which is supposed to be conservative
-fdPredsOfInst (Dict _ pred _) = [pred]
-fdPredsOfInst (Method _ _ _ theta _) = theta
-fdPredsOfInst other = [] -- LitInsts etc
+fdPredsOfInst (Dict {tci_pred = pred}) = [pred]
+fdPredsOfInst (Method {tci_theta = theta}) = theta
+fdPredsOfInst other = [] -- LitInsts etc
fdPredsOfInsts :: [Inst] -> [PredType]
fdPredsOfInsts insts = concatMap fdPredsOfInst insts
-isInheritableInst (Dict _ pred _) = isInheritablePred pred
-isInheritableInst (Method _ _ _ theta _) = all isInheritablePred theta
-isInheritableInst other = True
+isInheritableInst (Dict {tci_pred = pred}) = isInheritablePred pred
+isInheritableInst (Method {tci_theta = theta}) = all isInheritablePred theta
+isInheritableInst other = True
ipNamesOfInsts :: [Inst] -> [Name]
-- NB: ?x and %x get different Names
ipNamesOfInsts insts = [n | inst <- insts, n <- ipNamesOfInst inst]
-ipNamesOfInst (Dict _ (IParam n _) _) = [ipNameName n]
-ipNamesOfInst (Method _ _ _ theta _) = [ipNameName n | IParam n _ <- theta]
-ipNamesOfInst other = []
+ipNamesOfInst (Dict {tci_pred = IParam n _}) = [ipNameName n]
+ipNamesOfInst (Method {tci_theta = theta}) = [ipNameName n | IParam n _ <- theta]
+ipNamesOfInst other = []
tyVarsOfInst :: Inst -> TcTyVarSet
-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 {tci_ty = ty}) = tyVarsOfType ty
+tyVarsOfInst (Dict {tci_pred = pred}) = tyVarsOfPred pred
+tyVarsOfInst (Method {tci_oid = id, tci_tys = tys}) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id
+ -- The id might have free type variables; in the case of
+ -- locally-overloaded class methods, for example
tyVarsOfInsts insts = foldr (unionVarSet . tyVarsOfInst) emptyVarSet insts
~~~~~~~~~~
\begin{code}
isDict :: Inst -> Bool
-isDict (Dict _ _ _) = True
-isDict other = False
+isDict (Dict {}) = True
+isDict other = False
isClassDict :: Inst -> Bool
-isClassDict (Dict _ pred _) = isClassPred pred
-isClassDict other = False
+isClassDict (Dict {tci_pred = pred}) = isClassPred pred
+isClassDict other = False
isTyVarDict :: Inst -> Bool
-isTyVarDict (Dict _ pred _) = isTyVarClassPred pred
-isTyVarDict other = False
+isTyVarDict (Dict {tci_pred = pred}) = isTyVarClassPred pred
+isTyVarDict other = False
isIPDict :: Inst -> Bool
-isIPDict (Dict _ pred _) = isIPPred pred
-isIPDict other = False
+isIPDict (Dict {tci_pred = pred}) = isIPPred pred
+isIPDict 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
-
-isLinearInst :: Inst -> Bool
-isLinearInst (Dict _ pred _) = isLinearPred pred
-isLinearInst other = False
- -- We never build Method Insts that have
- -- linear implicit paramters in them.
- -- Hence no need to look for Methods
- -- See TcExpr.tcId
-
-linearInstType :: Inst -> TcType -- %x::t --> t
-linearInstType (Dict _ (IParam _ ty) _) = ty
+isMethodFor ids (Method {tci_oid = id}) = id `elemVarSet` ids
+isMethodFor ids inst = False
\end{code}
%* *
%************************************************************************
+-- newDictBndrs makes a dictionary at a binding site
+-- instCall makes a dictionary at an occurrence site
+-- and throws it into the LIE
+
\begin{code}
-newDicts :: InstOrigin
- -> TcThetaType
- -> TcM [Inst]
-newDicts orig theta
- = getInstLoc orig `thenM` \ loc ->
- newDictsAtLoc loc theta
+----------------
+newDictBndrsO :: InstOrigin -> TcThetaType -> TcM [Inst]
+newDictBndrsO orig theta = do { loc <- getInstLoc orig
+ ; newDictBndrs loc theta }
-cloneDict :: Inst -> TcM Inst -- Only used for linear implicit params
-cloneDict (Dict nm ty loc) = newUnique `thenM` \ uniq ->
- returnM (Dict (setNameUnique nm uniq) ty loc)
-
-newDictsAtLoc :: InstLoc -> TcThetaType -> TcM [Inst]
-newDictsAtLoc inst_loc theta = mapM (newDictAtLoc inst_loc) theta
-
-{-
-newDictOcc :: InstLoc -> TcPredType -> TcM Inst
-newDictOcc inst_loc (EqPred ty1 ty2)
- = do { unifyType ty1 ty2 -- We insist that they unify right away
- ; return ty1 } -- And return the relexive coercion
--}
-newDictAtLoc inst_loc pred
+newDictBndrs :: InstLoc -> TcThetaType -> TcM [Inst]
+newDictBndrs inst_loc theta = mapM (newDictBndr inst_loc) theta
+
+newDictBndr :: InstLoc -> TcPredType -> TcM Inst
+newDictBndr inst_loc pred
= do { uniq <- newUnique
; let name = mkPredName uniq (instLocSrcLoc inst_loc) pred
- ; return (Dict name pred inst_loc) }
+ ; return (Dict {tci_name = name, tci_pred = pred, tci_loc = inst_loc}) }
+
+----------------
+instCall :: InstOrigin -> [TcType] -> TcThetaType -> TcM HsWrapper
+-- Instantiate the constraints of a call
+-- (instCall o tys theta)
+-- (a) Makes fresh dictionaries as necessary for the constraints (theta)
+-- (b) Throws these dictionaries into the LIE
+-- (c) Eeturns an HsWrapper ([.] tys dicts)
+
+instCall orig tys theta
+ = do { loc <- getInstLoc orig
+ ; (dicts, dict_app) <- instCallDicts loc theta
+ ; extendLIEs dicts
+ ; return (dict_app <.> mkWpTyApps tys) }
+
+----------------
+instStupidTheta :: InstOrigin -> TcThetaType -> TcM ()
+-- Similar to instCall, but only emit the constraints in the LIE
+-- Used exclusively for the 'stupid theta' of a data constructor
+instStupidTheta orig theta
+ = do { loc <- getInstLoc orig
+ ; (dicts, _) <- instCallDicts loc theta
+ ; extendLIEs dicts }
+
+----------------
+instCallDicts :: InstLoc -> TcThetaType -> TcM ([Inst], HsWrapper)
+-- This is the key place where equality predicates
+-- are unleashed into the world
+instCallDicts loc [] = return ([], idHsWrapper)
+
+instCallDicts loc (EqPred ty1 ty2 : preds)
+ = do { unifyType ty1 ty2 -- For now, we insist that they unify right away
+ -- Later on, when we do associated types,
+ -- unifyType :: Type -> Type -> TcM ([Inst], Coercion)
+ ; (dicts, co_fn) <- instCallDicts loc preds
+ ; return (dicts, co_fn <.> WpTyApp ty1) }
+ -- We use type application to apply the function to the
+ -- coercion; here ty1 *is* the appropriate identity coercion
+
+instCallDicts loc (pred : preds)
+ = do { uniq <- newUnique
+ ; let name = mkPredName uniq (instLocSrcLoc loc) pred
+ dict = Dict {tci_name = name, tci_pred = pred, tci_loc = loc}
+ ; (dicts, co_fn) <- instCallDicts loc preds
+ ; return (dict:dicts, co_fn <.> WpApp (instToId dict)) }
+
+-------------
+cloneDict :: Inst -> TcM Inst -- Only used for linear implicit params
+cloneDict dict@(Dict nm ty loc) = do { uniq <- newUnique
+ ; return (dict {tci_name = setNameUnique nm uniq}) }
+cloneDict other = pprPanic "cloneDict" (ppr other)
-- For vanilla implicit parameters, there is only one in scope
-- at any time, so we used to use the name of the implicit parameter itself
let
pred = IParam ip_name ty
name = mkPredName uniq (instLocSrcLoc inst_loc) pred
- dict = Dict name pred inst_loc
+ dict = Dict {tci_name = name, tci_pred = pred, tci_loc = inst_loc}
in
returnM (mapIPName (\n -> instToId dict) ip_name, dict)
\end{code}
\begin{code}
-tcInstStupidTheta :: DataCon -> [TcType] -> TcM ()
--- Instantiate the "stupid theta" of the data con, and throw
--- the constraints into the constraint set
-tcInstStupidTheta data_con inst_tys
- | null stupid_theta
- = return ()
- | otherwise
- = do { stupid_dicts <- newDicts (OccurrenceOf (dataConName data_con))
- (substTheta tenv stupid_theta)
- ; extendLIEs stupid_dicts }
- where
- stupid_theta = dataConStupidTheta data_con
- tenv = zipTopTvSubst (dataConUnivTyVars data_con) inst_tys
-
newMethodFromName :: InstOrigin -> BoxyRhoType -> Name -> TcM TcId
newMethodFromName origin ty name
= tcLookupId name `thenM` \ id ->
checkKind tv ty
= do { let ty1 = ty
-- ty1 <- zonkTcType ty
- ; if typeKind ty1 `isSubKind` tyVarKind tv
+ ; if typeKind ty1 `isSubKind` Var.tyVarKind tv
then return ()
else
pprPanic "checkKind: adding kind constraint"
- (vcat [ppr tv <+> ppr (tyVarKind tv),
+ (vcat [ppr tv <+> ppr (Var.tyVarKind tv),
ppr ty <+> ppr ty1 <+> ppr (typeKind ty1)])
}
-- do { tv1 <- tcInstTyVar tv
let
(theta,tau) = tcSplitPhiTy (applyTys (idType id) tys)
meth_id = mkUserLocal (mkMethodOcc (getOccName id)) new_uniq tau loc
- inst = Method meth_id id tys theta inst_loc
+ inst = Method {tci_id = meth_id, tci_oid = id, tci_tys = tys,
+ tci_theta = theta, tci_loc = inst_loc}
loc = instLocSrcLoc inst_loc
in
returnM inst
\begin{code}
zonkInst :: Inst -> TcM Inst
-zonkInst (Dict name pred loc)
+zonkInst dict@(Dict { tci_pred = pred})
= zonkTcPredType pred `thenM` \ new_pred ->
- returnM (Dict name new_pred loc)
+ returnM (dict {tci_pred = new_pred})
-zonkInst (Method m id tys theta loc)
+zonkInst meth@(Method {tci_oid = id, tci_tys = tys, tci_theta = theta})
= zonkId id `thenM` \ 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 `thenM` \ new_tys ->
zonkTcThetaType theta `thenM` \ new_theta ->
- returnM (Method m new_id new_tys new_theta loc)
+ returnM (meth { tci_oid = new_id, tci_tys = new_tys, tci_theta = new_theta })
+ -- No need to zonk the tci_id
-zonkInst (LitInst nm lit ty loc)
+zonkInst lit@(LitInst {tci_ty = ty})
= zonkTcType ty `thenM` \ new_ty ->
- returnM (LitInst nm lit new_ty loc)
+ returnM (lit {tci_ty = new_ty})
zonkInsts insts = mappM zonkInst insts
\end{code}
pprInst, pprInstInFull :: Inst -> SDoc
-- Debugging: print the evidence :: type
-pprInst (LitInst nm lit ty loc) = ppr nm <+> dcolon <+> ppr ty
-pprInst (Dict nm pred loc) = ppr nm <+> dcolon <+> pprPred pred
+pprInst (LitInst {tci_name = nm, tci_ty = ty}) = ppr nm <+> dcolon <+> ppr ty
+pprInst (Dict {tci_name = nm, tci_pred = pred}) = ppr nm <+> dcolon <+> pprPred pred
-pprInst m@(Method inst_id id tys theta loc)
+pprInst (Method {tci_id = inst_id, tci_oid = id, tci_tys = tys})
= ppr inst_id <+> dcolon <+>
braces (sep [ppr id <+> ptext SLIT("at"),
brackets (sep (map pprParendType tys))])
= sep [quotes (pprInst inst), nest 2 (pprInstLoc (instLoc inst))]
tidyInst :: TidyEnv -> Inst -> Inst
-tidyInst env (LitInst nm lit ty loc) = LitInst nm lit (tidyType env ty) loc
-tidyInst env (Dict nm pred loc) = Dict nm (tidyPred env pred) loc
-tidyInst env (Method u id tys theta loc) = Method u id (tidyTypes env tys) theta loc
+tidyInst env lit@(LitInst {tci_ty = ty}) = lit {tci_ty = tidyType env ty}
+tidyInst env dict@(Dict {tci_pred = pred}) = dict {tci_pred = tidyPred env pred}
+tidyInst env meth@(Method {tci_tys = tys}) = meth {tci_tys = tidyTypes env tys}
tidyMoreInsts :: TidyEnv -> [Inst] -> (TidyEnv, [Inst])
-- This function doesn't assume that the tyvars are in scope
-- Methods
-lookupInst inst@(Method _ id tys theta loc)
- = do { dicts <- newDictsAtLoc loc theta
- ; let co_fn = mkInstCoFn tys dicts
- ; return (GenInst dicts (L span $ HsCoerce co_fn (HsVar id))) }
+lookupInst (Method {tci_oid = id, tci_tys = tys, tci_theta = theta, tci_loc = loc})
+ = do { (dicts, dict_app) <- instCallDicts loc theta
+ ; let co_fn = dict_app <.> mkWpTyApps tys
+ ; return (GenInst dicts (L span $ HsWrap co_fn (HsVar id))) }
where
span = instLocSrcSpan loc
-- [Same shortcut as in newOverloadedLit, but we
-- may have done some unification by now]
-lookupInst inst@(LitInst _nm (HsIntegral i from_integer_name) ty loc)
+lookupInst (LitInst {tci_lit = HsIntegral i from_integer_name, tci_ty = ty, tci_loc = loc})
| Just expr <- shortCutIntLit i ty
= returnM (GenInst [] (noLoc expr)) -- GenInst, not SimpleInst, because
-- expr may be a constructor application
(mkHsApp (L (instLocSrcSpan loc)
(HsVar (instToId method_inst))) integer_lit))
-lookupInst inst@(LitInst _nm (HsFractional f from_rat_name) ty loc)
+lookupInst (LitInst {tci_lit = HsFractional f from_rat_name, tci_ty = ty, tci_loc = loc})
| Just expr <- shortCutFracLit f ty
= returnM (GenInst [] (noLoc expr))
(HsVar (instToId method_inst))) rat_lit))
-- Dictionaries
-lookupInst (Dict _ pred loc)
+lookupInst (Dict {tci_pred = pred, tci_loc = loc})
= do { mb_result <- lookupPred pred
; case mb_result of {
Nothing -> return NoInstance ;
dfun = HsVar dfun_id
tys = map (substTyVar tenv') tyvars
; if null theta then
- returnM (SimpleInst (L src_loc $ HsCoerce (CoTyApps tys) dfun))
+ returnM (SimpleInst (L src_loc $ HsWrap (mkWpTyApps tys) dfun))
else do
- { dicts <- newDictsAtLoc loc theta
- ; let co_fn = mkInstCoFn tys dicts
- ; returnM (GenInst dicts (L src_loc $ HsCoerce co_fn dfun))
+ { (dicts, dict_app) <- instCallDicts loc theta
+ ; let co_fn = dict_app <.> mkWpTyApps tys
+ ; returnM (GenInst dicts (L src_loc $ HsWrap co_fn dfun))
}}}}
---------------