\begin{code}
module Inst (
- LIE, emptyLIE, unitLIE, plusLIE, consLIE,
- plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE,
- showLIE,
-
Inst,
- pprInst, pprInsts, pprInstsInFull, tidyInsts, tidyMoreInsts,
- newDictsFromOld, newDicts, cloneDict,
+ pprDFuns, pprDictsTheta, pprDictsInFull, -- User error messages
+ showLIE, pprInst, pprInsts, pprInstInFull, -- Debugging messages
+
+ tidyInsts, tidyMoreInsts,
+
+ newDictsFromOld, newDicts, newDictsAtLoc, cloneDict,
newOverloadedLit, newIPDict,
newMethod, newMethodFromName, newMethodWithGivenTy,
- tcInstClassOp, tcInstCall, tcInstDataCon, tcSyntaxName,
+ tcInstClassOp, tcInstCall, tcInstStupidTheta,
+ tcSyntaxName, tcStdSyntaxName,
tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE,
ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts,
instLoc, getDictClassTys, dictPred,
lookupInst, LookupInstResult(..),
+ tcExtendLocalInstEnv, tcGetInstEnvs,
isDict, isClassDict, isMethod,
isLinearInst, linearInstType, isIPDict, isInheritableInst,
isTyVarDict, isStdClassTyVarDict, isMethodFor,
- instBindingRequired, instCanBeGeneralised,
+ instBindingRequired,
zonkInst, zonkInsts,
instToId, instName,
#include "HsVersions.h"
import {-# SOURCE #-} TcExpr( tcCheckSigma )
+import {-# SOURCE #-} TcUnify ( unifyTauTy ) -- Used in checkKind (sigh)
-import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) )
-import TcHsSyn ( TcExpr, TcId, TcIdSet,
- mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId,
+import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..), LHsExpr, mkHsApp )
+import TcHsSyn ( TcId, TcIdSet,
+ mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId,
mkCoercion, ExprCoFn
)
import TcRnMonad
-import TcEnv ( tcGetInstEnv, tcLookupId, tcLookupTyCon, checkWellStaged, topIdLvl )
-import InstEnv ( InstLookupResult(..), lookupInstEnv )
-import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType,
- zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars
+import TcEnv ( tcLookupId, checkWellStaged, topIdLvl, tcMetaTy )
+import InstEnv ( DFunId, InstEnv, lookupInstEnv, checkFunDeps, extendInstEnv )
+import TcIface ( loadImportedInsts )
+import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zonkTcThetaType,
+ tcInstTyVar, tcInstType, tcSkolType
)
-import TcType ( Type, TcType, TcThetaType, TcTyVarSet,
- SourceType(..), PredType, TyVarDetails(VanillaTv),
- tcSplitForAllTys, tcSplitForAllTys, mkTyConApp,
- tcSplitPhiTy, mkGenTyConApp,
+import TcType ( Type, TcType, TcThetaType, TcTyVarSet, TcTyVar, TcPredType,
+ PredType(..), SkolemInfo(..), typeKind, mkSigmaTy,
+ tcSplitForAllTys, tcSplitForAllTys,
+ tcSplitPhiTy, tcIsTyVarTy, tcSplitDFunTy, tcSplitDFunHead,
isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys,
tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred,
isClassPred, isTyVarClassPred, isLinearPred,
getClassPredTys, getClassPredTys_maybe, mkPredName,
isInheritablePred, isIPPred,
- tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy
+ tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy,
+ pprPred, pprParendType, pprThetaArrow, pprTheta, pprClassPred
)
+import Type ( TvSubst, substTy, substTyVar, substTyWith, substTheta, zipTopTvSubst,
+ notElemTvSubst, extendTvSubstList )
+import Unify ( tcMatchTys )
+import Kind ( isSubKind )
+import Packages ( isHomeModule )
+import HscTypes ( ExternalPackageState(..) )
import CoreFVs ( idFreeTyVars )
-import DataCon ( DataCon,dataConSig )
-import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId, setIdUnique )
-import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass )
-import Name ( Name, mkMethodOcc, getOccName )
-import PprType ( pprPred, pprParendType )
-import Subst ( substTy, substTyWith, substTheta, mkTyVarSubst )
+import DataCon ( DataCon, dataConTyVars, dataConStupidTheta, dataConName )
+import Id ( Id, idName, idType, mkUserLocal, mkLocalId )
+import PrelInfo ( isStandardClass, isNoDictClass )
+import Name ( Name, mkMethodOcc, getOccName, getSrcLoc, nameModule,
+ isInternalName, setNameUnique, mkSystemVarNameEncoded )
+import NameSet ( addOneToNameSet )
import Literal ( inIntRange )
-import Var ( TyVar )
-import VarEnv ( TidyEnv, emptyTidyEnv, lookupSubstEnv, SubstResult(..) )
-import VarSet ( elemVarSet, emptyVarSet, unionVarSet )
+import Var ( TyVar, tyVarKind, setIdType )
+import VarEnv ( TidyEnv, emptyTidyEnv )
+import VarSet ( elemVarSet, emptyVarSet, unionVarSet, mkVarSet )
import TysWiredIn ( floatDataCon, doubleDataCon )
-import PrelNames( fromIntegerName, fromRationalName, rationalTyConName )
+import PrelNames ( integerTyConName, fromIntegerName, fromRationalName, rationalTyConName )
import BasicTypes( IPName(..), mapIPName, ipNameName )
import UniqSupply( uniqsFromSupply )
+import SrcLoc ( mkSrcSpan, noLoc, unLoc, Located(..) )
+import CmdLineOpts( DynFlags )
+import Maybes ( isJust )
import Outputable
\end{code}
instName inst = idName (instToId inst)
instToId :: Inst -> TcId
-instToId (Dict id _ _) = id
+instToId (LitInst nm _ ty _) = mkLocalId nm ty
+instToId (Dict nm pred _) = mkLocalId nm (mkPredTy pred)
instToId (Method id _ _ _ _ _) = id
-instToId (LitInst id _ _ _) = id
instLoc (Dict _ _ loc) = loc
instLoc (Method _ _ _ _ _ loc) = loc
instBindingRequired :: Inst -> Bool
instBindingRequired (Dict _ (ClassP clas _) _) = not (isNoDictClass clas)
instBindingRequired other = True
-
-instCanBeGeneralised :: Inst -> Bool
-instCanBeGeneralised (Dict _ (ClassP clas _) _) = not (isCcallishClass clas)
-instCanBeGeneralised other = True
\end{code}
newDictsAtLoc loc theta
cloneDict :: Inst -> TcM Inst
-cloneDict (Dict id ty loc) = newUnique `thenM` \ uniq ->
- returnM (Dict (setIdUnique id uniq) ty loc)
+cloneDict (Dict nm ty loc) = newUnique `thenM` \ uniq ->
+ returnM (Dict (setNameUnique nm uniq) ty loc)
newDictsFromOld :: Inst -> TcThetaType -> TcM [Inst]
newDictsFromOld (Dict _ _ loc) theta = newDictsAtLoc loc theta
= newUniqueSupply `thenM` \ us ->
returnM (zipWith mk_dict (uniqsFromSupply us) theta)
where
- mk_dict uniq pred = Dict (mkLocalId (mkPredName uniq loc pred) (mkPredTy pred))
+ mk_dict uniq pred = Dict (mkPredName uniq loc pred)
pred inst_loc
loc = instLocSrcLoc inst_loc
newIPDict :: InstOrigin -> IPName Name -> Type
-> TcM (IPName Id, Inst)
newIPDict orig ip_name ty
- = getInstLoc orig `thenM` \ inst_loc@(InstLoc _ loc _) ->
+ = getInstLoc orig `thenM` \ inst_loc ->
newUnique `thenM` \ uniq ->
let
pred = IParam ip_name ty
- id = mkLocalId (mkPredName uniq loc pred) (mkPredTy pred)
+ name = mkPredName uniq (instLocSrcLoc inst_loc) pred
+ dict = Dict name pred inst_loc
in
- returnM (mapIPName (\n -> id) ip_name, Dict id pred inst_loc)
+ returnM (mapIPName (\n -> instToId dict) ip_name, dict)
\end{code}
\begin{code}
-tcInstCall :: InstOrigin -> TcType -> TcM (ExprCoFn, TcType)
+tcInstCall :: InstOrigin -> TcType -> TcM (ExprCoFn, [TcTyVar], TcType)
tcInstCall orig fun_ty -- fun_ty is usually a sigma-type
- = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) ->
- newDicts orig theta `thenM` \ dicts ->
- extendLIEs dicts `thenM_`
- let
- inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts)
- in
- returnM (mkCoercion inst_fn, tau)
-
-tcInstDataCon :: InstOrigin -> DataCon
- -> TcM ([TcType], -- Types to instantiate at
- [Inst], -- Existential dictionaries to apply to
- [TcType], -- Argument types of constructor
- TcType, -- Result type
- [TyVar]) -- Existential tyvars
-tcInstDataCon orig data_con
- = let
- (tvs, stupid_theta, ex_tvs, ex_theta, arg_tys, tycon) = dataConSig data_con
- -- We generate constraints for the stupid theta even when
- -- pattern matching (as the Report requires)
- in
- tcInstTyVars VanillaTv (tvs ++ ex_tvs) `thenM` \ (all_tvs', ty_args', tenv) ->
- let
- stupid_theta' = substTheta tenv stupid_theta
- ex_theta' = substTheta tenv ex_theta
- arg_tys' = map (substTy tenv) arg_tys
-
- n_normal_tvs = length tvs
- ex_tvs' = drop n_normal_tvs all_tvs'
- result_ty = mkTyConApp tycon (take n_normal_tvs ty_args')
- in
- newDicts orig stupid_theta' `thenM` \ stupid_dicts ->
- newDicts orig ex_theta' `thenM` \ ex_dicts ->
-
- -- Note that we return the stupid theta *only* in the LIE;
- -- we don't otherwise use it at all
- extendLIEs stupid_dicts `thenM_`
-
- returnM (ty_args', ex_dicts, arg_tys', result_ty, ex_tvs')
+ = do { (tyvars, theta, tau) <- tcInstType fun_ty
+ ; dicts <- newDicts orig theta
+ ; extendLIEs dicts
+ ; let inst_fn e = unLoc (mkHsDictApp (mkHsTyApp (noLoc e) (mkTyVarTys tyvars))
+ (map instToId dicts))
+ ; return (mkCoercion inst_fn, tyvars, tau) }
+
+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 (dataConTyVars data_con) inst_tys
newMethodFromName :: InstOrigin -> TcType -> Name -> TcM TcId
newMethodFromName origin ty name
-- This is important because they are used by TcSimplify
-- to simplify Insts
+-- NB: the kind of the type variable to be instantiated
+-- might be a sub-kind of the type to which it is applied,
+-- notably when the latter is a type variable of kind ??
+-- Hence the call to checkKind
+-- A worry: is this needed anywhere else?
tcInstClassOp :: InstLoc -> Id -> [TcType] -> TcM Inst
tcInstClassOp inst_loc sel_id tys
= let
substTyWith tyvars tys rho
(preds,tau) = tcSplitPhiTy rho_ty
in
+ zipWithM_ checkKind tyvars tys `thenM_`
newMethod inst_loc sel_id tys preds tau
+checkKind :: TyVar -> TcType -> TcM ()
+-- Ensure that the type has a sub-kind of the tyvar
+checkKind tv ty
+ = do { ty1 <- zonkTcType ty
+ ; if typeKind ty1 `isSubKind` tyVarKind tv
+ then return ()
+ else do
+ { traceTc (text "checkKind: adding kind constraint" <+> ppr tv <+> ppr ty)
+ ; tv1 <- tcInstTyVar tv
+ ; unifyTauTy (mkTyVarTy tv1) ty1 }}
+
+
---------------------------
newMethod inst_loc id tys theta tau
= newUnique `thenM` \ new_uniq ->
newOverloadedLit :: InstOrigin
-> HsOverLit
-> TcType
- -> TcM TcExpr
+ -> TcM (LHsExpr TcId)
newOverloadedLit orig lit@(HsIntegral i fi) expected_ty
- | fi /= fromIntegerName -- Do not generate a LitInst for rebindable
- -- syntax. Reason: tcSyntaxName does unification
+ | fi /= fromIntegerName -- Do not generate a LitInst for rebindable syntax.
+ -- Reason: tcSyntaxName does unification
-- which is very inconvenient in tcSimplify
+ -- ToDo: noLoc sadness
= tcSyntaxName orig expected_ty (fromIntegerName, HsVar fi) `thenM` \ (_,expr) ->
- returnM (HsApp expr (HsLit (HsInteger i)))
-
+ mkIntegerLit i `thenM` \ integer_lit ->
+ returnM (mkHsApp (noLoc expr) integer_lit)
+ -- The mkHsApp will get the loc from the literal
| Just expr <- shortCutIntLit i expected_ty
= returnM expr
| fr /= fromRationalName -- c.f. HsIntegral case
= tcSyntaxName orig expected_ty (fromRationalName, HsVar fr) `thenM` \ (_,expr) ->
mkRatLit r `thenM` \ rat_lit ->
- returnM (HsApp expr rat_lit)
+ returnM (mkHsApp (noLoc expr) rat_lit)
+ -- The mkHsApp will get the loc from the literal
| Just expr <- shortCutFracLit r expected_ty
= returnM expr
| otherwise
= newLitInst orig lit expected_ty
+newLitInst :: InstOrigin -> HsOverLit -> TcType -> TcM (LHsExpr TcId)
newLitInst orig lit expected_ty
= getInstLoc orig `thenM` \ loc ->
newUnique `thenM` \ new_uniq ->
let
- lit_inst = LitInst lit_id lit expected_ty loc
- lit_id = mkSysLocal FSLIT("lit") new_uniq expected_ty
+ lit_nm = mkSystemVarNameEncoded new_uniq FSLIT("lit")
+ -- The "encoded" bit means that we don't need to z-encode
+ -- the string every time we call this!
+ lit_inst = LitInst lit_nm lit expected_ty loc
in
extendLIE lit_inst `thenM_`
- returnM (HsVar (instToId lit_inst))
+ returnM (L (instLocSrcSpan loc) (HsVar (instToId lit_inst)))
-shortCutIntLit :: Integer -> TcType -> Maybe TcExpr
+shortCutIntLit :: Integer -> TcType -> Maybe (LHsExpr TcId) -- Returns noLoc'd result :-)
shortCutIntLit i ty
- | isIntTy ty && inIntRange i -- Short cut for Int
- = Just (HsLit (HsInt i))
- | isIntegerTy ty -- Short cut for Integer
- = Just (HsLit (HsInteger i))
+ | isIntTy ty && inIntRange i -- Short cut for Int
+ = Just (noLoc (HsLit (HsInt i)))
+ | isIntegerTy ty -- Short cut for Integer
+ = Just (noLoc (HsLit (HsInteger i ty)))
| otherwise = Nothing
-shortCutFracLit :: Rational -> TcType -> Maybe TcExpr
+shortCutFracLit :: Rational -> TcType -> Maybe (LHsExpr TcId) -- Returns noLoc'd result :-)
shortCutFracLit f ty
| isFloatTy ty
= Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)])
= Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)])
| otherwise = Nothing
-mkRatLit :: Rational -> TcM TcExpr
+mkIntegerLit :: Integer -> TcM (LHsExpr TcId)
+mkIntegerLit i
+ = tcMetaTy integerTyConName `thenM` \ integer_ty ->
+ getSrcSpanM `thenM` \ span ->
+ returnM (L span $ HsLit (HsInteger i integer_ty))
+
+mkRatLit :: Rational -> TcM (LHsExpr TcId)
mkRatLit r
- = tcLookupTyCon rationalTyConName `thenM` \ rat_tc ->
- let
- rational_ty = mkGenTyConApp rat_tc []
- in
- returnM (HsLit (HsRat r rational_ty))
+ = tcMetaTy rationalTyConName `thenM` \ rat_ty ->
+ getSrcSpanM `thenM` \ span ->
+ returnM (L span $ HsLit (HsRat r rat_ty))
\end{code}
%* *
%************************************************************************
-Zonking makes sure that the instance types are fully zonked,
-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.
+Zonking makes sure that the instance types are fully zonked.
\begin{code}
zonkInst :: Inst -> TcM Inst
-zonkInst (Dict id pred loc)
+zonkInst (Dict name pred loc)
= zonkTcPredType pred `thenM` \ new_pred ->
- returnM (Dict id new_pred loc)
+ returnM (Dict name new_pred loc)
zonkInst (Method m id tys theta tau loc)
= zonkId id `thenM` \ new_id ->
zonkTcType tau `thenM` \ new_tau ->
returnM (Method m new_id new_tys new_theta new_tau loc)
-zonkInst (LitInst id lit ty loc)
+zonkInst (LitInst nm lit ty loc)
= zonkTcType ty `thenM` \ new_ty ->
- returnM (LitInst id lit new_ty loc)
+ returnM (LitInst nm lit new_ty loc)
zonkInsts insts = mappM zonkInst insts
\end{code}
instance Outputable Inst where
ppr inst = pprInst inst
-pprInsts :: [Inst] -> SDoc
-pprInsts insts = parens (sep (punctuate comma (map pprInst insts)))
+pprDictsTheta :: [Inst] -> SDoc
+-- Print in type-like fashion (Eq a, Show b)
+pprDictsTheta dicts = pprTheta (map dictPred dicts)
-pprInstsInFull insts
- = vcat (map go insts)
+pprDictsInFull :: [Inst] -> SDoc
+-- Print in type-like fashion, but with source location
+pprDictsInFull dicts
+ = vcat (map go dicts)
where
- go inst = sep [quotes (ppr inst), nest 2 (pprInstLoc (instLoc inst))]
+ go dict = sep [quotes (ppr (dictPred dict)), nest 2 (pprInstLoc (instLoc dict))]
-pprInst (LitInst u lit ty loc)
- = hsep [ppr lit, 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 (sep (map pprParendType tys)) {- ,
- ptext SLIT("theta"), ppr theta,
- ptext SLIT("tau"), ppr tau
- show_uniq u,
- ppr (instToId m) -}]
-
-show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
+pprInsts :: [Inst] -> SDoc
+-- Debugging: print the evidence :: type
+pprInsts insts = brackets (interpp'SP insts)
+
+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 m@(Method inst_id id tys theta tau loc)
+ = ppr inst_id <+> dcolon <+>
+ braces (sep [ppr id <+> ptext SLIT("at"),
+ brackets (sep (map pprParendType tys))])
+
+pprInstInFull inst
+ = sep [quotes (pprInst inst), nest 2 (pprInstLoc (instLoc inst))]
+
+pprDFuns :: [DFunId] -> SDoc
+-- Prints the dfun as an instance declaration
+pprDFuns dfuns = vcat [ hang (ppr (getSrcLoc dfun) <> colon)
+ 2 (ptext SLIT("instance") <+> sep [pprThetaArrow theta,
+ pprClassPred clas tys])
+ | dfun <- dfuns
+ , let (_, theta, clas, tys) = tcSplitDFunTy (idType dfun) ]
+ -- Print without the for-all, which the programmer doesn't write
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 (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 tau loc) = Method u id (tidyTypes env tys) theta tau loc
tidyMoreInsts :: TidyEnv -> [Inst] -> (TidyEnv, [Inst])
showLIE str
= do { lie_var <- getLIEVar ;
lie <- readMutVar lie_var ;
- traceTc (str <+> pprInstsInFull (lieToList lie)) }
+ traceTc (str <+> vcat (map pprInstInFull (lieToList lie))) }
\end{code}
%************************************************************************
%* *
+ Extending the instance environment
+%* *
+%************************************************************************
+
+\begin{code}
+tcExtendLocalInstEnv :: [DFunId] -> TcM a -> TcM a
+ -- Add new locally-defined instances
+tcExtendLocalInstEnv dfuns thing_inside
+ = do { traceDFuns dfuns
+ ; env <- getGblEnv
+ ; dflags <- getDOpts
+ ; inst_env' <- foldlM (addInst dflags) (tcg_inst_env env) dfuns
+ ; let env' = env { tcg_insts = dfuns ++ tcg_insts env,
+ tcg_inst_env = inst_env' }
+ ; setGblEnv env' thing_inside }
+
+addInst :: DynFlags -> InstEnv -> DFunId -> TcM InstEnv
+-- Check that the proposed new instance is OK,
+-- and then add it to the home inst env
+addInst dflags home_ie dfun
+ = do { -- Instantiate the dfun type so that we extend the instance
+ -- envt with completely fresh template variables
+ -- This is important because the template variables must
+ -- not overlap with anything in the things being looked up
+ -- (since we do unification).
+ -- We use tcSkolType because we don't want to allocate fresh
+ -- *meta* type variables.
+ (tvs', theta', tau') <- tcSkolType (InstSkol dfun) (idType dfun)
+ ; let (cls, tys') = tcSplitDFunHead tau'
+ dfun' = setIdType dfun (mkSigmaTy tvs' theta' tau')
+
+ -- Load imported instances, so that we report
+ -- duplicates correctly
+ ; pkg_ie <- loadImportedInsts cls tys'
+
+ -- Check functional dependencies
+ ; case checkFunDeps (pkg_ie, home_ie) dfun' of
+ Just dfuns -> funDepErr dfun dfuns
+ Nothing -> return ()
+
+ -- Check for duplicate instance decls
+ ; let { (matches, _) = lookupInstEnv dflags (pkg_ie, home_ie) cls tys'
+ ; dup_dfuns = [dup_dfun | (_, (_, dup_tys, dup_dfun)) <- matches,
+ isJust (tcMatchTys (mkVarSet tvs') tys' dup_tys)] }
+ -- Find memebers of the match list which
+ -- dfun itself matches. If the match is 2-way, it's a duplicate
+ ; case dup_dfuns of
+ dup_dfun : _ -> dupInstErr dfun dup_dfun
+ [] -> return ()
+
+ -- OK, now extend the envt
+ ; return (extendInstEnv home_ie dfun') }
+
+
+traceDFuns dfuns
+ = traceTc (text "Adding instances:" <+> vcat (map pp dfuns))
+ where
+ pp dfun = ppr dfun <+> dcolon <+> ppr (idType dfun)
+
+funDepErr dfun dfuns
+ = addDictLoc dfun $
+ addErr (hang (ptext SLIT("Functional dependencies conflict between instance declarations:"))
+ 2 (pprDFuns (dfun:dfuns)))
+dupInstErr dfun dup_dfun
+ = addDictLoc dfun $
+ addErr (hang (ptext SLIT("Duplicate instance declarations:"))
+ 2 (pprDFuns [dfun, dup_dfun]))
+
+addDictLoc dfun thing_inside
+ = setSrcSpan (mkSrcSpan loc loc) thing_inside
+ where
+ loc = getSrcLoc dfun
+\end{code}
+
+
+%************************************************************************
+%* *
\subsection{Looking up Insts}
%* *
%************************************************************************
\begin{code}
-data LookupInstResult s
+data LookupInstResult
= NoInstance
- | SimpleInst TcExpr -- Just a variable, type application, or literal
- | GenInst [Inst] TcExpr -- The expression and its needed insts
+ | SimpleInst (LHsExpr TcId) -- Just a variable, type application, or literal
+ | GenInst [Inst] (LHsExpr TcId) -- The expression and its needed insts
-lookupInst :: Inst -> TcM (LookupInstResult s)
+lookupInst :: Inst -> TcM LookupInstResult
-- It's important that lookupInst does not put any new stuff into
-- the LIE. Instead, any Insts needed by the lookup are returned in
-- the LookupInstResult, where they can be further processed by tcSimplify
--- Dictionaries
-lookupInst dict@(Dict _ pred@(ClassP clas tys) loc)
- = getDOpts `thenM` \ dflags ->
- tcGetInstEnv `thenM` \ inst_env ->
- case lookupInstEnv dflags inst_env clas tys of
-
- FoundInst tenv dfun_id
- -> -- It's possible that not all the tyvars are in
- -- the substitution, tenv. For example:
- -- instance C X a => D X where ...
- -- (presumably there's a functional dependency in class C)
- -- Hence the mk_ty_arg to instantiate any un-substituted tyvars.
- getStage `thenM` \ use_stage ->
- checkWellStaged (ptext SLIT("instance for") <+> quotes (ppr pred))
- (topIdLvl dfun_id) use_stage `thenM_`
- traceTc (text "lookupInst" <+> ppr dfun_id <+> ppr (topIdLvl dfun_id) <+> ppr use_stage) `thenM_`
- let
- (tyvars, rho) = tcSplitForAllTys (idType dfun_id)
- mk_ty_arg tv = case lookupSubstEnv tenv tv of
- Just (DoneTy ty) -> returnM ty
- Nothing -> tcInstTyVar VanillaTv tv `thenM` \ tc_tv ->
- returnM (mkTyVarTy tc_tv)
- in
- mappM mk_ty_arg tyvars `thenM` \ ty_args ->
- let
- dfun_rho = substTy (mkTyVarSubst tyvars ty_args) rho
- (theta, _) = tcSplitPhiTy dfun_rho
- ty_app = mkHsTyApp (HsVar dfun_id) ty_args
- in
- if null theta then
- returnM (SimpleInst ty_app)
- else
- newDictsAtLoc loc theta `thenM` \ dicts ->
- let
- rhs = mkHsDictApp ty_app (map instToId dicts)
- in
- returnM (GenInst dicts rhs)
-
- other -> returnM NoInstance
-
-lookupInst (Dict _ _ _) = returnM NoInstance
-
-- Methods
lookupInst inst@(Method _ id tys theta _ loc)
= newDictsAtLoc loc theta `thenM` \ dicts ->
- returnM (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) (map instToId dicts)))
+ returnM (GenInst dicts (mkHsDictApp (mkHsTyApp (L span (HsVar id)) tys) (map instToId dicts)))
+ where
+ span = instLocSrcSpan loc
-- Literals
-- may have done some unification by now]
-lookupInst inst@(LitInst u (HsIntegral i from_integer_name) ty loc)
+lookupInst inst@(LitInst _nm (HsIntegral i from_integer_name) ty loc)
| Just expr <- shortCutIntLit i ty
= returnM (GenInst [] expr) -- GenInst, not SimpleInst, because
-- expr may be a constructor application
= ASSERT( from_integer_name == fromIntegerName ) -- A LitInst invariant
tcLookupId fromIntegerName `thenM` \ from_integer ->
tcInstClassOp loc from_integer [ty] `thenM` \ method_inst ->
+ mkIntegerLit i `thenM` \ integer_lit ->
returnM (GenInst [method_inst]
- (HsApp (HsVar (instToId method_inst)) (HsLit (HsInteger i))))
+ (mkHsApp (L (instLocSrcSpan loc)
+ (HsVar (instToId method_inst))) integer_lit))
-
-lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc)
+lookupInst inst@(LitInst _nm (HsFractional f from_rat_name) ty loc)
| Just expr <- shortCutFracLit f ty
= returnM (GenInst [] expr)
tcLookupId fromRationalName `thenM` \ from_rational ->
tcInstClassOp loc from_rational [ty] `thenM` \ method_inst ->
mkRatLit f `thenM` \ rat_lit ->
- returnM (GenInst [method_inst] (HsApp (HsVar (instToId method_inst)) rat_lit))
+ returnM (GenInst [method_inst] (mkHsApp (L (instLocSrcSpan loc)
+ (HsVar (instToId method_inst))) rat_lit))
+
+-- Dictionaries
+lookupInst dict@(Dict _ pred@(ClassP clas tys) loc)
+ = do { pkg_ie <- loadImportedInsts clas tys
+ -- Suck in any instance decls that may be relevant
+ ; tcg_env <- getGblEnv
+ ; dflags <- getDOpts
+ ; case lookupInstEnv dflags (pkg_ie, tcg_inst_env tcg_env) clas tys of {
+ ([(tenv, (_,_,dfun_id))], []) -> instantiate_dfun tenv dfun_id pred loc ;
+ (matches, unifs) -> do
+ { traceTc (text "lookupInst fail" <+> vcat [text "dict" <+> ppr pred,
+ text "matches" <+> ppr matches,
+ text "unifs" <+> ppr unifs])
+ ; return NoInstance } } }
+ -- In the case of overlap (multiple matches) we report
+ -- NoInstance here. That has the effect of making the
+ -- context-simplifier return the dict as an irreducible one.
+ -- Then it'll be given to addNoInstanceErrs, which will do another
+ -- lookupInstEnv to get the detailed info about what went wrong.
+
+lookupInst (Dict _ _ _) = returnM NoInstance
+
+-----------------
+instantiate_dfun :: TvSubst -> DFunId -> TcPredType -> InstLoc -> TcM LookupInstResult
+instantiate_dfun tenv dfun_id pred loc
+ = -- tenv is a substitution that instantiates the dfun_id
+ -- to match the requested result type.
+ --
+ -- We ASSUME that the dfun is quantified over the very same tyvars
+ -- that are bound by the tenv.
+ --
+ -- However, the dfun
+ -- might have some tyvars that *only* appear in arguments
+ -- dfun :: forall a b. C a b, Ord b => D [a]
+ -- We instantiate b to a flexi type variable -- it'll presumably
+ -- become fixed later via functional dependencies
+ traceTc (text "lookupInst success" <+>
+ vcat [text "dict" <+> ppr pred,
+ text "witness" <+> ppr dfun_id <+> ppr (idType dfun_id) ]) `thenM_`
+ -- Record that this dfun is needed
+ record_dfun_usage dfun_id `thenM_`
+
+ getStage `thenM` \ use_stage ->
+ checkWellStaged (ptext SLIT("instance for") <+> quotes (ppr pred))
+ (topIdLvl dfun_id) use_stage `thenM_`
+
+ -- It's possible that not all the tyvars are in
+ -- the substitution, tenv. For example:
+ -- instance C X a => D X where ...
+ -- (presumably there's a functional dependency in class C)
+ -- Hence the open_tvs to instantiate any un-substituted tyvars.
+ let
+ (tyvars, rho) = tcSplitForAllTys (idType dfun_id)
+ open_tvs = filter (`notElemTvSubst` tenv) tyvars
+ in
+ mappM tcInstTyVar open_tvs `thenM` \ open_tvs' ->
+ let
+ tenv' = extendTvSubstList tenv open_tvs (mkTyVarTys open_tvs')
+ -- Since the open_tvs' are freshly made, they cannot possibly be captured by
+ -- any nested for-alls in rho. So the in-scope set is unchanged
+ dfun_rho = substTy tenv' rho
+ (theta, _) = tcSplitPhiTy dfun_rho
+ ty_app = mkHsTyApp (L (instLocSrcSpan loc) (HsVar dfun_id))
+ (map (substTyVar tenv') tyvars)
+ in
+ if null theta then
+ returnM (SimpleInst ty_app)
+ else
+ newDictsAtLoc loc theta `thenM` \ dicts ->
+ let
+ rhs = mkHsDictApp ty_app (map instToId dicts)
+ in
+ returnM (GenInst dicts rhs)
+
+record_dfun_usage dfun_id = do
+ dflags <- getDOpts
+ let dfun_name = idName dfun_id
+ dfun_mod = nameModule dfun_name
+ if isInternalName dfun_name || not (isHomeModule dflags dfun_mod)
+ then return () -- internal, or in another package
+ else do tcg_env <- getGblEnv
+ updMutVar (tcg_inst_uses tcg_env)
+ (`addOneToNameSet` idName dfun_id)
+
+tcGetInstEnvs :: TcM (InstEnv, InstEnv)
+-- Gets both the external-package inst-env
+-- and the home-pkg inst env (includes module being compiled)
+tcGetInstEnvs = do { eps <- getEps; env <- getGblEnv;
+ return (eps_inst_env eps, tcg_inst_env env) }
\end{code}
tcSyntaxName :: InstOrigin
-> TcType -- Type to instantiate it at
-> (Name, HsExpr Name) -- (Standard name, user name)
- -> TcM (Name, TcExpr) -- (Standard name, suitable expression)
+ -> TcM (Name, HsExpr TcId) -- (Standard name, suitable expression)
-- NB: tcSyntaxName calls tcExpr, and hence can do unification.
-- So we do not call it from lookupInst, which is called from tcSimplify
tcSyntaxName orig ty (std_nm, HsVar user_nm)
| std_nm == user_nm
- = newMethodFromName orig ty std_nm `thenM` \ id ->
- returnM (std_nm, HsVar id)
+ = tcStdSyntaxName orig ty std_nm
tcSyntaxName orig ty (std_nm, user_nm_expr)
= tcLookupId std_nm `thenM` \ std_id ->
let
-- C.f. newMethodAtLoc
([tv], _, tau) = tcSplitSigmaTy (idType std_id)
- tau1 = substTyWith [tv] [ty] tau
+ sigma1 = substTyWith [tv] [ty] tau
-- Actually, the "tau-type" might be a sigma-type in the
-- case of locally-polymorphic methods.
in
- addErrCtxtM (syntaxNameCtxt user_nm_expr orig tau1) $
- tcCheckSigma user_nm_expr tau1 `thenM` \ expr ->
- returnM (std_nm, expr)
+ addErrCtxtM (syntaxNameCtxt user_nm_expr orig sigma1) $
+
+ -- Check that the user-supplied thing has the
+ -- same type as the standard one.
+ -- Tiresome jiggling because tcCheckSigma takes a located expression
+ getSrcSpanM `thenM` \ span ->
+ tcCheckSigma (L span user_nm_expr) sigma1 `thenM` \ expr ->
+ returnM (std_nm, unLoc expr)
+
+tcStdSyntaxName :: InstOrigin
+ -> TcType -- Type to instantiate it at
+ -> Name -- Standard name
+ -> TcM (Name, HsExpr TcId) -- (Standard name, suitable expression)
+
+tcStdSyntaxName orig ty std_nm
+ = newMethodFromName orig ty std_nm `thenM` \ id ->
+ returnM (std_nm, HsVar id)
syntaxNameCtxt name orig ty tidy_env
= getInstLoc orig `thenM` \ inst_loc ->
projects / ghc-hetmet.git / blobdiff