\begin{code}
module Inst (
- LIE, emptyLIE, unitLIE, plusLIE, consLIE,
- plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE,
showLIE,
Inst,
- pprInst, pprInsts, pprInstsInFull, tidyInsts, tidyMoreInsts,
+ pprInst, pprInsts, pprInstsInFull, pprDFuns,
+ tidyInsts, tidyMoreInsts,
newDictsFromOld, newDicts, cloneDict,
newOverloadedLit, newIPDict,
newMethod, newMethodFromName, newMethodWithGivenTy,
- tcInstClassOp, tcInstCall, tcInstDataCon, tcSyntaxName,
+ tcInstClassOp, tcInstCall, tcInstDataCon,
+ 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( tcExpr )
+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, zapToType,
+import TcEnv ( tcLookupId, checkWellStaged, topIdLvl, tcMetaTy )
+import InstEnv ( DFunId, InstEnv, lookupInstEnv, checkFunDeps, extendInstEnv )
+import TcIface ( loadImportedInsts )
+import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType,
zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars
)
import TcType ( Type, TcType, TcThetaType, TcTyVarSet,
- SourceType(..), PredType, TyVarDetails(VanillaTv),
+ PredType(..), TyVarDetails(VanillaTv), typeKind,
tcSplitForAllTys, tcSplitForAllTys, mkTyConApp,
- tcSplitPhiTy, mkGenTyConApp,
+ tcSplitPhiTy, tcIsTyVarTy, tcSplitDFunTy,
isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys,
tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred,
- isClassPred, isTyVarClassPred, isLinearPred, predHasFDs,
+ isClassPred, isTyVarClassPred, isLinearPred,
getClassPredTys, getClassPredTys_maybe, mkPredName,
- isInheritablePred, isIPPred,
- tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy
+ isInheritablePred, isIPPred, matchTys,
+ tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy,
+ pprPred, pprParendType, pprThetaArrow, pprClassPred
)
+import Kind ( isSubKind )
+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 PrelInfo ( isStandardClass, isNoDictClass )
+import Name ( Name, mkMethodOcc, getOccName, getSrcLoc, isHomePackageName, isInternalName )
+import NameSet ( addOneToNameSet )
import Subst ( substTy, substTyWith, substTheta, mkTyVarSubst )
import Literal ( inIntRange )
-import Var ( TyVar )
+import Var ( TyVar, tyVarKind )
import VarEnv ( TidyEnv, emptyTidyEnv, lookupSubstEnv, SubstResult(..) )
-import VarSet ( elemVarSet, emptyVarSet, unionVarSet )
+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, Located(..) )
+import CmdLineOpts( DynFlags, DynFlag( Opt_AllowUndecidableInstances ), dopt )
+import Maybes ( isJust )
import Outputable
\end{code}
getDictClassTys (Dict _ pred _) = getClassPredTys pred
-- fdPredsOfInst is used to get predicates that contain functional
--- dependencies; i.e. should participate in improvement
-fdPredsOfInst (Dict _ pred _) | predHasFDs pred = [pred]
- | otherwise = []
-fdPredsOfInst (Method _ _ _ theta _ _) = filter predHasFDs theta
-fdPredsOfInst other = []
+-- dependencies *or* might do so. The "might do" part is because
+-- a constraint (C a b) might have a superclass with FDs
+-- 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
fdPredsOfInsts :: [Inst] -> [PredType]
fdPredsOfInsts insts = concatMap fdPredsOfInst insts
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}
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
+ id = mkLocalId name (mkPredTy pred)
in
returnM (mapIPName (\n -> id) ip_name, Dict id pred inst_loc)
\end{code}
newDicts orig theta `thenM` \ dicts ->
extendLIEs dicts `thenM_`
let
- inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts)
+ inst_fn e = DictApp (mkHsTyApp (noLoc e) (mkTyVarTys tyvars)) (map instToId dicts)
in
returnM (mkCoercion inst_fn, tau)
-- 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 VanillaTv tv
+ ; unifyTauTy (mkTyVarTy tv1) ty1 }}
+
+
---------------------------
newMethod inst_loc id tys theta tau
= newUnique `thenM` \ new_uniq ->
newOverloadedLit :: InstOrigin
-> HsOverLit
-> TcType
- -> TcM TcExpr
-newOverloadedLit orig lit expected_ty
- = zapToType expected_ty `thenM_`
- -- The expected type might be a 'hole' type variable,
- -- in which case we must zap it to an ordinary type variable
- new_over_lit orig lit expected_ty
-
-new_over_lit orig lit@(HsIntegral i fi) expected_ty
- | fi /= fromIntegerName -- Do not generate a LitInst for rebindable
- -- syntax. Reason: tcSyntaxName does unification
+ -> 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
-- which is very inconvenient in tcSimplify
- = tcSyntaxName orig expected_ty fromIntegerName fi `thenM` \ (expr, _) ->
- returnM (HsApp expr (HsLit (HsInteger i)))
+ -- ToDo: noLoc sadness
+ = tcSyntaxName orig expected_ty (fromIntegerName, noLoc (HsVar fi)) `thenM` \ (_,expr) ->
+ mkIntegerLit i `thenM` \ integer_lit ->
+ returnM (mkHsApp expr integer_lit)
| Just expr <- shortCutIntLit i expected_ty
= returnM expr
| otherwise
= newLitInst orig lit expected_ty
-new_over_lit orig lit@(HsFractional r fr) expected_ty
+newOverloadedLit orig lit@(HsFractional r fr) expected_ty
| fr /= fromRationalName -- c.f. HsIntegral case
- = tcSyntaxName orig expected_ty fromRationalName fr `thenM` \ (expr, _) ->
- mkRatLit r `thenM` \ rat_lit ->
- returnM (HsApp expr rat_lit)
+ = tcSyntaxName orig expected_ty (fromRationalName, noLoc (HsVar fr)) `thenM` \ (_,expr) ->
+ mkRatLit r `thenM` \ rat_lit ->
+ returnM (mkHsApp expr rat_lit)
| 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 ->
lit_id = mkSysLocal FSLIT("lit") new_uniq expected_ty
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}
show_uniq u,
ppr (instToId m) -}]
+
+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
+
show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}")
tidyInst :: TidyEnv -> Inst -> Inst
%************************************************************************
%* *
+ 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 { -- 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 (matchTys (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) }
+ where
+ (tvs, _, cls, tys) = tcSplitDFunTy (idType 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
+ = addSrcSpan (mkSrcSpan loc loc) thing_inside
+ where
+ loc = getSrcLoc dfun
+\end{code}
+
+%************************************************************************
+%* *
\subsection{Looking up Insts}
%* *
%************************************************************************
\begin{code}
data LookupInstResult s
= 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)
-- It's important that lookupInst does not put any new stuff into
-- 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
= 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)
| Just expr <- shortCutFracLit f ty
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 { dflags <- getDOpts
+ ; if all tcIsTyVarTy tys &&
+ not (dopt Opt_AllowUndecidableInstances dflags)
+ -- Common special case; no lookup
+ -- NB: tcIsTyVarTy... don't look through newtypes!
+ -- Don't take this short cut if we allow undecidable instances
+ -- because we might have "instance T a where ...".
+ -- [That means we need -fallow-undecidable-instances in the
+ -- client module, as well as the module with the instance decl.]
+ then return NoInstance
+
+ else do
+ { pkg_ie <- loadImportedInsts clas tys
+ -- Suck in any instance decls that may be relevant
+ ; tcg_env <- getGblEnv
+ ; 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" <+> vcat [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 tenv dfun_id pred loc
+ = -- Record that this dfun is needed
+ record_dfun_usage dfun_id `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 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_`
+ 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 (L (instLocSrcSpan loc) (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)
+
+record_dfun_usage dfun_id
+ | isInternalName dfun_name = return () -- From this module
+ | not (isHomePackageName dfun_name) = return () -- From another package package
+ | otherwise = getGblEnv `thenM` \ tcg_env ->
+ updMutVar (tcg_inst_uses tcg_env)
+ (`addOneToNameSet` idName dfun_id)
+ where
+ dfun_name = idName dfun_id
+
+tcGetInstEnvs :: TcM (InstEnv, InstEnv)
+-- Gets both the home-pkg inst env (includes module being compiled)
+-- and the external-package inst-env
+tcGetInstEnvs = do { eps <- getEps; env <- getGblEnv;
+ return (tcg_inst_env env, eps_inst_env eps) }
\end{code}
\begin{code}
tcSyntaxName :: InstOrigin
-> TcType -- Type to instantiate it at
- -> Name -> Name -- (Standard name, user name)
- -> TcM (TcExpr, TcType) -- Suitable expression with its type
+ -> (Name, LHsExpr Name) -- (Standard name, user name)
+ -> TcM (Name, LHsExpr 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 user_nm
+tcSyntaxName orig ty (std_nm, L span (HsVar user_nm))
| std_nm == user_nm
- = newMethodFromName orig ty std_nm `thenM` \ id ->
- returnM (HsVar id, idType id)
+ = addSrcSpan span (tcStdSyntaxName orig ty std_nm)
- | otherwise
+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
+ -- Actually, the "tau-type" might be a sigma-type in the
+ -- case of locally-polymorphic methods.
in
- addErrCtxtM (syntaxNameCtxt user_nm orig tau1) $
- tcExpr (HsVar user_nm) tau1 `thenM` \ user_fn ->
- returnM (user_fn, tau1)
+ addErrCtxtM (syntaxNameCtxt user_nm_expr orig tau1) $
+
+ -- Check that the user-supplied thing has the
+ -- same type as the standard one
+ tcCheckSigma user_nm_expr tau1 `thenM` \ expr ->
+ returnM (std_nm, expr)
+
+tcStdSyntaxName :: InstOrigin
+ -> TcType -- Type to instantiate it at
+ -> Name -- Standard name
+ -> TcM (Name, LHsExpr TcId) -- (Standard name, suitable expression)
+
+tcStdSyntaxName orig ty std_nm
+ = newMethodFromName orig ty std_nm `thenM` \ id ->
+ getSrcSpanM `thenM` \ span ->
+ returnM (std_nm, L span (HsVar id))
syntaxNameCtxt name orig ty tidy_env
= getInstLoc orig `thenM` \ inst_loc ->
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