\begin{code}
module Inst (
- LIE, emptyLIE, unitLIE, plusLIE, consLIE,
- plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE,
showLIE,
Inst,
#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
zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars
)
import TcType ( Type, TcType, TcThetaType, TcTyVarSet,
- PredType(..), TyVarDetails(VanillaTv),
+ PredType(..), TyVarDetails(VanillaTv), typeKind,
tcSplitForAllTys, tcSplitForAllTys, mkTyConApp,
tcSplitPhiTy, tcIsTyVarTy, tcSplitDFunTy,
isIntTy,isFloatTy, isIntegerTy, isDoubleTy,
isClassPred, isTyVarClassPred, isLinearPred,
getClassPredTys, getClassPredTys_maybe, mkPredName,
isInheritablePred, isIPPred, matchTys,
- tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy
+ tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy,
+ pprPred, pprParendType, pprThetaArrow, pprClassPred
)
+import Kind ( isSubKind )
import HscTypes ( ExternalPackageState(..) )
import CoreFVs ( idFreeTyVars )
import DataCon ( DataCon,dataConSig )
import PrelInfo ( isStandardClass, isNoDictClass )
import Name ( Name, mkMethodOcc, getOccName, getSrcLoc, isHomePackageName, isInternalName )
import NameSet ( addOneToNameSet )
-import PprType ( pprPred, pprParendType, pprThetaArrow, pprClassPred )
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, mkVarSet )
import TysWiredIn ( floatDataCon, doubleDataCon )
import PrelNames ( integerTyConName, fromIntegerName, fromRationalName, rationalTyConName )
import BasicTypes( IPName(..), mapIPName, ipNameName )
import UniqSupply( uniqsFromSupply )
-import CmdLineOpts( DynFlags )
+import SrcLoc ( mkSrcSpan, noLoc, Located(..) )
+import CmdLineOpts( DynFlags, DynFlag( Opt_AllowUndecidableInstances ), dopt )
import Maybes ( isJust )
import Outputable
\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
+ -> 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
- = tcSyntaxName orig expected_ty (fromIntegerName, HsVar fi) `thenM` \ (_,expr) ->
- mkIntegerLit i `thenM` \ integer_lit ->
- returnM (HsApp expr integer_lit)
+ -- 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
newOverloadedLit orig lit@(HsFractional r fr) expected_ty
| 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)
+ = 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))
+ = Just (noLoc (HsLit (HsInt i)))
| isIntegerTy ty -- Short cut for Integer
- = Just (HsLit (HsInteger i ty))
+ = 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
-mkIntegerLit :: Integer -> TcM TcExpr
+mkIntegerLit :: Integer -> TcM (LHsExpr TcId)
mkIntegerLit i
= tcMetaTy integerTyConName `thenM` \ integer_ty ->
- returnM (HsLit (HsInteger i integer_ty))
+ getSrcSpanM `thenM` \ span ->
+ returnM (L span $ HsLit (HsInteger i integer_ty))
-mkRatLit :: Rational -> TcM TcExpr
+mkRatLit :: Rational -> TcM (LHsExpr TcId)
mkRatLit r
= tcMetaTy rationalTyConName `thenM` \ rat_ty ->
- returnM (HsLit (HsRat r rat_ty))
+ getSrcSpanM `thenM` \ span ->
+ returnM (L span $ HsLit (HsRat r rat_ty))
\end{code}
-- Add new locally-defined instances
tcExtendLocalInstEnv dfuns thing_inside
= do { traceDFuns dfuns
- ; eps <- getEps
; env <- getGblEnv
; dflags <- getDOpts
- ; inst_env' <- foldlM (extend dflags (eps_inst_env eps))
- (tcg_inst_env env)
- dfuns
+ ; 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 }
- where
- extend dflags pkg_ie home_ie dfun
- = do { checkNewInst dflags (home_ie, pkg_ie) dfun
- ; return (extendInstEnv home_ie dfun) }
-checkNewInst :: DynFlags -> (InstEnv, InstEnv) -> DFunId -> TcM ()
--- Check that the proposed new instance is OK
-checkNewInst dflags ies dfun
- = do { -- Check functional dependencies
- case checkFunDeps ies dfun of
+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)
- (matches, _) = lookupInstEnv dflags ies 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
traceDFuns dfuns
= traceTc (text "Adding instances:" <+> vcat (map pp dfuns))
pp dfun = ppr dfun <+> dcolon <+> ppr (idType dfun)
funDepErr dfun dfuns
- = addSrcLoc (getSrcLoc dfun) $
+ = addDictLoc dfun $
addErr (hang (ptext SLIT("Functional dependencies conflict between instance declarations:"))
2 (pprDFuns (dfun:dfuns)))
dupInstErr dfun dup_dfun
- = addSrcLoc (getSrcLoc 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}
%************************************************************************
\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
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
tcInstClassOp loc from_integer [ty] `thenM` \ method_inst ->
mkIntegerLit i `thenM` \ integer_lit ->
returnM (GenInst [method_inst]
- (HsApp (HsVar (instToId method_inst)) integer_lit))
+ (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)
- | all tcIsTyVarTy tys -- Common special case; no lookup
- -- NB: tcIsTyVarTy... don't look through newtypes!
- = returnM NoInstance
-
- | otherwise
- = do { pkg_ie <- loadImportedInsts clas tys
+ = 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
- ; 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" <+> vcat [text "matches" <+> ppr matches,
text "unifs" <+> ppr unifs])
- ; return NoInstance } } }
+ ; 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.
let
dfun_rho = substTy (mkTyVarSubst tyvars ty_args) rho
(theta, _) = tcSplitPhiTy dfun_rho
- ty_app = mkHsTyApp (HsVar dfun_id) ty_args
+ ty_app = mkHsTyApp (L (instLocSrcSpan loc) (HsVar dfun_id)) ty_args
in
if null theta then
returnM (SimpleInst ty_app)
\begin{code}
tcSyntaxName :: InstOrigin
-> TcType -- Type to instantiate it at
- -> (Name, HsExpr Name) -- (Standard name, user name)
- -> TcM (Name, TcExpr) -- (Standard name, suitable expression)
+ -> (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, HsVar user_nm)
+tcSyntaxName orig ty (std_nm, L span (HsVar user_nm))
| std_nm == user_nm
- = tcStdSyntaxName orig ty std_nm
+ = addSrcSpan span (tcStdSyntaxName orig ty std_nm)
tcSyntaxName orig ty (std_nm, user_nm_expr)
= tcLookupId std_nm `thenM` \ std_id ->
-- Check that the user-supplied thing has the
-- same type as the standard one
- tcCheckSigma user_nm_expr tau1 `thenM` \ expr ->
+ tcCheckSigma user_nm_expr tau1 `thenM` \ expr ->
returnM (std_nm, expr)
tcStdSyntaxName :: InstOrigin
- -> TcType -- Type to instantiate it at
- -> Name -- Standard name
- -> TcM (Name, TcExpr) -- (Standard name, suitable expression)
+ -> 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 ->
- returnM (std_nm, HsVar 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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