-module Check where
+{-# OPTIONS -Wall -fno-warn-name-shadowing #-}
+module Check(
+ checkModule, envsModule,
+ checkExpr, checkType,
+ primCoercionError,
+ Menv, Venv, Tvenv, Envs(..),
+ CheckRes(..), splitTy, substl) where
import Maybe
import Control.Monad.Reader
+-- just for printing warnings
+import System.IO.Unsafe
import Core
-import Printer
+import Printer()
import List
import Env
+import PrimEnv
{- Checking is done in a simple error monad. In addition to
allowing errors to be captured, this makes it easy to guarantee
instance Monad CheckRes where
OkC a >>= k = k a
- FailC s >>= k = fail s
+ FailC s >>= _ = fail s
return = OkC
fail = FailC
{- Environments. -}
type Tvenv = Env Tvar Kind -- type variables (local only)
-type Tcenv = Env Tcon Kind -- type constructors
+type Tcenv = Env Tcon KindOrCoercion -- type constructors
type Tsenv = Env Tcon ([Tvar],Ty) -- type synonyms
type Cenv = Env Dcon Ty -- data constructors
type Venv = Env Var Ty -- values
type Menv = Env AnMname Envs -- modules
data Envs = Envs {tcenv_::Tcenv,tsenv_::Tsenv,cenv_::Cenv,venv_::Venv} -- all the exportable envs
+ deriving Show
-{- Extend an environment, checking for illegal shadowing of identifiers. -}
-extendM :: (Ord a, Show a) => Env a b -> (a,b) -> CheckResult (Env a b)
-extendM env (k,d) =
+{- Extend an environment, checking for illegal shadowing of identifiers (for term
+ variables -- shadowing type variables is allowed.) -}
+data EnvType = Tv | NotTv
+ deriving Eq
+
+extendM :: (Ord a, Show a) => EnvType -> Env a b -> (a,b) -> CheckResult (Env a b)
+extendM envType env (k,d) =
case elookup env k of
- Just _ -> fail ("multiply-defined identifier: " ++ show k)
- Nothing -> return (eextend env (k,d))
+ Just _ | envType == NotTv -> fail ("multiply-defined identifier: "
+ ++ show k)
+ _ -> return (eextend env (k,d))
+
+extendVenv :: (Ord a, Show a) => Env a b -> (a,b) -> CheckResult (Env a b)
+extendVenv = extendM NotTv
+
+extendTvenv :: (Ord a, Show a) => Env a b -> (a,b) -> CheckResult (Env a b)
+extendTvenv = extendM Tv
lookupM :: (Ord a, Show a) => Env a b -> a -> CheckResult b
lookupM env k =
{- Main entry point. -}
checkModule :: Menv -> Module -> CheckRes Menv
-checkModule globalEnv mod@(Module mn tdefs vdefgs) =
+checkModule globalEnv (Module mn tdefs vdefgs) =
runReaderT
(do (tcenv, tsenv, cenv) <- mkTypeEnvs tdefs
- (e_venv,l_venv) <- foldM (checkVdefg True (tcenv,tsenv,eempty,cenv))
+ (e_venv,_) <- foldM (checkVdefg True (tcenv,tsenv,eempty,cenv))
(eempty,eempty)
vdefgs
return (eextend globalEnv
(mn,Envs{tcenv_=tcenv,tsenv_=tsenv,cenv_=cenv,venv_=e_venv})))
- (mn, globalEnv)
+ -- avoid name shadowing
+ (mn, eremove globalEnv mn)
+
+-- Like checkModule, but doesn't typecheck the code, instead just
+-- returning declared types for top-level defns.
+-- This is necessary in order to handle circular dependencies, but it's sort
+-- of unpleasant.
+envsModule :: Menv -> Module -> Menv
+envsModule globalEnv (Module mn tdefs vdefgs) =
+ let (tcenv, tsenv, cenv) = mkTypeEnvsNoChecking tdefs
+ e_venv = foldr vdefgTypes eempty vdefgs in
+ eextend globalEnv (mn,
+ (Envs{tcenv_=tcenv,tsenv_=tsenv,cenv_=cenv,venv_=e_venv}))
+ where vdefgTypes :: Vdefg -> Venv -> Venv
+ vdefgTypes (Nonrec (Vdef (v,t,_))) e =
+ add [(v,t)] e
+ vdefgTypes (Rec vds) e =
+ add (map (\ (Vdef (v,t,_)) -> (v,t)) vds) e
+ add :: [(Qual Var,Ty)] -> Venv -> Venv
+ add pairs e = foldr addOne e pairs
+ addOne :: (Qual Var, Ty) -> Venv -> Venv
+ addOne ((Nothing,_),_) e = e
+ addOne ((Just _,v),t) e = eextend e (v,t)
checkTdef0 :: (Tcenv,Tsenv) -> Tdef -> CheckResult (Tcenv,Tsenv)
checkTdef0 (tcenv,tsenv) tdef = ch tdef
ch (Data (m,c) tbs _) =
do mn <- getMname
requireModulesEq m mn "data type declaration" tdef False
- tcenv' <- extendM tcenv (c,k)
+ tcenv' <- extendM NotTv tcenv (c, Kind k)
return (tcenv',tsenv)
where k = foldr Karrow Klifted (map snd tbs)
- ch (Newtype (m,c) tbs rhs) =
+ ch (Newtype (m,c) coVar tbs rhs) =
do mn <- getMname
requireModulesEq m mn "newtype declaration" tdef False
- tcenv' <- extendM tcenv (c,k)
+ tcenv' <- extendM NotTv tcenv (c, Kind k)
+ -- add newtype axiom to env
+ tcenv'' <- envPlusNewtype tcenv' (m,c) coVar tbs rhs
tsenv' <- case rhs of
Nothing -> return tsenv
- Just rep -> extendM tsenv (c,(map fst tbs,rep))
- return (tcenv', tsenv')
+ Just rep -> extendM NotTv tsenv (c,(map fst tbs,rep))
+ return (tcenv'', tsenv')
+ where k = foldr Karrow Klifted (map snd tbs)
+
+processTdef0NoChecking :: (Tcenv,Tsenv) -> Tdef -> (Tcenv,Tsenv)
+processTdef0NoChecking (tcenv,tsenv) tdef = ch tdef
+ where
+ ch (Data (_,c) tbs _) = (eextend tcenv (c, Kind k), tsenv)
+ where k = foldr Karrow Klifted (map snd tbs)
+ ch (Newtype tc@(_,c) coercion tbs rhs) =
+ let tcenv' = eextend tcenv (c, Kind k)
+ -- add newtype axiom to env
+ tcenv'' = case rhs of
+ Just rep ->
+ eextend tcenv'
+ (snd coercion, Coercion $ DefinedCoercion tbs
+ (foldl Tapp (Tcon tc) (map Tvar (fst (unzip tbs))), rep))
+ Nothing -> tcenv'
+ tsenv' = maybe tsenv
+ (\ rep -> eextend tsenv (c, (map fst tbs, rep))) rhs in
+ (tcenv'', tsenv')
where k = foldr Karrow Klifted (map snd tbs)
+
+envPlusNewtype :: Tcenv -> Qual Tcon -> Qual Tcon -> [Tbind] -> Maybe Ty
+ -> CheckResult Tcenv
+envPlusNewtype tcenv tyCon coVar tbs rhs =
+ case rhs of
+ Nothing -> return tcenv
+ Just rep -> extendM NotTv tcenv
+ (snd coVar, Coercion $ DefinedCoercion tbs
+ (foldl Tapp (Tcon tyCon)
+ (map Tvar (fst (unzip tbs))),
+ rep))
checkTdef :: Tcenv -> Cenv -> Tdef -> CheckResult Cenv
checkTdef tcenv cenv = ch
where
ch (Data (_,c) utbs cdefs) =
do cbinds <- mapM checkCdef cdefs
- foldM extendM cenv cbinds
+ foldM (extendM NotTv) cenv cbinds
where checkCdef (cdef@(Constr (m,dcon) etbs ts)) =
do mn <- getMname
requireModulesEq m mn "constructor declaration" cdef
False
- tvenv <- foldM extendM eempty tbs
+ tvenv <- foldM (extendM Tv) eempty tbs
ks <- mapM (checkTy (tcenv,tvenv)) ts
mapM_ (\k -> require (baseKind k)
("higher-order kind in:\n" ++ show cdef ++ "\n" ++
(foldr tArrow
(foldl Tapp (Tcon (Just mn,c))
(map (Tvar . fst) utbs)) ts) tbs
- ch (tdef@(Newtype c tbs (Just t))) =
- do tvenv <- foldM extendM eempty tbs
- k <- checkTy (tcenv,tvenv) t
- require (k==Klifted) ("bad kind:\n" ++ show tdef)
+ ch (tdef@(Newtype tc _ tbs (Just t))) =
+ do tvenv <- foldM (extendM Tv) eempty tbs
+ kRhs <- checkTy (tcenv,tvenv) t
+ require (kRhs `eqKind` Klifted) ("bad kind:\n" ++ show tdef)
+ kLhs <- checkTy (tcenv,tvenv)
+ (foldl Tapp (Tcon tc) (map Tvar (fst (unzip tbs))))
+ require (kLhs `eqKind` kRhs)
+ ("Kind mismatch in newtype axiom types: " ++ show tdef
+ ++ " kinds: " ++
+ (show kLhs) ++ " and " ++ (show kRhs))
return cenv
- ch (tdef@(Newtype c tbs Nothing)) =
+ ch (Newtype _ _ _ Nothing) =
{- should only occur for recursive Newtypes -}
return cenv
+processCdef :: Cenv -> Tdef -> Cenv
+processCdef cenv = ch
+ where
+ ch (Data (_,c) utbs cdefs) = do
+ let cbinds = map checkCdef cdefs
+ foldl eextend cenv cbinds
+ where checkCdef (Constr (mn,dcon) etbs ts) =
+ (dcon,t mn)
+ where tbs = utbs ++ etbs
+ t mn = foldr Tforall
+ (foldr tArrow
+ (foldl Tapp (Tcon (mn,c))
+ (map (Tvar . fst) utbs)) ts) tbs
+ ch _ = cenv
+
mkTypeEnvs :: [Tdef] -> CheckResult (Tcenv, Tsenv, Cenv)
mkTypeEnvs tdefs = do
(tcenv, tsenv) <- foldM checkTdef0 (eempty,eempty) tdefs
cenv <- foldM (checkTdef tcenv) eempty tdefs
return (tcenv, tsenv, cenv)
+mkTypeEnvsNoChecking :: [Tdef] -> (Tcenv, Tsenv, Cenv)
+mkTypeEnvsNoChecking tdefs =
+ let (tcenv, tsenv) = foldl processTdef0NoChecking (eempty,eempty) tdefs
+ cenv = foldl processCdef eempty tdefs in
+ (tcenv, tsenv, cenv)
+
requireModulesEq :: Show a => Mname -> AnMname -> String -> a
-> Bool -> CheckResult ()
requireModulesEq (Just mn) m msg t _ = require (mn == m) (mkErrMsg msg t)
-requireModulesEq Nothing m msg t emptyOk = require emptyOk (mkErrMsg msg t)
+requireModulesEq Nothing _ msg t emptyOk = require emptyOk (mkErrMsg msg t)
mkErrMsg :: Show a => String -> a -> String
mkErrMsg msg t = "wrong module name in " ++ msg ++ ":\n" ++ show t
checkVdefg :: Bool -> (Tcenv,Tsenv,Tvenv,Cenv) -> (Venv,Venv)
-> Vdefg -> CheckResult (Venv,Venv)
-checkVdefg top_level (tcenv,tsenv,tvenv,cenv) (e_venv,l_venv) vdefg =
+checkVdefg top_level (tcenv,tsenv,tvenv,cenv) (e_venv,l_venv) vdefg = do
+ mn <- getMname
case vdefg of
Rec vdefs ->
- do e_venv' <- foldM extendM e_venv e_vts
- l_venv' <- foldM extendM l_venv l_vts
+ do (e_venv', l_venv') <- makeEnv mn vdefs
let env' = (tcenv,tsenv,tvenv,cenv,e_venv',l_venv')
- mapM_ (\ (vdef@(Vdef ((m,v),t,e))) ->
- do mn <- getMname
- requireModulesEq m mn "value definition" vdef True
- k <- checkTy (tcenv,tvenv) t
- require (k==Klifted) ("unlifted kind in:\n" ++ show vdef)
- t' <- checkExp env' e
- requireM (equalTy tsenv t t')
- ("declared type doesn't match expression type in:\n" ++ show vdef ++ "\n" ++
- "declared type: " ++ show t ++ "\n" ++
- "expression type: " ++ show t')) vdefs
- return (e_venv',l_venv')
- where e_vts = [ (v,t) | Vdef ((Just _,v),t,_) <- vdefs ]
- l_vts = [ (v,t) | Vdef ((Nothing,v),t,_) <- vdefs]
- Nonrec (vdef@(Vdef ((m,v),t,e))) ->
- do mn <- getMname
- requireModulesEq m mn "value definition" vdef True
- k <- checkTy (tcenv,tvenv) t
- require (k /= Kopen) ("open kind in:\n" ++ show vdef)
- require ((not top_level) || (k /= Kunlifted)) ("top-level unlifted kind in:\n" ++ show vdef)
- t' <- checkExp (tcenv,tsenv,tvenv,cenv,e_venv,l_venv) e
- requireM (equalTy tsenv t t')
- ("declared type doesn't match expression type in:\n" ++ show vdef ++ "\n" ++
- "declared type: " ++ show t ++ "\n" ++
- "expression type: " ++ show t')
- if isNothing m then
- do l_venv' <- extendM l_venv (v,t)
- return (e_venv,l_venv')
- else
- do e_venv' <- extendM e_venv (v,t)
- return (e_venv',l_venv)
+ mapM_ (checkVdef (\ vdef k -> require (k `eqKind` Klifted)
+ ("unlifted kind in:\n" ++ show vdef)) env')
+ vdefs
+ return (e_venv', l_venv')
+ Nonrec vdef ->
+ do let env' = (tcenv, tsenv, tvenv, cenv, e_venv, l_venv)
+ checkVdef (\ vdef k -> do
+ require (not (k `eqKind` Kopen)) ("open kind in:\n" ++ show vdef)
+ require ((not top_level) || (not (k `eqKind` Kunlifted)))
+ ("top-level unlifted kind in:\n" ++ show vdef)) env' vdef
+ makeEnv mn [vdef]
+
+ where makeEnv mn vdefs = do
+ ev <- foldM extendVenv e_venv e_vts
+ lv <- foldM extendVenv l_venv l_vts
+ return (ev, lv)
+ where e_vts = [ (v,t) | Vdef ((Just m,v),t,_) <- vdefs,
+ not (vdefIsMainWrapper mn (Just m))]
+ l_vts = [ (v,t) | Vdef ((Nothing,v),t,_) <- vdefs]
+ checkVdef checkKind env (vdef@(Vdef ((m,_),t,e))) = do
+ mn <- getMname
+ let isZcMain = vdefIsMainWrapper mn m
+ unless isZcMain $
+ requireModulesEq m mn "value definition" vdef True
+ k <- checkTy (tcenv,tvenv) t
+ checkKind vdef k
+ t' <- checkExp env e
+ requireM (equalTy tsenv t t')
+ ("declared type doesn't match expression type in:\n"
+ ++ show vdef ++ "\n" ++
+ "declared type: " ++ show t ++ "\n" ++
+ "expression type: " ++ show t')
+vdefIsMainWrapper :: AnMname -> Mname -> Bool
+vdefIsMainWrapper enclosing defining =
+ enclosing == mainMname && defining == wrapperMainMname
+
checkExpr :: AnMname -> Menv -> [Tdef] -> Venv -> Tvenv
-> Exp -> Ty
-checkExpr mn menv tdefs venv tvenv e = case (runReaderT (do
+checkExpr mn menv tdefs venv tvenv e = case runReaderT (do
(tcenv, tsenv, cenv) <- mkTypeEnvs tdefs
- checkExp (tcenv, tsenv, tvenv, cenv, venv, eempty) e)
- (mn, menv)) of
- OkC t -> t
- FailC s -> reportError s
+ -- Since the preprocessor calls checkExpr after code has been
+ -- typechecked, we expect to find the external env in the Menv.
+ case (elookup menv mn) of
+ Just thisEnv ->
+ checkExp (tcenv, tsenv, tvenv, cenv, (venv_ thisEnv), venv) e
+ Nothing -> reportError e ("checkExpr: Environment for " ++
+ show mn ++ " not found")) (mn,menv) of
+ OkC t -> t
+ FailC s -> reportError e s
+
+checkType :: AnMname -> Menv -> [Tdef] -> Tvenv -> Ty -> Kind
+checkType mn menv tdefs tvenv t = case runReaderT (do
+ (tcenv, _, _) <- mkTypeEnvs tdefs
+ checkTy (tcenv, tvenv) t) (mn, menv) of
+ OkC k -> k
+ FailC s -> reportError tvenv s
checkExp :: (Tcenv,Tsenv,Tvenv,Cenv,Venv,Venv) -> Exp -> CheckResult Ty
-checkExp (tcenv,tsenv,tvenv,cenv,e_venv,l_venv) = ch
+checkExp (tcenv,tsenv,tvenv,cenv,e_venv,l_venv) = ch
where
- ch e0 =
+ ch e0 =
case e0 of
Var qv ->
qlookupM venv_ e_venv l_venv qv
k' <- checkTy (tcenv,tvenv) t
case t' of
Tforall (tv,k) t0 ->
- do require (k' <= k)
+ do require (k' `subKindOf` k)
("kind doesn't match at type application in:\n" ++ show e0 ++ "\n" ++
"operator kind: " ++ show k ++ "\n" ++
"operand kind: " ++ show k')
_ -> fail ("bad operator type at application in:\n" ++ show e0 ++ "\n" ++
"operator type: " ++ show t1)
Lam (Tb tb) e ->
- do tvenv' <- extendM tvenv tb
+ do tvenv' <- extendTvenv tvenv tb
t <- checkExp (tcenv,tsenv,tvenv',cenv,e_venv,l_venv) e
return (Tforall tb t)
Lam (Vb (vb@(_,vt))) e ->
require (baseKind k)
("higher-order kind in:\n" ++ show e0 ++ "\n" ++
"kind: " ++ show k)
- l_venv' <- extendM l_venv vb
+ l_venv' <- extendVenv l_venv vb
t <- checkExp (tcenv,tsenv,tvenv,cenv,e_venv,l_venv') e
require (not (isUtupleTy vt)) ("lambda-bound unboxed tuple in:\n" ++ show e0)
return (tArrow vt t)
ok [] _ = fail ("missing default alternative in literal case:\n" ++ show e0)
in ok as [l]
[Adefault _] -> return ()
- [] -> fail ("no alternatives in case:\n" ++ show e0)
- l_venv' <- extendM l_venv (v,t)
+ _ -> fail ("no alternatives in case:\n" ++ show e0)
+ l_venv' <- extendVenv l_venv (v,t)
t:ts <- mapM (checkAlt (tcenv,tsenv,tvenv,cenv,e_venv,l_venv') t) alts
bs <- mapM (equalTy tsenv t) ts
require (and bs)
" match case return type in:\n" ++ show e0 ++ "\n" ++
"alt type: " ++ show t ++ " return type: " ++ show resultTy)
return t
- Cast e t ->
- do ch e
- checkTy (tcenv,tvenv) t
- return t
- Note s e ->
+ c@(Cast e t) ->
+ do eTy <- ch e
+ (fromTy, toTy) <- checkTyCo (tcenv,tvenv) t
+ require (eTy == fromTy) ("Type mismatch in cast: c = "
+ ++ show c ++ "\nand eTy = " ++ show eTy
+ ++ "\n and " ++ show fromTy)
+ return toTy
+ Note _ e ->
ch e
External _ t ->
do checkTy (tcenv,eempty) t {- external types must be closed -}
{- check existentials -}
let (etvs,eks) = unzip etbs
let (etvs',eks') = unzip etbs'
- require (eks == eks')
+ require (all (uncurry eqKind)
+ (zip eks eks'))
("existential kinds don't match in:\n" ++ show a0 ++ "\n" ++
"kinds declared in data constructor: " ++ show eks ++
"kinds declared in case alternative: " ++ show eks')
- tvenv' <- foldM extendM tvenv etbs
+ tvenv' <- foldM extendTvenv tvenv etbs
{- check term variables -}
let vts = map snd vbs
mapM_ (\vt -> require ((not . isUtupleTy) vt)
("pattern constructor type doesn't match scrutinee type in:\n" ++ show a0 ++ "\n" ++
"pattern constructor type: " ++ show ct_res ++ "\n" ++
"scrutinee type: " ++ show t0)
- l_venv' <- foldM extendM l_venv vbs
+ l_venv' <- foldM extendVenv l_venv vbs
t <- checkExp (tcenv,tsenv,tvenv',cenv,e_venv,l_venv') e
checkTy (tcenv,tvenv) t {- check that existentials don't escape in result type -}
return t
checkExp env e
checkTy :: (Tcenv,Tvenv) -> Ty -> CheckResult Kind
-checkTy (tcenv,tvenv) = ch
+checkTy es@(tcenv,tvenv) = ch
where
ch (Tvar tv) = lookupM tvenv tv
- ch (Tcon qtc) = qlookupM tcenv_ tcenv eempty qtc
+ ch (Tcon qtc) = do
+ kOrC <- qlookupM tcenv_ tcenv eempty qtc
+ case kOrC of
+ Kind k -> return k
+ Coercion (DefinedCoercion [] (t1,t2)) -> return $ Keq t1 t2
+ Coercion _ -> fail ("Unsaturated coercion app: " ++ show qtc)
ch (t@(Tapp t1 t2)) =
- do k1 <- ch t1
- k2 <- ch t2
- case k1 of
- Karrow k11 k12 ->
- do require (k2 <= k11)
- ("kinds don't match in type application: " ++ show t ++ "\n" ++
- "operator kind: " ++ show k11 ++ "\n" ++
- "operand kind: " ++ show k2)
- return k12
- _ -> fail ("applied type has non-arrow kind: " ++ show t)
+ case splitTyConApp_maybe t of
+ Just (tc, tys) -> do
+ tcK <- qlookupM tcenv_ tcenv eempty tc
+ case tcK of
+ Kind _ -> checkTapp t1 t2
+ Coercion (DefinedCoercion tbs (from,to)) -> do
+ -- makes sure coercion is fully applied
+ require (length tys == length tbs) $
+ ("Arity mismatch in coercion app: " ++ show t)
+ let (tvs, tks) = unzip tbs
+ argKs <- mapM (checkTy es) tys
+ let kPairs = zip argKs tks
+ let kindsOk = all (uncurry eqKind) kPairs
+ if not kindsOk &&
+ all (uncurry subKindOf) kPairs
+ -- GHC occasionally generates code like:
+ -- :Co:TTypeable2 (->)
+ -- where in this case, :Co:TTypeable2 expects an
+ -- argument of kind (*->(*->*)) and (->) has kind
+ -- (?->(?->*)). I'm not sure whether or not it's
+ -- sound to apply an arbitrary coercion to an
+ -- argument that's a subkind of what it expects.
+ then warn $ "Applying coercion " ++ show tc ++
+ " to arguments of kind " ++ show argKs
+ ++ " when it expects: " ++ show tks
+ else require kindsOk
+ ("Kind mismatch in coercion app: " ++ show tks
+ ++ " and " ++ show argKs ++ " t = " ++ show t)
+ return $ Keq (substl tvs tys from) (substl tvs tys to)
+ Nothing -> checkTapp t1 t2
+ where checkTapp t1 t2 = do
+ k1 <- ch t1
+ k2 <- ch t2
+ case k1 of
+ Karrow k11 k12 -> do
+ require (k2 `subKindOf` k11) kindError
+ return k12
+ where kindError =
+ "kinds don't match in type application: "
+ ++ show t ++ "\n" ++
+ "operator kind: " ++ show k11 ++ "\n" ++
+ "operand kind: " ++ show k2
+ _ -> fail ("applied type has non-arrow kind: " ++ show t)
+
ch (Tforall tb t) =
- do tvenv' <- extendM tvenv tb
- checkTy (tcenv,tvenv') t
-
+ do tvenv' <- extendTvenv tvenv tb
+ checkTy (tcenv,tvenv') t
+ ch (TransCoercion t1 t2) = do
+ (ty1,ty2) <- checkTyCo es t1
+ (ty3,ty4) <- checkTyCo es t2
+ require (ty2 == ty3) ("Types don't match in trans. coercion: " ++
+ show ty2 ++ " and " ++ show ty3)
+ return $ Keq ty1 ty4
+ ch (SymCoercion t1) = do
+ (ty1,ty2) <- checkTyCo es t1
+ return $ Keq ty2 ty1
+ ch (UnsafeCoercion t1 t2) = do
+ checkTy es t1
+ checkTy es t2
+ return $ Keq t1 t2
+ ch (LeftCoercion t1) = do
+ k <- checkTyCo es t1
+ case k of
+ ((Tapp u _), (Tapp w _)) -> return $ Keq u w
+ _ -> fail ("Bad coercion kind in operand of left: " ++ show k)
+ ch (RightCoercion t1) = do
+ k <- checkTyCo es t1
+ case k of
+ ((Tapp _ v), (Tapp _ x)) -> return $ Keq v x
+ _ -> fail ("Bad coercion kind in operand of left: " ++ show k)
+ ch (InstCoercion ty arg) = do
+ forallK <- checkTyCo es ty
+ case forallK of
+ ((Tforall (v1,k1) b1), (Tforall (v2,k2) b2)) -> do
+ require (k1 `eqKind` k2) ("Kind mismatch in argument of inst: "
+ ++ show ty)
+ argK <- checkTy es arg
+ require (argK `eqKind` k1) ("Kind mismatch in type being "
+ ++ "instantiated: " ++ show arg)
+ let newLhs = substl [v1] [arg] b1
+ let newRhs = substl [v2] [arg] b2
+ return $ Keq newLhs newRhs
+ _ -> fail ("Non-forall-ty in argument to inst: " ++ show ty)
+
+checkTyCo :: (Tcenv, Tvenv) -> Ty -> CheckResult (Ty, Ty)
+checkTyCo es@(tcenv,_) t@(Tapp t1 t2) =
+ (case splitTyConApp_maybe t of
+ Just (tc, tys) -> do
+ tcK <- qlookupM tcenv_ tcenv eempty tc
+ case tcK of
+ -- todo: avoid duplicating this code
+ -- blah, this almost calls for a different syntactic form
+ -- (for a defined-coercion app): (TCoercionApp Tcon [Ty])
+ Coercion (DefinedCoercion tbs (from, to)) -> do
+ require (length tys == length tbs) $
+ ("Arity mismatch in coercion app: " ++ show t)
+ let (tvs, tks) = unzip tbs
+ argKs <- mapM (checkTy es) tys
+ let kPairs = zip argKs tks
+ let kindsOk = all (uncurry eqKind) kPairs
+ if not kindsOk &&
+ all (uncurry subKindOf) kPairs
+ -- see comments in checkTy about this
+ then warn $ "Applying coercion " ++ show tc ++
+ " to arguments of kind " ++ show argKs
+ ++ " when it expects: " ++ show tks
+ else require kindsOk
+ ("Kind mismatch in coercion app: " ++ show tks
+ ++ " and " ++ show argKs ++ " t = " ++ show t)
+ return (substl tvs tys from, substl tvs tys to)
+ _ -> checkTapp t1 t2
+ _ -> checkTapp t1 t2)
+ where checkTapp t1 t2 = do
+ (lhsRator, rhsRator) <- checkTyCo es t1
+ (lhs, rhs) <- checkTyCo es t2
+ -- Comp rule from paper
+ checkTy es (Tapp lhsRator lhs)
+ checkTy es (Tapp rhsRator rhs)
+ return (Tapp lhsRator lhs, Tapp rhsRator rhs)
+checkTyCo (tcenv, tvenv) (Tforall tb t) = do
+ tvenv' <- extendTvenv tvenv tb
+ (t1,t2) <- checkTyCo (tcenv, tvenv') t
+ return (Tforall tb t1, Tforall tb t2)
+checkTyCo es t = do
+ k <- checkTy es t
+ case k of
+ Keq t1 t2 -> return (t1, t2)
+ -- otherwise, expand by the "refl" rule
+ _ -> return (t, t)
+
{- Type equality modulo newtype synonyms. -}
equalTy :: Tsenv -> Ty -> Ty -> CheckResult Bool
equalTy tsenv t1 t2 =
expand (Tforall tb t) =
do t' <- expand t
return (Tforall tb t')
+ expand (TransCoercion t1 t2) = do
+ exp1 <- expand t1
+ exp2 <- expand t2
+ return $ TransCoercion exp1 exp2
+ expand (SymCoercion t) = do
+ exp <- expand t
+ return $ SymCoercion exp
+ expand (UnsafeCoercion t1 t2) = do
+ exp1 <- expand t1
+ exp2 <- expand t2
+ return $ UnsafeCoercion exp1 exp2
+ expand (LeftCoercion t1) = do
+ exp1 <- expand t1
+ return $ LeftCoercion exp1
+ expand (RightCoercion t1) = do
+ exp1 <- expand t1
+ return $ RightCoercion exp1
+ expand (InstCoercion t1 t2) = do
+ exp1 <- expand t1
+ exp2 <- expand t2
+ return $ InstCoercion exp1 exp2
expapp (t@(Tcon (m,tc))) ts =
do env <- mlookupM tsenv_ tsenv eempty m
case elookup env tc of
- Just (formals,rhs) | (length formals) == (length ts) -> return (substl formals ts rhs)
+ Just (formals,rhs) | (length formals) == (length ts) ->
+ return (substl formals ts rhs)
_ -> return (foldl Tapp t ts)
expapp (Tapp t1 t2) ts =
do t2' <- expand t2
expapp t ts =
do t' <- expand t
return (foldl Tapp t' ts)
-
-mlookupM :: (Envs -> Env a b) -> Env a b -> Env a b -> Mname
+mlookupM :: (Eq a, Show a) => (Envs -> Env a b) -> Env a b -> Env a b -> Mname
-> CheckResult (Env a b)
mlookupM _ _ local_env Nothing = return local_env
-mlookupM selector external_env _ (Just m) = do
+mlookupM selector external_env local_env (Just m) = do
mn <- getMname
if m == mn
then return external_env
globalEnv <- getGlobalEnv
case elookup globalEnv m of
Just env' -> return (selector env')
- Nothing -> fail ("undefined module name: " ++ show m)
+ Nothing -> fail ("Check: undefined module name: "
+ ++ show m ++ show (edomain local_env))
-qlookupM :: (Ord a, Show a) => (Envs -> Env a b) -> Env a b -> Env a b
+qlookupM :: (Ord a, Show a,Show b) => (Envs -> Env a b) -> Env a b -> Env a b
-> Qual a -> CheckResult b
-qlookupM selector external_env local_env (m,k) =
+qlookupM selector external_env local_env (m,k) =
do env <- mlookupM selector external_env local_env m
- lookupM env k
-
+ lookupM env k
checkLit :: Lit -> CheckResult Ty
-checkLit lit =
+checkLit (Literal lit t) =
case lit of
- Lint _ t ->
- do {- require (elem t [tIntzh, {- tInt32zh,tInt64zh, -} tWordzh, {- tWord32zh,tWord64zh, -} tAddrzh, tCharzh])
- ("invalid int literal: " ++ show lit ++ "\n" ++ "type: " ++ show t) -}
+ Lint _ ->
+ do require (t `elem` intLitTypes)
+ ("invalid int literal: " ++ show lit ++ "\n" ++ "type: " ++ show t)
return t
- Lrational _ t ->
- do {- require (elem t [tFloatzh,tDoublezh])
- ("invalid rational literal: " ++ show lit ++ "\n" ++ "type: " ++ show t) -}
+ Lrational _ ->
+ do require (t `elem` ratLitTypes)
+ ("invalid rational literal: " ++ show lit ++ "\n" ++ "type: " ++ show t)
return t
- Lchar _ t ->
- do {- require (t == tCharzh)
- ("invalid char literal: " ++ show lit ++ "\n" ++ "type: " ++ show t) -}
+ Lchar _ ->
+ do require (t `elem` charLitTypes)
+ ("invalid char literal: " ++ show lit ++ "\n" ++ "type: " ++ show t)
return t
- Lstring _ t ->
- do {- require (t == tAddrzh)
- ("invalid string literal: " ++ show lit ++ "\n" ++ "type: " ++ show t) -}
+ Lstring _ ->
+ do require (t `elem` stringLitTypes)
+ ("invalid string literal: " ++ show lit ++ "\n" ++ "type: " ++ show t)
return t
{- Utilities -}
Tforall (t',k) (f ((t,Tvar t'):env) t1)
else
Tforall (t,k) (f (filter ((/=t).fst) env) t1)
+ TransCoercion t1 t2 -> TransCoercion (f env t1) (f env t2)
+ SymCoercion t1 -> SymCoercion (f env t1)
+ UnsafeCoercion t1 t2 -> UnsafeCoercion (f env t1) (f env t2)
+ LeftCoercion t1 -> LeftCoercion (f env t1)
+ RightCoercion t1 -> RightCoercion (f env t1)
+ InstCoercion t1 t2 -> InstCoercion (f env t1) (f env t2)
where free = foldr union [] (map (freeTvars.snd) env)
t' = freshTvar free
freeTvars :: Ty -> [Tvar]
freeTvars (Tcon _) = []
freeTvars (Tvar v) = [v]
-freeTvars (Tapp t1 t2) = (freeTvars t1) `union` (freeTvars t2)
+freeTvars (Tapp t1 t2) = freeTvars t1 `union` freeTvars t2
freeTvars (Tforall (t,_) t1) = delete t (freeTvars t1)
+freeTvars (TransCoercion t1 t2) = freeTvars t1 `union` freeTvars t2
+freeTvars (SymCoercion t) = freeTvars t
+freeTvars (UnsafeCoercion t1 t2) = freeTvars t1 `union` freeTvars t2
+freeTvars (LeftCoercion t) = freeTvars t
+freeTvars (RightCoercion t) = freeTvars t
+freeTvars (InstCoercion t1 t2) = freeTvars t1 `union` freeTvars t2
{- Return any tvar *not* in the argument list. -}
freshTvar :: [Tvar] -> Tvar
freshTvar tvs = maximum ("":tvs) ++ "x" -- one simple way!
+primCoercionError :: Show a => a -> b
+primCoercionError s = error $ "Bad coercion application: " ++ show s
+
-- todo
-reportError s = error $ ("Core parser error: checkExpr failed with " ++ s)
+reportError :: Show a => a -> String -> b
+reportError e s = error $ ("Core type error: checkExpr failed with "
+ ++ s ++ " and " ++ show e)
+
+warn :: String -> CheckResult ()
+warn s = (unsafePerformIO $ putStrLn ("WARNING: " ++ s)) `seq` return ()
\ No newline at end of file