-- | -- Module : $Header$ -- Copyright : (c) 2013-2016 Galois, Inc. -- License : BSD3 -- Maintainer : cryptol@galois.com -- Stability : provisional -- Portability : portable {-# LANGUAGE Safe #-} {-# LANGUAGE DeriveAnyClass #-} {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE RecordWildCards #-} {-# LANGUAGE RecursiveDo #-} module Cryptol.TypeCheck.Monad ( module Cryptol.TypeCheck.Monad , module Cryptol.TypeCheck.InferTypes ) where import Cryptol.ModuleSystem.Name (FreshM(..),Supply) import Cryptol.Parser.Position import qualified Cryptol.Parser.AST as P import Cryptol.TypeCheck.AST import Cryptol.TypeCheck.Subst import Cryptol.TypeCheck.Unify(mgu, Result(..), UnificationError(..)) import Cryptol.TypeCheck.InferTypes import qualified Cryptol.TypeCheck.Solver.CrySAT as CrySAT import Cryptol.Utils.PP(pp, (<+>), Doc, text, quotes) import Cryptol.Utils.Panic(panic) import qualified Control.Applicative as A import Control.Monad.Fix(MonadFix(..)) import qualified Data.Map as Map import qualified Data.Set as Set import Data.Map (Map) import Data.Set (Set) import Data.List(find, minimumBy, groupBy, sortBy) import Data.Maybe(mapMaybe) import Data.Function(on) import MonadLib hiding (mapM) import GHC.Generics (Generic) import Control.DeepSeq import Prelude () import Prelude.Compat -- | Information needed for type inference. data InferInput = InferInput { inpRange :: Range -- ^ Location of program source , inpVars :: Map Name Schema -- ^ Variables that are in scope , inpTSyns :: Map Name TySyn -- ^ Type synonyms that are in scope , inpNewtypes :: Map Name Newtype -- ^ Newtypes in scope , inpNameSeeds :: NameSeeds -- ^ Private state of type-checker , inpMonoBinds :: Bool -- ^ Should local bindings without -- signatures be monomorphized? , inpSolverConfig :: SolverConfig -- ^ Options for the constraint solver , inpPrimNames :: !PrimMap -- ^ The mapping from 'Ident' to 'Name', -- for names that the typechecker -- needs to refer to. , inpSupply :: !Supply -- ^ The supply for fresh name generation } deriving Show -- | This is used for generating various names. data NameSeeds = NameSeeds { seedTVar :: !Int , seedGoal :: !Int } deriving (Show, Generic, NFData) -- | The initial seeds, used when checking a fresh program. nameSeeds :: NameSeeds nameSeeds = NameSeeds { seedTVar = 10, seedGoal = 0 } -- | The results of type inference. data InferOutput a = InferFailed [(Range,Warning)] [(Range,Error)] -- ^ We found some errors | InferOK [(Range,Warning)] NameSeeds Supply a -- ^ Type inference was successful. deriving Show runInferM :: TVars a => InferInput -> InferM a -> IO (InferOutput a) runInferM info (IM m) = CrySAT.withSolver (inpSolverConfig info) $ \solver -> do rec ro <- return RO { iRange = inpRange info , iVars = Map.map ExtVar (inpVars info) , iTVars = [] , iTSyns = fmap mkExternal (inpTSyns info) , iNewtypes = fmap mkExternal (inpNewtypes info) , iSolvedHasLazy = iSolvedHas finalRW -- RECURSION , iMonoBinds = inpMonoBinds info , iSolver = solver , iPrimNames = inpPrimNames info } (result, finalRW) <- runStateT rw $ runReaderT ro m -- RECURSION let theSu = iSubst finalRW defSu = defaultingSubst theSu warns = [(r,apSubst theSu w) | (r,w) <- iWarnings finalRW ] case iErrors finalRW of [] -> case (iCts finalRW, iHasCts finalRW) of (cts,[]) | nullGoals cts -> return $ InferOK warns (iNameSeeds finalRW) (iSupply finalRW) (apSubst defSu result) (cts,has) -> return $ InferFailed warns $ dropErrorsFromSameLoc [ ( goalRange g , UnsolvedGoal False (apSubst theSu g) ) | g <- fromGoals cts ++ map hasGoal has ] errs -> return $ InferFailed warns $ dropErrorsFromSameLoc [(r,apSubst theSu e) | (r,e) <- errs] where mkExternal x = (IsExternal, x) rw = RW { iErrors = [] , iWarnings = [] , iSubst = emptySubst , iExistTVars = [] , iNameSeeds = inpNameSeeds info , iCts = emptyGoals , iHasCts = [] , iSolvedHas = Map.empty , iSupply = inpSupply info } dropErrorsFromSameLoc = map chooseBestError . groupBy ((==) `on` fst) . sortBy (cmpRange `on` fst) addErrorSize (r,e) = (length (show (pp e)), (r,e)) chooseBestError = snd . minimumBy (compare `on` fst) . map addErrorSize -- The actual order does not matter cmpRange (Range x y z) (Range a b c) = compare (x,y,z) (a,b,c) newtype InferM a = IM { unIM :: ReaderT RO (StateT RW IO) a } data DefLoc = IsLocal | IsExternal -- | Read-only component of the monad. data RO = RO { iRange :: Range -- ^ Source code being analysed , iVars :: Map Name VarType -- ^ Type of variable that are in scope {- NOTE: We assume no shadowing between these two, so it does not matter where we look first. Similarly, we assume no shadowing with the existential type variable (in RW). See `checkTShadowing`. -} , iTVars :: [TParam] -- ^ Type variable that are in scope , iTSyns :: Map Name (DefLoc, TySyn) -- ^ Type synonyms that are in scope , iNewtypes :: Map Name (DefLoc, Newtype) -- ^ Newtype declarations in scope -- -- NOTE: type synonyms take precedence over newtype. The reason is -- that we can define local type synonyms, but not local newtypes. -- So, either a type-synonym shadows a newtype, or it was declared -- at the top-level, but then there can't be a newtype with the -- same name (this should be caught by the renamer). , iSolvedHasLazy :: Map Int (Expr -> Expr) -- ^ NOTE: This field is lazy in an important way! It is the -- final version of `iSolvedHas` in `RW`, and the two are tied -- together through recursion. The field is here so that we can -- look thing up before they are defined, which is OK because we -- don't need to know the results until everything is done. , iMonoBinds :: Bool -- ^ When this flag is set to true, bindings that lack signatures -- in where-blocks will never be generalized. Bindings with type -- signatures, and all bindings at top level are unaffected. , iSolver :: CrySAT.Solver , iPrimNames :: !PrimMap } -- | Read-write component of the monad. data RW = RW { iErrors :: ![(Range,Error)] -- ^ Collected errors , iWarnings :: ![(Range,Warning)] -- ^ Collected warnings , iSubst :: !Subst -- ^ Accumulated substitution , iExistTVars :: [Map Name Type] -- ^ These keeps track of what existential type variables are available. -- When we start checking a function, we push a new scope for -- its arguments, and we pop it when we are done checking the function -- body. The front element of the list is the current scope, which is -- the only thing that will be modified, as follows. When we encounter -- a existential type variable: -- 1. we look in all scopes to see if it is already defined. -- 2. if it was not defined, we create a fresh type variable, -- and we add it to the current scope. -- 3. it is an error if we encounter an existential variable but we -- have no current scope. , iSolvedHas :: Map Int (Expr -> Expr) -- ^ Selector constraints that have been solved (ref. iSolvedSelectorsLazy) -- Generating names , iNameSeeds :: !NameSeeds -- Constraints that need solving , iCts :: !Goals -- ^ Ordinary constraints , iHasCts :: ![HasGoal] {- ^ Tuple/record projection constraints. The `Int` is the "name" of the constraint, used so that we can name it solution properly. -} , iSupply :: !Supply } instance Functor InferM where fmap f (IM m) = IM (fmap f m) instance A.Applicative InferM where pure = return (<*>) = ap instance Monad InferM where return x = IM (return x) fail x = IM (fail x) IM m >>= f = IM (m >>= unIM . f) instance MonadFix InferM where mfix f = IM (mfix (unIM . f)) instance FreshM InferM where liftSupply f = IM $ do rw <- get let (a,s') = f (iSupply rw) set rw { iSupply = s' } return a io :: IO a -> InferM a io m = IM $ inBase m -- | The monadic computation is about the given range of source code. -- This is useful for error reporting. inRange :: Range -> InferM a -> InferM a inRange r (IM m) = IM $ mapReader (\ro -> ro { iRange = r }) m inRangeMb :: Maybe Range -> InferM a -> InferM a inRangeMb Nothing m = m inRangeMb (Just r) m = inRange r m -- | This is the current range that we are working on. curRange :: InferM Range curRange = IM $ asks iRange -- | Report an error. recordError :: Error -> InferM () recordError e = do r <- curRange IM $ sets_ $ \s -> s { iErrors = (r,e) : iErrors s } recordWarning :: Warning -> InferM () recordWarning w = do r <- curRange IM $ sets_ $ \s -> s { iWarnings = (r,w) : iWarnings s } getSolver :: InferM CrySAT.Solver getSolver = do RO { .. } <- IM ask return iSolver -- | Retrieve the mapping between identifiers and declarations in the prelude. getPrimMap :: InferM PrimMap getPrimMap = do RO { .. } <- IM ask return iPrimNames -------------------------------------------------------------------------------- newGoal :: ConstraintSource -> Prop -> InferM Goal newGoal goalSource goal = do goalRange <- curRange return Goal { .. } -- | Record some constraints that need to be solved. -- The string explains where the constraints came from. newGoals :: ConstraintSource -> [Prop] -> InferM () newGoals src ps = addGoals =<< mapM (newGoal src) ps {- | The constraints are removed, and returned to the caller. The substitution IS applied to them. -} getGoals :: InferM [Goal] getGoals = do goals <- applySubst =<< IM (sets $ \s -> (iCts s, s { iCts = emptyGoals })) return (fromGoals goals) -- | Add a bunch of goals that need solving. addGoals :: [Goal] -> InferM () addGoals gs = IM $ sets_ $ \s -> s { iCts = foldl (flip insertGoal) (iCts s) gs } -- | Collect the goals emitted by the given sub-computation. -- Does not emit any new goals. collectGoals :: InferM a -> InferM (a, [Goal]) collectGoals m = do origGs <- applySubst =<< getGoals' a <- m newGs <- getGoals setGoals' origGs return (a, newGs) where -- retrieve the type map only getGoals' = IM $ sets $ \ RW { .. } -> (iCts, RW { iCts = emptyGoals, .. }) -- set the type map directly setGoals' gs = IM $ sets $ \ RW { .. } -> ((), RW { iCts = gs, .. }) {- | Record a constraint that when we select from the first type, we should get a value of the second type. The returned function should be used to wrap the expression from which we are selecting (i.e., the record or tuple). Plese note that the resulting expression should not be forced before the constraint is solved. -} newHasGoal :: P.Selector -> Type -> Type -> InferM (Expr -> Expr) newHasGoal l ty f = do goalName <- newGoalName g <- newGoal CtSelector (pHas l ty f) IM $ sets_ $ \s -> s { iHasCts = HasGoal goalName g : iHasCts s } solns <- IM $ fmap iSolvedHasLazy ask return $ case Map.lookup goalName solns of Just e1 -> e1 Nothing -> panic "newHasGoal" ["Unsolved has goal in result"] -- | Add a previously generate has constrained addHasGoal :: HasGoal -> InferM () addHasGoal g = IM $ sets_ $ \s -> s { iHasCts = g : iHasCts s } -- | Get the `Has` constraints. Each of this should either be solved, -- or added back using `addHasGoal`. getHasGoals :: InferM [HasGoal] getHasGoals = do gs <- IM $ sets $ \s -> (iHasCts s, s { iHasCts = [] }) applySubst gs -- | Specify the solution (`Expr -> Expr`) for the given constraint (`Int`). solveHasGoal :: Int -> (Expr -> Expr) -> InferM () solveHasGoal n e = IM $ sets_ $ \s -> s { iSolvedHas = Map.insert n e (iSolvedHas s) } -------------------------------------------------------------------------------- newName :: (NameSeeds -> (a , NameSeeds)) -> InferM a newName upd = IM $ sets $ \s -> let (x,seeds) = upd (iNameSeeds s) in (x, s { iNameSeeds = seeds }) -- | Generate a new name for a goal. newGoalName :: InferM Int newGoalName = newName $ \s -> let x = seedGoal s in (x, s { seedGoal = x + 1}) -- | Generate a new free type variable. newTVar :: Doc -> Kind -> InferM TVar newTVar src k = newTVar' src Set.empty k -- | Generate a new free type variable that depends on these additional -- type parameters. newTVar' :: Doc -> Set TVar -> Kind -> InferM TVar newTVar' src extraBound k = do bound <- getBoundInScope let vs = Set.union extraBound bound newName $ \s -> let x = seedTVar s in (TVFree x k vs src, s { seedTVar = x + 1 }) -- | Generate a new free type variable. newTParam :: Maybe Name -> Kind -> InferM TParam newTParam nm k = newName $ \s -> let x = seedTVar s in (TParam { tpUnique = x , tpKind = k , tpName = nm } , s { seedTVar = x + 1 }) -- | Generate an unknown type. The doc is a note about what is this type about. newType :: Doc -> Kind -> InferM Type newType src k = TVar `fmap` newTVar src k -------------------------------------------------------------------------------- -- | Record that the two types should be syntactically equal. unify :: Type -> Type -> InferM [Prop] unify t1 t2 = do t1' <- applySubst t1 t2' <- applySubst t2 case mgu t1' t2' of OK (su1,ps) -> extendSubst su1 >> return ps Error err -> do case err of UniTypeLenMismatch _ _ -> recordError (TypeMismatch t1' t2') UniTypeMismatch s1 s2 -> recordError (TypeMismatch s1 s2) UniKindMismatch k1 k2 -> recordError (KindMismatch k1 k2) UniRecursive x t -> recordError (RecursiveType (TVar x) t) UniNonPolyDepends x vs -> recordError (TypeVariableEscaped (TVar x) vs) UniNonPoly x t -> recordError (NotForAll x t) return [] -- | Apply the accumulated substitution to something with free type variables. applySubst :: TVars t => t -> InferM t applySubst t = do su <- getSubst return (apSubst su t) -- | Get the substitution that we have accumulated so far. getSubst :: InferM Subst getSubst = IM $ fmap iSubst get -- | Add to the accumulated substitution. extendSubst :: Subst -> InferM () extendSubst su = IM $ sets_ $ \s -> s { iSubst = su @@ iSubst s } -- | Variables that are either mentioned in the environment or in -- a selector constraint. varsWithAsmps :: InferM (Set TVar) varsWithAsmps = do env <- IM $ fmap (Map.elems . iVars) ask fromEnv <- forM env $ \v -> case v of ExtVar sch -> getVars sch CurSCC _ t -> getVars t sels <- IM $ fmap (map (goal . hasGoal) . iHasCts) get fromSels <- mapM getVars sels fromEx <- (getVars . concatMap Map.elems) =<< IM (fmap iExistTVars get) return (Set.unions fromEnv `Set.union` Set.unions fromSels `Set.union` fromEx) where getVars x = fvs `fmap` applySubst x -------------------------------------------------------------------------------- -- | Lookup the type of a variable. lookupVar :: Name -> InferM VarType lookupVar x = do mb <- IM $ asks $ Map.lookup x . iVars case mb of Just t -> return t Nothing -> do mbNT <- lookupNewtype x case mbNT of Just nt -> return (ExtVar (newtypeConType nt)) Nothing -> do recordError $ UndefinedVariable x a <- newType (text "type of" <+> pp x) KType return $ ExtVar $ Forall [] [] a -- | Lookup a type variable. Return `Nothing` if there is no such variable -- in scope, in which case we must be dealing with a type constant. lookupTVar :: Name -> InferM (Maybe Type) lookupTVar x = IM $ asks $ fmap (TVar . tpVar) . find this . iTVars where this tp = tpName tp == Just x -- | Lookup the definition of a type synonym. lookupTSyn :: Name -> InferM (Maybe TySyn) lookupTSyn x = fmap (fmap snd . Map.lookup x) getTSyns -- | Lookup the definition of a newtype lookupNewtype :: Name -> InferM (Maybe Newtype) lookupNewtype x = fmap (fmap snd . Map.lookup x) getNewtypes -- | Check if we already have a name for this existential type variable and, -- if so, return the definition. If not, try to create a new definition, -- if this is allowed. If not, returns nothing. existVar :: Name -> Kind -> InferM Type existVar x k = do scopes <- iExistTVars <$> IM get case msum (map (Map.lookup x) scopes) of Just ty -> return ty Nothing -> case scopes of [] -> do recordError $ ErrorMsg $ text "Undefined type" <+> quotes (pp x) newType (text "undefined existential type varible" <+> quotes (pp x)) k sc : more -> do ty <- newType (text "existential type variable" <+> quotes (pp x)) k IM $ sets_ $ \s -> s{ iExistTVars = Map.insert x ty sc : more } return ty -- | Returns the type synonyms that are currently in scope. getTSyns :: InferM (Map Name (DefLoc,TySyn)) getTSyns = IM $ asks iTSyns -- | Returns the newtype declarations that are in scope. getNewtypes :: InferM (Map Name (DefLoc,Newtype)) getNewtypes = IM $ asks iNewtypes -- | Get the set of bound type variables that are in scope. getTVars :: InferM (Set Name) getTVars = IM $ asks $ Set.fromList . mapMaybe tpName . iTVars -- | Return the keys of the bound variables that are in scope. getBoundInScope :: InferM (Set TVar) getBoundInScope = IM $ asks $ Set.fromList . map tpVar . iTVars -- | Retrieve the value of the `mono-binds` option. getMonoBinds :: InferM Bool getMonoBinds = IM (asks iMonoBinds) {- | We disallow shadowing between type synonyms and type variables because it is confusing. As a bonus, in the implementation we don't need to worry about where we lookup things (i.e., in the variable or type synonym environment. -} checkTShadowing :: String -> Name -> InferM () checkTShadowing this new = do ro <- IM ask rw <- IM get let shadowed = do _ <- Map.lookup new (iTSyns ro) return "type synonym" `mplus` do guard (new `elem` mapMaybe tpName (iTVars ro)) return "type variable" `mplus` do _ <- msum (map (Map.lookup new) (iExistTVars rw)) return "type" case shadowed of Nothing -> return () Just that -> recordError $ ErrorMsg $ text "Type" <+> text this <+> quotes (pp new) <+> text "shadows an existing" <+> text that <+> text "with the same name." -- | The sub-computation is performed with the given type parameter in scope. withTParam :: TParam -> InferM a -> InferM a withTParam p (IM m) = do case tpName p of Just x -> checkTShadowing "variable" x Nothing -> return () IM $ mapReader (\r -> r { iTVars = p : iTVars r }) m withTParams :: [TParam] -> InferM a -> InferM a withTParams ps m = foldr withTParam m ps -- | The sub-computation is performed with the given type-synonym in scope. withTySyn :: TySyn -> InferM a -> InferM a withTySyn t (IM m) = do let x = tsName t checkTShadowing "synonym" x IM $ mapReader (\r -> r { iTSyns = Map.insert x (IsLocal,t) (iTSyns r) }) m withNewtype :: Newtype -> InferM a -> InferM a withNewtype t (IM m) = IM $ mapReader (\r -> r { iNewtypes = Map.insert (ntName t) (IsLocal,t) (iNewtypes r) }) m -- | The sub-computation is performed with the given variable in scope. withVarType :: Name -> VarType -> InferM a -> InferM a withVarType x s (IM m) = IM $ mapReader (\r -> r { iVars = Map.insert x s (iVars r) }) m withVarTypes :: [(Name,VarType)] -> InferM a -> InferM a withVarTypes xs m = foldr (uncurry withVarType) m xs withVar :: Name -> Schema -> InferM a -> InferM a withVar x s = withVarType x (ExtVar s) -- | The sub-computation is performed with the given variables in scope. withMonoType :: (Name,Located Type) -> InferM a -> InferM a withMonoType (x,lt) = withVar x (Forall [] [] (thing lt)) -- | The sub-computation is performed with the given variables in scope. withMonoTypes :: Map Name (Located Type) -> InferM a -> InferM a withMonoTypes xs m = foldr withMonoType m (Map.toList xs) -- | The sub-computation is performed with the given type synonyms -- and variables in scope. withDecls :: ([TySyn], Map Name Schema) -> InferM a -> InferM a withDecls (ts,vs) m = foldr withTySyn (foldr add m (Map.toList vs)) ts where add (x,t) = withVar x t -- | Perform the given computation in a new scope (i.e., the subcomputation -- may use existential type variables). inNewScope :: InferM a -> InferM a inNewScope m = do curScopes <- iExistTVars <$> IM get IM $ sets_ $ \s -> s { iExistTVars = Map.empty : curScopes } a <- m IM $ sets_ $ \s -> s { iExistTVars = curScopes } return a -------------------------------------------------------------------------------- -- Kind checking newtype KindM a = KM { unKM :: ReaderT KRO (StateT KRW InferM) a } data KRO = KRO { lazyTVars :: Map Name Type -- ^ lazy map, with tyvars. , allowWild :: Bool -- ^ are type-wild cards allowed? } data KRW = KRW { typeParams :: Map Name Kind -- ^ kinds of (known) vars. } instance Functor KindM where fmap f (KM m) = KM (fmap f m) instance A.Applicative KindM where pure = return (<*>) = ap instance Monad KindM where return x = KM (return x) fail x = KM (fail x) KM m >>= k = KM (m >>= unKM . k) {- | The arguments to this function are as follows: (type param. name, kind signature (opt.), a type representing the param) The type representing the parameter is just a thunk that we should not force. The reason is that the type depnds on the kind of parameter, that we are in the process of computing. As a result we return the value of the sub-computation and the computed kinds of the type parameters. -} runKindM :: Bool -- Are type-wild cards allowed? -> [(Name, Maybe Kind, Type)] -- ^ See comment -> KindM a -> InferM (a, Map Name Kind) runKindM wildOK vs (KM m) = do (a,kw) <- runStateT krw (runReaderT kro m) return (a, typeParams kw) where tys = Map.fromList [ (x,t) | (x,_,t) <- vs ] kro = KRO { allowWild = wildOK, lazyTVars = tys } krw = KRW { typeParams = Map.fromList [ (x,k) | (x,Just k,_) <- vs ] } -- | This is what's returned when we lookup variables during kind checking. data LkpTyVar = TLocalVar Type (Maybe Kind) -- ^ Locally bound variable. | TOuterVar Type -- ^ An outer binding. -- | Check if a name refers to a type variable. kLookupTyVar :: Name -> KindM (Maybe LkpTyVar) kLookupTyVar x = KM $ do vs <- lazyTVars `fmap` ask ss <- get case Map.lookup x vs of Just t -> return $ Just $ TLocalVar t $ Map.lookup x $ typeParams ss Nothing -> lift $ lift $ do t <- lookupTVar x return (fmap TOuterVar t) -- | Are type wild-cards OK in this context? kWildOK :: KindM Bool kWildOK = KM $ fmap allowWild ask -- | Reports an error. kRecordError :: Error -> KindM () kRecordError e = kInInferM $ recordError e kRecordWarning :: Warning -> KindM () kRecordWarning w = kInInferM $ recordWarning w -- | Generate a fresh unification variable of the given kind. kNewType :: Doc -> Kind -> KindM Type kNewType src k = do tps <- KM $ do vs <- asks lazyTVars return $ Set.fromList [ tv | TVar tv <- Map.elems vs ] kInInferM $ TVar `fmap` newTVar' src tps k -- | Lookup the definition of a type synonym. kLookupTSyn :: Name -> KindM (Maybe TySyn) kLookupTSyn x = kInInferM $ lookupTSyn x -- | Lookup the definition of a newtype. kLookupNewtype :: Name -> KindM (Maybe Newtype) kLookupNewtype x = kInInferM $ lookupNewtype x kExistTVar :: Name -> Kind -> KindM Type kExistTVar x k = kInInferM $ existVar x k -- | Replace the given bound variables with concrete types. kInstantiateT :: Type -> [(TParam,Type)] -> KindM Type kInstantiateT t as = return (apSubst su t) where su = listSubst [ (tpVar x, t1) | (x,t1) <- as ] {- | Record the kind for a local type variable. This assumes that we already checked that there was no other valid kind for the variable (if there was one, it gets over-written). -} kSetKind :: Name -> Kind -> KindM () kSetKind v k = KM $ sets_ $ \s -> s{ typeParams = Map.insert v k (typeParams s)} -- | The sub-computation is about the given range of the source code. kInRange :: Range -> KindM a -> KindM a kInRange r (KM m) = KM $ do e <- ask s <- get (a,s1) <- lift $ lift $ inRange r $ runStateT s $ runReaderT e m set s1 return a kNewGoals :: ConstraintSource -> [Prop] -> KindM () kNewGoals c ps = kInInferM $ newGoals c ps kInInferM :: InferM a -> KindM a kInInferM m = KM $ lift $ lift m