{-# LANGUAGE CPP #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TupleSections #-} module Wingman.Machinery where import Control.Applicative (empty) import Control.Concurrent.Chan.Unagi.NoBlocking (newChan, writeChan, OutChan, tryRead, tryReadChan) import Control.Lens ((<>~)) import Control.Monad.Reader import Control.Monad.State.Class (gets, modify, MonadState) import Control.Monad.State.Strict (StateT (..), execStateT) import Control.Monad.Trans.Maybe import Data.Coerce import Data.Foldable import Data.Functor ((<&>)) import Data.Generics (everything, gcount, mkQ) import Data.Generics.Product (field') import Data.List (sortBy) import qualified Data.Map as M import Data.Maybe (mapMaybe, isNothing) import Data.Monoid (getSum) import Data.Ord (Down (..), comparing) import qualified Data.Set as S import Data.Traversable (for) import Development.IDE.Core.Compile (lookupName) import Development.IDE.GHC.Compat hiding (isTopLevel, empty) import Refinery.Future import Refinery.ProofState import Refinery.Tactic import Refinery.Tactic.Internal import System.Timeout (timeout) import Wingman.Context (getInstance) import Wingman.GHC (tryUnifyUnivarsButNotSkolems, updateSubst, tacticsGetDataCons, freshTyvars, tryUnifyUnivarsButNotSkolemsMany) import Wingman.Judgements import Wingman.Simplify (simplify) import Wingman.Types #if __GLASGOW_HASKELL__ < 900 import FunDeps (fd_eqs, improveFromInstEnv) import Pair (unPair) #else import GHC.Tc.Instance.FunDeps (fd_eqs, improveFromInstEnv) import GHC.Data.Pair (unPair) #endif substCTy :: TCvSubst -> CType -> CType substCTy subst = coerce . substTy subst . coerce getSubstForJudgement :: MonadState TacticState m => Judgement -> m TCvSubst getSubstForJudgement j = do -- NOTE(sandy): It's OK to use mempty here, because coercions _can_ give us -- substitutions for skolems. let coercions = j_coercion j unifier <- gets ts_unifier pure $ unionTCvSubst unifier coercions ------------------------------------------------------------------------------ -- | Produce a subgoal that must be solved before we can solve the original -- goal. newSubgoal :: Judgement -> Rule newSubgoal j = do ctx <- ask unifier <- getSubstForJudgement j subgoal $ normalizeJudgement ctx $ substJdg unifier $ unsetIsTopHole $ normalizeJudgement ctx j tacticToRule :: Judgement -> TacticsM () -> Rule tacticToRule jdg (TacticT tt) = RuleT $ execStateT tt jdg >>= flip Subgoal Axiom consumeChan :: OutChan (Maybe a) -> IO [a] consumeChan chan = do tryReadChan chan >>= tryRead >>= \case Nothing -> pure [] Just (Just a) -> (a:) <$> consumeChan chan Just Nothing -> pure [] ------------------------------------------------------------------------------ -- | Attempt to generate a term of the right type using in-scope bindings, and -- a given tactic. runTactic :: Int -- ^ Timeout -> Context -> Judgement -> TacticsM () -- ^ Tactic to use -> IO (Either [TacticError] RunTacticResults) runTactic duration ctx jdg t = do let skolems = S.fromList $ foldMap (tyCoVarsOfTypeWellScoped . unCType) $ (:) (jGoal jdg) $ fmap hi_type $ toList $ hyByName $ jHypothesis jdg tacticState = defaultTacticState { ts_skolems = skolems } let stream = hoistListT (flip runReaderT ctx . unExtractM) $ runStreamingTacticT t jdg tacticState (in_proofs, out_proofs) <- newChan (in_errs, out_errs) <- newChan timed_out <- fmap isNothing $ timeout duration $ consume stream $ \case Left err -> writeChan in_errs $ Just err Right proof -> writeChan in_proofs $ Just proof writeChan in_proofs Nothing solns <- consumeChan out_proofs let sorted = flip sortBy solns $ comparing $ \(Proof ext _ holes) -> Down $ scoreSolution ext jdg $ fmap snd holes case sorted of ((Proof syn _ subgoals) : _) -> pure $ Right $ RunTacticResults { rtr_trace = syn_trace syn , rtr_extract = simplify $ syn_val syn , rtr_subgoals = fmap snd subgoals , rtr_other_solns = reverse . fmap pf_extract $ sorted , rtr_jdg = jdg , rtr_ctx = ctx , rtr_timed_out = timed_out } _ -> fmap Left $ consumeChan out_errs tracePrim :: String -> Trace tracePrim = flip rose [] ------------------------------------------------------------------------------ -- | Mark that a tactic used the given string in its extract derivation. Mainly -- used for debugging the search when things go terribly wrong. tracing :: Functor m => String -> TacticT jdg (Synthesized ext) err s m a -> TacticT jdg (Synthesized ext) err s m a tracing s = mappingExtract (mapTrace $ rose s . pure) ------------------------------------------------------------------------------ -- | Mark that a tactic performed recursion. Doing so incurs a small penalty in -- the score. markRecursion :: Functor m => TacticT jdg (Synthesized ext) err s m a -> TacticT jdg (Synthesized ext) err s m a markRecursion = mappingExtract (field' @"syn_recursion_count" <>~ 1) ------------------------------------------------------------------------------ -- | Map a function over the extract created by a tactic. mappingExtract :: Functor m => (ext -> ext) -> TacticT jdg ext err s m a -> TacticT jdg ext err s m a mappingExtract f (TacticT m) = TacticT $ StateT $ \jdg -> mapExtract id f $ runStateT m jdg ------------------------------------------------------------------------------ -- | Given the results of running a tactic, score the solutions by -- desirability. -- -- NOTE: This function is completely unprincipled and was just hacked together -- to produce the right test results. scoreSolution :: Synthesized (LHsExpr GhcPs) -> Judgement -> [Judgement] -> ( Penalize Int -- number of holes , Reward Bool -- all bindings used , Penalize Int -- unused top-level bindings , Penalize Int -- number of introduced bindings , Reward Int -- number used bindings , Penalize Int -- number of recursive calls , Penalize Int -- size of extract ) scoreSolution ext goal holes = ( Penalize $ length holes , Reward $ S.null $ intro_vals S.\\ used_vals , Penalize $ S.size unused_top_vals , Penalize $ S.size intro_vals , Reward $ S.size used_vals + length used_user_vals , Penalize $ getSum $ syn_recursion_count ext , Penalize $ solutionSize $ syn_val ext ) where initial_scope = hyByName $ jEntireHypothesis goal intro_vals = M.keysSet $ hyByName $ syn_scoped ext used_vals = S.intersection intro_vals $ syn_used_vals ext used_user_vals = filter (isLocalHypothesis . hi_provenance) $ mapMaybe (flip M.lookup initial_scope) $ S.toList $ syn_used_vals ext top_vals = S.fromList . fmap hi_name . filter (isTopLevel . hi_provenance) . unHypothesis $ syn_scoped ext unused_top_vals = top_vals S.\\ used_vals ------------------------------------------------------------------------------ -- | Compute the number of 'LHsExpr' nodes; used as a rough metric for code -- size. solutionSize :: LHsExpr GhcPs -> Int solutionSize = everything (+) $ gcount $ mkQ False $ \case (_ :: LHsExpr GhcPs) -> True newtype Penalize a = Penalize a deriving (Eq, Ord, Show) via (Down a) newtype Reward a = Reward a deriving (Eq, Ord, Show) via a ------------------------------------------------------------------------------ -- | Generate a unique unification variable. newUnivar :: MonadState TacticState m => m Type newUnivar = do freshTyvars $ mkInfForAllTys [alphaTyVar] alphaTy ------------------------------------------------------------------------------ -- | Attempt to unify two types. unify :: CType -- ^ The goal type -> CType -- ^ The type we are trying unify the goal type with -> RuleM () unify goal inst = do skolems <- gets ts_skolems case tryUnifyUnivarsButNotSkolems skolems goal inst of Just subst -> modify $ updateSubst subst Nothing -> cut ------------------------------------------------------------------------------ -- | Get a substition out of a theta's fundeps learnFromFundeps :: ThetaType -> RuleM () learnFromFundeps theta = do inst_envs <- asks ctxInstEnvs skolems <- gets ts_skolems subst <- gets ts_unifier let theta' = substTheta subst theta fundeps = foldMap (foldMap fd_eqs . improveFromInstEnv inst_envs (\_ _ -> ())) theta' case tryUnifyUnivarsButNotSkolemsMany skolems $ fmap unPair fundeps of Just subst -> modify $ updateSubst subst Nothing -> cut cut :: RuleT jdg ext err s m a cut = RuleT Empty ------------------------------------------------------------------------------ -- | Attempt to unify two types. canUnify :: MonadState TacticState m => CType -- ^ The goal type -> CType -- ^ The type we are trying unify the goal type with -> m Bool canUnify goal inst = do skolems <- gets ts_skolems case tryUnifyUnivarsButNotSkolems skolems goal inst of Just _ -> pure True Nothing -> pure False ------------------------------------------------------------------------------ -- | Prefer the first tactic to the second, if the bool is true. Otherwise, just run the second tactic. -- -- This is useful when you have a clever pruning solution that isn't always -- applicable. attemptWhen :: TacticsM a -> TacticsM a -> Bool -> TacticsM a attemptWhen _ t2 False = t2 attemptWhen t1 t2 True = commit t1 t2 ------------------------------------------------------------------------------ -- | Run the given tactic iff the current hole contains no univars. Skolems and -- already decided univars are OK though. requireConcreteHole :: TacticsM a -> TacticsM a requireConcreteHole m = do jdg <- goal skolems <- gets ts_skolems let vars = S.fromList $ tyCoVarsOfTypeWellScoped $ unCType $ jGoal jdg case S.size $ vars S.\\ skolems of 0 -> m _ -> failure TooPolymorphic ------------------------------------------------------------------------------ -- | The 'try' that comes in refinery 0.3 causes unnecessary backtracking and -- balloons the search space. This thing just tries it, but doesn't backtrack -- if it fails. -- -- NOTE(sandy): But there's a bug! Or at least, something not understood here. -- Using this everywhere breaks te tests, and neither I nor TOTBWF are sure -- why. Prefer 'try' if you can, and only try this as a last resort. -- -- TODO(sandy): Remove this when we upgrade to 0.4 try' :: Functor m => TacticT jdg ext err s m () -> TacticT jdg ext err s m () try' t = commit t $ pure () ------------------------------------------------------------------------------ -- | Sorry leaves a hole in its extract exact :: HsExpr GhcPs -> TacticsM () exact = rule . const . pure . pure . noLoc ------------------------------------------------------------------------------ -- | Lift a function over 'HyInfo's to one that takes an 'OccName' and tries to -- look it up in the hypothesis. useNameFromHypothesis :: (HyInfo CType -> TacticsM a) -> OccName -> TacticsM a useNameFromHypothesis f name = do hy <- jHypothesis <$> goal case M.lookup name $ hyByName hy of Just hi -> f hi Nothing -> failure $ NotInScope name ------------------------------------------------------------------------------ -- | Lift a function over 'HyInfo's to one that takes an 'OccName' and tries to -- look it up in the hypothesis. useNameFromContext :: (HyInfo CType -> TacticsM a) -> OccName -> TacticsM a useNameFromContext f name = do lookupNameInContext name >>= \case Just ty -> f $ createImportedHyInfo name ty Nothing -> failure $ NotInScope name ------------------------------------------------------------------------------ -- | Find the type of an 'OccName' that is defined in the current module. lookupNameInContext :: MonadReader Context m => OccName -> m (Maybe CType) lookupNameInContext name = do ctx <- asks ctxModuleFuncs pure $ case find ((== name) . fst) ctx of Just (_, ty) -> pure ty Nothing -> empty getDefiningType :: TacticsM CType getDefiningType = do calling_fun_name <- asks (fst . head . ctxDefiningFuncs) maybe (failure $ NotInScope calling_fun_name) pure =<< lookupNameInContext calling_fun_name ------------------------------------------------------------------------------ -- | Build a 'HyInfo' for an imported term. createImportedHyInfo :: OccName -> CType -> HyInfo CType createImportedHyInfo on ty = HyInfo { hi_name = on , hi_provenance = ImportPrv , hi_type = ty } getTyThing :: OccName -> TacticsM (Maybe TyThing) getTyThing occ = do ctx <- ask case lookupOccEnv (ctx_occEnv ctx) occ of Just (elt : _) -> do mvar <- lift $ ExtractM $ lift $ lookupName (ctx_hscEnv ctx) (ctx_module ctx) $ gre_name elt pure mvar _ -> pure Nothing ------------------------------------------------------------------------------ -- | Like 'getTyThing' but specialized to classes. knownClass :: OccName -> TacticsM (Maybe Class) knownClass occ = getTyThing occ <&> \case Just (ATyCon tc) -> tyConClass_maybe tc _ -> Nothing ------------------------------------------------------------------------------ -- | Like 'getInstance', but uses a class that it just looked up. getKnownInstance :: OccName -> [Type] -> TacticsM (Maybe (Class, PredType)) getKnownInstance f tys = runMaybeT $ do cls <- MaybeT $ knownClass f MaybeT $ getInstance cls tys ------------------------------------------------------------------------------ -- | Lookup the type of any 'OccName' that was imported. Necessarily done in -- IO, so we only expose this functionality to the parser. Internal Haskell -- code that wants to lookup terms should do it via 'KnownThings'. getOccNameType :: OccName -> TacticsM Type getOccNameType occ = do getTyThing occ >>= \case Just (AnId v) -> pure $ varType v _ -> failure $ NotInScope occ getCurrentDefinitions :: TacticsM [(OccName, CType)] getCurrentDefinitions = do ctx_funcs <- asks ctxDefiningFuncs for ctx_funcs $ \res@(occ, _) -> pure . maybe res (occ,) =<< lookupNameInContext occ ------------------------------------------------------------------------------ -- | Given two types, see if we can construct a homomorphism by mapping every -- data constructor in the domain to the same in the codomain. This function -- returns 'Just' when all the lookups succeeded, and a non-empty value if the -- homomorphism *is not* possible. uncoveredDataCons :: Type -> Type -> Maybe (S.Set (Uniquely DataCon)) uncoveredDataCons domain codomain = do (g_dcs, _) <- tacticsGetDataCons codomain (hi_dcs, _) <- tacticsGetDataCons domain pure $ S.fromList (coerce hi_dcs) S.\\ S.fromList (coerce g_dcs)