{-# OPTIONS_GHC -fno-warn-unused-top-binds #-} {-| Module : Gargantext.API.Ngrams Description : Server API Copyright : (c) CNRS, 2017-Present License : AGPL + CECILL v3 Maintainer : team@gargantext.org Stability : experimental Portability : POSIX Ngrams API -- | TODO get ngrams filtered by NgramsType add get -} {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TemplateHaskell #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE TypeFamilies #-} module Gargantext.API.Ngrams ( TableNgramsApi , TableNgramsApiGet , TableNgramsApiPut , getTableNgrams , setListNgrams --, rmListNgrams TODO fix before exporting , apiNgramsTableCorpus , apiNgramsTableDoc , NgramsStatePatch , NgramsTablePatch , NgramsTableMap , NgramsTerm(..) , NgramsElement(..) , mkNgramsElement , RootParent(..) , MSet , mSetFromList , mSetToList , Repo(..) , r_version , r_state , r_history , NgramsRepo , NgramsRepoElement(..) , saveRepo , initRepo , RepoEnv(..) , renv_var , renv_lock , TabType(..) , HasRepoVar(..) , HasRepoSaver(..) , HasRepo(..) , RepoCmdM , QueryParamR , TODO -- Internals , getNgramsTableMap , dumpJsonTableMap , tableNgramsPull , tableNgramsPut , Version , Versioned(..) , currentVersion , listNgramsChangedSince ) where import Control.Concurrent import Control.Lens ((.~), view, (^.), (^..), (+~), (%~), (.~), sumOf, at, _Just, Each(..), (%%~), mapped) import Control.Monad.Reader import Data.Aeson hiding ((.=)) import qualified Data.Aeson.Text as DAT import Data.Either (Either(..)) import Data.Foldable import qualified Data.List as List import Data.Map.Strict (Map) import qualified Data.Map.Strict as Map import qualified Data.Map.Strict.Patch as PM import Data.Maybe (fromMaybe) import Data.Monoid import Data.Ord (Down(..)) import Data.Patch.Class (Action(act), Transformable(..), ours) import qualified Data.Set as S import qualified Data.Set as Set import Data.Swagger hiding (version, patch) import Data.Text (Text, isInfixOf, unpack) import Data.Text.Lazy.IO as DTL import Formatting (hprint, int, (%)) import Formatting.Clock (timeSpecs) import GHC.Generics (Generic) import Servant hiding (Patch) import System.Clock (getTime, TimeSpec, Clock(..)) import System.IO (stderr) import Test.QuickCheck (elements) import Test.QuickCheck.Arbitrary (Arbitrary, arbitrary) import Prelude (error) import Gargantext.Prelude import Gargantext.API.Admin.Types (HasSettings) -- import qualified Gargantext.API.Metrics as Metrics import Gargantext.API.Ngrams.Types import Gargantext.Core.Types (ListType(..), NodeId, ListId, DocId, Limit, Offset, HasInvalidError, TODO, assertValid) import Gargantext.Core.Utils (something) -- import Gargantext.Core.Viz.Graph.API (recomputeGraph) -- import Gargantext.Core.Viz.Graph.Distances (Distance(Conditional)) import Gargantext.Database.Action.Metrics.NgramsByNode (getOccByNgramsOnlyFast') import Gargantext.Database.Query.Table.Node.Select import Gargantext.Database.Query.Table.Ngrams hiding (NgramsType(..), ngrams, ngramsType, ngrams_terms) import Gargantext.Database.Admin.Config (userMaster) import Gargantext.Database.Query.Table.Node.Error (HasNodeError) import Gargantext.Database.Admin.Types.Node (NodeType(..)) import Gargantext.Database.Prelude (HasConnectionPool, HasConfig) import qualified Gargantext.Database.Query.Table.Ngrams as TableNgrams -- import Gargantext.Database.Query.Table.Node (getNode) -- import Gargantext.Database.Schema.Node (NodePoly(..)) {- -- TODO sequences of modifications (Patchs) type NgramsIdPatch = Patch NgramsId NgramsPatch ngramsPatch :: Int -> NgramsPatch ngramsPatch n = NgramsPatch (DM.fromList [(1, StopTerm)]) (Set.fromList [n]) Set.empty toEdit :: NgramsId -> NgramsPatch -> Edit NgramsId NgramsPatch toEdit n p = Edit n p ngramsIdPatch :: Patch NgramsId NgramsPatch ngramsIdPatch = fromList $ catMaybes $ reverse [ replace (1::NgramsId) (Just $ ngramsPatch 1) Nothing , replace (1::NgramsId) Nothing (Just $ ngramsPatch 2) , replace (2::NgramsId) Nothing (Just $ ngramsPatch 2) ] -- applyPatchBack :: Patch -> IO Patch -- isEmptyPatch = Map.all (\x -> Set.isEmpty (add_children x) && Set.isEmpty ... ) -} ------------------------------------------------------------------------ ------------------------------------------------------------------------ ------------------------------------------------------------------------ {- -- TODO: Replace.old is ignored which means that if the current list -- `MapTerm` and that the patch is `Replace CandidateTerm StopTerm` then -- the list is going to be `StopTerm` while it should keep `MapTerm`. -- However this should not happen in non conflicting situations. mkListsUpdate :: NgramsType -> NgramsTablePatch -> [(NgramsTypeId, NgramsTerm, ListTypeId)] mkListsUpdate nt patches = [ (ngramsTypeId nt, ng, listTypeId lt) | (ng, patch) <- patches ^.. ntp_ngrams_patches . ifolded . withIndex , lt <- patch ^.. patch_list . new ] mkChildrenGroups :: (PatchSet NgramsTerm -> Set NgramsTerm) -> NgramsType -> NgramsTablePatch -> [(NgramsTypeId, NgramsParent, NgramsChild)] mkChildrenGroups addOrRem nt patches = [ (ngramsTypeId nt, parent, child) | (parent, patch) <- patches ^.. ntp_ngrams_patches . ifolded . withIndex , child <- patch ^.. patch_children . to addOrRem . folded ] -} ------------------------------------------------------------------------ saveRepo :: ( MonadReader env m, MonadBase IO m, HasRepoSaver env ) => m () saveRepo = liftBase =<< view repoSaver listTypeConflictResolution :: ListType -> ListType -> ListType listTypeConflictResolution _ _ = undefined -- TODO Use Map User ListType ngramsStatePatchConflictResolution :: TableNgrams.NgramsType -> NodeId -> NgramsTerm -> ConflictResolutionNgramsPatch ngramsStatePatchConflictResolution _ngramsType _nodeId _ngramsTerm = (ours, (const ours, ours), (False, False)) -- (False, False) mean here that Mod has always priority. -- (True, False) <- would mean priority to the left (same as ours). -- undefined {- TODO think this through -}, listTypeConflictResolution) -- Current state: -- Insertions are not considered as patches, -- they do not extend history, -- they do not bump version. insertNewOnly :: a -> Maybe b -> a insertNewOnly m = maybe m (const $ error "insertNewOnly: impossible") -- TODO error handling {- unused -- TODO refactor with putListNgrams copyListNgrams :: RepoCmdM env err m => NodeId -> NodeId -> NgramsType -> m () copyListNgrams srcListId dstListId ngramsType = do var <- view repoVar liftBase $ modifyMVar_ var $ pure . (r_state . at ngramsType %~ (Just . f . something)) saveRepo where f :: Map NodeId NgramsTableMap -> Map NodeId NgramsTableMap f m = m & at dstListId %~ insertNewOnly (m ^. at srcListId) -- TODO refactor with putListNgrams -- The list must be non-empty! -- The added ngrams must be non-existent! addListNgrams :: RepoCmdM env err m => NodeId -> NgramsType -> [NgramsElement] -> m () addListNgrams listId ngramsType nes = do var <- view repoVar liftBase $ modifyMVar_ var $ pure . (r_state . at ngramsType . _Just . at listId . _Just <>~ m) saveRepo where m = Map.fromList $ (\n -> (n ^. ne_ngrams, n)) <$> nes -} -- UNSAFE rmListNgrams :: RepoCmdM env err m => ListId -> TableNgrams.NgramsType -> m () rmListNgrams l nt = setListNgrams l nt mempty -- | TODO: incr the Version number -- && should use patch -- UNSAFE setListNgrams :: RepoCmdM env err m => NodeId -> TableNgrams.NgramsType -> Map NgramsTerm NgramsRepoElement -> m () setListNgrams listId ngramsType ns = do var <- view repoVar liftBase $ modifyMVar_ var $ pure . ( r_state . at ngramsType %~ (Just . (at listId .~ ( Just ns)) . something ) ) saveRepo currentVersion :: RepoCmdM env err m => m Version currentVersion = do var <- view repoVar r <- liftBase $ readMVar var pure $ r ^. r_version -- tableNgramsPut :: (HasInvalidError err, RepoCmdM env err m) commitStatePatch :: RepoCmdM env err m => Versioned NgramsStatePatch -> m (Versioned NgramsStatePatch) commitStatePatch (Versioned p_version p) = do var <- view repoVar vq' <- liftBase $ modifyMVar var $ \r -> do let q = mconcat $ take (r ^. r_version - p_version) (r ^. r_history) (p', q') = transformWith ngramsStatePatchConflictResolution p q r' = r & r_version +~ 1 & r_state %~ act p' & r_history %~ (p' :) {- -- Ideally we would like to check these properties. However: -- * They should be checked only to debug the code. The client data -- should be able to trigger these. -- * What kind of error should they throw (we are in IO here)? -- * Should we keep modifyMVar? -- * Should we throw the validation in an Exception, catch it around -- modifyMVar and throw it back as an Error? assertValid $ transformable p q assertValid $ applicable p' (r ^. r_state) -} pure (r', Versioned (r' ^. r_version) q') saveRepo pure vq' -- This is a special case of tableNgramsPut where the input patch is empty. tableNgramsPull :: RepoCmdM env err m => ListId -> TableNgrams.NgramsType -> Version -> m (Versioned NgramsTablePatch) tableNgramsPull listId ngramsType p_version = do var <- view repoVar r <- liftBase $ readMVar var let q = mconcat $ take (r ^. r_version - p_version) (r ^. r_history) q_table = q ^. _PatchMap . at ngramsType . _Just . _PatchMap . at listId . _Just pure (Versioned (r ^. r_version) q_table) -- Apply the given patch to the DB and returns the patch to be applied on the -- client. -- TODO-ACCESS check tableNgramsPut :: (HasNodeError err, HasInvalidError err, HasConfig env, HasConnectionPool env, HasSettings env, RepoCmdM env err m) => TabType -> ListId -> Versioned NgramsTablePatch -> m (Versioned NgramsTablePatch) tableNgramsPut tabType listId (Versioned p_version p_table) | p_table == mempty = do let ngramsType = ngramsTypeFromTabType tabType tableNgramsPull listId ngramsType p_version | otherwise = do let ngramsType = ngramsTypeFromTabType tabType (p0, p0_validity) = PM.singleton listId p_table (p, p_validity) = PM.singleton ngramsType p0 assertValid p0_validity assertValid p_validity ret <- commitStatePatch (Versioned p_version p) <&> v_data %~ (view (_PatchMap . at ngramsType . _Just . _PatchMap . at listId . _Just)) {- node <- getNode listId let nId = _node_id node _uId = _node_userId node mCId = _node_parentId node -- printDebug "[tableNgramsPut] updating graph with nId" nId -- printDebug "[tableNgramsPut] updating graph with uId" uId -- _ <- recomputeGraph uId nId Conditional printDebug "[tableNgramsPut] tabType" tabType printDebug "[tableNgramsPut] listId" listId _ <- case mCId of Nothing -> do printDebug "[tableNgramsPut] can't update charts, no parent, nId" nId pure () Just cId -> do case tabType of Authors -> do -- printDebug "[tableNgramsPut] Authors, updating Pie, cId" cId _ <- Metrics.updatePie cId (Just listId) tabType Nothing pure () Institutes -> do -- printDebug "[tableNgramsPut] Institutes, updating Tree, cId" cId -- printDebug "[tableNgramsPut] updating tree StopTerm, cId" cId _ <- Metrics.updateTree cId (Just listId) tabType StopTerm -- printDebug "[tableNgramsPut] updating tree CandidateTerm, cId" cId _ <- Metrics.updateTree cId (Just listId) tabType CandidateTerm -- printDebug "[tableNgramsPut] updating tree MapTerm, cId" cId _ <- Metrics.updateTree cId (Just listId) tabType MapTerm pure () Sources -> do -- printDebug "[tableNgramsPut] Sources, updating chart, cId" cId _ <- Metrics.updateChart cId (Just listId) tabType Nothing pure () Terms -> do -- printDebug "[tableNgramsPut] Terms, updating Metrics (Histo), cId" cId _ <- Metrics.updateChart cId (Just listId) tabType Nothing _ <- Metrics.updatePie cId (Just listId) tabType Nothing _ <- Metrics.updateScatter cId (Just listId) tabType Nothing _ <- Metrics.updateTree cId (Just listId) tabType StopTerm _ <- Metrics.updateTree cId (Just listId) tabType CandidateTerm _ <- Metrics.updateTree cId (Just listId) tabType MapTerm pure () _ -> do printDebug "[tableNgramsPut] no update for tabType = " tabType pure () pure () -} pure ret {- { _ne_list :: ListType If we merge the parents/children we can potentially create cycles! , _ne_parent :: Maybe NgramsTerm , _ne_children :: MSet NgramsTerm } -} getNgramsTableMap :: RepoCmdM env err m => NodeId -> TableNgrams.NgramsType -> m (Versioned NgramsTableMap) getNgramsTableMap nodeId ngramsType = do v <- view repoVar repo <- liftBase $ readMVar v pure $ Versioned (repo ^. r_version) (repo ^. r_state . at ngramsType . _Just . at nodeId . _Just) dumpJsonTableMap :: RepoCmdM env err m => Text -> NodeId -> TableNgrams.NgramsType -> m () dumpJsonTableMap fpath nodeId ngramsType = do m <- getNgramsTableMap nodeId ngramsType liftBase $ DTL.writeFile (unpack fpath) (DAT.encodeToLazyText m) pure () type MinSize = Int type MaxSize = Int -- | TODO Errors management -- TODO: polymorphic for Annuaire or Corpus or ... -- | Table of Ngrams is a ListNgrams formatted (sorted and/or cut). -- TODO: should take only one ListId getTime' :: MonadBase IO m => m TimeSpec getTime' = liftBase $ getTime ProcessCPUTime getTableNgrams :: forall env err m. (RepoCmdM env err m, HasNodeError err, HasConnectionPool env, HasConfig env) => NodeType -> NodeId -> TabType -> ListId -> Limit -> Maybe Offset -> Maybe ListType -> Maybe MinSize -> Maybe MaxSize -> Maybe OrderBy -> (NgramsTerm -> Bool) -> m (Versioned NgramsTable) getTableNgrams _nType nId tabType listId limit_ offset listType minSize maxSize orderBy searchQuery = do t0 <- getTime' -- lIds <- selectNodesWithUsername NodeList userMaster let ngramsType = ngramsTypeFromTabType tabType offset' = maybe 0 identity offset listType' = maybe (const True) (==) listType minSize' = maybe (const True) (<=) minSize maxSize' = maybe (const True) (>=) maxSize selected_node n = minSize' s && maxSize' s && searchQuery (n ^. ne_ngrams) && listType' (n ^. ne_list) where s = n ^. ne_size selected_inner roots n = maybe False (`Set.member` roots) (n ^. ne_root) --------------------------------------- sortOnOrder Nothing = identity sortOnOrder (Just TermAsc) = List.sortOn $ view ne_ngrams sortOnOrder (Just TermDesc) = List.sortOn $ Down . view ne_ngrams sortOnOrder (Just ScoreAsc) = List.sortOn $ view ne_occurrences sortOnOrder (Just ScoreDesc) = List.sortOn $ Down . view ne_occurrences --------------------------------------- selectAndPaginate :: Map NgramsTerm NgramsElement -> [NgramsElement] selectAndPaginate tableMap = roots <> inners where list = tableMap ^.. each rootOf ne = maybe ne (\r -> fromMaybe (panic "getTableNgrams: invalid root") (tableMap ^. at r)) (ne ^. ne_root) selected_nodes = list & take limit_ . drop offset' . filter selected_node . sortOnOrder orderBy roots = rootOf <$> selected_nodes rootsSet = Set.fromList (_ne_ngrams <$> roots) inners = list & filter (selected_inner rootsSet) --------------------------------------- setScores :: forall t. Each t t NgramsElement NgramsElement => Bool -> t -> m t setScores False table = pure table setScores True table = do let ngrams_terms = unNgramsTerm <$> (table ^.. each . ne_ngrams) t1 <- getTime' occurrences <- getOccByNgramsOnlyFast' nId listId ngramsType ngrams_terms t2 <- getTime' liftBase $ hprint stderr ("getTableNgrams/setScores #ngrams=" % int % " time=" % timeSpecs % "\n") (length ngrams_terms) t1 t2 {- occurrences <- getOccByNgramsOnlySlow nType nId (lIds <> [listId]) ngramsType ngrams_terms -} let setOcc ne = ne & ne_occurrences .~ sumOf (at (unNgramsTerm (ne ^. ne_ngrams)) . _Just) occurrences pure $ table & each %~ setOcc --------------------------------------- -- lists <- catMaybes <$> listsWith userMaster -- trace (show lists) $ -- getNgramsTableMap ({-lists <>-} listIds) ngramsType let scoresNeeded = needsScores orderBy tableMap1 <- getNgramsTableMap listId ngramsType t1 <- getTime' tableMap2 <- tableMap1 & v_data %%~ setScores scoresNeeded . Map.mapWithKey ngramsElementFromRepo t2 <- getTime' tableMap3 <- tableMap2 & v_data %%~ fmap NgramsTable . setScores (not scoresNeeded) . selectAndPaginate t3 <- getTime' liftBase $ hprint stderr ("getTableNgrams total=" % timeSpecs % " map1=" % timeSpecs % " map2=" % timeSpecs % " map3=" % timeSpecs % " sql=" % (if scoresNeeded then "map2" else "map3") % "\n" ) t0 t3 t0 t1 t1 t2 t2 t3 pure tableMap3 scoresRecomputeTableNgrams :: forall env err m. (RepoCmdM env err m, HasNodeError err, HasConnectionPool env, HasConfig env) => NodeId -> TabType -> ListId -> m Int scoresRecomputeTableNgrams nId tabType listId = do tableMap <- getNgramsTableMap listId ngramsType _ <- tableMap & v_data %%~ setScores . Map.mapWithKey ngramsElementFromRepo pure $ 1 where ngramsType = ngramsTypeFromTabType tabType setScores :: forall t. Each t t NgramsElement NgramsElement => t -> m t setScores table = do let ngrams_terms = unNgramsTerm <$> (table ^.. each . ne_ngrams) occurrences <- getOccByNgramsOnlyFast' nId listId ngramsType ngrams_terms let setOcc ne = ne & ne_occurrences .~ sumOf (at (unNgramsTerm (ne ^. ne_ngrams)) . _Just) occurrences pure $ table & each %~ setOcc -- APIs -- TODO: find a better place for the code above, All APIs stay here data OrderBy = TermAsc | TermDesc | ScoreAsc | ScoreDesc deriving (Generic, Enum, Bounded, Read, Show) instance FromHttpApiData OrderBy where parseUrlPiece "TermAsc" = pure TermAsc parseUrlPiece "TermDesc" = pure TermDesc parseUrlPiece "ScoreAsc" = pure ScoreAsc parseUrlPiece "ScoreDesc" = pure ScoreDesc parseUrlPiece _ = Left "Unexpected value of OrderBy" instance ToParamSchema OrderBy instance FromJSON OrderBy instance ToJSON OrderBy instance ToSchema OrderBy instance Arbitrary OrderBy where arbitrary = elements [minBound..maxBound] needsScores :: Maybe OrderBy -> Bool needsScores (Just ScoreAsc) = True needsScores (Just ScoreDesc) = True needsScores _ = False type TableNgramsApiGet = Summary " Table Ngrams API Get" :> QueryParamR "ngramsType" TabType :> QueryParamR "list" ListId :> QueryParamR "limit" Limit :> QueryParam "offset" Offset :> QueryParam "listType" ListType :> QueryParam "minTermSize" MinSize :> QueryParam "maxTermSize" MaxSize :> QueryParam "orderBy" OrderBy :> QueryParam "search" Text :> Get '[JSON] (Versioned NgramsTable) type TableNgramsApiPut = Summary " Table Ngrams API Change" :> QueryParamR "ngramsType" TabType :> QueryParamR "list" ListId :> ReqBody '[JSON] (Versioned NgramsTablePatch) :> Put '[JSON] (Versioned NgramsTablePatch) type RecomputeScoresNgramsApiGet = Summary " Recompute scores for ngrams table" :> QueryParamR "ngramsType" TabType :> QueryParamR "list" ListId :> "recompute" :> Post '[JSON] Int type TableNgramsApiGetVersion = Summary " Table Ngrams API Get Version" :> QueryParamR "ngramsType" TabType :> QueryParamR "list" ListId :> Get '[JSON] Version type TableNgramsApi = TableNgramsApiGet :<|> TableNgramsApiPut :<|> RecomputeScoresNgramsApiGet :<|> "version" :> TableNgramsApiGetVersion getTableNgramsCorpus :: (RepoCmdM env err m, HasNodeError err, HasConnectionPool env, HasConfig env) => NodeId -> TabType -> ListId -> Limit -> Maybe Offset -> Maybe ListType -> Maybe MinSize -> Maybe MaxSize -> Maybe OrderBy -> Maybe Text -- full text search -> m (Versioned NgramsTable) getTableNgramsCorpus nId tabType listId limit_ offset listType minSize maxSize orderBy mt = getTableNgrams NodeCorpus nId tabType listId limit_ offset listType minSize maxSize orderBy searchQuery where searchQuery (NgramsTerm nt) = maybe (const True) isInfixOf mt nt getTableNgramsVersion :: (RepoCmdM env err m, HasNodeError err, HasConnectionPool env, HasConfig env) => NodeId -> TabType -> ListId -> m Version getTableNgramsVersion _nId _tabType _listId = currentVersion -- TODO: limit? -- Versioned { _v_version = v } <- getTableNgramsCorpus nId tabType listId 100000 Nothing Nothing Nothing Nothing Nothing Nothing -- This line above looks like a waste of computation to finally get only the version. -- See the comment about listNgramsChangedSince. -- | Text search is deactivated for now for ngrams by doc only getTableNgramsDoc :: (RepoCmdM env err m, HasNodeError err, HasConnectionPool env, HasConfig env) => DocId -> TabType -> ListId -> Limit -> Maybe Offset -> Maybe ListType -> Maybe MinSize -> Maybe MaxSize -> Maybe OrderBy -> Maybe Text -- full text search -> m (Versioned NgramsTable) getTableNgramsDoc dId tabType listId limit_ offset listType minSize maxSize orderBy _mt = do ns <- selectNodesWithUsername NodeList userMaster let ngramsType = ngramsTypeFromTabType tabType ngs <- selectNgramsByDoc (ns <> [listId]) dId ngramsType let searchQuery (NgramsTerm nt) = flip S.member (S.fromList ngs) nt getTableNgrams NodeDocument dId tabType listId limit_ offset listType minSize maxSize orderBy searchQuery apiNgramsTableCorpus :: ( RepoCmdM env err m , HasNodeError err , HasInvalidError err , HasConnectionPool env , HasConfig env , HasSettings env ) => NodeId -> ServerT TableNgramsApi m apiNgramsTableCorpus cId = getTableNgramsCorpus cId :<|> tableNgramsPut :<|> scoresRecomputeTableNgrams cId :<|> getTableNgramsVersion cId apiNgramsTableDoc :: ( RepoCmdM env err m , HasNodeError err , HasInvalidError err , HasConnectionPool env , HasConfig env , HasSettings env ) => DocId -> ServerT TableNgramsApi m apiNgramsTableDoc dId = getTableNgramsDoc dId :<|> tableNgramsPut :<|> scoresRecomputeTableNgrams dId :<|> getTableNgramsVersion dId -- > index all the corpus accordingly (TODO AD) -- Did the given list of ngrams changed since the given version? -- The returned value is versioned boolean value, meaning that one always retrieve the -- latest version. -- If the given version is negative then one simply receive the latest version and True. -- Using this function is more precise than simply comparing the latest version number -- with the local version number. Indeed there might be no change to this particular list -- and still the version number has changed because of other lists. -- -- Here the added value is to make a compromise between precision, computation, and bandwidth: -- * currentVersion: good computation, good bandwidth, bad precision. -- * listNgramsChangedSince: good precision, good bandwidth, bad computation. -- * tableNgramsPull: good precision, good bandwidth (if you use the received data!), bad computation. listNgramsChangedSince :: RepoCmdM env err m => ListId -> TableNgrams.NgramsType -> Version -> m (Versioned Bool) listNgramsChangedSince listId ngramsType version | version < 0 = Versioned <$> currentVersion <*> pure True | otherwise = tableNgramsPull listId ngramsType version & mapped . v_data %~ (== mempty)