slowly figuring out how to populate the herbrand

haskell-experiments/src/Datalog/NaiveQE.hs

@@ -19,6 +19,8 @@ import Data.Map qualified as Map
 import Datalog.DatalogDB
 import Datalog.DatalogParser
 import Control.Exception
+import Data.Maybe
+import Data.Functor ((<&>))
 
 data (DatalogDB db) => NaiveQE db = NaiveQE 
   {
@@ -41,8 +43,16 @@ instance QueryEngine NaiveQE where
 
 computeHerbrand :: (DatalogDB db) => db -> Map Text Relation
 computeHerbrand db =
-  computeHerbrandSub Map.empty where
-  computeHerbrandSub :: Map Text Relation -> Map Text Relation
-  computeHerbrandSub facts = facts
-    -- for_ (Map.toList myMap) $ \(k,v) ->
+  computeHerbrandSub initialFacts where
+    initialFacts :: Map Text Relation =
+      Map.fromList $ catMaybes $ relationNames db <&> (\relationName -> do
+        relation <- lookupRelation db relationName
+        pure (relationName, relation))
+    updateFacts :: Map Text Relation -> Maybe (Map Text Relation)
+    updateFacts facts = Nothing -- Just facts
+    computeHerbrandSub :: Map Text Relation -> Map Text Relation
+    computeHerbrandSub facts = 
+      case updateFacts facts of
+        Just moreFacts -> computeHerbrandSub moreFacts
+        Nothing -> facts