added an API to extract the constants

haskell-experiments/src/Datalog/DatalogDB.hs

@@ -61,6 +61,7 @@ class DatalogDB db where
   lookupRelation :: db -> Text -> Maybe Relation
   insertRelation :: db -> Relation -> db
   addConstants :: db -> Set Constant -> db
+  allConstants :: db -> Set Constant
 
 lookupRelationArity :: DatalogDB db => Text -> db -> Int -> Set [Constant] -> Relation
 lookupRelationArity relationName db newArity tuples =

haskell-experiments/src/Datalog/InMemoryDB.hs

@@ -48,6 +48,9 @@ instance DatalogDB InMemoryDB where
   relationNames :: InMemoryDB -> [Text]
   relationNames db = keys (_relations db)
 
+  allConstants :: InMemoryDB -> Set Constant
+  allConstants db = _constants db
+
 withFacts :: [Text] -> InMemoryDB
 withFacts =
   foldr (addFact . extractFact) emptyDB

haskell-experiments/src/Datalog/NaiveQE.hs

@@ -17,6 +17,7 @@ import Datalog.DatalogDB
 import Datalog.DatalogParser
 import Control.Exception
 import Data.Maybe
+import Utility.Utility
 
 data (DatalogDB db) => NaiveQE db = NaiveQE 
   {
@@ -64,5 +65,6 @@ computeHerbrand db =
       foldr amalgamateRule newFacts (_rules relation) where
       amalgamateRule :: RelationRule -> NewFacts -> NewFacts
       amalgamateRule (RelationRule headVars body) newFacts  = 
+        -- allMaps headVars (allConstants db)
         newFacts
 

haskell-experiments/test/Test/Datalog/InMemoryDBSpec.hs

@@ -31,7 +31,7 @@ spec = do
               [ "parent(\"alice\", \"bob\")."
               , "parent(\"bob\", \"carol\")."
               ]
-      _constants db
+      allConstants db
         `shouldBe` Set.fromList (Sym <$> ["alice", "bob", "carol"])
       _relations db
         `shouldBe` Map.fromList
@@ -79,7 +79,7 @@ spec = do
               , _rules = [ancestorRule, ancestorRule2]
               }
 
-      _constants db
+      allConstants db
         `shouldBe` Set.fromList (Sym <$> ["alice", "bob", "carol"])
 
       _relations db
@@ -109,7 +109,7 @@ spec = do
       _relations db
         `shouldBe` Map.singleton "ancestor" ancestorRelation
 
-      _constants db
+      allConstants db
         `shouldBe` Set.fromList (Sym <$> ["patriarch"])
       Set.fromList (relationNames db) `shouldBe` Set.fromList [ "ancestor" ]
 
@@ -133,7 +133,7 @@ spec = do
       _relations db
         `shouldBe` Map.singleton "equivalent" equivalentRelation
 
-      _constants db
+      allConstants db
         `shouldBe` Set.empty
       relationNames db `shouldBe` [ "equivalent" ]
 
@@ -174,7 +174,7 @@ spec = do
       _relations db
         `shouldBe` Map.singleton "equivalent" equivalentRelation
 
-      _constants db
+      allConstants db
         `shouldBe` Set.empty
       Set.fromList (relationNames db) `shouldBe` Set.fromList [ "equivalent" ]