From 7855e5ce20c4a0a6bb4fd6546cfd6a0e92ad7af8 Mon Sep 17 00:00:00 2001
From: Felix Dilke <felix.dilke@obsidian.systems>
Date: Tue, 27 Jan 2026 12:41:23 +0000
Subject: [PATCH] added relation references

---
 .../src/Datalog/NaiveDatabase.hs              | 16 ++++--
 .../test/Test/Datalog/NaiveDatabaseSpec.hs    | 56 +++++++++----------
 2 files changed, 37 insertions(+), 35 deletions(-)

diff --git a/haskell-experiments/src/Datalog/NaiveDatabase.hs b/haskell-experiments/src/Datalog/NaiveDatabase.hs
index f874e71..ade7f27 100644
--- a/haskell-experiments/src/Datalog/NaiveDatabase.hs
+++ b/haskell-experiments/src/Datalog/NaiveDatabase.hs
@@ -33,9 +33,14 @@ data RuleElement = -- entry occurring in a head or body relation - constant or v
   RuleElementVariable Text
   deriving (Show, Eq)
 
+data RuleBodyElement = RuleBodyElement {
+  _subRelationName :: Text,
+  _ruleElements :: [RuleElement]
+} deriving (Show, Eq)
+
 data RelationRule = RelationRule {
   headVariables :: [Text],
-  body :: [(Relation, [RuleElement])]
+  bodyElements :: [RuleBodyElement]
 } deriving (Show, Eq)
 
 data Relation = Relation {
@@ -201,11 +206,14 @@ withFactsAndRules facts rules =
         extractVarName (RuleElementConstant constant) = throw $ UnexpectedConstantException constant
         newRule = RelationRule {
           headVariables = extractVarName <$> variables',
-          body = fromBodyConstraint <$> (_bodyConstraints context'')
+          bodyElements = fromBodyConstraint <$> (_bodyConstraints context'')
         } where
-          fromBodyConstraint :: BodyConstraint -> (Relation, [RuleElement])
+          fromBodyConstraint :: BodyConstraint -> RuleBodyElement
           fromBodyConstraint (BodyConstraint subRelation elements) =
-            (subRelation, toRuleElement <$> elements) 
+            RuleBodyElement {
+              _subRelationName = _name subRelation, 
+              _ruleElements = toRuleElement <$> elements
+            } 
           toRuleElement :: ConstraintElement -> RuleElement
           toRuleElement (ConstraintElementConstant constant) = RuleElementConstant constant
           toRuleElement (ConstraintElementIndex index) = variables' !! index
diff --git a/haskell-experiments/test/Test/Datalog/NaiveDatabaseSpec.hs b/haskell-experiments/test/Test/Datalog/NaiveDatabaseSpec.hs
index 9105d74..e18a460 100644
--- a/haskell-experiments/test/Test/Datalog/NaiveDatabaseSpec.hs
+++ b/haskell-experiments/test/Test/Datalog/NaiveDatabaseSpec.hs
@@ -50,40 +50,34 @@ spec = do
             map (Sym <$>) [["alice", "bob"], ["bob", "carol"]], 
           _rules = []
         }
+      let ancestorRule = RelationRule {
+          headVariables = [ "X", "Y", "Z" ], 
+          bodyElements = [
+              RuleBodyElement {
+                _subRelationName = "parent",
+                _ruleElements = [
+                  RuleElementVariable "X", RuleElementVariable "Z"
+                ]
+              },
+              RuleBodyElement {
+                _subRelationName = "ancestor",
+                _ruleElements = [
+                  RuleElementVariable "Z",RuleElementVariable "Y"
+                ]
+              }
+            ]
+          }
       let ancestorRelation = Relation {
-              _arity = 2, 
-              _name = "ancestor",
-              _tuples = Set.empty,
-              _rules = []
-            }
+          _arity = 2, 
+          _name = "ancestor",
+          _tuples = Set.empty,
+          _rules = [ ancestorRule ]
+        }
       relations db `shouldBe`
         Map.fromList [
-          ("ancestor", 
-          Relation {
-              _arity = 2, 
-              _name = "ancestor",
-              _tuples = Set.empty,
-              _rules = [
-                RelationRule {
-                  headVariables = [ "X", "Y", "Z" ], 
-                  body = [
-                    (
-                      parentRelation, [
-                          RuleElementVariable "X",
-                          RuleElementVariable "Z"
-                        ]
-                    ),(
-                      ancestorRelation,[
-                        RuleElementVariable "Z",
-                        RuleElementVariable "Y"
-                        ]
-                      )
-                    ]
-                  }
-                ]
-              } ),
-            ("parent", parentRelation )
-          ]
+          ("ancestor", ancestorRelation),
+          ("parent", parentRelation )
+        ]
 
     it "can do basic queries" $ do
       let db = NaiveDatabase.withFacts