From fb2699624f8e83c887fd55f745b5dc9c6f73fa43 Mon Sep 17 00:00:00 2001
From: Felix Dilke <felix.dilke@obsidian.systems>
Date: Wed, 28 Jan 2026 11:55:08 +0000
Subject: [PATCH] eliminated duplicate variable lookup

---
 .../src/Datalog/NaiveDatabase.hs              | 25 ++++++-------------
 1 file changed, 8 insertions(+), 17 deletions(-)

diff --git a/haskell-experiments/src/Datalog/NaiveDatabase.hs b/haskell-experiments/src/Datalog/NaiveDatabase.hs
index e04bcda..e3771f9 100644
--- a/haskell-experiments/src/Datalog/NaiveDatabase.hs
+++ b/haskell-experiments/src/Datalog/NaiveDatabase.hs
@@ -127,9 +127,7 @@ withFactsAndRules facts = foldr (addRule . extractRule) (withFacts facts)
     variableNames = extractVariableNames terms
     headTermToElement :: Term -> RuleElement
     headTermToElement (Var name) = 
-      case (elemIndex name) variableNames of
-          Just index -> RuleElementVariable index
-          Nothing -> throw $ VariableLookupException name variableNames
+      RuleElementVariable $ lookupVariable name variableNames
     headTermToElement constant = RuleElementConstant constant
     relationMap :: Map RelationId Relation = relations db
     relationMap' = Map.insert relationName relation relationMap
@@ -155,30 +153,23 @@ withFactsAndRules facts = foldr (addRule . extractRule) (withFacts facts)
     subRelation = lookupRelation subRelationName relationMap newArity Set.empty
     relationMap :: Map RelationId Relation = relations (_db context)
     relationMap' = Map.insert subRelationName subRelation relationMap
-    -- extraVariables = bodyTermToElement <$> terms where
-    --   bodyTermToElement :: Term -> RuleElement
-    --   bodyTermToElement (Var name) = 
-    --     case (elemIndex name) variableNames of
-    --         Just index -> RuleElementVariable index
-    --         Nothing -> throw $ VariableLookupException name variableNames
-    --   bodyTermToElement constant = RuleElementConstant constant
     extraConstants = mapMaybe constantFromTerm subTerms where
       constantFromTerm :: Term -> Maybe Constant
       constantFromTerm (Var _) = Nothing
       constantFromTerm constant = Just constant
-    -- variables' = nub $ _headEntries context ++ extraVariables
     constants' = Set.union (constants (_db context)) $ Set.fromList extraConstants
     constraints = _bodyConstraints context
     newConstraint = BodyConstraint subRelation subRuleElements where
       subRuleElements = toRuleElement <$> subTerms
       toRuleElement :: Term -> RuleElement
-      toRuleElement (Var varName) = RuleElementVariable $ lookupVariable varName
+      toRuleElement (Var varName) = RuleElementVariable $ lookupVariable varName variableNames
       toRuleElement constant = RuleElementConstant constant
-      lookupVariable :: Text -> Int
-      lookupVariable varName = 
-        case (elemIndex varName) variableNames of
-            Just index -> index
-            Nothing -> throw $ VariableLookupException varName variableNames
+
+  lookupVariable :: Text -> [Text] -> Int
+  lookupVariable varName variableNames = 
+    case (elemIndex varName) variableNames of
+        Just index -> index
+        Nothing -> throw $ VariableLookupException varName variableNames
 
   addRule :: (Literal, [Literal]) -> NaiveDatabase -> NaiveDatabase
   addRule (ruleHead, body) db  =