From a967a8e53235f79ad7cc888771927ed1a57eb97d Mon Sep 17 00:00:00 2001
From: Patrick Aldis <patricktaldis@gmail.com>
Date: Tue, 3 Mar 2026 14:26:31 +0000
Subject: [PATCH] Datalog Parser annotates SrcLoc

---
 datalog/src/Datalog/Parser.hs | 67 +++++++++++++++--------------------
 1 file changed, 28 insertions(+), 39 deletions(-)

diff --git a/datalog/src/Datalog/Parser.hs b/datalog/src/Datalog/Parser.hs
index dac730f..7a80615 100644
--- a/datalog/src/Datalog/Parser.hs
+++ b/datalog/src/Datalog/Parser.hs
@@ -1,11 +1,9 @@
-{-# LANGUAGE MultilineStrings #-}
 {-# LANGUAGE BlockArguments #-}
+{-# LANGUAGE MultilineStrings #-}
 
 module Datalog.Parser (
     parseTerm,
-    parseAtom,
     parseRule,
-    parseQuery,
     parseProgram,
 )
 where
@@ -13,7 +11,8 @@ where
 import Data.Text (Text)
 import Data.Text qualified as T
 import Data.Void (Void)
-import Datalog.Syntax
+import Datalog.Syntax hiding (Atom, Program, Rule, Term)
+import Datalog.Syntax (Atom' (..), Program' (..), Rule' (..), Term' (..))
 import Text.Megaparsec
 import Text.Megaparsec.Char
 import Text.Megaparsec.Char.Lexer qualified as L
@@ -21,6 +20,11 @@ import Text.Pretty.Simple
 
 type Parser = Parsec Void Text
 
+type Atom = Atom' SrcLoc
+type Term = Term' SrcLoc
+type Rule = Rule' SrcLoc
+type Program = Program' SrcLoc
+
 lexeme :: (MonadParsec e Text m) => m a -> m a
 lexeme = L.lexeme whitespace
 
@@ -41,61 +45,46 @@ comma, period :: (MonadParsec e Text m) => m ()
 comma = () <$ symbol ","
 period = () <$ symbol "."
 
-parseCon :: (MonadParsec e Text m) => m Term
-parseCon = Con () . ConId . T.pack <$> lexeme (liftA2 (:) (numberChar <|> lowerChar) (many alphaNumChar))
+parseCon :: Parser Term
+parseCon = parseThingWithSub Con $ ConId . T.pack <$> lexeme (liftA2 (:) (numberChar <|> lowerChar) (many alphaNumChar))
 
-parseVar :: (MonadParsec e Text m) => m Term
-parseVar = Var () . VarId . T.pack <$> lexeme (liftA2 (:) upperChar (many alphaNumChar))
+parseVar :: Parser Term
+parseVar = parseThingWithSub Var $ VarId . T.pack <$> lexeme (liftA2 (:) upperChar (many alphaNumChar))
 
 parseTerm :: Parser Term
 parseTerm = parseVar <|> parseCon
 
 parseAtom :: Parser Atom
-parseAtom = do
+parseAtom = parseThingWithSub (\loc (rel, args) -> Atom loc rel args) do
     rel <- RelId . T.pack <$> lexeme (liftA2 (:) lowerChar (many alphaNumChar))
     args <- parens (parseTerm `sepBy` comma)
-    return (Atom () rel args)
+    return (rel, args)
 
 parseQuery :: Parser [Atom]
 parseQuery = parseAtom `sepBy` comma
 
-parseFact :: Parser Rule
-parseFact = do
-    headAtom <- parseAtom
-    period
-    return (Rule () headAtom [])
-
 parseRule :: Parser Rule
-parseRule =
-    try parseFact <|> do
+parseRule = parseThingWithSub (\loc (a, as) -> Rule loc a as) $
+        try rule1 <|> rule2
+  where
+    rule1 = do
+        headAtom <- parseAtom
+        period
+        return (headAtom, [])
+    rule2 = do
         headAtom <- parseAtom <* symbol ":-"
         bodyAtoms <- parseQuery
         period
-        return (Rule () headAtom bodyAtoms)
-parseRule' :: Parser (Rule' SrcLoc)
-parseRule' = _
+        return (headAtom, bodyAtoms)
 
--- parseProgram :: Parser Program
-parseProgram :: Parser (Program' SrcLoc)
-parseProgram = do
-    -- annotateSrcLoc $
+parseProgram :: Parser Program
+parseProgram = parseThingWithSub Program (many parseRule)
+
+parseThingWithSub :: (SrcLoc -> c -> f SrcLoc) -> Parser c -> Parser (f SrcLoc)
+parseThingWithSub f parseSub = do
     s <- getSourcePos
-    c <- many parseRule'
-    e <- getSourcePos
-    -- Program _ <$> many parseRule
-    pure $ Program (SrcLoc s e) c
-
-parseProgram' :: Parser (Program' SrcLoc)
-parseProgram' = parseThingWithSub (many parseRule') Program
-
-parseThingWithSub :: (Parser c) -> (SrcLoc -> c -> f SrcLoc) -> Parser (f SrcLoc)
-parseThingWithSub parseSub f = do
-    -- annotateSrcLoc $
-    s <- getSourcePos
-    -- c <- many parseRule'
     c <- parseSub
     e <- getSourcePos
-    -- Program _ <$> many parseRule
     pure $ f (SrcLoc s e) c
 
 annotateSrcLoc :: (Functor f) => Parser (f a) -> Parser (f SrcLoc)