From 7ae868932d5aa11df631a04b86e9293010610cec Mon Sep 17 00:00:00 2001
From: Igor Ranieri <igor@elland.me>
Date: Wed, 24 Sep 2025 10:13:16 +0200
Subject: [PATCH] Add located combinator; improved anchor matches with tests

---
 src/Lexer.hs | 22 +++++++++++++---------
 test/Spec.hs |  5 +++++
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/Lexer.hs b/src/Lexer.hs
index 5b29aa8..abced93 100644
--- a/src/Lexer.hs
+++ b/src/Lexer.hs
@@ -175,22 +175,26 @@ anchors = do
   where
     anchor' = (string "#" <|> string "\\#")
 
+located :: Parser a -> Parser (SourcePos, a)
+located p = (,) <$> getPosition <*> p
+
+startPosition :: Parser a -> Parser SourcePos
+startPosition = fmap fst . located
+
 -- "Module.Name"
 -- "Module.Name#anchor"
+-- "Module.Name\#anchor" -- this has been deprecated for 9 years, thanks Ben
 modules :: Lexer
 modules = do
-    pos <- getPosition
-    void $ char '"'
-    pos' <- getPosition
-    modName <- modId
+    startPos <- startPosition $ char '"'
+    (modPos, modName) <- located modId
     anch <- option [] do
-        pos'' <- getPosition
-        void $ try (string "#" <|> string "\\#")
-        a <- Text.pack <$> many (satisfy (\c -> c /= '"' && not (isSpace c)))
-        pure [(pos'', Anchor a)]
+        anchPos <- startPosition (string "#" <|> string' "\\#")
+        txt <- Text.pack <$> many (satisfy (\c -> c /= '"' && not (isSpace c)))
+        pure [(anchPos, Anchor txt)]
 
     void $ char '"'
-    pure $ [(pos, Module), (pos', Token modName)] <> anch
+    pure $ [(startPos, Module), (modPos, Token modName)] <> anch
   where
     modId = intercalate "." <$> (fmap Text.pack <$> (conId `sepBy1` (char '.')))
 
diff --git a/test/Spec.hs b/test/Spec.hs
index 9f76b8b..d202ac2 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -54,6 +54,11 @@ modules = do
                       , (1, 18, Anchor "myAnchor")
                       ]
 
+    "\"OtherModule.Name\\#myAnchor\""
+        `shouldLexTo` [ (1, 1, Module)
+                      , (1, 2, Token "OtherModule.Name")
+                      , (1, 18, Anchor "myAnchor")
+                      ]
 link :: Expectation
 link =
     "[link to](http://some.website)"