From a646a997acc9cf6bba70c0af4452f6b33ecb009c Mon Sep 17 00:00:00 2001
From: konsumlamm <konsumlamm@gmail.com>
Date: Thu, 4 Dec 2025 16:27:05 +0100
Subject: [PATCH 1/2] Remove `insertBehind`

---
 CHANGELOG.md                          |  2 ++
 src/Data/PQueue/Prio/Internals.hs     | 17 -----------------
 src/Data/PQueue/Prio/Max.hs           |  1 -
 src/Data/PQueue/Prio/Max/Internals.hs |  9 ---------
 src/Data/PQueue/Prio/Min.hs           |  1 -
 5 files changed, 2 insertions(+), 28 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d79032..5d90532 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## 1.7.0.0
 
+* Remove `insertBehind`
+
 * Change `Read` and `Show` instances to use `fromList`
   ([#144](https://github.com/lspitzner/pqueue/issues/144))
 
diff --git a/src/Data/PQueue/Prio/Internals.hs b/src/Data/PQueue/Prio/Internals.hs
index a6ce92c..bf89b48 100644
--- a/src/Data/PQueue/Prio/Internals.hs
+++ b/src/Data/PQueue/Prio/Internals.hs
@@ -17,7 +17,6 @@ module Data.PQueue.Prio.Internals (
   size,
   singleton,
   insert,
-  insertBehind,
   insertEager,
   union,
   getMin,
@@ -235,22 +234,6 @@ insertEager k a (MinPQ n k' a' ts)
   | k <= k' = MinPQ (n + 1) k a  (insertEagerHeap k' a' ts)
   | otherwise = MinPQ (n + 1) k' a' (insertEagerHeap k a ts)
 
--- | \(O(n)\) (an earlier implementation had \(O(1)\) but was buggy).
--- Insert an element with the specified key into the priority queue,
--- putting it behind elements whose key compares equal to the
--- inserted one.
-{-# DEPRECATED insertBehind "This function is not reliable." #-}
-insertBehind :: Ord k => k -> a -> MinPQueue k a -> MinPQueue k a
-insertBehind k v q =
-  let (smaller, larger) = spanKey (<= k) q
-  in  foldr (uncurry insert) (insert k v larger) smaller
-
-spanKey :: Ord k => (k -> Bool) -> MinPQueue k a -> ([(k, a)], MinPQueue k a)
-spanKey p q = case minViewWithKey q of
-  Just (t@(k, _), q') | p k ->
-    let (kas, q'') = spanKey p q' in (t : kas, q'')
-  _ -> ([], q)
-
 -- | Amortized \(O(\log \min(n_1,n_2))\), worst-case \(O(\log \max(n_1,n_2))\). Returns the union
 -- of the two specified queues.
 union :: Ord k => MinPQueue k a -> MinPQueue k a -> MinPQueue k a
diff --git a/src/Data/PQueue/Prio/Max.hs b/src/Data/PQueue/Prio/Max.hs
index 1bc39d6..cb22c52 100644
--- a/src/Data/PQueue/Prio/Max.hs
+++ b/src/Data/PQueue/Prio/Max.hs
@@ -32,7 +32,6 @@ module Data.PQueue.Prio.Max (
   empty,
   singleton,
   insert,
-  insertBehind,
   union,
   unions,
   -- * Query
diff --git a/src/Data/PQueue/Prio/Max/Internals.hs b/src/Data/PQueue/Prio/Max/Internals.hs
index 8d9d994..b23e0d6 100644
--- a/src/Data/PQueue/Prio/Max/Internals.hs
+++ b/src/Data/PQueue/Prio/Max/Internals.hs
@@ -20,7 +20,6 @@ module Data.PQueue.Prio.Max.Internals (
   empty,
   singleton,
   insert,
-  insertBehind,
   union,
   unions,
   -- * Query
@@ -218,14 +217,6 @@ singleton = coerce Q.singleton
 insert :: Ord k => k -> a -> MaxPQueue k a -> MaxPQueue k a
 insert = coerce Q.insert
 
--- | \(O(n)\) (an earlier implementation had \(O(1)\) but was buggy).
--- Insert an element with the specified key into the priority queue,
--- putting it behind elements whose key compares equal to the
--- inserted one.
-{-# DEPRECATED insertBehind "This function is not reliable." #-}
-insertBehind :: Ord k => k -> a -> MaxPQueue k a -> MaxPQueue k a
-insertBehind = coerce Q.insertBehind
-
 -- | Amortized \(O(\log \min(n_1,n_2))\), worst-case \(O(\log \max(n_1,n_2))\). Returns the union
 -- of the two specified queues.
 union :: Ord k => MaxPQueue k a -> MaxPQueue k a -> MaxPQueue k a
diff --git a/src/Data/PQueue/Prio/Min.hs b/src/Data/PQueue/Prio/Min.hs
index bf39e3e..38f5be8 100644
--- a/src/Data/PQueue/Prio/Min.hs
+++ b/src/Data/PQueue/Prio/Min.hs
@@ -42,7 +42,6 @@ module Data.PQueue.Prio.Min (
   empty,
   singleton,
   insert,
-  insertBehind,
   union,
   unions,
   -- * Query

From 112046285a2432a72bf427cb5a6eedddf131042b Mon Sep 17 00:00:00 2001
From: konsumlamm <konsumlamm@gmail.com>
Date: Thu, 4 Dec 2025 16:40:26 +0100
Subject: [PATCH 2/2] Update changelog

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5d90532..917ee38 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 ## 1.7.0.0
 
-* Remove `insertBehind`
+* Remove `insertBehind` ([#145](https://github.com/lspitzner/pqueue/pull/145))
 
 * Change `Read` and `Show` instances to use `fromList`
   ([#144](https://github.com/lspitzner/pqueue/issues/144))