From 180e9514a3169665daa8786be2abbf0594ce2120 Mon Sep 17 00:00:00 2001
From: Giacomo Cavalieri <giacomo.cavalieri@icloud.com>
Date: Mon, 27 Jan 2025 17:07:18 +0100
Subject: [PATCH] deprecate list.pop and list.pop_map

---
 CHANGELOG.md         |  1 +
 src/gleam/list.gleam | 23 ++++++++++++++++-------
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6fb78ec5..ae8733bc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Fixed a bug that would result in `list.unique` having quadratic runtime.
+- The `pop` and `pop_map` functions in the `list` module have been deprecated.
 
 ## v0.53.0 - 2025-01-23
 
diff --git a/src/gleam/list.gleam b/src/gleam/list.gleam
index fb66b890..a4e2b270 100644
--- a/src/gleam/list.gleam
+++ b/src/gleam/list.gleam
@@ -1663,6 +1663,7 @@ pub fn key_filter(
 /// // -> Error(Nil)
 /// ```
 ///
+@deprecated("This function will be removed in the next gleam_stdlib version")
 pub fn pop(
   in list: List(a),
   one_that is_desired: fn(a) -> Bool,
@@ -1703,6 +1704,7 @@ fn pop_loop(haystack, predicate, checked) {
 /// // -> Error(Nil)
 /// ```
 ///
+@deprecated("This function will be removed in the next gleam_stdlib version")
 pub fn pop_map(
   in haystack: List(a),
   one_that is_desired: fn(a) -> Result(b, c),
@@ -1749,13 +1751,20 @@ fn pop_map_loop(
 /// ```
 ///
 pub fn key_pop(list: List(#(k, v)), key: k) -> Result(#(v, List(#(k, v))), Nil) {
-  pop_map(list, fn(entry) {
-    let #(k, v) = entry
-    case k {
-      k if k == key -> Ok(v)
-      _ -> Error(Nil)
-    }
-  })
+  key_pop_loop(list, key, [])
+}
+
+fn key_pop_loop(
+  list: List(#(k, v)),
+  key: k,
+  checked: List(#(k, v)),
+) -> Result(#(v, List(#(k, v))), Nil) {
+  case list {
+    [] -> Error(Nil)
+    [#(k, v), ..rest] if k == key ->
+      Ok(#(v, reverse_and_prepend(checked, rest)))
+    [first, ..rest] -> key_pop_loop(rest, key, [first, ..checked])
+  }
 }
 
 /// Given a list of 2-element tuples, inserts a key and value into the list.