From 71244e633c6f4a26a05bd40c1229437be51ff861 Mon Sep 17 00:00:00 2001
From: gusty <1261319+gusty@users.noreply.github.com>
Date: Sat, 24 Jan 2026 19:41:23 +0100
Subject: [PATCH] Add function setItem

---
 src/FSharpPlus/Operators.fs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/FSharpPlus/Operators.fs b/src/FSharpPlus/Operators.fs
index 44130d98f..8d1eba66d 100644
--- a/src/FSharpPlus/Operators.fs
+++ b/src/FSharpPlus/Operators.fs
@@ -3,6 +3,8 @@ namespace FSharpPlus
 open System
 open FSharpPlus.Control
 
+#nowarn "0077" // Member constraints with the name 'set_Item' ...
+
 /// Generic functions and operators
 [<AutoOpenAttribute>]
 module Operators =
@@ -849,6 +851,17 @@ module Operators =
     /// <category index="16">Indexable</category>
     let inline tryItem (n: 'K) (source: '``Indexed<'T>``) : 'T option = TryItem.Invoke n source
 
+    /// <summary>
+    /// Mutates an item at the given key/index.
+    /// </summary>
+    /// <param name="item">The key/index where to set the value.</param>
+    /// <param name="value">The value to set.</param>
+    /// <param name="source">The input collection.</param>
+    /// <returns>unit</returns>
+    /// <remarks>This function requires that the source type has a mutable indexer.</remarks>
+    /// <category index="16">Indexable</category>
+    let inline setItem (item: 'K) (value: 'T) (source: ^``Indexed<'T>``) = (^``Indexed<'T>`` : (member set_Item : 'K -> 'T -> unit) (source, item, value))
+
     /// <summary>
     /// Maps with access to the index.
     /// </summary>