feat: Collection::filter

Author: Fureev Eugene

CHANGELOG.md

@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog][keepachangelog] and this project adheres to [Semantic Versioning][semver].
 
+## v4.17.1
+
+### Changed
+
+- `Collection::filter(Closure $func = null)` - The argument `$func` may be `null`
+
 ## v4.17.0
 
 ### Added

src/Structures/Collections/ArrayCollection.php

@@ -282,7 +282,7 @@ private function getProperty(mixed $target, string|int $keyName, bool $throwOnMi
      * @return static
      * @psalm-return static<TKey,T>
      */
-    public function filter(Closure $func): static
+    public function filter(Closure $func = null): static
     {
         return $this->createFrom(array_filter($this->elements, $func, ARRAY_FILTER_USE_BOTH));
     }

src/Structures/Collections/ReadableCollection.php

@@ -162,13 +162,13 @@ public function exists(Closure $func): bool;
      * Returns all the elements of this collection that satisfy the predicate $func.
      * The order of the elements is preserved.
      *
-     * @param Closure $func The predicate used for filtering.
-     * @psalm-param Closure(T, TKey):bool $func
+     * @param null|Closure $func The predicate used for filtering.
+     * @psalm-param null|Closure(T, TKey):bool $func
      *
      * @return ReadableCollection<mixed> A collection with the results of the filter operation.
      * @psalm-return ReadableCollection<TKey, T>
      */
-    public function filter(Closure $func): ReadableCollection;
+    public function filter(Closure $func = null): ReadableCollection;
 
     /**
      * Applies the given function to each element in the collection and returns