feat: allow noop mapper for mapFromIterable

Author: simPod

src/ds.php

@@ -31,7 +31,7 @@ function mapFromEntries(iterable $entries): Map
 
 /**
  * @param iterable<K, V> $iterable
- * @param callable(K, V): Pair<KReturn, VReturn> $mapper
+ * @param callable(K, V): Pair<KReturn, VReturn>|null $mapper   If not provided then the output for `iterable<K, V>` is `Map<K, V>`
  *
  * @return Map<KReturn, VReturn>
  *
@@ -40,11 +40,13 @@ function mapFromEntries(iterable $entries): Map
  * @template KReturn
  * @template VReturn
  */
-function mapFromIterable(iterable $iterable, callable $mapper): Map
+function mapFromIterable(iterable $iterable, callable|null $mapper = null): Map
 {
     /** @var Map<KReturn, VReturn> $map */
     $map = new Map();
 
+    $mapper ??= static fn ($key, $value) => new Pair($key, $value);
+
     foreach ($iterable as $key => $value) {
         $keyValue = $mapper($key, $value);
         $map->put($keyValue->key, $keyValue->value);

tests/DsTest.php

@@ -53,6 +53,22 @@ public function testMapFromIterable(): void
         self::assertFalse($map->get(4));
     }
 
+    public function testMapFromIterableNoopMapper(): void
+    {
+        /** @var callable():Generator<int, bool> $iterableFactory */
+        $iterableFactory = static function (): Generator {
+            yield 1 => true;
+            yield 2 => false;
+            yield 2 => true;
+        };
+
+        $map = mapFromIterable($iterableFactory());
+
+        self::assertCount(2, $map);
+        self::assertTrue($map->get(1));
+        self::assertTrue($map->get(2));
+    }
+
     public function testMappedValueSetsFromIterable(): void
     {
         /** @var callable():Generator<int, string> $iterableFactory */