diff --git a/Makefile b/Makefile
index b78ec91..3eb5475 100644
--- a/Makefile
+++ b/Makefile
@@ -23,6 +23,9 @@ style-check:
 style-fix:
 	$(docker) vendor/bin/phpcbf -p --standard=PSR12 src
 
+stan:
+	$(docker) vendor/bin/phpstan analyse
+
 unit:
 	$(docker) -dzend_extension=xdebug.so -dxdebug.mode=coverage  vendor/bin/phpunit
 
diff --git a/src/MappedWithKeys.php b/src/MappedWithKeys.php
new file mode 100644
index 0000000..41f884c
--- /dev/null
+++ b/src/MappedWithKeys.php
@@ -0,0 +1,92 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ElegantBro\Arrayee;
+
+use ElegantBro\Interfaces\Arrayee;
+use Exception;
+use function call_user_func;
+
+/**
+ * @template In
+ * @template Out
+ */
+final class MappedWithKeys implements Arrayee
+{
+    /**
+     * @var Arrayee
+     */
+    private $arrayee;
+
+    /**
+     * @var callable
+     */
+    private $valFunc;
+
+    /**
+     * @var callable
+     */
+    private $keyFunc;
+
+    /**
+     * @param Arrayee<In> $arrayee
+     * @param callable $valFunc
+     * @return self<Out>
+     */
+    public static function preserveKeys(Arrayee $arrayee, callable $valFunc): self
+    {
+        return new self(
+            $arrayee,
+            static function ($key) {
+                return $key;
+            },
+            $valFunc
+        );
+    }
+
+    /**
+     * @param Arrayee<In> $arrayee
+     * @param callable $keyFunc
+     * @return self<Out>
+     */
+    public static function preserveValues(Arrayee $arrayee, callable $keyFunc): self
+    {
+        return new self(
+            $arrayee,
+            $keyFunc,
+            static function ($key, $val) {
+                return $val;
+            },
+        );
+    }
+
+    /**
+     * MappedWithKeys constructor.
+     * @param Arrayee<In> $arrayee
+     * @param callable $keyFunc
+     * @param callable $valFunc
+     */
+    public function __construct(Arrayee $arrayee, callable $keyFunc, callable $valFunc)
+    {
+        $this->arrayee = $arrayee;
+        $this->keyFunc = $keyFunc;
+        $this->valFunc = $valFunc;
+    }
+
+    /**
+     * @return array<Out>
+     * @throws Exception
+     */
+    public function asArray(): array
+    {
+        $res = [];
+        foreach ($this->arrayee->asArray() as $key => $val) {
+            $res[
+                call_user_func($this->keyFunc, $key, $val)
+            ] = call_user_func($this->valFunc, $key, $val);
+        }
+
+        return $res;
+    }
+}
diff --git a/tests/MappedWithKeysTest.php b/tests/MappedWithKeysTest.php
new file mode 100644
index 0000000..bb622c3
--- /dev/null
+++ b/tests/MappedWithKeysTest.php
@@ -0,0 +1,89 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ElegantBro\Arrayee\Tests;
+
+use ElegantBro\Arrayee\Just;
+use ElegantBro\Arrayee\MappedWithKeys;
+use Exception;
+use PHPUnit\Framework\TestCase;
+use function strtoupper;
+
+final class MappedWithKeysTest extends TestCase
+{
+    /**
+     * @throws Exception
+     */
+    public function testAsArray(): void
+    {
+        self::assertEquals(
+            [
+                2 => 'FOO',
+                6 => 'BAR',
+                10 => 'BAZ',
+            ],
+            (new MappedWithKeys(
+                new Just([
+                    1 => 'foo',
+                    3 => 'bar',
+                    5 => 'baz',
+                ]),
+                static function(int $key): int {
+                    return $key * 2;
+                },
+                static function(int $key, string $val): string {
+                    return strtoupper($val);
+                },
+            ))->asArray()
+        );
+    }
+
+    /**
+     * @throws Exception
+     */
+    public function testPreserveKeys(): void
+    {
+        self::assertEquals(
+            [
+                1 => 'FOO',
+                3 => 'BAR',
+                5 => 'BAZ',
+            ],
+            MappedWithKeys::preserveKeys(
+                new Just([
+                    1 => 'foo',
+                    3 => 'bar',
+                    5 => 'baz',
+                ]),
+                static function(int $key, string $val): string {
+                    return strtoupper($val);
+                },
+            )->asArray()
+        );
+    }
+
+    /**
+     * @throws Exception
+     */
+    public function testPreserveValues(): void
+    {
+        self::assertEquals(
+            [
+                2 => 'foo',
+                6 => 'bar',
+                10 => 'baz',
+            ],
+            MappedWithKeys::preserveValues(
+                new Just([
+                    1 => 'foo',
+                    3 => 'bar',
+                    5 => 'baz',
+                ]),
+                static function(int $key): int {
+                    return $key * 2;
+                },
+            )->asArray()
+        );
+    }
+}