[Functional] toArrayList cast for Option.

Author: whsv26

src/Fp/Functional/Option/Option.php

@@ -5,6 +5,7 @@
 namespace Fp\Functional\Option;
 
 use Error;
+use Fp\Collections\ArrayList;
 use Fp\Functional\Either\Either;
 use Fp\Functional\Either\Left;
 use Fp\Functional\Either\Right;
@@ -663,4 +664,36 @@ public static function condLazy(bool $condition, callable $some): Option
             ? self::some($some())
             : self::none();
     }
+
+    /**
+     * Convert optional value to ArrayList collection
+     * via transformation function $callback.
+     *
+     * ```php
+     * >>> Option::some(1)
+     *     ->toArrayList(ArrayList::singleton(...))
+     *     ->toArray();
+     * => [1]
+     *
+     * >>> Option::some([1])
+     *     ->toArrayList(ArrayList::collect(...))
+     *     ->toArray();
+     * => [1]
+     *
+     * >>> Option::none()
+     *     ->toArrayList(ArrayList::collect(...))
+     *     ->toArray();
+     * => []
+     * ```
+     *
+     * @template TOutValue
+     * @param callable(A): ArrayList<TOutValue> $callback
+     * @return ArrayList<TOutValue>
+     */
+    public function toArrayList(callable $callback): ArrayList
+    {
+        return $this->isSome()
+            ? $callback($this->value)
+            : new ArrayList([]);
+    }
 }

tests/Runtime/Classes/Option/OptionTest.php

@@ -6,6 +6,7 @@
 
 use Error;
 use Exception;
+use Fp\Collections\ArrayList;
 use Fp\Functional\Either\Left;
 use Fp\Functional\Either\Right;
 use Fp\Functional\Option\None;
@@ -197,4 +198,22 @@ public function testFlatTap(): void
         $this->assertEquals(1, Option::some(1)->flatTap(fn($e) => Option::some(2))->get());
         $this->assertNull(Option::some(1)->flatTap(fn($e) => Option::none())->get());
     }
+
+    public function testToArrayList(): void
+    {
+        $this->assertEquals(
+            [1],
+            Option::some(1)->toArrayList(fn(int $val) => ArrayList::singleton($val))->toArray()
+        );
+
+        $this->assertEquals(
+            [1],
+            Option::some([1])->toArrayList(fn(array $val) => ArrayList::collect($val))->toArray()
+        );
+
+        $this->assertEquals(
+            [],
+            Option::none()->toArrayList(fn(array $val) => ArrayList::collect($val))->toArray()
+        );
+    }
 }

tests/Static/Classes/Option/OptionStaticTest.php

@@ -4,6 +4,7 @@
 
 namespace Tests\Static\Classes\Option;
 
+use Fp\Collections\ArrayList;
 use Fp\Functional\Option\Option;
 
 final class OptionStaticTest
@@ -44,4 +45,13 @@ public function testFlatMap(): ?string
             ->flatMap(fn(int $v) => Option::fromNullable((string) $v))
             ->get();
     }
+
+    /**
+     * @return ArrayList<1>
+     */
+    public function testToArrayList(): ArrayList
+    {
+        return Option::fromNullable(1)
+            ->toArrayList(fn(int $v) => ArrayList::singleton($v));
+    }
 }