tasks

// ...

use Illuminate\Http\Request;

// Show Tasks
// ...

// Add New Task
Route::post('/task', function (Request $request) {
    // Validate input
    $validator = Validator::make($request->all(), [
        'name' => 'required|max:255',
    ]);

    if ($validator->fails()) {
        return redirect('/')
            ->withInput()
            ->withErrors($validator);
    }

    // Create task
    $task = new Task;
    $task->name = $request->name;
    $task->save();

    return redirect('/');
});