TYPO3 - Call another repository

Is it possible to call a function in different controllers? I need to call FindByCategoryGrouped($catId) in designRepository.php and getCategories($catId) from categoryRepository.php

public function listAction() {
    $this->settings['flexform']['showCategory'] ? $catId = $this->settings['flexform']['showCategory']:$catId = $this->settings['listView']['showCategory'];
    // print $catId;
    if (!$catId || $this->settings['flexform']['showCategory'] == '-1') {
        $designs = $this->designRepository->findAll(); 
    } else {
        // $designs = $this->designRepository->findByCategory($catId);
        $designs = $this->designRepository->findByCategoryGrouped($catId);  // THIS
        $categories = $this->categoryRepository->getCategories($catId); // THIS
    }
    // indhold forsvinder hvis næste linje slettes
    $this->view->assign('designs', $designs, "L", $GLOBALS['TSFE']->sys_language_uid);
    $this->view->assign('catId', $catId);
    $this->view->assign('categories', $categories);
}

You can inject every repository of every installed extbase extension. Just add the dependency injection code to your controller. Depending on your TYPO3 version ist either:

TYPO3 >= 6.0:

/**
 * @var \Vendor\Extension\Domain\Repository\SomeRepository
 * @inject
 */
protected $someRepository;

Note that the @inject Annotation does not perform very well in comparison to a dedicated inject method. So if you need to tweek the performance of your application and have many injections in yout controller you should consider switching to inject methods:

/**
 * @var \Vendor\Extension\Domain\Repository\SomeRepository
 */
protected $someRepository;

/**
 * @param \Vendor\Extension\Domain\Repository\SomeRepository
 */
public function injectSomeRepository(\Vendor\Extension\Domain\Repository\SomeRepository $someRepository) {
  $this->someRepository = $someRepository;
}

TYPO3 = 4.7:

/**
 * @var Tx_MyExtension_Domain_Repository_SomeRepository
 * @inject
 */
 protected $someRepository;

TYPO3 < 4.7

/**
 * @var Tx_MyExtension_Domain_Repository_SomeRepository
 */
 protected $someRepository;

/**
 * Inject SomeRepository
 * @param Tx_MyExtension_Domain_Repository_SomeRepository $someRepository
 * @return void
 */
public function injectSomeRepository(Tx_MyExtension_Domain_Repository_SomeRepository $someRepository) {
  $this->someRepository = $someRepository;
}

In any case you can use $this->someRepository with all its methods in the controller you injected the repository into.

Edit: fixed typo.

Edit: After adding a Dependency Injection, you have to clear the cache!