TYPO3 Core

Currently arrow functions (like delta functions or closure functions) are assigned to class properties.

public handleSubmit = (event: Event): void => { }

which could be simplified as real functions

public handleSubmit(event: Event): void { }

In PHP the original scenario would look like

class Thing
{
  public $handleSubmit;

  public function __construct()
  {
    $this->handleSubmit = function($event) {}
  }
}