Interface segregation here makes more sense

src/EventDispatcher/EventDispatcherInterface.php

@@ -8,14 +8,9 @@
 interface EventDispatcherInterface
 {
     /**
-     * @param $eventName
+     * Dispatches an event
+     * @param string $eventName The name of the event
      * @param array ...$arguments
      */
     public function dispatch($eventName, ...$arguments);
-
-    /**
-     * @param string $eventName
-     * @param callable $callable
-     */
-    public function addListener($eventName, callable $callable);
-}
+}

src/EventDispatcher/EventListenerInterface.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace HelloFresh\Engine\EventDispatcher;
+
+/**
+ * Base type for an event listener.
+ */
+interface EventListenerInterface
+{
+    /**
+     * Adds a listener to an event
+     * @param string $eventName The event name
+     * @param callable $callable The callable that will be called when the event happens
+     */
+    public function addListener($eventName, callable $callable);
+}

src/EventDispatcher/EventDispatcher.php → src/EventDispatcher/InMemoryDispatcher.php

@@ -7,9 +7,9 @@
 use Collections\MapInterface;
 
 /**
- * Event dispatcher implementation.
+ * In Memory Event dispatcher implementation.
  */
-class EventDispatcher implements EventDispatcherInterface
+class InMemoryDispatcher implements EventDispatcherInterface, EventListenerInterface
 {
     /**
      * @var MapInterface