Re: [Haskell-beginners] Using Traversal as a kind of pointer

Hi Elise, I'm not quite sure if I completely understood your use case, but if you only want to modify the lifeforms that are colliding with the player, then you could have something like: world & liveforms . filtered (collidingWith player) %~ \liveform -> ... with liveforms :: Lens' World [Lifeform] collidingWith :: Player -> Lifeform -> Bool I would consider this as a quite nice solution. Greetings, Daniel