Because it doesn ' t work well ! Circular reasoning aside , there is no predefined pop function . This only really comes up when you want an arbitrary element , which you ' d probably write as set . iter . next . andthenset . take . Rust could fairly easily support a safe pop method by making it stochastic , but the usecases is pretty uncommon . It ' s only an attacker vulnerability if you expose it . Creating hash maps was a big problem because all sorts of things make hash maps of user data especially JSON , but not many attackers get mutable access to them . <| sep |> Cake I will survive and Stickshifts and Safetybelts are super fun to play Radiohead My Iron LunghOe 2 zsKsn 90 is probably my favorite Hendrix I like that some of his songs are easy to score 100 % The Wind Cries Mary for example but very hard to make sound good Rage Against the Machine obviously