Yes, but they don't always have convenient literal notation or a consistent sequence abstraction that encompasses all collection types. For instance, I love Rac

Yes, but they don't always have convenient literal notation or a consistent sequence abstraction that encompasses all collection types. For instance, I love Racket, but the hash literals are very noisy and apply implicit quoting, so they almost never get used. (Though Racket does a good job in most places of having a unified collection interface.) Emacs Lisp has the same problem but nothing coming anywhere close to a collection interface.