For example, I’ve seen someone defining a package like so:
(defpackage :foobar
(:use :cl))
instead of:
(defpackage foobar
(:use cl))
Is there any actual difference? Or it’s just a personal preference, and has no effect on the program at all?
As an aside, I think that every Common Lisp implementation should support a modern mode. The upcasing behaviour of CL — defensible at the time — is in hindsight an easily-fixable mistake.