list-all-packages ⟨no arguments⟩ → packages

packages — a list of package objects.

list-all-packages returns a fresh list of all registered packages.

(let ((before (list-all-packages))) 
   (make-package 'temp) 
   (set-difference (list-all-packages) before)) → (#<PACKAGE "TEMP">)

defpackage, delete-package, make-package