LispWorks runs a top-level REPL on startup. The listener by default appears with a prompt. The name of the current package (that is, the value of cl:*package*) is printed followed by a positive integer, like this:
CL-USER 1 >
Enter a Lisp form after the prompt and press Return:
CL-USER 1 > (print 42)
42
42
CL-USER 2 >
The first `42' printed is the output of the call to print. You see it here because output sent to *standard-output* is written to the listener.
The second `42' printed is the return value of the call to print.
After the return value a new prompt appears. Notice that it contains `2' after the package name: your successive inputs are numbered. You can now proceed to develop and test pieces of your application code:
CL-USER 2 > (defstruct animal species name weight)
ANIMAL
CL-USER 3 > (make-animal :species "Hippopotamus" :name "Hilda" :weight 42)
#S(ANIMAL :SPECIES "Hippopotamus" :NAME "Hilda" :WEIGHT 42)
LispWorks User Guide and Reference Manual - 13 Feb 2015