Hi,
I am new here and a Lisp beginner at his first significant development.
I am having problem to use the :step option of the (trace) form as documented here:
http://ecls.sourceforge.net/new-manual/re02.html

I am using the ECL 12.2.1 REPL on Linux i686.

CL-USER[1]> (defun factorial (n)
    (if (plusp n)
      (* n (factorial (1- n)))
      1))
FACTORIAL
CL-USER[2]> (trace (factorial :step t))

Condition of type: SIMPLE-ERROR
Not a valid argument to TRACE: (FACTORIAL :STEP T)
Available restarts:

1. (RESTART-TOPLEVEL) Go back to Top-Level REPL.

Broken at SI:BYTECODES. [Evaluation of: (TRACE (FACTORIAL :STEP T))] In: #<process TOP-LEVEL>.
** BREAK [LEVEL 2]> 

What am I doing wrong? Does the (trace) macro accept lists, doesn't it?

BTW the equivalent and very similar option in another Lisp (GNU CLISP) works:
(trace (factorial :step-if t))

Thanks
--
Antonio Bonifati
http://ninuzzo.github.com/