I suppose it is a bug that it just tacks on  'simp   to make   ((mlist simp) ....)  instead of looking for msimpind.


The simplifer looks for, but doesn't find, the msimpind property for mlist:


(%i4) :lisp(setf (get 'mlist 'msimpind) (list 'mlist 'simp))
(MLIST SIMP)

(%i4)  (x : [a], y : [b])$
(%i5) :lisp(eq (car (meval '$x)) (car (meval '$y)))
T