Currently, attempting to produce the arglist for make-instance given some class name causes an error because the compute-applicable-methods-using-classes function isn't defined by ECL. Attached is a patch that adds a stub version of the function which at least makes it possible to type make-instance calls without interruption by an error. In fact, you even get an arglist, although it isn't necessarily correct - for instance, given a defclass such as (defclass foo () (myslot :initarg myinitarg)), Slime presents the arglist as (make-instance 'foo &rest initargs &key (myslot clos::+initform-unsupplied+)), using the slot name rather than the initarg name. I haven't investigated where that comes from, but it's better than nothing.