Morally equivalent

[John Haman]

The documentation for push is

> push is a Lisp macro in ‘subr.el’.
>
> (push NEWELT PLACE)
>
> Add NEWELT to the list stored in the generalized variable PLACE.
> This is morally equivalent to (setf PLACE (cons NEWELT PLACE)),
> except that PLACE is evaluated only once (after NEWELT).
>
>   Other relevant functions are documented in the list group.
>   Probably introduced at or before Emacs version 21.1.

What is a 'moral equivalence' in Emacs Lisp?

--
Dr. John Haman
Bethesda, MD