[plt-scheme] How to insert an element in empty list?

Majorinc, Kazimir writes: 

...
> > x
> (1)
> > y
> ((1))
> > z
> ((1)) 
> 
> Now, when I insert an element in x, the lists y and z (and possibly many 
> others) automatically change in the same time. 
> 
> > (set-rest! x (list 2))
> > x
> (1 2)
> > y
> ((1 2))
> > z
> ((1 2))
> > 
> 
> It is  normal because y and z actually contain that same list. How can I 
> make it work the same way if x is initially empty list (not list with one 
> element)?

The action you call "insertion" is a physical modification of the relevant
structure, the changing of one, or both fields of a 'dotted pair'. But the
empty list is simply an irreducible constant, no way to modify it, since it
has no internal structure: there were LISPs where NIL was just zero, and
the atom NIL *was* the empty list. Modifying zero could be harmful for
your health... 

In your case you must replace x by something else, in y and z. 

Jerzy Karczmarczuk