Punto paso por referencia

span class="kw2"> let
    f = proc(x,y)
        begin
            set x = +(x,2);
            set y = +(y,3);
            -(x,y)
        end
    g = proc(m,n,o)
        begin
            set n = (m n o);
            set o = (m n o);
            -(n,o)
        end
    x = 5
    y = 7
    z = 9
    in
        begin
      set x = (g f y (g f y z));
      set y = (g f z (g f x z));
      set z = (g f x (g f z x));
            +(x,+(y,z))
        end