Correction: Strange Error in Mozart 1.2.5 Upon Usage of '!' Operator

[Benjamin L. Russell]

Okay, that makes sense.  It must be a bug in the
online Tutorial.  I'll probably report it to the
author as soon as I get an opportunity.

The author probably meant to express the following
code snippet, instead (the locations of the Y and !Y
variables in the "local" block have been transposed):

----- code begins immediately after this line -----
local
   Y = 1
in
   local
      M = f(M !Y)
      [X1 Y] = L
      L = [1 2]
   in
      {Browse [M L]}
   end
end
----- code ends immediately before this line -----

Running this code snippet generates the following
output in the Oz browser (assuming Minimal Graph
representation mode):

----- output follows immediately after this line -----
[R1=f(R1 2) [1 2]
----- output ends immediately before this line -----

Thank you.

-- Benjamin L. Russell

--- Maximilian Wilson <wilson.max at gmail.com> wrote:

> On 11/18/05, Benjamin L. Russell
> <dekudekuplex at yahoo.com> wrote:
> > ----- code begins immediately after this line
> -----
> > local
> >    Y = 1
> > in
> >    local
> >       M = f(M Y)
> >       [X1 !Y] = L
> >       L = [1 2]
> >    in
> >       {Browse [M L]}
> >    end
> > end
> > ----- code ends immediately before this line -----
> 
> [X1 !Y] = L asserts that there is a new variable X1
> such that [X1 Y] =
> [1 2], where Y is the original variable Y (!
> prevents variable
> creation, of course). Thus it is equivalent to [X1
> 1] = [1 2]. This
> implies that X1 = 1 and 1 = 2, which is of course
> impossible.
> 
> I haven't done that tutorial so I don't know why it
> would be
> instructing you to do this.
> 
> Max Wilson
> 
> --
> Be pretty if you are,
> Be witty if you can,
> But be cheerful if it kills you.
>