Re: listing/1 behavior

[Lindsey Spratt]

This issue came up on this list just recently ("Bug with streams or 
listing?"). I answered it with the following:

The problem here is that listing/1 does not write to stdout (which is 
what tell/1 redirects) but rather to top_level_output. I don't know if 
there's any way to redirect top_level_output. (I would think listing/1 
*should* use stdout.)

You can write listing/1 to an arbitrary stream using a *mirror*:

?- open('foo', write, S), add_stream_mirror(top_level_output, S), 
listing(kb), close(S).

This will write the listing for kb to file 'foo'.

On Nov 23, 2005, at 11:44 AM, Nuno Morgadinho wrote:

> Shouldn't listing/1 use the output stream set by tell/1?
>
> example:-
>         tell('example.pl'),
>         listing(something/2),
>         told.
>
>
> This doesn't work for me with gprolog-1.2.18 on x86.