[PPL-devel] Unwanted prompt in the output

[Roberto Bagnara]

Hi there,

I have question: if I create a file that contains
only a blank line (i.e., "\n") and I call it `test'
and I do `pl <test >out', the `out' file contains
the string "1 ?- |    ".  Notice that, to avoid
ambiguities I am using the C syntax for strings,
so by omitting "\n" I imply that the line above
is not terminated.  However, the problem is the
presence of "|    ", not the absence of the
end-of-line character.

If I modify the `test' file so that it contains two lines,
one blank as before followed by one containing "halt.\n"
and I do the same thing as before, `out' will then
contain "1 ?- ", i.e., without the vertical bar.
Is this behavior the intended one?  I have tested
with several other Prolog systems and they do not
seem to make this kind of distinction between EOF
on input or an explicit "halt." occurring in it.
Cheers,

     Roberto

P.S. This question arose during the investigation of
      a more complex problem that is much more difficult
      to reproduce (and explain :-)

-- 
Prof. Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/
mailto:bagnara at cs.unipr.it