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Re: [vox-tech] entering a prolog program?
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Re: [vox-tech] entering a prolog program?

On Sat, Nov 20, 2010 at 07:32:55PM -0600, Chanoch (Ken) Bloom wrote:
> On Fri, 2010-11-19 at 20:05 -0800, Brian Lavender wrote:
> > Can you type in axioms into prolog from the command line? All I seem to
> > be able to do is load a program and query it. 
> > 
> > Can I just enter the following program at the prolog prompt?
> > 
> > factorial(0,1).
> >   
> > factorial(A,B) :-  
> >            A > 0, 
> >            C is A-1,
> >            factorial(C,D),
> >            B is A*D. 
> > 
> > 
> > All I seem to be able to do is load it. I am using SWI prolog.
> > 
> > $ swipl
> > ?- ['factorial.pl'].
> > true.
> > 
> > If I try the following, I get an error. 
> > 
> > ?- factorial(0, 1).
> > ERROR: toplevel: Undefined procedure: factorial/2 (DWIM could not correct goal)
> Typing [user]. the way you typed ['factorial.pl']. will enter an
> interactive rule entry mode. When you're finished with that mode, hit
> Ctrl-D to return to query mode.

Thanks. For the life of me I could not find that in the documentation.

Brian Lavender

"Program testing can be used to show the presence of bugs, but never to
show their absence!"

Professor Edsger Dijkstra
1972 Turing award recipient
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