Re: uncaught exception: error(existence_error(procedure, even/1), top_level/0)

James Gale <[email protected]> writes:

> Hi I'm a newbee to prolog, and have just installed gnu prolog but what every
> I enter into the console I get this error, uncaught exception:
> error(existence_error(procedure,even/1),top_level/0)
>
> example.
>
> GNU Prolog 1.3.1
> By Daniel Diaz
> Copyright (C) 1999-2009 Daniel Diaz
> | ?- even(X).
> uncaught exception: error(existence_error(procedure,even/1),top_level/0)

I'm a bit rusty, and only just installed gprolog myself, and am not
familiar with its messages.  But it looks to me like there is no
predicate 'even/1' defined -- "existence_error(procedure,even/1).

Try something like reverse([1,2,3],X).  If that doesn't work, you have
an installation error.

>
> not sure if the installation was wrong, but got not errors or I'm missing
> something very simple.
> also is there a good FAQ's page for this interpreter.

Google "gprolog tutorial"  I get lots of hits.  I think you need a tutorial
rather than a FAQ.  Work through some of these.

>
> many thanks
>
> James.
>
> ps. sorry if this is a silly posting but didn't know what else to try :S 

Good luck.   This looks like a low traffic list, so I thought I'd go ahead and answer
instead of waiting for a expert.

John Velman