James Gale wrote: > > 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) > > 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. > > many thanks > > James. > > ps. sorry if this is a silly posting but didn't know what else to try :S > >
I had the same error, but I figured it out :) What you have to do is create a "logic database". This is a simple text file with the facts and the rules of the program (or the "program's universe" if u like :P) Make a blank text file and enter: even(a). even(b). compile with: pe...@ubuntu:~/prog/prolog$ gplc nubble.pro execute with: pe...@ubuntu:~/prog/prolog$ ./nubble This is what you get: GNU Prolog 1.3.0 By Daniel Diaz Copyright (C) 1999-2007 Daniel Diaz | ?- even(X). X = a ? ; X = b yes | ?- even(a). yes | ?- even(c). no | ?- I hope this helps :) -- View this message in context: http://old.nabble.com/uncaught-exception%3A-error%28existence_error%28procedure%2Ceven-1%29%2Ctop_level-0%29-tp22366566p26804308.html Sent from the Gnu - Prolog - Users mailing list archive at Nabble.com. _______________________________________________ Users-prolog mailing list Users-prolog@gnu.org http://lists.gnu.org/mailman/listinfo/users-prolog
