is_odd(X) :- 1 is mod(X,2). is_even(X) :- 0 is mod(X,2).
is_odd(X)
GNU Prolog 1.3.1
By Daniel Diaz
Copyright (C) 1999-2009 Daniel Diaz
uncaught exception: error(syntax_error('user_input:1 (char:10) . or operator expected after expression'),read_term/3)