Subversion Repositories programming

even(X) :- 0 is X mod 2.
odd(X) :- 1 is X mod 2.

none([],0,0).

none([H|T],NO,NE) :- odd(H),
                     none(T,N,NE),
                     NO is N+1.

none([_|T],NO,NE) :- none(T,NO,N),
                     NE is N+1.