euler4.pl

euler4(Answer) :-
    findall(X, palindromes(X), Palindromes),
    max_list(Palindromes, Answer).

palindromes(Z) :-
    between(100, 999, X),
    between(X, 999, Y),
    Z is X * Y,
    is_palindrome(Z).

is_palindrome(Number) :-
    number_chars(Number, List),
    reverse(List, List).