% '2011-04-05' to date(2011, 4, 5)

atom_to_date(Atom, date(Year, Month, Day)):-
    atom_codes(Atom, [Y1, Y2, Y3, Y4, 45, M1, M2, 45, D1, D2]),
    number_codes(Year, [Y1, Y2, Y3, Y4]),
    (M1 = 48 -> number_codes(Month, [M2]) ; number_codes(Month, [M1, M2])),
    (D1 = 48 -> number_codes(Day, [D2]) ; number_codes(Month, [D1, D2])).