% Reference 9.6: substring and replace have finite boundary behavior.
%% ?- answer(X0, X1).

answer(prefix, X) :- substring('eyeprologlanglet', 0, 9, X).
answer(middle, X) :- substring('eyeprologlanglet', 9, 2, X).
answer(suffix, X) :- substring('eyeprologlanglet', 8, 3, X).
answer(empty_at_end, X) :- substring('eyeprologlanglet', 16, 0, X).
answer(out_of_range_rejected, ok) :- \+ substring('eyeprologlanglet', 16, 2, X).
answer(replace_all, X) :- replace('banana', 'na', 'NA', X).
answer(replace_missing, X) :- replace('banana', 'x', 'y', X).