mba:crypto_xps johnz$ swipl
Welcome to SWI-Prolog (threaded, 64 bits, version 8.0.3)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit http://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- consult('crypto.pro').
true.

?- display_bindings.
lo ---> 0
hi ---> 9
true.

?- solve_one.
Problem : numbers = {2, 3, 1, 1, 6} and goal = 6
Solution: ( 6 + ( ( 2 + 3 ) * ( 1 - 1 ) ) )
true .

?- demo(5).
Problem : numbers = {3, 2, 3, 5, 8} and goal = 0
Solution: ( ( 3 + 2 ) * ( ( 3 + 5 ) - 8 ) )
Problem : numbers = {6, 1, 5, 5, 8} and goal = 0
Solution: ( ( 5 - 5 ) * ( 8 + (6 + 1 ) ) ) 
Problem : numbers = {7, 4, 0, 9, 0} and goal = 0
Solution: ( ( 0 + 9 ) * ( 0 * ( 7 + 4 ) ) ) 
Problem : numbers = {0, 2, 2, 2, 8} and goal = 0
Solution: ( ( 8 / ( 0 + 2 ) ) - ( 2 + 2 ) ) 
Problem : numbers = {2, 5, 2, 5, 9} and goal = 0
Solution: ( 9 * ( ( 2 + 5 ) - ( 2 + 5 ) ) ) 
true .

?- display_bindings.
lo ---> 0
hi ---> 9
crypto_problem ---> problem(numbers(2,5,2,5,9),goal(0))
solution ---> solution(ex(9, *, ex(ex(2, +, 5), -, ex(2, +, 5)))) 
true.

?- solve(problem(numbers(0,0,0,0,7),goal(8))).
Problem : numbers = {0, 0, 0, 0, 7} and goal = 8
No solution to this problem.
true .

?- display_bindings.
lo ---> 0
hi ---> 9
crypto_problem ---> problem(numbers(0,0,0,0,7),goal(8))
solution ---> solution(none)
true.

?- halt.
mba:crypto_xps johnz$