The top-level interpreter

I have shown lots of definitions. How can you use them?

All Prolog systems come with a top-level interpreter. This is a program which reads questions from the user, and calls Prolog's inference mechanism to determine their truth.

Loop:
    Display a '?-' prompt.
    Read the next question.
    If it is true,
        display the variable bindings
    otherwise
        say 'no'
    endif.
    Goto Loop.