问如何输入5个数字并确定顺序？斯威-普罗格

EN

:- use_module(library(dcg/basics)).

rpn :-
    prompt(_, '(number or command followed by Enter; ? for help) '),
    repl([]).

repl(Stack) :-
    get_token(T),
    repl(T, Stack).

get_token(T) :-
    read_line_to_codes(user_input, Input),
    (   Input == end_of_file
    ->  T = quit
    ;   (   phrase(( whites, token(T), whites ), Input)
        ->  true
        ;   T = error(Input)
        )
    ).

token(number(N)) --> number(N).
token(print_stack) --> "p".
token(highest) --> "H".
token(second_highest) --> "h".
token(lowest) --> "L".
token(second_lowest) --> "l".
token(clear) --> "c".
token(help) --> "?".
token(quit) --> "q" | "quit" | "exit".

repl(quit, _) :-
    format("Goodbye!~n").
repl(error(E), Stack) :-
    format("Bad input: `~s'~n", [E]),
    repl(Stack).
repl(help, Stack) :-
    format("Add a number to the list or type:~n"),
    format("   'H' to show highest number~n"),
    format("   'h' to show second-highest number~n"),
    format("   'L' to show lowest number~n"),
    format("   'l' to show second-lowest number~n"),
    format("   'p' to print the stack, top to bottom~n"),
    format("   'c' to clear the stack~n"),
    format("   '?' to show this help~n"),
    format("then press Enter~n"),
    repl(Stack).
repl(print_stack, Stack) :-
    reverse(Stack, S),
    forall(member(X, S), format("~w~n", [X])),
    repl(Stack).
repl(highest, Stack) :-
    max_list(Stack, X),
    format("Highest: ~w~n", [X]),
    repl(Stack).
repl(second_highest, Stack) :-
    sort(0, @>=, Stack, [_,X|_]), % this keeps duplicates!
    format("Second highest: ~w~n", [X]),
    repl(Stack).
repl(lowest, Stack) :-
    min_list(Stack, X),
    format("Lowest: ~w~n", [X]),
    repl(Stack).
repl(second_lowest, Stack) :-
    sort(0, @>=, Stack, [_,X|_]),
    format("Second lowest: ~w~n", [X]),
    repl(Stack).
repl(clear, _) :-
    repl([]).
repl(number(N), Stack) :-
    repl([N|Stack]).

?- rpn.
(number or command followed by Enter; ? for help) 46
(number or command followed by Enter; ? for help) 1
(number or command followed by Enter; ? for help) 234
(number or command followed by Enter; ? for help) 67
(number or command followed by Enter; ? for help) 8
(number or command followed by Enter; ? for help) ?
Add a number to the list or type:
   'H' to show highest number
   'h' to show second-highest number
   'L' to show lowest number
   'l' to show second-lowest number
   'p' to print the stack, top to bottom
   'c' to clear the stack
   '?' to show this help
then press Enter
(number or command followed by Enter; ? for help) h
Second highest: 67
(number or command followed by Enter; ? for help) H
Highest: 234
(number or command followed by Enter; ? for help) p
46
1
234
67
8
(number or command followed by Enter; ? for help) c
(number or command followed by Enter; ? for help) p
(number or command followed by Enter; ? for help) quit
Goodbye!
true.