Question

I’m using prolog script to do all queries, the code goes like:

:- initialization(run).

writeln(T) :- write(T), nl.

queryAll :-
    forall(query(Q), (Q ->
        writeln('yes':Q) ;
        writeln('no ':Q))).

run :-
    queryAll,
    halt.

query( (1,2,3) = (X,Y,Z) ).

the problem is that queryAll will only print “yes” or “no” while I want to see the unification results like:

X = 1
Y = 2
Z = 3

How to do this in prolog?
Thanks in advance.

Answer 1

here a sample of gprolog builtins that could be useful to build a better experience for your customers:

| ?- read_term_from_atom('X+Y = 1+2.', T, [variable_names(L)]).

L = ['X'=A,'Y'=B]
T = A+B=1+2

yes
| ?- read_term_from_atom('X+Y = 1+2.', T, [variable_names(L)]),call(T).

L = ['X'=1,'Y'=2]
T = 1+2=1+2

Note that you should change the query/1 content: instead of

query( (1,2,3) = (X,Y,Z) ).

should be

query( '(1,2,3) = (X,Y,Z).' ). % note the dot terminated atom

and then the loop could be, for instance

queryAll :-
    forall(query(Q), 
        ( read_term_from_atom(Q, T, [variable_names(L)]),
          ( T -> writeln('yes':L) ; writeln('no ':Q) )
        )).

I get the hint from this answer.