Too many stacked strings

[SymonJory]

Hi,

I'm running the following code:

from pyswip import *
prolog = Prolog()
prolog.assertz("smokes(j)")
prolog.assertz("smokes(b)")
prolog.assertz("friends(j,b)")
prolog.assertz("friends(b,j)")
prolog.assertz("cancer(X) :- smokes(X)")
prolog.assertz("smokes(Y) :- friends(X,Y), smokes(X)")
q = prolog.query("smokes(Z)")
print(list(q))

This returns the error "Too many stacked strings". I'm sure there is an obvious problem with my code, but I don't see what the problem in my code is. I'd benefit from any trouble-shooting.

best,

Symon

[SymonJory]

I believe this is due to looping. It could be solved by reference to swipl's "distinct". Does pyswip have a version of "distinct"?

[SymonJory]

Solved the problem. For others who want to avoid this, the following code should run fine:

from pyswip import *
prolog = Prolog()
prolog.assertz("smokes(j)")
prolog.assertz("smokes(b)")
prolog.assertz("friends(j,b)")
prolog.assertz("friends(b,j)")
prolog.assertz("cancer(X) :- smokes(X)")

prolog.assertz("distinct(smokes(Y) :- friends(X,Y), smokes(X))")

q = prolog.query("smokes(Z)")
print(list(q))