Ah, thanks. Now I've got it.
This is working:
?- [user].
|: fembots(["Alita", "Isla", "Chi"]).
|: buildfembot(X) :- fembots(L),member(X, L),print("Start building…").
|: ^D% user://9 compiled 0.06 sec, 3 clauses
?- buildfembot("Alita").
"Start building…"
true .
The variable for the list only needs to be on the right side. I got confused with the idea of singelton variables. I thought I need the same on both sides, but it's only important that they occur more than once.
I nearly had this part: buildfembot(X) :- fembots(L),member(X, L)
Here: sublist(A,B) :- alist(A),member(A,B). Doesn't work.
Also doesnt work: sublist(A,B) :- alist(B),member(A,B).
I didn't need the variable for the list I wanted to retrieve, and it might even not possible to hand it over that way. If it is possible, then I still don't know that part. However, that's no problem. The right style in Prolog seems to be to break these things in little parts anyways.
I started reading "Prolog Programming - A First Course, Paul Brna"