prime generator for prolog

prime.pl

fill([], _, 0).
fill([X|Xs], X, N) :- succ(N0, N), fill(Xs, X, N0).

prime(N, 1) :- write('is prime'), nl.

prime(N, N) :-
  D1 is N - 1,
  write(D1), nl,
  prime(N, D1).

prime(N, D) :-
  write(D), nl,
  0 < mod(N,D),
  D1 is D - 1,
  prime(N, D1).
  
loop(0, X, List).
loop(N, X, List) :-
  append([X], List, L1),
  N1 is N - 1,
  loop(N1, L1, X).
    
change_element(C, I, Old, New, Val) :-
  print(New), nl,
  C = I 
  ->
    append(New, [Val], N),
    C1 = C + 1,
    change_element(C1, I, Old, N, Val)
  ;
    length(Old, L),
    C < L ->
      nth0(C, Old, E),
      append(New, [E], N),
      C1 is C + 1,
      change_element(C1, I, Old, N, Val)
    ;
      true.
      
  
steploop(Start, List, Step) :-
  print(List), nl,
  length(List, L),
  Start < L ->
    NList = [],
    change_element(0, Start, List, NList, 1),
    S1 is Start + Step,
    steploop(S1, NList, Step)
  ;
    true.
  
ifloop(I, List, Condition) :-
  length(List, L),
  I < L,
  nth0(I, List, E),
  E is Condition -> print(I), nl ; true,
  I1 is I + 1,
  ifloop(I1, List, Condition).
  
primeloop(I, List) :-
  length(List, L),
  I < L,
  nth0(I, List, X),
  % print(X), nl,
  X = 1 -> steploop(I, List, I) ;
  I1 is I + 1,
  primeloop(I1, List).

subloop(0, X, List).
subloop(I, X, List) :-
  print(List), nl,
  append(List, [X], L),
  I1 is I - 1,
  subloop(I1, X, L).

genprime(N) :-
  I is N,
  % print('start'), nl,
  List = [0,1],
  % print(List), nl,
  L = [],
  subloop(I, 0, L),
  append(List, L, List),
  print('list '),
  print(L), nl,
  primeloop(0, List),
  ifloop(0, List, 1),
  print(List) , nl.