gistfile1.prolog

note(a).
note(b).
note(c).
%note(d).
%note(e).
%note(f).
%note(g).
%note(csharp).
%note(asharp).
%note(dsharp).
%note(fsharp).


notes(X) :-
  bagof(N, note(N),X).

next_note(X) :-
	notes(Y),
	length(Y,Length),
	random(0,Length,Index),
	nth0(Index,Y,X).

pattern(notes,Length,_Constraint,R) :-
	get_note_list(Length,Length,R).

get_note_list(0,_,R):-
	!,R.

get_note_list(X,X,Res) :-
	NewX is X-1,
	next_note(Res),
	get_note_list(NewX,X,[Res]).

get_note_list(X,T,R) :-
	NewX is X-1,
	next_note(Y),
	Res = [Y|R],
	get_note_list(NewX,T,Res).    

%%%SHOULD BE
get_note_list(0,_).
get_note_list(N,Out) :-
	NewN is N-1,
	next_note(Res),
	get_note_list(NewN,R),
	Out = [Res|R],!.