import cp.

% Returns all permutations
permutation_cp1(N) = solve_all(X) =>
   X = new_list(N),
   X :: 1..N,
   all_different(X).

% Find next permutation on backtracking
permutation_cp2(N,X) =>
   X = new_list(N),
   X :: 1..N,
   all_different(X),
   solve(X).

% Use the cp approach on a list L.
permutation_cp_list(L) = Perms =>
  Perms = [ [L[I] : I in P] : P in permutation_cp1(L.len)].