recur.js

function solve_board_step(solve_state) {
    if (solve_state.p >= solve_state.max_length) {
        solve_state.finish_callback(solve_state.solutions);
        return;
    }

    ++ solve_state.p;
    solve_state.solutions = evolve_solutions(solve_state.solutions,
                                             solve_state.weights,
                                             solve_state.dir_step);
    solve_state.step_callback(solve_state.p, solve_state.max_length);

    setTimeout(function() { solve_board_step(solve_state); }, 0);
}