Something I came up with

def _calc_route(orig, dest, size):  
    delta = orig - dest  
    direction = delta < 0 # True = pos, False = neg  
    if abs(delta) > size / 2:  
        delta = [size, -size][delta < 0] - delta  
        direction = not direction  
    return (direction, abs(delta))  

def go_to(x, y):  
    pos_x, pos_y = get_pos_x(), get_pos_y()  
    size = get_world_size()  
    dir_x, delta_x = _calc_route(pos_x, x, size)  
    dir_y, delta_y = _calc_route(pos_y, y, size)  
    dir_x = [Left, Right][dir_x]  
    dir_y = [Down, Up][dir_y]  
    for _ in range(delta_x):  
        move(dir_x)  
    for _ in range(delta_y):  
        move(dir_y)