import json


def dump_jsonl(obj):
    """Convert JSON object into 'JSON Lines' format string.
    See http://jsonlines.org/ for the detail of the format.

    Parameters
    ----------
    obj : list of JSON compatible objects
        Objects to be dumped.

    Returns
    -------
    str
        Resulting string.
    """
    if not isinstance(obj, list):
        raise TypeError('The most outer structure must be list.')
    return '\n'.join(json.dumps(obj_, ensure_ascii=True) for obj_ in obj)