@sig(["a"]/ H >> [["a"]] )
def subsequences(xs):
    """
    subsequences :: [a] -> [[a]]

    The subsequences function returns the list of all subsequences of the
    argument.
    """
    ret = L[[L[[]]]]
    for r, _ in enumerate(xs):
        ret += L[(L[x] for x in itertools.combinations(xs, r+1))]
    return ret
dataset/ETHPy150Open billpmurphy/hask/hask/Data/List.py/subsequences/swapped operands of `/`