@sig(H[(Ord, "b")]/ ("a"/ H >> "b") >> ["a"] >> ["a"])
def sortOn(f, xs):
    """
    sortOn :: Ord b => (a -> b) -> [a] -> [a]

    Sort a list by comparing the results of a key function applied to each
    element.

    Note: Current implementation is not lazy
    """
    raise NotImplementedError()
dataset/ETHPy150Open billpmurphy/hask/hask/Data/List.py/sortOn/swapped operands of `/`