isn't that just saying that 'head' shouldn't return [] on an empty list, because [] has a type which is never the type of what 'head' should return? that's sepa

isn't that just saying that 'head' shouldn't return [] on an empty list, because [] has a type which is never the type of what 'head' should return? that's separate from why 'head's type isn't [a] -> Maybe a.