Currently, we document this law:

> If defined, some and many should be the least solutions of the equations:

> some v = (:) <$> v <*> many v

> many v = some v <|> pure []

This seems a bit too strong. I believe we should weaken "should be the least solutions of" to "should obey". This allows non-bottoming implementations for more types. I would be surprised if the change would meaningfully weaken the value of the law for reasoning about real programs.

For example, we currently require

some Nothing = Nothing

some (Just x) = _|_

many Nothing = Just []

many (Just x) = _|_

But if we weaken the law, we could instead use

some Nothing = Nothing

some (Just x) = Just (repeat x)

many Nothing = Just []

many (Just x) = Just (repeat x)

This seems strictly, albeit slightly, more interesting.

More significantly, I think, the instance for functor products can also get much better-defined:

some (x :*: y) = some x :*: some y

many (x :*: y) = many x :*: many y

That strikes me as an improvement that may actually be of some practical value.

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