book-monads/src/ch04/s00-concerns.md

Concerns (questions) with the current implementaion

There exist alternative Functor implementations

See the relevant subchapter

It might be better to have a per-lifetime trait for Functors

See the relevant subchapter

Stackless is kind of bad

See the relevant subchapter

WeakFunctor::F<'a, A> is not (yet) covariant over the lifetime 'a

See the relevant subchapter

Fail/FailMonad/etc. have unclear semantics

See the relevant subchapter

Can WeakFunctor be an associated type of a Functor instead of its supertype?