Function : compose “.“, Id
Monad: compose “>>=“, return
Imperative (with side effects eg. state, I/O, exception ) to Pure function by hiding or embellishment in Pure function but return “embellished” result.
10. 2 Monoid
Monoid in category of endo functors = Monad
Ref Book :
What is the significance of monoids in category theory? by Bartosz Milewski