Monads with Java 8

Question

In the interests of helping to understand what a monad is, can someone provide an example using java ? Are they possible ?

Lambda expressions are possible using java

Answer 1

Despite all controversy about Optional satisfying, or not, the Monad laws, I usually like to look at Stream, Optional and CompletableFuture in the same way. In truth, all them provide a flatMap() and that is all I care and let me embrace the "the tasteful composition of side effects" (cited by Erik Meijer). So we may have corresponding Stream, Optional and CompletableFuture in the following way:

Regarding Monads, I usually simplify it only thinking on flatMap()(from "Principles of Reactive Programming" course by Erik Meijer):