97 Things Every Java Programmer Should Know by Kevlin Henney

Author:Kevlin Henney
Language: eng
Format: epub
Publisher: O'Reilly Media
Published: 2020-05-15T00:00:00+00:00

Optional Is a Lawbreaking Monad but a Good Type

Nicolai Parlog

In most programming languages, empty-or-not-empty types are well-behaved monads. (Yes, I used the M-word—don’t worry, no math.) This means their mechanics fulfill a couple of definitions and follow a number of laws that guarantee safe (de)composition of computations.

Optional’s methods fulfill these definitions but break the laws. Not without consequences...

Monad Definition

You need three things to define a monad—in Optional’s terms:

The type Optional<T> itself

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.