Monads in Kotlin

In this talk, I discuss what a monad is and some of the advantages of using them in your code base. I also walk through how one might implement some common monads, like the Try or Option monads.

Transcript

1. Monads in Kotlin Amplify your workflow with some functional programming Zach Smith @zws33
5. • A higher order function is one that does at least one of the following: ◦ takes one or more functions as arguments ◦ returns a function as its result Higher order functions
13. A monad is something that implements map and flatmap
14. A monad is something that implements map and flatmap • List
15. A monad is something that implements map and flatmap • List • Observable • Single
20. A monad wraps a value in a meaningful context. • List -> Collection • Observable -> Changing values over time • Single -> A single value over time
21. A monad wraps a value in a meaningful context. • List -> Collection • Observable -> Changing values over time • Single -> A single value over time • Try -> Success or failure • Option -> Presence or absence of value
22. Let’s build the Try monad
27. https://hackernoon.com/kotlin-functors-applicatives-and-monads-in-pictures-part-1-3-c47a1b1ce251
29. https://hackernoon.com/kotlin-functors-applicatives-and-monads-in-pictures-part-3-3-832d58d92445
38. A monad wraps a value in a meaningful context. A monad implements map and flatmap. • List -> Collection • Observable -> Changing values over time • Single -> A single value over time • Try -> Success or failure • Option -> Presence or absence of value
39. Arrow Functional companion to Kotlin’s Standard Library • Popular data types, type classes and abstractions for functional programming: ◦ Option ◦ Try ◦ Either ◦ IO ◦ Functor ◦ Applicative ◦ Monad https://arrow-kt.io/
40. Resources • Kotlin Functors, Applicatives, And Monads in Pictures ◦ https://hackernoon.com/kotlin-functors-applicatives-and-monads-in-pictures-part-1-3-c47a1b1ce251 • Arrow Library ◦ https://arrow-kt.io/ ◦ https://github.com/arrow-kt/arrow • The Observable disguised as an IO Monad ◦ https://medium.com/@luijar/the-observable-disguised-as-an-io-monad-c89042aa8f31 • Why Monads Are Useful ◦ https://jameswestby.net/weblog/tech/why-monads-are-useful.html
41. Thank you! Zach Smith Github: zws33 Twitter: @zws33