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Functional Kotlin

You're reading from   Functional Kotlin Extend your OOP skills and implement Functional techniques in Kotlin and Arrow

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Product type Paperback
Published in Feb 2018
Publisher Packt
ISBN-13 9781788476485
Length 350 pages
Edition 1st Edition
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Authors (2):
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Mario Arias Mario Arias
Author Profile Icon Mario Arias
Mario Arias
Rivu Chakraborty Rivu Chakraborty
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Rivu Chakraborty
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Toc

Table of Contents (16) Chapters Close

Preface 1. Kotlin – Data Types, Objects, and Classes FREE CHAPTER 2. Getting Started with Functional Programming 3. Immutability - It's Important 4. Functions, Function Types, and Side Effects 5. More on Functions 6. Delegates in Kotlin 7. Asynchronous Programming with Coroutines 8. Collections and Data Operations in Kotlin 9. Functional Programming and Reactive Programming 10. Functors, Applicatives, and Monads 11. Working with Streams in Kotlin 12. Getting Started with Arrow 13. Arrow Types 14. Kotlin's Quick Start 15. Other Books You May Enjoy

Pipes


A pipe function takes a T value and invokes a (T) -> R function with it:

import arrow.syntax.function.pipe

fun main(args: Array<String>) {
    val strong: (String) -> String = { body -> "<strong>$body</strong>" }

   "From a pipe".pipe(strong).pipe(::println)
}

A pipe is similar to function composition, but instead of generating new functions, we can chain function invocations to produce new values, reducing nesting calls. Pipes are known in other languages, such as Elm and Ocaml, as the operator |>:

fun main(args: Array<String>) {
   splitter(filterBills(calculatePrice(Quote(20.0, "Foo", "Shoes", 1)))) //Nested

   Quote(20.0, "Foo", "Shoes", 1) pipe ::calculatePrice pipe ::filterBills pipe ::splitter //Pipe
}

Both lines are equivalent, but the first one must be understood backwards and the second one should read from left to right:

import arrow.syntax.function.pipe
import arrow.syntax.function.pipe3
import arrow.syntax.function.reverse

fun main(args...
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