The FP ecosystem in Kotlin

@pacoworks Paco Estevez “Stop ****ing up our language” The FP
ecosystem in Kotlin

@pacoworks Arrow: arrow-kt.io 2

@pacoworks Version 0.10 - Released this month! 2.5 years running
3

@pacoworks Stop 4 First interaction with Kotlin leadership

@pacoworks 5 Meme: “I’m Spanish but I haven’t come to
talk about FP”

@pacoworks Funktionale + Kategory = Arrow 6

@pacoworks Tens of known Apps, as many backends Talks around
the world Multiple books 3k Github stars 7

@pacoworks Consultancies 8 Legitimate now

@pacoworks What is in it? 9

@pacoworks Boring libraries 10 Prelude Effect system Optics Metaprogramming utils
soon

@pacoworks Incubator libraries 11 Recursion Schemes MTL Free AQL Streams
Collections

@pacoworks Most important contribution? 12

@pacoworks 13

@pacoworks 14

@pacoworks 15

@pacoworks 16

@pacoworks Arrow Docs 17

@pacoworks Arrow Fx 20

@pacoworks Principles 21 Based off existing research Uses coroutines Flattened
IO combinators

@pacoworks Primitives 22 fx for syntax effect to wrap !
to compute

@pacoworks Future of Fx 24 Bifunctor IO Reader + Bifunctor
IO Streams

@pacoworks Arrow Core 25

@pacoworks Prelude I 26 Anaemic stdlib Datatypes

@pacoworks Kind<F, A> 27

@pacoworks F 28

@pacoworks class ForList private constructor() 29

@pacoworks class ForSequence private constructor() class ForOption private constructor() class
ForTry private constructor() class ForId private constructor() class ForSet private constructor() 30

@pacoworks Kind<ForOption, A> isomorphism Option<A> 31 <--- <---

@pacoworks class Option<A>: Kind<ForOption, A> 32

@pacoworks fun Kind<ForOption, A>.fix(): Option<A> = 33

@pacoworks Extension functions are checked at compile time 34

@pacoworks fun Kind<ForOption, A>.fix(): Option<A> = this as Option<A> 35
Safe! Pinkie promise Totally ok

@pacoworks Prelude II 36 Anaemic stdlib Datatypes Typeclasses

@pacoworks fun <F, A, B> Kind<F, A>.map( f: (A) ->
B, ): Kind<F, B> 37

@pacoworks 38

@pacoworks Arrow Meta 40

@pacoworks Tinkering… 41 Quasiquoting Hacking the typechecker Purity checker Coherent
typeclass implementation

@pacoworks …in the real world 42 Early days Lots of
potential experiments Focus on industrial uses

@pacoworks Growing an ecosystem 43

@pacoworks Letting talent flourish 44 Optics - Simon Vergauwen Recursion
Schemes - Aedan Smith Free - Pablo Guardiola

@pacoworks Sister projects 45 Ank Helios Kessel Hoplite KotlinTest

@pacoworks Papers in Practice 46 The Frank language: Do be
do be do Selective Applicative Functors Build Systems a la Carte Defunctionalized Kind Projections

@pacoworks Come join us! 47

@pacoworks Community ❤ gitter.im/arrow-kt/ 48 138 github contributors Gitter.im chat
Kotlinlang slack #arrow

@pacoworks Arrow: arrow-kt.io pacoworks.com @pacoworks github.com/pakoito Slides: tinyurl.com/ArrowAle19 49 Special
thanks to all Arrow contributors & supporters!

The FP ecosystem in Kotlin

The FP ecosystem in Kotlin

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