Functional companion to Kotlin's Standard Library
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raulraja Bump Kotlin version to 1.3-RC and updated Coroutines (#1057)
* Update version on build.gradle

* Add wrapper for old behavior

* Update to use kotlin.coroutines

* add flatMap to SuccessOrFailure

* Use short version of constructor

* Update kotlinx.coroutines

* Fix scheduler creation

* Fix ContinuationUtils

* Remove helpers for SuccessOrError to discourage its use

* Move Continuation to Core

* Removed unsafe and other @deprecated functions + General warning cleanup

* Fix `try` docs

* Bump version to 0.8.0-SNAPSHOT

* Bump kotlin version to 1.3.0-rc-190

* Rebase from Paco's branch and most warnings addressed
Latest commit 7d54b31 Oct 20, 2018

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Λrrow is a library for Typed Functional Programming in Kotlin.

Arrow aims to provide a lingua franca of interfaces and abstractions across Kotlin libraries. For this, it includes the most popular data types, type classes and abstractions such as Option, Try, Either, IO, Functor, Applicative, Monad to empower users to write pure FP apps and libraries built atop higher order abstractions.

Use the list below to learn more about Λrrow's main features.

Curated external links

Basic Setup

Make sure to have the latest version of JDK 1.8 installed.

Add it in your root build.gradle at the end of repositories.

allprojects {
    repositories {

Add the dependencies into the project's build.gradle

def arrow_version = "0.7.3"
dependencies {
    compile "io.arrow-kt:arrow-core:$arrow_version"
    compile "io.arrow-kt:arrow-syntax:$arrow_version"
    compile "io.arrow-kt:arrow-typeclasses:$arrow_version" 
    compile "io.arrow-kt:arrow-data:$arrow_version" 
    compile "io.arrow-kt:arrow-instances-core:$arrow_version"
    compile "io.arrow-kt:arrow-instances-data:$arrow_version"
    kapt    "io.arrow-kt:arrow-annotations-processor:$arrow_version" 
    compile "io.arrow-kt:arrow-free:$arrow_version" //optional
    compile "io.arrow-kt:arrow-mtl:$arrow_version" //optional
    compile "io.arrow-kt:arrow-effects:$arrow_version" //optional
    compile "io.arrow-kt:arrow-effects-rx2:$arrow_version" //optional
    compile "io.arrow-kt:arrow-effects-reactor:$arrow_version" //optional
    compile "io.arrow-kt:arrow-effects-kotlinx-coroutines:$arrow_version" //optional
    compile "io.arrow-kt:arrow-optics:$arrow_version" //optional
    compile "io.arrow-kt:arrow-generic:$arrow_version" //optional
    compile "io.arrow-kt:arrow-recursion:$arrow_version" //optional

Additional Setup

For projects that wish to use their own @higherkind, @optics and other meta programming facilities provided by Λrrow the setup below is also required:

Add the dependencies into the project's build.gradle

apply plugin: 'kotlin-kapt' //optional
apply from: rootProject.file('gradle/generated-kotlin-sources.gradle') //only for Android projects

def arrow_version = "0.7.3"
dependencies {
    kapt    'io.arrow-kt:arrow-annotations-processor:$arrow_version' //optional


apply plugin: 'idea'

idea {
    module {
        sourceDirs += files(
        generatedSourceDirs += files(


Copyright (C) 2017 The Λrrow Authors

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.