code-by-sia / arrow

Functional companion to Kotlin's Standard Library

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.

• Documentation
• Patterns: tutorials and approaches to day-to-day challenges using FP
• Libraries: all the libraries provided by Λrrow
• Type classes: defining behaviors for data
• Data types: common abstractions
• Effects: interfacing with external systems
• Optics: inspecting and modifying data structures

Curated external links

• Projects and Examples
• Media: blogs, presentations, etc.

If you have a blog post, talk, or upcoming event on Arrow, please considering opening an issue or PR to add to the collection over at the Arrow Media repo.

About this repository

This repository orchestrates the global configuration and checks of the Λrrow libraries:

	Library	SSH	HTTPS
	Λrrow Ank	[email protected]:arrow-kt/arrow-ank.git	https://github.com/arrow-kt/arrow-ank.git
	Λrrow Core	[email protected]:arrow-kt/arrow-core.git	https://github.com/arrow-kt/arrow-core.git
	Λrrow Fx	[email protected]:arrow-kt/arrow-fx.git	https://github.com/arrow-kt/arrow-fx.git
	Λrrow Incubator	[email protected]:arrow-kt/arrow-incubator.git	https://github.com/arrow-kt/arrow-incubator.git
	Λrrow Integrations	[email protected]:arrow-kt/arrow-integrations.git	https://github.com/arrow-kt/arrow-integrations.git
	Λrrow Optics	[email protected]:arrow-kt/arrow-optics.git	https://github.com/arrow-kt/arrow-optics.git
	Λrrow UI	[email protected]:arrow-kt/arrow-ui.git	https://github.com/arrow-kt/arrow-ui.git

and other related repositories:

	Repository	SSH	HTTPS
	Λrrow Site	[email protected]:arrow-kt/arrow-site.git	https://github.com/arrow-kt/arrow-site.git
	Λrrow Examples	[email protected]:arrow-kt/arrow-examples.git	https://github.com/arrow-kt/arrow-examples.git

Find more details in Move arrow repository content to multi-repo.

Join Us

Arrow is an inclusive community powered by awesome individuals like you. As an actively growing ecosystem, Arrow and its associated libraries and toolsets are in need of new contributors! We have issues suited for all levels, from entry to advanced, and our maintainers are happy to provide 1:1 mentoring. All are welcome in Arrow.

If you’re looking to contribute, have questions, or want to keep up-to-date about what’s happening, please follow us here and say hello!

• Arrow on Twitter
• #arrow on Kotlin Slack
• #arrow-contributors on Kotlin Slack
• Arrow on Gitter

Find more details in CONTRIBUTING.

Setup

Next development version

If you want to try the last features, replace 0.10.5 by 0.11.0-SNAPSHOT in the following guideline.

JDK

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

Android

Arrow supports Android out of the box starting on API 21 and up.

We'll be working on a Arrow-Android integration module that adds some helpers and integrations.

Gradle

Basic Setup

In your project's root build.gradle append these repositories to your list:

allprojects {
    repositories {
        mavenCentral()
        jcenter()
        maven { url "https://dl.bintray.com/arrow-kt/arrow-kt/" } 
        maven { url "https://oss.jfrog.org/artifactory/oss-snapshot-local/" } // for SNAPSHOT builds
    }
}

Add the dependencies into the project's build.gradle:

Λrrow Core

apply plugin: 'kotlin-kapt'

def arrow_version = "0.10.5"
dependencies {
    implementation "io.arrow-kt:arrow-core:$arrow_version"
    implementation "io.arrow-kt:arrow-syntax:$arrow_version"
    kapt    "io.arrow-kt:arrow-meta:$arrow_version"
}

Λrrow Core + Λrrow Optics

apply plugin: 'kotlin-kapt'

def arrow_version = "0.10.5"
dependencies {
    implementation "io.arrow-kt:arrow-optics:$arrow_version"
    implementation "io.arrow-kt:arrow-syntax:$arrow_version"
    kapt    "io.arrow-kt:arrow-meta:$arrow_version"
}

Λrrow Core + Λrrow Fx

apply plugin: 'kotlin-kapt'

def arrow_version = "0.10.5"
dependencies {
    implementation "io.arrow-kt:arrow-fx:$arrow_version"
    implementation "io.arrow-kt:arrow-syntax:$arrow_version"
    kapt    "io.arrow-kt:arrow-meta:$arrow_version"
}

Λrrow Core + Λrrow Optics + Λrrow Fx

apply plugin: 'kotlin-kapt'

def arrow_version = "0.10.5"
dependencies {
    implementation "io.arrow-kt:arrow-fx:$arrow_version"
    implementation "io.arrow-kt:arrow-optics:$arrow_version"
    implementation "io.arrow-kt:arrow-syntax:$arrow_version"
    kapt    "io.arrow-kt:arrow-meta:$arrow_version"
}

Other libraries

Here is the complete [library list]({{ '/quickstart/libraries/' | relative_url }}) for a more granular dependency set-up.

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 = "0.10.5"
dependencies {
    ...
    kapt    "io.arrow-kt:arrow-meta:$arrow_version" //optional
    ...
}

gradle/generated-kotlin-sources.gradle

apply plugin: 'idea'

idea {
    module {
        sourceDirs += files(
                'build/generated/source/kapt/main',
                'build/generated/source/kapt/debug',
                'build/generated/source/kapt/release',
                'build/generated/source/kaptKotlin/main',
                'build/generated/source/kaptKotlin/debug',
                'build/generated/source/kaptKotlin/release',
                'build/tmp/kapt/main/kotlinGenerated')
        generatedSourceDirs += files(
                'build/generated/source/kapt/main',
                'build/generated/source/kapt/debug',
                'build/generated/source/kapt/release',
                'build/generated/source/kaptKotlin/main',
                'build/generated/source/kaptKotlin/debug',
                'build/generated/source/kaptKotlin/release',
                'build/tmp/kapt/main/kotlinGenerated')
    }
}

Maven

Basic Setup

Add to your pom.xml file the following properties:

<properties>
    <kotlin.version>1.3.0</kotlin.version>
     <arrow.version>0.10.5</arrow.version>
</properties>

Add the dependencies that you want to use

<dependency>
    <groupId>io.arrow-kt</groupId>
    <artifactId>arrow-core</artifactId>
    <version>${arrow.version}</version>
</dependency>
<dependency>
    <groupId>io.arrow-kt</groupId>
    <artifactId>arrow-syntax</artifactId>
    <version>${arrow.version}</version>
</dependency>

Enabling kapt

Enable annotation processing using kotlin plugin

<plugin>
    <groupId>org.jetbrains.kotlin</groupId>
    <artifactId>kotlin-maven-plugin</artifactId>
    <version>${kotlin.version}</version>
    <executions>
        <execution>
            <id>kapt</id>
            <goals>
                <goal>kapt</goal>
            </goals>
            <configuration>
                <sourceDirs>
                    <sourceDir>src/main/kotlin</sourceDir>
                </sourceDirs>
                <annotationProcessorPaths>
                    <annotationProcessorPath>
                        <groupId>io.arrow-kt</groupId>
                        <artifactId>arrow-meta</artifactId>
                        <version>${arrow.version}</version>
                    </annotationProcessorPath>
                </annotationProcessorPaths>
            </configuration>
        </execution>
        <execution>
            <id>compile</id>
            <phase>compile</phase>
            <goals>
                <goal>compile</goal>
            </goals>
            <configuration>
                <sourceDirs>
                    <sourceDir>src/main/kotlin</sourceDir>
                </sourceDirs>
            </configuration>
        </execution>
        <execution>
            <id>test-compile</id>
            <phase>test-compile</phase>
            <goals>
                <goal>test-compile</goal>
            </goals>
        </execution>
    </executions>
</plugin>

License

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

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.