README.md

layout	title	permalink
quickstart-core	Core	/core/

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Arrow Core. Functional companion to Kotlin’s Standard Library

Arrow Core includes types such as [Either]({{ '/apidocs/arrow-core/arrow.core/-either/' | relative_url }}), [Validated]({{ '/apidocs/arrow-core/arrow.core/-validated/' | relative_url }}) and many extensions to [Iterable]({{ '/apidocs/arrow-core/arrow.core/index.html#functions' | relative_url }}) that can be used when implementing [error handling patterns]({{ ' /patterns/error_handling/' | relative_url }}).

Core also includes the base continuation effects system, which includes patterns to remove callbacks and enables controlled effects in direct syntax. Some applications of the effect system reduce boilerplate and enable direct syntax including [monad comprehensions and computation expressions]( {{ '/patterns/monad_comprehensions/' | relative_url }}).

## Arrow Core Overview

#### Quick Start - [Gradle Setup]({{ '/core/#Gradle-kotlin' | relative_url }}) - [Maven Setup]({{ '/core/#Maven' | relative_url }})

#### Extensions and data types - [Either]({{ '/apidocs/arrow-core/arrow.core/-either/' | relative_url }}) - [Validated]({{ '/apidocs/arrow-core/arrow.core/-validated/' | relative_url }}) - [Option]({{ '/apidocs/arrow-core/arrow.core/-option/' | relative_url }}) - [NonEmptyList]({{ '/apidocs/arrow-core/arrow.core/-non-empty-list/' | relative_url }}) - [Ior]({{ '/apidocs/arrow-core/arrow.core/-ior/' | relative_url }}) - [Eval]({{ '/apidocs/arrow-core/arrow.core/-eval/' | relative_url }}) - [Monoid]({{ '/arrow/typeclasses/monoid/' | relative_url }}) - [Semiring]({{ '/apidocs/arrow-core/arrow.typeclasses/-semiring/' | relative_url }}) - [Extensions]({{ '/apidocs/arrow-core/arrow.core/index.html#functions' | relative_url }})

#### Tutorials - [Error Handling]({{ '/patterns/error_handling/' | relative_url }}) - [Monads]({{ '/patterns/monads/' | relative_url }}) - [Monad Comprehensions]({{ '/patterns/monad_comprehensions/' | relative_url }}) - [Coroutines & Computation blocks]({{ '/fx/coroutines/' | relative_url }})

#### Additional information - [Kotlin's Std Lib Guide](https://kotlinlang.org/api/latest/jvm/stdlib/) - [Pure & Referentially Transparent Functions]({{ '/fx/purity-and-referentially-transparent-functions/' | relative_url }}) - [Why suspend over IO monad]({{ '/effects/io/' | relative_url }})

## Setup

{: .setup-subtitle} Configure Arrow for your project

![Jdk]({{ "/img/quickstart/jdk-logo.svg" | relative_url }} "jdk")

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

![Android]({{ "/img/quickstart/android-logo.svg" | relative_url }} "android")

Arrow supports Android starting on API 21 and up.

Gradle Kotlin DSL Gradle Groovy DSL Maven

Basic Setup

In your project's root build.gradle.kts, append this repository to your list:

allprojects {
    repositories {
        mavenCentral()
    }
}

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

dependencies {
    implementation("io.arrow-kt:arrow-core:1.0.1")
}

BOM file

To avoid specifying the Arrow version for every dependency, a BOM file is available:

dependencies {
    implementation(platform("io.arrow-kt:arrow-stack:1.0.1"))

    implementation("io.arrow-kt:arrow-core")
    ...
}

Next development version

If you want to try the latest features, replace 1.0.1 with 1.0.2-SNAPSHOT and add this configuration:

allprojects {
    repositories {
        ...
        maven(url = "https://oss.sonatype.org/content/repositories/snapshots/")
    }

    // To use latest artifacts
    configurations.all { resolutionStrategy.cacheChangingModulesFor(0, "seconds") }
}

Basic Setup

In your project's root build.gradle, append this repository to your list:

allprojects {
    repositories {
        mavenCentral()
    }
}

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

Arrow Core

def arrow_version = "1.0.1"
dependencies {
    implementation "io.arrow-kt:arrow-core:$arrow_version"
}

BOM file

To avoid specifying the Arrow version for every dependency, a BOM file is available:

def arrow_version = "1.0.1"
dependencies {
    implementation platform("io.arrow-kt:arrow-stack:$arrow_version")

    implementation "io.arrow-kt:arrow-core"
    ...
}

Next development version

If you want to try the latest features, replace 1.0.1 with 1.0.2-SNAPSHOT and add this configuration:

allprojects {
    repositories {
        ...
        maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
    }

    // To use latest artifacts
    configurations.all { resolutionStrategy.cacheChangingModulesFor 0, 'seconds' }
}

Basic Setup

Make sure to have at least the latest version of JDK 1.8 installed. Add to your pom.xml file the following properties:

<properties>
    <kotlin.version>1.5.31</kotlin.version>
    <arrow.version>1.0.1</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>

BOM file

To avoid specifying the Arrow version for every dependency, a BOM file is available:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.arrow-kt</groupId>
            <artifactId>arrow-stack</artifactId>
            <version>${arrow.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement><dependencies>
...
</dependencies>

Next development version

If you want to try the latest features, replace 1.0.1 with 1.0.2-SNAPSHOT and add this configuration:

<repository>
    <snapshotss>
        <url>https://oss.sonatype.org/content/repositories/snapshots/</url>
        <updatePolicy>always</updatePolicy>
    </snapshots>
</repository>