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Overview
Arrow is a Typed Functional Programming library for Kotlin. It provides data types such as Either and Option, operators such as zipOrAccumulate, and APIs around typed errors, coroutines/resources, resilience, and immutable data.
Features and best fit
Based on official documentation; not hands-on tested · Content checked:
Key features
Represent success and failure with Either, Option, and accumulation
Either, Option, and operators such as zipOrAccumulate let applications represent domain errors and validation results explicitly instead of relying only on exceptions.
Sources: [1]
Use functional APIs for coroutines, resources, and resilience
The official README highlights documentation for typed errors, coroutines/resources, resilience, immutable data, and collection/function utilities.
Sources: [1]
Best fit
Fits Kotlin backends that want explicit domain-error models
It is useful in application and domain layers where success/failure branches should be visible in function types and handled deliberately by callers.
Sources: [1]
Before adoption
Adopt it as a programming abstraction rather than an application framework
Arrow is not an HTTP server or DI container. Incremental adoption around Either and typed errors is easier to maintain when the team agrees on common idioms.
Sources: [1]
Arrow 2.2.3 includes Kotlin 2.4.0 updates and Jackson integration improvements
The 2.2.3 release includes updates for Kotlin 2.4.0 and improvements to Jackson integration for non-empty collections, so Kotlin/Jackson upgrades should be checked against Arrow release notes.
Sources: [2]
Official sources
- [1]Arrow README(2026-10-06)
- [2]Arrow 2.2.3 release(2026-10-06)
Supplemental curator note
It fits Kotlin backends that want explicit domain-error models. Adopt it incrementally as a programming abstraction rather than expecting an application framework.
Try it in 3 steps
- 1
Get the source
git clone --depth 1 https://github.com/arrow-kt/arrow.git - 2
Enter the repository
cd arrow - 3
Check the official steps
Continue with the commands in the README Installation, Quick Start, or Getting Started section.
find . -maxdepth 1 -iname 'README*' -exec sed -n '1,220p' {} \; -quit
Growth
Growth trends · Last 30 days
6,581 Stars
Trend data is still being collected.
Development activity
Last 90 days · weekly
- Commits (last 30 days)
- 9
- Open PRs
- 11
Development activity is still being collected.
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Categories and tags
Categories
GitHub data
GitHub dataView detailed GitHub data
GitHub Topics
- functional-programming
- kotlin-library
- monads
- functional-data-structure
- kotlin
- fp-types
- for-comprehension
- optics
- polymorphism
- typed-lambda-calculus
- typeclasses
- arrow
- Stars
- 6,581
- Forks
- 474
- Watchers
- 88
- Open issues
- 22
- Contributors
- 264
- Owner type
- Organization
- Primary language
- Kotlin
- License
- Apache-2.0
- Repository last updated
- Oct 5, 2026
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