​​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, Either, IO, Functor, Applicative, Monad to empower users to write pure FP apps and libraries built atop higher order abstractions.

Arrow is a family of different projects, including:

- Arrow Fx is a next-generation Typed FP Effects Library that makes effectful and polymorphic programming first class in Kotlin, and acts as an extension to the Kotlin native suspend system.
- Arrow Optics offers an Optics DSL to compose different Optics while improving ease of use and readability. To avoid boilerplate, Arrow will generate this property-like DSL using @optics annotation.
- Λrrow Meta is a meta-programming library that cooperates with the Kotlin compiler in all its phases, bringing its full power to the community.

https://arrow-kt.io