Overview of libraries

Arrow is not a single library, but a collection of them. The guiding principle is that each Arrow library should be self-contained: each library improves or extends a single commonly-used library in the Kotlin ecosystem (like arrow-core and arrow-fx-coroutines) or a particular Kotlin language feature (like arrow-optics), or focuses on a particular set of tasks (like arrow-resilience).

Note that during the transition to Arrow 2.x some libraries were further split. If you are an Arrow 1.x user you can follow the deprecation warnings to make the switch to the new organization, or read our 1.2.0 migration guide.

Library	Features
arrow-core Companion to Kotlin's standard library	Typed errors, including Raise, Either, and Option Non-empty collections Memoized recursive functions
arrow-fx-coroutines Companion to KotlinX Coroutines	High-level concurrency, including parMap and parZip Resource management (with suspend)
arrow-autoclose	Resource management (no suspend)
suspendapp	Graceful shutdown
arrow-resilience	Resilience patterns
arrow-optics + arrow-optics-ksp-plugin Companion to data and sealed classes	Utilities for immutable data
arrow-fx-stm	Software Transactional Memory (STM)
arrow-atomic Multiplatform-ready references	Atomic references
arrow-collectors Companion to fold and reduce	Aggregation with single traversal
arrow-eval More powerful laziness	Control over evaluation
arrow-functions Part of arrow-core in 1.x	Utilities for functions
arrow-core-high-arity	arrow-core for more than 10 parameters

Library	Integrates with
arrow-core-serialization	KotlinX Serialization for core types
arrow-cache4k	cache4k for memoization
arrow-optics-compose	Compose state management with optics