Additional functional programming idioms over and above what is available from Arrow.

Expressive validation library for Kotlin

DSL for accessing and modifying deeply nested JSON for KotlinX Serialization with Arrow Optics

Boilerplate-free Kotlin config library for loading configuration files as data classes

Toolset for creating simple parsers from raw input types, to properly validated parsed types

Parser-combinators with Kotlin Coroutines

Better initial-style DSLs in Kotlin