Functional libs 🌀

vavr ❤️ , VΛVΓ (Vavr, formerly called Javaslang) is a non-commercial, non-profit object-functional library that runs with Java 8+. It aims to reduce the lines of code and increase code quality.
- homepage: http://vavr.io/
  - documentation: http://docs.vavr.io/
- code repo: https://github.com/vavr-io/vavr
- contains persistent (immutable) collections 📌
- has simple Kotlin integration 🍩: https://github.com/vavr-io/vavr-kotlin
cyclops ❤️ , An advanced, but easy to use, platform for writing functional applications in Java 8.
- homepage: http://cyclops-react.io/
- code repo: https://github.com/aol/cyclops-react
- contains persistent (immutable) collections 📌
- excellent ecosystem integration, see the cyclops integration modules
  - related/similar lib integration: RxJava, Reactor, guava, vavr, functionaljava...
Functional Java , Functional programming in Java
- code repo: https://github.com/functionaljava/functionaljava
- contains persistent (immutable) collections 📌
procrastination , A small, straightforward library bringing the benefits of functional programming to Java 11
- code repo: https://github.com/gdejohn/procrastination
- contains persistent (immutable) collections 📌
jOOL , The Missing Parts in Java 8 jOOλ improves the JDK libraries in areas where the Expert Group's focus was elsewhere. It adds tuple support, function support, and a lot of additional functionality around sequential Streams.
- code repo: https://github.com/jOOQ/jOOL
Speedment , is a Stream ORM Java Toolkit and Runtime https://github.com/speedment/speedment
guava
- code repo: https://github.com/google/guava
- it is well known that guava is more than a collection lib
- contains immutable collections
  - https://github.com/google/guava/wiki/ImmutableCollectionsExplained
  - NOT persistent collections! 😱 not nice!
    - implementation of java collections, has update operations actually and update operations throw UnsupportedOperationException 😱, not nice!