Pluggable type-checking for Java
An advanced, but easy to use, platform for writing functional applications in Java 8.
Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching, folds, optics and typeclasses.
Functional programming in Java
jOOλ - 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. The JDK 8's main efforts (default methods, lambdas, and the Stream API) were focused around maintaining backwards compatibility and implementing a functional API for parallelism.
Stream utilities for Java 8
RxJava bindings for JavaFX
Enhancing Java Stream API
vÊŒvr (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.