Top 5 Java Functional Projects

Eclipse Collections

9 2,354 8.1 Java

Eclipse Collections is a collections framework for Java with optimized data structures and a rich, functional and fluent API.

Project mention: Yet another introduction to Functional Programming | dev.to | 2023-07-12

eclipse-collections for Java.

kamilalisp

2 261 8.4 Java

A functional, flexible and concise Lisp.

Project mention: KamilaLisp – A functional, flexible and concise Lisp | news.ycombinator.com | 2024-03-01

InfluxDB

www.influxdata.com sponsored

Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
safeql

4 15 0.0 Java

Composable / async / functional / type-safe / parallel-pipelined queries and relations without SQL injection or N+1s. (by karmakaze)

Project mention: Sketch of a Post-ORM | news.ycombinator.com | 2023-06-02

I want sum types.
I want a statically-typed way of constructing composable queries that follow SQL rather than reinvent a different thing. It doesn't have to be the same syntax but it has to be the same structuring.
I started writing one[0] and stopped before doing all the boilerplate code generation, having moved on from the JVM ecosystem for the time being. One thing it does is treat most things like sets so we don't end up with N+1 queries. Another trick it uses is collapsing constant expressions via an expression evaluation library[1].
[0] https://github.com/karmakaze/safeql
[1] https://github.com/karmakaze/moja

RustScript

1 8 2.8 Java

RustScript is a functional scripting language with as much relation to Rust as JavaScript has to Java. (by WilliamRagstad)
moja

4 1 1.8 Java

Composable computation pipelines for Java: Async, Lazy, Option, Try, Result, Multi (List), Stated, Reader, Logger, Writer.

Project mention: Sketch of a Post-ORM | news.ycombinator.com | 2023-06-02

I want sum types.
I want a statically-typed way of constructing composable queries that follow SQL rather than reinvent a different thing. It doesn't have to be the same syntax but it has to be the same structuring.
I started writing one[0] and stopped before doing all the boilerplate code generation, having moved on from the JVM ecosystem for the time being. One thing it does is treat most things like sets so we don't end up with N+1 queries. Another trick it uses is collapsing constant expressions via an expression evaluation library[1].
[0] https://github.com/karmakaze/safeql
[1] https://github.com/karmakaze/moja

WorkOS

workos.com sponsored

The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.

NOTE: The open source projects on this list are ordered by number of github stars. The number of mentions indicates repo mentiontions in the last 12 Months or since we started tracking (Dec 2020).