Lessor known Apache Machine Learning languages

Machine learning is a very popular topic in recent times, and we keep hearing about languages such as R, Python and Spark. In addition to these we have commercially available machine learning languages and tools from SAS, IBM, Microsoft, Oracle, Google, Amazon, etc., etc. Everyone want a slice of the machine learning market!

The Apache Foundation supports the development of new open source projects in a number of areas. One such area is machine learning. If you have read anything about machine learning you will have come across Spark, and maybe you might believe that everyone is using it. Sadly this isn't true for lots of reasons, but it is very popular. Spark is one of the project support by the Apache Foundation.

But are there any other machine learning projects being supported under the Apache Foundation that are an alternative to Spark? The follow lists the alternatives and lessor know projects: (most of these are incubator/retired/graduated Apache projects)

Flink	Flink is an open source system for expressive, declarative, fast, and efficient data analysis. Stratosphere combines the scalability and programming flexibility of distributed MapReduce-like platforms with the efficiency, out-of-core execution, and query optimization capabilities found in parallel databases. Flink was originally known as Stratosphere when it entered the Incubator. Documentation (graduated)
HORN	HORN is a neuron-centric programming APIs and execution framework for large-scale deep learning, built on top of Apache Hama. Wiki Page (Retired)
HiveMail	Hivemall is a library for machine learning implemented as Hive UDFs/UDAFs/UDTFs Apache Hivemall offers a variety of functionalities: regression, classification, recommendation, anomaly detection, k-nearest neighbor, and feature engineering. It also supports state-of-the-art machine learning algorithms such as Soft Confidence Weighted, Adaptive Regularization of Weight Vectors, Factorization Machines, and AdaDelta. Apache Hivemall offers a variety of functionalities: regression, classification, recommendation, anomaly detection, k-nearest neighbor, and feature engineering. It also supports state-of-the-art machine learning algorithms such as Soft Confidence Weighted, Adaptive Regularization of Weight Vectors, Factorization Machines, and AdaDelta. Documentation (incubator)
MADlib	Apache MADlib is an open-source library for scalable in-database analytics. It provides data-parallel implementations of mathematical, statistical and machine learning methods for structured and unstructured data. Key features include: Operate on the data locally in-database. Do not move data between multiple runtime environments unnecessarily; Utilize best of breed database engines, but separate the machine learning logic from database specific implementation details; Leverage MPP shared nothing technology, such as the Greenplum Database and Apache HAWQ (incubating), to provide parallelism and scalability. Documentation (graduated)
MXNet	A Flexible and Efficient Library for Deep Learning . MXNet provides optimized numerical computation for GPUs and distributed ecosystems, from the comfort of high-level environments like Python and R MXNet automates common workflows, so standard neural networks can be expressed concisely in just a few lines of code. Webpage (incubator)
OpenNLP	OpenNLP is a machine learning based toolkit for the processing of natural language text. OpenNLP supports the most common NLP tasks, such as tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, chunking, parsing, language detection and coreference resolution. Documentation (graduated)
PredictionIO	PredictionIO is an open source Machine Learning Server built on top of state-of-the-art open source stack, that enables developers to manage and deploy production-ready predictive services for various kinds of machine learning tasks. Documentation (graduated)
SAMOA	SAMOA provides a collection of distributed streaming algorithms for the most common data mining and machine learning tasks such as classification, clustering, and regression, as well as programming abstractions to develop new algorithms that run on top of distributed stream processing engines (DSPEs). It features a pluggable architecture that allows it to run on several DSPEs such as Apache Storm, Apache S4, and Apache Samza. Documentation (incubator)
SINGA	SINGA is a distributed deep learning platform. An intuitive programming model based on the layer abstraction is provided, which supports a variety of popular deep learning models. SINGA architecture supports both synchronous and asynchronous training frameworks. Hybrid training frameworks can also be customized to achieve good scalability. SINGA provides different neural net partitioning schemes for training large models. Documentation (incubator)
Storm	Storm is a distributed, fault-tolerant, and high-performance realtime computation system that provides strong guarantees on the processing of data. Storm makes it easy to reliably process unbounded streams of data, doing for realtime processing what Hadoop did for batch processing. Storm is simple, can be used with any programming language. Documentation (graduated)
SystemML	SystemML provides declarative large-scale machine learning (ML) that aims at flexible specification of ML algorithms and automatic generation of hybrid runtime plans ranging from single node, in-memory computations, to distributed computations such as Apache Hadoop MapReduce and Apache Spark. Documentation (graduated)