MirageOS

"MirageOS is a 'library operating system' for constructing secure, high-performance network applications across a variety of cloud computing and mobile platforms. It works by treating the Xen hypervisor as a stable hardware platform, allowing us to focus on high-performance protocol implementations without worrying about having to support the thousands of device drivers found in a traditional OS.

Code can be developed in a high-level functional programming language (OCaml) on a desktop OS such as Linux or Mac OSX, and is then compiled into a fully-standalone, specialised unikernel. These unikernels run directly on Xen hypervisor APIs. Since the Xen powers most public clouds such as Amazon EC2, Rackspace Cloud, and many others, MirageOS lets your servers run more cheaply, securely and faster in any Xen based cloud or hosting service.

MirageOS is based around the OCaml language, with syntax extensions and 50+ libraries which map directly to operating system constructs when being compiled for production deployment. As such, MirageOS includes clean-slate functional implementations of protocols ranging from TCP/IP, DNS, SSH, Openflow (switch/controller), HTTP, XMPP and Xen inter-VM transports."

https://mirage.io/

https://github.com/mirage/mirage