Moebius Linux is a Raspberry PI armhf distribution built from scratch and targeted to have a small footprint. 20Mb of RAM (with ssh) and a 128Mb SD are minimum requirements. Size, speed and optimizations are main goals for this distro, take a look at it and contribute if you like it
The XPS is a scalable platform for meta-programming and domain engineering. It provides a virtual machine, compiler, and runtime library that make it possible to efficiently develop, debug, and run programs based on XPL (eXtensible Programming Language)