Mu
Mu is a prototype-based, homoiconic programming language (essentially a clone of Io). Mu aims to have a smaller standard library than Io, better documentation, and simpler embedding.
The current version of Mu is written in Crystal, but I would like to eventually port it to Rust.
At this point, the language is not complete, although it can run some incredibly limited functions. Most significantly, it is missing method support, which severely limits how much you can do within the language itself.