If you are not familiar with eLua you should take a look at eLuaproject.net. Simply speaking eLua is an embedded program running inside microcontroller which is capable to run code written in Lua language. This is simple programming/scripting language which is fast and lightweight. It doesn’t need any operating system rather it’s a bare-metal software. So it runs fast, takes small amount of RAM.
So this is a nice candidate for embedded projects. Some time ago Karl has shown mbed platform running eLua. It proved it’s efficiency. The only annoying thing in running Lua programs, that in order to edit or create new program, they had to be loaded from PC in to SD and then run.
Eventually he started to look for faster options and decided to write a simple editor which would run in microcontroller itself. He wrote editor in same Lua language which is about 440 lines of code. Editor is capable to perform many basic operations like scroll, delete, insert, copy, cut paste and finally execute the code. Editor runs through terminal screen where programs can be edited and run on the fly.