Seems pretty cool, and it'll definitely be interesting to see what people will do with it. However, some parts of this (introspection and modification of ASTs)

Seems pretty cool, and it'll definitely be interesting to see what people will do with it. However, some parts of this (introspection and modification of ASTs) are already possible in other languages, such as Scala (through the presentation compiler and the macro system) or even Smalltalk (which doesn't have code in text files).