Meta Programming System (MPS):
To me this smells a little bit of the now defunct project "Oslo" but taken much further:
The major goal of MPS is to allow extending languages. This is because every existing language already has a strict language syntax defined, which limits its flexibility.
The problem in extending language syntax is mainly the textual presentation of code. This is especially true if we want to use different language extensions, where each one may have its own syntax.
This naturally leads to the idea of non-textual presentation of program code. A major benefit of this approach is that it eliminates the need for code parsing. Our solution is to have code always maintained in an Abstract Syntax Tree (AST), which consists of nodes with properties, children and references, and fully describes the program code.
At the same time, MPS offers an efficient way to keep writing code in a text-like manner.
An interesting aspect is that collections are part of the language - there is a shared collections language. It reminds me of the interesting debate in the Lang.next panel discussion about collection libraries (I think that's where it was mentioned at least.)