I think everybody has a slightly different perspective on this. I've been working closely with Denny's prototype project (which included the javascript version of 'eneyj' that Lucas was inspired by) at https://github.com/google/abstracttext/ (I assume this will move somewhere under wikimedia now?). The prototype does to an extent define its own "language" - specifically it defines (human) language-independent "Z Objects" (implemented as a subset of json) which encapsulate all kinds of computing objects: functions, tests, numeric values, strings, languages (human and programming), etc.

I think right now this may be a little more complex than is actually necessary (are strict types necessary? maybe a 'validator' and a 'test' should be the same thing?); on the other hand something like this is needed to be able to have a wiki-style community editable library of functions, renderers, etc. and I really like the underlying approach (similar to Wikidata) to take all the human-language components off into label structures that are not the fundamental identifiers.

ZObjects for "implementations" of functions contain the actual code, along with a key indicating the programming language of the code. Another ZObject can call the function in some context which chooses an implementation to run it. At a basic level this is working, but there's a lot more to do to get where we want and be actually useful...

   Arthur