All of my software that is not brief and trivial and so benefiting from it is licensed under the AGPLv3, although I don't use the or any later versions clause, as I don't trust licenses that have yet to be written, and the recent events make me feel all the superior for not having done so. I'm glad to see more AGPLv3 software. My opinion on a batch compiler is different from my opinion on an interactive environment and I'll share a method on how to make money with the AGPLv3:

For a batch compiler, that is a language that doesn't need the compiler to run, write an AGPLv3 compiler without a linking exception and then demand sufficient funds be raised to release a version with the linking exception. This is then a way to write a Free Software compiler and still demand money for it, for many to actually want to use it. I wouldn't license something such as a Lisp compiler with the exception, however, as the implementation generally exists with the program and that removes some advantages of it being AGPLv3. Fortunately, it seems the author has used the AGPLv3 and any desired exception uses vague language not in the license, so it's legally irrelevant. I'd find it best if there were no exception for this program, but it's not my decision.

In closing, this has made me want again to write my own Scheme implementation, so perhaps I'll do that at some point soon.