I think the CPython AST module is written as a C extension module so currently it's a no-go. I don't think there's a fundamental reason Grumpy couldn't run a pure Python AST module, though.

The ast module itself is in Python, but it imports the _ast module which is an extension module. This actually isn't that big of a deal, though, as the entire AST is defined in a DSL (see https://cpython-devguide.readthedocs.io/en/latest/compiler.h... for some details), so you just have to write some code to generate _ast in Python instead of C (which PyPy may have already done).

So I take that means Grumpy can't run itself?

Correct, Grumpy cannot yet run Grumpy :)