PyPy is to RPython as GraalPython is to Graal. GraalPython is an implementation of Python on the Graal JIT. It employs what they call a “self-rewriting AST.” Graal is an AST interpreter. GraalPython uses the Truffle language framework and runs on the Truffle VM. What benchmarks should be run to compare GraalPython’s performance versus e.g. PyPy or CPython? From my observations, the Truffle VM seems to have zero overhead language interoperability— it can even inline across language boundaries!