The RPython toolchain translates interpreters to JIT compilers. The interpreter may be written in any style; the corresponding JIT compiler is defined by annotations on the main loops of the interpreter.
In practice, there are only two styles of interpreter used with RPython. One is AST walking, which is also the only style supported by the Truffle ecosystem. The other style is bytecode evaluation, as traditionally used by Python implementations like PyPy.
Which other styles of interpreter are supported by RPython? That seems like too open of a question, so I want to ask something narrower: which other styles are not well-supported?