Graal is a JIT compiler. Truffle is a framework/DSL for building self-optimizing AST interpreters. Truffle also provides a partial evaluator that works with Graal for the metacompilation part. However, any interpreter you build with Truffle will run fine on any JVM. It'll be pretty slow without Graal, but it's a functional AST interpreter all the same. You could even use Native Image to AOT compile it to native code and cut the JVM out if you wanted.