[groovy2shoes]

In fact, that ought to work not just in Racket, but in any Scheme implementation that conforms to R5RS or later (or even R4RS plus appendix).

The Klisp authors picked a pretty bad example for demonstrating the power of fexprs. You can think of them as being first-class macros in a way [0].

Joe Marshall demonstrated that fexprs can be divided into two distinct classes: safe and unsafe [1]. He showed that all safe fexprs could be implemented as macros with no loss of expressiveness. (An unsafe fexpr is one that relies on metacircular fixpoints (whatever that means)).

[0]: That's not exactly true. Macros are syntactic transformers whereas fexprs are procedures that can syntactically modify and selectively evaluate its arguments in a given environment. Despite this semantic difference, there's a very large overlap in their use-cases.

[1]: https://www.brinckerhoff.org/scraps/joe-marshall-on-FEXPRS-a...