> Whatever Scheme implementations are shown should be fully conformant
> Schemes.

There are no fully conformant Schemes. It's probably not possible to
make a fully conformant implementation of a useful general-purpose
programming language.

In Scheme, continuations (especially their interactions with threads and
FFI) tend to be a common pain point, as well as macro hygiene, library
systems, the number tower, and sometimes Unicode.

> Chibi Scheme is another full Scheme that has been successfully compiled
> with Emscripten, by the way.

Gambit's call/cc is probably more general than Chibi's. But Chibi's
macro support is very good. This illustrates the above problem.

We should have a compatibility matrix somewhere on Scheme.org.
Preferably generated by a standard test suite at some point once we are
ready for that level of automation.