Why S7 Scheme? (2020)

I'm grateful for the author's "other options that were considered" section with eight alternatives to S7. But Embeddable Common Lisp (ECL) is the only one listed that he doesn't write a few sentences about, to contrast its pros and cons versus S7. I'd love to hear more.

I have found S7 scheme to be a delight to use as a configuration/extension language. I find it much more intuitive then something like Lua or even embedded python. Because of its heritage, most of the s7 scheme uses I've seen online are music related, but it really shines outside of that field as well.

S7 is very cool indeed. It also comes as a single C file, which makes it easy to embed.

As a CHICKEN maintainer, I'd love to hear what the author was missing in the FFI part of the manual.

Is there a SLIME-equivalent to achieve REPL driven programming for applications with s7 embedded in them?

(2020)