>Rust semantics with LISP syntax. A transparent s-expression frontend that compiles directly to Rust — no runtime, no GC

The first paragraph says literally that.

Yeah, it sort of reminds me of the microcode assembly of a few of the lisp machines, that, while in s-expressions were also clearly not lisp themselves. But could be an interesting target for some lisp macros.

A let that defines variables that have a lifetime beyond the scope of the expression? Yeah, that's really unusual. And it's not even the oddest looking thing from the first example block of code.