Yeah, it wasn't until I read your comment that I realized that 'Kleisli' was documented. I suspect I've been making a similar mistake any time I peruse Rust doc

Yeah, it wasn't until I read your comment that I realized that 'Kleisli' was documented. I suspect I've been making a similar mistake any time I peruse Rust documentation. (I don't write any Rust myself, or I assume I'd have figured it out by now.)