There have been a lot of “modern” libraries within Common Lisp, but there isn’t a coherent way to “look at” them together.
So the impression of CL as this “frozen in time” language persists (I think of it more as a system than a language, but still).
CIEL is one attempt, by Vindarel (who’s also making a video course at Udemy and contributes a lot to the Cookbook), to bring together “the best bits” from libraries such as
fiveam, and more.
See the documentation for details on all these features. If all you’ve known is the old, bare-bones CL, you’re in for a surprise.
This, or something like it, is sorely needed, to have a “pseudo-standard” to allow people to write “similar-looking code”, without having CLHS as the only common ground. I wish him luck.
P.S. I made some quality-of-life improvements in a personal fork, based on my attempt to get this working on my MacBook.