A couple of years ago I finally started to understand the Waters series facility [1], which was offered as an alternative to Loop. It's a bit finicky, and the

A couple of years ago I finally started to understand the Waters series facility [1], which was offered as an alternative to Loop. It's a bit finicky, and the error messages are often mystifying, but I have come to quite like it for some more complicated looping situations. The thing that finally made it accessible to me was a blog post by Joe Marshall, Series tips and tricks [2] Ironically enough, once my use of it advanced enough, I found myself writing producing forms which are just a restricted form of Loop invocation - Series turns out to compile down to Loop. It's just that I (and others, apparently) find Series expressions more pleasant to deal with than Loop expressions. [1] https://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node347.html#SECTION003400000000000000000 https://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node347.html#... [2] http://funcall.blogspot.com/2022/07/series-tips-and-tricks.html http://funcall.blogspot.com/2022/07/series-tips-and-tricks.h...