No, I had missed NuBeautifier in my search after NuPrettifier! :-)
However, NuBeautifier isn't exactly what I'm searching for: it handles indentation but doesn't decide where the line breaks go. (I need it for formatting data undecorated by humans.)
Example with Racket's pretty-write:
(pretty-write '(track (artist "Electric Moon") (album "The Doomsday Machine") (number 3) (name "Spaceman")))
; =>
(track
(artist "Electric Moon")
(album "The Doomsday Machine")
(number 3)
(name "Spaceman"))
Thanks!
Best regards,
Christoffer