https://groups.google.com/forum/#!topic/scalaz/9X_putSGoCY
https://groups.google.com/forum/#!searchin/scalaz/code$20of$...
Calling Tony Morris a rapist was probably the highlight of the affair: https://twitter.com/shajra/status/544712807220908032
Up until they realized they couldn't take over the community, Lars Hupel and Miles Sabin had no publicly stated plans to leave Scalaz.
Cats initial commit is early 2015.
https://github.com/typelevel/cats/commits/master?page=74
I have no idea why everyone dislikes them so much. I use Scalaz, and it's pretty great. From what I've seen Cats is nearly the same thing, I just saw no reason to switch. In what way do you believe Cats is significantly different from Scalaz, beyond the fact that you apparently dislike the people involved?
Incidentally, scalaz-streaming was also pretty nice - mathematically I liked it but it was simply not as performant as Akka streaming. I'd love to use it if it becomes fast.