The ICFP programming contest is happening this weekend: http://icfpcontest.org/. I’ve participated 2013 and 2014 and it was a lot of fun both times 😉

what were the challenges in the previous ones?

last year we needed to write an AI for a variant of pac-man running on a lisp-machine and also writing AI for the ghosts for a different architecture

and the year before we needed to guess programs. you can read more about it here: http://icfpc2013.cloudapp.net/

Is there way to make slack not post a snippet of whatever link is posted?

You can disable this feature for your account in settings, but it's not configurable per-link AFAIK