The speaker actually begins talking about racket and how they use it at about 6 minutes into the video. Here's a link:
<a href="https://www.youtube.com/watch?v=oSmqbnhHp1c&t=6m0s" rel="nofollow">https://www.youtube.com/watch?v=oSmqbnhHp1c&t=6m0s</a><p>Interesting to hear how they replaced GOAL in their toolchain. The people I've met who used GOAL in the past talked at length about how much they miss it.