If I recall correctly, Skylight hooks into the ruby interpreter to do real time performance monitoring for Rails apps. They felt they couldn't get the performance they needed out of pure ruby, and felt that writing their hooks in Rust would be safer than in C. You can see Yehuda's presentation here. It's about an hour and 10 minutes in:
http://www.meetup.com/Rust-Bay-Area/events/143439552/
If I recall correctly, Skylight hooks into the ruby interpreter to do real time performance monitoring for Rails apps. They felt they couldn't get the performance they needed out of pure ruby, and felt that writing their hooks in Rust would be safer than in C. You can see Yehuda's presentation here. It's about an hour and 10 minutes in:
https://air.mozilla.org/sprocketnes-practical-systems-progra...