Perhaps the wording in the blog post is too strong, because people in this thread seem to be interpreting it as a hard rule. The wording was:

> When someone tells us in an interview they’re excited about working here because they like functional programming (say), we count that as an indication they might not be a good fit.

When we do interviewers each person fills out a scorecard for the candidate with several criteria: things like technical skills, communication, UX thinking, interest in the company product/mission, etc.

Under "technical skills" I would usually have counted interest in Elm as a positive, as long as they weren't expecting to only write it. As I mentioned elsewhere in the thread, they'd also be likely to be contributing to Ruby on Rails codebases... so they better be open to, and maybe even excited by, different paradigms, because that's going to be part of the job.