Thank you for sharing your feedback. Your approach certainly makes sense and I'm also not a fan of listing specific programming languages (as well as stacks, frameworks, platforms or products) as strict requirements. However, in my book, it makes sense only for mature companies and later-stage startups. Early-stage (especially, bootstrapped, small and non-VC-backed) startups simply cannot afford to spend time for training on the job.
I think with the right, bright people, they'll train themselves in no time. But sure, that shifts the problem from getting "people who know F#" to "people who are very intelligent and experienced", which might be equally hard if not more so.
I believe it's worth it, but have no data to back it up.
Fair enough.
Very good point regards training on the job. Indeed a factor to consider in discussion about early stage recruiting!!!
My organisations job ad is looking for people with "several years of programming experience by the way we do things in C# and F# but do not expect you to have".
Then we weed out the huge majority by issuing a tiny take-home code test (think a few fizzbuzz-style questions) that applicants can complete in whatever language or environment they want.
So far, we've received positive feedback on the approach, but also very few truly talented applicants. I think the latter is because we're extremely picky, but I don't know.
What I do know is that we wouldn't get better or more qualified applicants by limiting our search to a few languages. Some of the best so far have come with a language we would never have thought to list.