I look forward to reading the hilarious threads that will be spawned when you take to linux-kernel, freebsd-hackers, openbsd-misc, etc. and inform them they should be developing their kernels in Haskell.
Functional programming's unpopularity is not rooted in any real or imagined inability to write operating systems.
Well you also have to account for the fact that they've spent a lot of time working with their tools and are quite invested in them.
Perhaps they would balk at the idea of writing a kernel in Haskell, but it has been done before.
If you mean Metasepi, it's still under development:
http://metasepi.org (mostly in Japanese) http://www.ipa.go.jp/files/000036232.pdf (Slides in English)
Thanks, I had forgotten about Metasepi!
Aren't Operating Systems lower level than OpenSSL?