> Flushing down 40-60 hours a week on a useless piece of knowledge That is only if it's actually useless. I haven't programmed in haskell for many years, yet I

> Flushing down 40-60 hours a week on a useless piece of knowledge That is only if it's actually useless. I haven't programmed in haskell for many years, yet I am very glad I did. It was hard at first, but it made me think about code, data and transformation from a different perspective, expanding the repertoire of paradigms, regardless of which language I code in. YMMV, but personally, I'd much rather hire or work with someone with 3y java + 1y erlang experience, than just 5y java experience. In general a polyglot rather than monoglot, especially if it's a different coding paradigm. Nevertheless, I may not actually want them coding random bits of work in erlang or whatever random language.