I actually used Functional Jobs to locate a job with an established company that was creating an internal team set to use exclusively a functional language. My experience was not good at all. It turned out that they meant that they had acquired a start-up that made their own proprietary functional language (from scratch, not even building on the parser or lexer or anything from previous languages). The team also said, with a straight face, that they didn&#x27;t believe in unit testing -- like, they didn&#x27;t believe that it was even in principle a reasonable thing to do at any time.<p>It really opened my eyes to the fact that when someone claims their team uses &quot;exclusively functional programming&quot; that person actually may not even know what immutability or algebraic data types are. I had always been working on an assumption before that there was a vague correlation between wanting to work with functional techniques and being a quality-minded engineer -- but my experience after getting a job from a place that posted on Functional Jobs totally changed that. I try to be way, way more skeptical now, which is why I am quite skeptical that Jet is using F# more as a hiring trick than as a true engineering ethos.