I didn't conclude it wasn't ready; it was an open question documenting my own concerns. The IDE support is poor compared to C#, which is what we're currently using. Roslyn isn't just about open source (nor writing a compiler in C#!); there's a bunch of functionality (like refactor, diagnostics, code fixes) that will breed a bunch of new tools that F# is sadly not on the boat for :(
Don't get discouraged by the comments, your post is fair. I was a team lead at one of the companies mentioned by the OP, and using F# was a painful and ultimately a major failure, because of poor tooling and difficulties in hiring skilled developers in the language. It's not impossible to succeed, but there are a lot of ways to making it much harder -- one of this being choosing a niche language without a compelling reason to do so.
There is nothing wrong with F#, the language (even though I don't particularly like its syntax), but clearly one has to account for the costs of reskilling the team on a new language, as well as a new paradigm, making a bet on a language with a still uncertain future (will it ever become a mainstream language?) and really non-existent tooling support.
Given that both C# and F# are general purpose, hybrid languages, I don't see a compelling story -- in 2014 -- behind F# that makes it such as huge deal as its advocates make it.
The onus is on them to bring convincing evidence to the table that, once factored in the risks and the costs that arise from the shortcomings, the benefits are still a good bargain in the real world, and with real people, outside of the easy fake example one finds on blogs etc.
There's no reason you couldn't implement those things for F#... the compiler, the libraries and the visual tooling is all open source now and accepting contributions. In fact I suspect it would be easier than trying to use Roslyn.
Your post is reasoned and fair, and some of the bizarrely defensive replies you have received are just wholly undeserved. People vest too much of their ego into technology choices, and it reflects in that sort of over the top hostility.
Calling a reasoned, even-handed assessment "ridiculous" sets a pretty bad tone at the outset. That tone continues through your post (e.g. hiring difficulties are "nonsense").
The submission asks a question that many shops confront when F# is proposed. And the reality today is that many come to the conclusion that no, it isn't ready for production, for many of the reasons the submission notes. Your outrage will not change this reality.
