I remember thinking, "Wouldn't it be neat to scrape some web sites?" I couldn't find anything in OCaml, but .NET had the HtmlAgilityPack written in C# for Windows. Pop over to github, pull down the source, recompile? Badda bing, badda boom, it's running in Linux. And I'm able to use it in F# without really having to know C# (Even though that's not the case). I realized that I could do that for literally thousands of different apps and utilities. So you had this entire ecosystem of programmers making open source stuff for windows that you could easily use in linux. That was the deal-closer.
Plus it looked like Mono had finished going through it's almost-ready-but-not-quite stage. I would still love to be able to permanently load .NET apps in Apache and call them a la fastCGI, but heck, even that might be a solved problem by now.
Finally there was the F# community, which was basically a bunch of old OO MS hacks like myself trying to find their way along mixed in with some really nice academic types who were helpful. OCaml, sadly, did not have that kind of feel. Instead there was a lot of French. And searching around the web for answers to how to do really simple things, like get started, write a web app, or cross-system develop.
The barrier to entry was just too high.
But, like I said, that's changing.
Maybe there are better hybrid languages, but compared to Scala I wouldn't even try calling OCaml or F# hybrids. OO/FP interop in those languages feels like the language designers were actively sabotaging it.
What swayed me at the time was the fact that you had to roll your own libraries for so many things that you get out of the box with .NET. I understand that's changing, but in my mind it's just not ready yet. Maybe in a year or two. I'm still thinking of moving on to something else. It's either going to be OCaml or Haskell.
Would love to see some folks doing this same kind of thing with F#, talking about real-world production systems.
I've done some small app work with it, and blogged about it ( http://tiny-giant-books.com/blog/real-world-f-programming-pa... ), but what the F# community could use is some fans like OCaml has with Jane Street.