>>but I am still new to this and suddenly it hit me that an ASP .NET web api site could rely almost entirely on things other than C#.

Seems to me that as the market moves closer and closer to "write once, run anywhere" models such as HTML5 rather than parochial silos to create artificial advantage for vendors and practitioners, it pays to remember that Dr Dave had this figured out 20 years ago and had ambitious plans for multiple OS runtimes so FP would run anywhere. He also valued local data which of course is essential for today's mobile platforms. Were he of a certain type he could be loudly proclaiming his own brilliant foresight about things presented as breathtaking inventions by today's gurus, but I guess he's more interested in violins these days and doesn't value vanity as highly any more.