[fizbin]

My experience with writing real production Haskell code is this: your first large Haskell project will be a failure, largely from missed deadlines and being unable to properly judge what is going to be easy and what hard. (Unless you deliberately aim low and spend much more time than is really justifiable on something you could have done in some language you know better in a few days)

Your second one will take longer than it would have in PHP or J2EE or whatever else you're used to building web stuff in. It will, like the first, also be ugly but unlike the first project will eventually work. It'll also fall over catastrophically early on, but will be salvageable. Once past its initial deployment/perf issues, it'll sit and hum away quietly in a corner with much less care and feeding than traditional web technologies. (Though you'll keep wanting to go back to it, because it's more fun to work in that than whatever else you're working on)

The third production Haskell project will come together much more quickly. Unfortunately, by this time you'll probably be bringing other people on and this will be their first big Haskell project. (See above about what happens to first big Haskell projects) So the parts delegated to other programmers will fail to work, and there will need to be lots of hand-holding and discussion of type design at first.

Selling management on this is indeed difficult. I'll admit that I'm still not clear on how we sold the first (failed) project to management or how I convinced my boss to let me use Haskell a second time. I mean, I was there, but I don't know how I did it.