This concept of `day-to-day work' is a curious one. Haskell is not a mature language, and probably shouldn't ever be one.
I see where you are coming from here, but I think that train has already started and can't be stopped.
Yeah, it's too late. Too many people have their pay checks riding on GHC, the Hackage library set (now up to 740 libraries and tools!), and the continued development of the language in general.
If Haskell's not "mature" yet, then perhaps it has reached its early twenties, with an reliable heavy duty optimizing compiler, fast runtime, large library set, standard documentation, testing, debugging and packaging tools, and large community.
We're serious about this thing.
So, what fills its shoes as a great research language with great tools?
I think the great thing about Haskell is that it works so well now and yet there's room for growth as well. That means that not only is research with the language more efficient, but also that the research tends to be more applicative to people using it. Consider, for example, the fact that the Haskell Workshop has grown into a symposium [1] and that there are so many relevant workshops affiliated with ICFP [2]. [1] http://www.haskell.org/haskell-symposium/ [2] http://www.icfpconference.org/#Affiliated Sean