I still wonder about this. I'm competent enough at Haskell to have made several additions to GHC itself, though I readily admit I'm no SPJ. I also believe that for a general purpose program, Haskell _should_ be a good choice. But in practice I make mostly web apps and no amount of "write down the types then fill in the gaps and compose it all together" can replace the amount of scaffolding that things like Rails give me.