This may be nitpicking but certain classes of programs cannot be realistically built with Haskell. Anytime you need to tightly control latency (soft realtime) won't really work since you have both a garbage collector and lazy evaluation. Memory constrained systems are pretty tough as well since you don't really get insight into allocation/deallocation, which also makes structuring your data into a particular memory layout tricky compared to C(++) for instance.
Not to say that Haskell isn't awesome. It should probably be used for more systems. It just can't be the "hammer" to make every problem into a nail.