Certainly, I couldn't have done what I did without Haskell, or with more traditional languages, like C++.
The most challenging task I've done with Haskell, was to find the right combination of parameters in orden to sum an array of satellital images, preserving a set of constrains. I couldn't have dreamed of doing that without Haskell. It was the right choice for the job.
When they discovered the tools I've used, they recognized the problem, but they treated me bad, so I search for another job.