Changing my team's main language to Haskell has been a hard sell for me, even getting people interested in trying it has been difficult. Folks really seem to think that it is an arcane language - which after using it for a bit I can say it is the least arcane lang I've worked with. Co-workers have been impressed with pattern matching and other features that their main langs don't provide but that's not enough to incite some dabbling. Haskell is here to stay, but is somehow still in chicken-egg mode. It needs further adoption before people start adopting it.