That's assuming people are rational and willing to put up with large up-front costs on the promise of future returns.
Haskell is different, and learning Haskell is closer to learning programming all over again than just picking up another algolish language. Most programmers don't even seem willing to do the latter, much less learn something truly novel.
The people who do use Haskell professionally (e.g. Standard Charter or some number of hedge funds) seem to be very happy with it.
Now, there are some core problems--largely with education and ecosystem maturity--that make Haskell harder to adopt. Recently, people have actually started working on both of these[1]. But neither is a quality of the language itself.
Haskell is different, and learning Haskell is closer to learning programming all over again than just picking up another algolish language. Most programmers don't even seem willing to do the latter, much less learn something truly novel.
The people who do use Haskell professionally (e.g. Standard Charter or some number of hedge funds) seem to be very happy with it.
Now, there are some core problems--largely with education and ecosystem maturity--that make Haskell harder to adopt. Recently, people have actually started working on both of these[1]. But neither is a quality of the language itself.
[1]: http://fpcomplete.com/