If you have any questions and/or comments about Nim, I'm ready to answer.
Nim is not as mature nor battle-tested as Haskell. Haskell has more users and it is more widely spread, so it would be a safe(r) bet.
I'm also coming from Python, and I have tried several languages (including Haskell) until I kinda settled with Nim.
I really like the similarities in the syntax between Nim and Python, which allows me to easily transfer my "Python thinking" into Nim code. There is also a possibility to only translate some slow/CPU-intensive parts of Python code to Nim, and then call it from Python (FFI).
Regarding community - the Nim community (IRC/Gitter) has been very welcoming to me and to my beginner/dumb questions - I guess this is the advantage of a small community - there's a sense of a connection and people want to help each other.
I'll copy-paste my Reddit comment:
Like pypy, numba was also on my radar, but I couldn't make it work by just slapping `@jit` decorator to the original code, and I didn't want to go into figuring out what's wrong nor making modifications to the original code.
>> I suspect it should be on par with Nim.
Somebody else  has run a comparison including Numba, where Numba is 1.5x faster than NumPy.
This means, if we can compare tests on the different machines, that Nim should be about 2x faster than Numba.
> What about Cython?
I haven't tried it. It would be interesting to see the results.