Just a bit of evangelism.

Original post of drawing Ulam's spiral of primes:
http://users.softlab.ece.ntua.gr/~ttsiod/primes.html

the Python code:
https://github.com/ttsiodras/PrimeSpirals/blob/master/primeSpirals.py

Direct translation to D:
https://gist.github.com/thedeemon/8295146

Result is somewhat shorter and two orders of magnitude faster even with the same very very slow and unoptimal algorithm. And, it seems, 2x faster than PyPy and Shedskin that do pretty much the same thing.

http://www.reddit.com/r/programming/comments/1ujoyk/the_ulam_spiral_python_50x_speedup_with_pypy/

But if it's in D how will your type mismatches leap out of the shadows at you at runtime?