Finding zeros in digits of powers of two

I wrote the Haskell version first, then the C version for speed.

Both programs take an optional command-line argument, the power of two to start from (e.g. zeros 10 starts from 1024).

Try it in C

$ gcc -O2 zeros.c -lgmp -o zeros
$ ./zeros

Try it in Haskell

$ ghc -O2 -dynamic -o zeros.haskell zeros.hs
$ ./zeros.haskell