Benchmark games, Rust, big ints and Pi

[bearophile]

There is some discussion in the Rust Reddit, as Rust since some 
time has some benchmarks on the Computer Game site:
http://www.reddit.com/r/rust/comments/1xcq1q/c_gcc_vs_rust_wtf/

The source code of the Rust benchmarks is probably here:
https://github.com/mozilla/rust/tree/master/src/test/bench

They are mostly discussing about the very slow big int 
implementation.

A short D implementation of the the pidigits benchmark that uses 
Phobos BigInts (this is not meant to compete with the entries 
that use GMP. A D entry using GMP is possible), adapted from the 
C entry by the good Ledrug:

http://dpaste.dzfl.pl/821527e71343

I have not compared them, but I think it's 3-4 times slower than 
the best entry (that uses GMP).

I suspect that if Phobos BigInts gets mutable buffers 
(https://d.puremagic.com/issues/show_bug.cgi?id=7013 ), this code 
could be modified to be rather faster.

Bye,
bearophile