too early for D2 and too late for D1

[Adam D. Ruppe]

Walter Bright wrote:
> My experience in tuning D code for speed is that if you write "C++"
> code in D, you will get the same performance as C++. However, D
> makes it a *lot* easier to reorganize/refactor code to try and make
> it run faster, and this makes for better algorithms and hence
> faster code.

Anecdote: Friday, I was asked to justify my decision to use D to a
company exec.

He pointed me to some benchmarks that had ruby vs python vs php vs C++ and asked
how D would stack up. (The benchmark was sorting
an array of integers, nothing really fancy.)

Of them, Python had the shortest code, but C++ was the fastest, by
far. Not really surprising.


I first ported C++ to D. Equal lines of code, equal performance.
The optimized builds did show D lagging ~20% behind g++ though.
But, 20% behind g++ is still about 8x faster than the interpreted
languages, so not bad.

But, then I made a few minor tweaks. Slicing instead of copying.
Array operations and foreach instead of iterator loops, stuff like
that.

The D code was now the shortest of all - even beating Python by a
couple lines - while being just as readable and editable as the
"productivity languages".


And, to my surprise, the standard compile actually *beat* the
optimized C++ build, running twice as fast! I was expecting
it to be about equal, but instead, it just spanked it.


Shorter code, easier to read code *AND* faster code, it beat all
the competition in all the categories. Very pleasing result for
everyone involved.


Now, I dislike benchmarks as a general rule. Real world code is
a lot more complex than these trivial things realize. But hell,
when they work /for/ me, I won't complain.

(Also, while a weaker comparison, I find this same trend continues
to apps as a whole too. My D web app is about 1/8 the size in code
of the smallest open source PHP program I found with similar
features. 40% faster too. But Perpetually Hideous Programs are,
well, perpetually hideous. Beating PHP is no great feat.)