On Monday, 31 March 2014 at 13:05:24 UTC, bearophile wrote:
OK, thank you. So the price for that "in" is to use a dup :-)
(Or use lower level code).
Bye,
bearophile
I'd think so yes. But given you are calling "array" for every
iteration, it doesn't look like a ludicrous overhead.
That said, if you were reduce *into* your actual seed (the dup'ed
array) instead of duplicating it on every iteration, it should be
better.
I think your code is simplified, but consider this:
//----
uint[] foo3(const(uint[])[] X)
{
assert(!X.empty);
auto seed = X.front.dup;
X.popFront();
return reduce!((i, j) => i[] |= j[])
(seed, X);
}
//----
This gives the same "logical" result, but reuses the seed
contents on every iteration.
Then, the original dup looks less gratuitous: You are allocating
your result.
