This Rosettacode code task (in two different D versions) seems to
show some D/Phobos regressions (or just some problems):
http://rosettacode.org/wiki/Parallel_calculations#D
In the second version (that works with dmd 2.066alpha) I have had
to comment out the pure nothrow here, despite this used to
compile few months ago:
this(in ulong n) /*pure nothrow*/ {
super(&run);
num = n;
fac = new ulong[0];
}
The situation with the first version is worse. This is a
compilable first version (at the moment the first version on the
site doesn't have a decompose() function):
import std.stdio, std.algorithm, std.parallelism, std.typecons;
ulong[] decompose(ulong n) pure nothrow {
typeof(return) result;
for (ulong i = 2; n >= i * i; i++)
for (; n % i == 0; n /= i)
result ~= i;
if (n != 1)
result ~= n;
return result;
}
void main() {
immutable ulong[] data = [
2UL^^59-1, 2UL^^59-1, 2UL^^59-1, 112_272_537_195_293UL,
115_284_584_522_153, 115_280_098_190_773,
115_797_840_077_099, 112_582_718_962_171,
112_272_537_095_293, 1_099_726_829_285_419];
//auto factors = taskPool.amap!(n => tuple(decompose(n),
n))(data);
//static enum genPair = (ulong n) pure => tuple(decompose(n),
n); // ?
static genPair(ulong n) pure { return tuple(decompose(n), n);
}
auto factors = taskPool.amap!genPair(data);
auto pairs = factors.map!(p => tuple(p[0].reduce!min, p[1]));
writeln("N. with largest min factor: ", pairs.reduce!max[1]);
}
A problem (that is not a regression) is that taskPool.amap
doesn't seem able to accept a lambda for some reason.
It can't accept the static enum lambda either, for other unknown
reasons.
But even using a normal static inner function, the program
asserts most times at run-time (but not always), while few months
ago it used to work reliably. So perhaps in this messy situation
there's some material for bug reports. Opinions and suggestions
are welcome.
Bye,
bearophile
