On Sunday, 6 December 2015 at 12:23:05 UTC, Tim K. wrote:
Hi! I have the following code:
int main(string[] argv)
{
import std.algorithm: sum;
import std.stdio: writeln;
uint[3] a1 = [1, 2, 3];
uint[] a2;
for (int i = 1; i <= 3; ++i)
a2 ~= i;
writeln("a1: ", sum(a1));
writeln("a2: ", sum(a2));
return 0;
}
This throws the error:
dummy.d(11): Error: template std.algorithm.iteration.sum cannot
deduce function from argument types !()(uint[3]), candidates
are:
/usr/include/dmd/phobos/std/algorithm/iteration.d(3916):
std.algorithm.iteration.sum(R)(R r) if (isInputRange!R &&
!isInfinite!R && is(typeof(r.front + r.front)))
/usr/include/dmd/phobos/std/algorithm/iteration.d(3927):
std.algorithm.iteration.sum(R, E)(R r, E seed) if
(isInputRange!R && !isInfinite!R && is(typeof(seed = seed +
r.front)))
So a dynamic array works just fine. In fact, if I uncomment the
line in question the program compiles and outputs the correct
value (for a2). Why does "sum" not work on static arrays?
Regards
So that you do not shoot yourself in the foot too easily. A
static array is a value type so it is passed by value to
functions. If you pass a 1M array to a function... well, I guesse
you don't want to do that.
The solution is to slice it: a1[].sum; That way you avoid the
problem.
