```d
import std.stdio;
import std.algorithm;
int potentiallyExpensiveCalculation(int arg)
{
writefln("eval %s",arg);
return arg;
}
int[] args = [1,2,3,-1,2];
auto best = args.map!(a =>
potentiallyExpensiveCalculation(a)).minIndex;
```
This needs n-1 compares, but is also computing
potentiallyExpensiveCalculation twice as many times as necessary.
Why does map not fully resolve to the results before it is passed
to minIndex, so that two ints are compared not two
potentiallyExpensiveCalculation of ints.
I didn't know map was lazy...
I could put .array between map and minIndex but that defeats the
purpose of ranges.
