joiner and map, strange behavior

[Stephan Schiffels]

Hi,

I am struggling with understanding this behavior. In the code 
below, the function "getVec" is called 8 times, but it should be 
called only 4 times (once for each call inside of map).

Any explanations?

Stephan


import std.stdio;
import std.algorithm;
import std.array;

int[] getVec(size_t i) {
   writeln("getVec is called");
   auto vals = [
     [1, 2, 3, 4],
     [5, 6, 7, 8],
     [9, 10, 11, 12],
     [13, 14, 15, 16]
   ];
   return vals[i];
}


void main() {

   auto result = [0, 1, 2, 3].map!(getVec).joiner.array;
   writeln(result);

}