Trying to understand map being a template

[Paul Backus]

On Friday, 5 January 2024 at 20:41:53 UTC, Noé Falzon wrote:
> In fact, how can the template be instantiated at all in the 
> following example, where no functions can possibly be known at 
> compile time:
>
> ```
> auto do_random_map(int delegate(int)[] funcs, int[] values)
> {
> 	auto func = funcs.choice;
> 	return values.map!func;
> }
> ```
>
> Thank you for the insights!

It works for the same reason this example works:

```d
void printVar(alias var)()
{
     import std.stdio;
     writeln(__traits(identifier, var), " = ", var);
}

void main()
{
     int x = 123;
     int y = 456;

     printVar!x; // x = 123
     printVar!y; // y = 456
     x = 789;
     printVar!x; // x = 789
}
```