Confusion about `Random`

[Salih Dincer]

On Thursday, 22 December 2022 at 16:23:16 UTC, jwatson-CO-edu 
wrote:
> What is the reason for this? Has the compiler optimized away 
> the `uniform` call to a single double number?
> What is the main difference between Program 1 and Program 2?  
> Both seem to:
> * Have a global RNG `rnd`
> * Seed RNG after `main` starts.
> * Generates a random number on [1,0) from a function.
>
> So I would expect both programs to behave the same...

I made your code runnable based on the information you provided 
us. There seems to be no problem if you try. You can try using 
static this.

```d
import std.random;

static this() { } // can try using

Mt19937 rnd;
void init_random() {
   rnd = Random(unpredictableSeed);
}

double rand01() {
     return uniform(0, 1.0, rnd);
}

void main()
{
   init_random();

   struct Atom { double num; }
   alias atom = Atom* function();
   atom[string] primitiveSymbols = [
     "rand" : () => new Atom(rand01)
   ];
   import std.stdio;
   writeln(*primitiveSymbols["rand"]()); // Atom(0.630001)
}
```
SDB at 79