srand in D

[Ali Çehreli]

On 1/8/22 12:27 PM, kdevel wrote:
> On Sunday, 31 October 2021 at 17:02:00 UTC, Ali Çehreli wrote:
>> Just comment that line out. :) D's pseudo-random generators start 
>> randomized by default:
> 
> [...]
> 
>>   https://dlang.org/phobos/std_random.html
> 
> Klicking at "Run" always delivers "mango":
> 
> https://dlang.org/phobos/std_random.html#uniform
> 
> A very unbalanced die

That example wrapped in a program is the following:

import std.stdio;
import std.random;

void main() {
     auto rnd = MinstdRand0(42);

     writeln(rnd.uniform!ubyte); // 102
     writeln(rnd.uniform!ulong); // 4838462006927449017

     enum Fruit { apple, mango, pear }
     version (X86_64) // https://issues.dlang.org/show_bug.cgi?id=15147
         writeln(rnd.uniform!Fruit); // Fruit.mango
}

Apparently, the programmer wanted uniformly distributed randomness that 
is reproducible. That's why they use a generator that is seeded with 42 
there.

It does produce random results but the first Fruit happens to be "mango" 
with that seed.

TIL, I can use uniform with a type as in uniform!Fruit. Pretty cool. :)

Ali