automate tuple creation

[Ali Çehreli]

On 1/19/22 13:59, forkit wrote:

 > void createBoolMatrix(ref uint[][] m)
 > {
 >      auto rnd = Random(unpredictableSeed);

That works but would be unnecessarily slow and be against the idea of 
random number generators. The usual approach is, once you have a 
randomized sequence, you just continue using it. For example, I move rnd 
to module scope and initialize it once.

Random rnd;

shared static this() {
   rnd = Random(unpredictableSeed);
}

auto randomValue() {
   return cast(uint)rnd.dice(0.6, 1.4);
}

// Returning a dynamically allocated array looks expensive
// here. Why not use a struct or std.typecons.Tuple instead?
auto randomTuple() {
   return [ randomValue(), randomValue() ];
}

void createBoolMatrix(ref uint[][] m, size_t count)
{
   import std.algorithm : map;
   import std.range : iota;
   m = count.iota.map!(i => randomTuple()).array;
}

Ali