Once again, is seek enlightenment. I have the code (below) that works (with 1 mod), but I can't explain why. I have an interest in random numbers. So I tried the iterator code from Higher Order Perl to create an independent RNG as an iterators.

The code contains page references to HOP as to where the individual parts came from that I pulled together. For 5 hours, I couldn't get a successful run. The commented line labeled "!!! Important ..." was missing.

It was way back in the iterator chapter, and simply called "a bit of sugar". There is no explanation of that sort of magic it is causing the Perl interpreter to do. It seems to be a duplicate definition for the function 'Iterator' .

Can someone explain what this 'sugar' does and how? 

use strict;

# Definition from HOP page 122
sub NEXTVAL { $_[0]->() }

# HOP top of page 123, called "a bit of sugar" ???
#sub Iterator (&) { return $_[0] }  #!!Important to make this work unc
+omment!!!

#HOP page 156
sub make_rand
{
  my $seed = shift || (time & 0x7ffff);
  print "Seed=$seed\n";
  return Iterator {
          #print " << $seed\n";
          $seed = (13  * $seed + 31011) & 0x7ffffff;
          #print " >> $seed\n";
          return $seed;
         };
}


# My test code
my $rng = make_rand();  # a reference to an "Iterator" code different 
                        # from the one defined originally ??

my @bucket;
my $i;
my $t;

#printf " ==%d\n",(2**31);

#  HOP pages 156,7
for $i (1..10000){
  my $rndx = NEXTVAL ($rng);
  #print " $rndx  ";
  $rndx %= 100;
  #print " $rndx\n";
  $bucket[$rndx] ++;
}

# test code
$t=0;
for $i (0..99) {
  print "$bucket[$i]-  ";
  $t+=$bucket[$i];
}
printf "\nAvg= %6.2f\n", $t/100;

__END__

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Aside: While very "advanced", I would probably *not* use this technique due to the corresponding very high "obscure" and "unmaintainable" score.

It is always better to have seen your target for yourself, rather than depend upon someone else's description.

In reply to "a bit of sugar "(HOP) by Wiggins

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