Re (tilly) 1 (perl): What Happened...(perils of porting from c)

[tilly]

Here is a native Perlish thing that basically does what I think you really want. Note how much shorter this is than the C version.

use strict;

nested_for(
  sub {print "@_\n";},
  [1..2], ['a'..'c'], ['A'..'D']
);

sub nested_for {
  ret_iter(@_)->();
}

sub ret_iter {
  my $fn = shift;
  my $range = shift;
  my $sub = sub {$fn->($_, @_) for @$range};
  return @_ ? ret_iter($sub, @_) : $sub;
}

Also note the lack of pointer arithmetic to mess up on. :-)

[Madams]

Oh Wow!

I bow to tilly!

I am going to REALLY study this: it works! correctly! it's one-third the size! it looks tricky but not f**** insane! and NO POINTER ARITHMETIC!!!!

This is the sort of answer that shows that i'm a tyro at perl AND why! I'm obviously still stuck in some sort of tunnel vision caused by programming in c/c++.

To me this is a great Zen Koan to meditate on!

Thanks tilly, and everyone who responded to this query!

---madams :) x $POSIX::LDBL_MAX

[Roy Johnson]

That was beautiful. I'm writing primarily so more people can see it. I also did a little rewrite that isn't an improvement, per se, but is AWTDI and may help people understand what's going on. (Iterating instead of recursing.)

sub ret_iter {
  my $sub = shift;
  while (my $range = pop) {
    my $inner = $sub;
    $sub = sub { $inner->(@_, $_) for @$range };
  }
  return $sub;
}

I made it so it changes elements on the right fastest, like a counter.