You can tighten things up a little by initializing with the first element rather than dealing with undef: 
sub argmax(&@) {
  return() unless @_ > 1;
  my $block = shift;
  my $index = shift;
  my $max = $block->($index);
  for (@_) {
    my $val = $block->($_);
    ($max, $index) = ($val, $_) if $val > $max;
  }
  return wantarray ? ($index, $max) : $index;
}

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In reply to Re: argmin & argmax by Roy Johnson
in thread argmin & argmax by blokhead

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