# Takes an array ref and a target item
# Returns the index of the item in the array or
# -1 if its not there.
sub binsearch {
  my $arref = shift;
  my $target = shift;

  my $len = scalar @$arref;
  my $midpoint = floor( $len / 2); # Get the center, rounding down when we have 1 element left we don't get undef
  my $cmp = $target cmp $arref->[$midpoint]; # make the comparison once

  return $midpoint unless $cmp; # We've found it!
  return -1 if $len == 1; # Must not be there
  return binsearch ([$arref->[0..$midpoint],$target) if $cmp == -1; # Its in the lower half, check to the midpoint because its rounded down
  return binsearch ([$arref->[$midpoint+1..$len-1],$target) if $cmp == 1; # Its in the upper half, check to the midpoint +1 for reason stated above
  croak "Something really weird happened. Might want to run make test on perl itsself.";
}