=head1 TITLE

Built-ins: Merge and generalize C<index> and C<rindex>

=head1 VERSION

  Maintainer: Damian Conway <damian@conway.org>
  Date: 7 Aug 2000
  Mailing List: perl6-language@perl.org
  Number: 53
  Version: 10
  Status: Developing

=head1 ABSTRACT

This RFC proposes that the C<index> and C<rindex> functions be merged
and generalized, by adding a fourth parameter to C<index>.

=head1 DESCRIPTION

At present C<index> only returns the index of the first occurrence of a
specified substring. It is proposed that C<index> take a fourth parameter
telling it which occurrence of a specified substring to locate:

        $first = index $string, $substring, 0, 1;	# first occurrence
        $first = index $string, $substring, 0, 2;	# second occurrence
        $first = index $string, $substring, 0, 3;	# third occurrence

If omitted, this fourth parameter would default to 1, thus preversing
the current behaviour.

The C<rindex> function would be unnecessary, being replaced by:

        $last = index $string, $substring, -1, -1;	# last occurence
        

=head1 IMPLEMENTATION

Dammit, Jim, I'm a doctor, not an engineer!