Yesterday, for the last day of The Perl Conference (formerly known as YAPC) in Glasgow, Scotland, Curtis "Ovid" Poe delivered a very inspiring keynote address on the future of Perl.

Ovid's idea was to imagine where Perl 5 would stand in ten years from now.

These are some of the things Perl would have in 10 years in Ovid's vision:

• (Non experimental) Function signatures along with a gradual typing system;
• A simple core OO system (see http://blogs.perl.org/users/ovid/2018/07/the-future-of-perl-5.html)
• An inline keyword to support functions in-lining to boost performance while not repeating oneself;

As an example for the first point above, consider the following subroutine:

sub fibonacci {
    my $n = shift;
    return 1 if $n == 1 or $n == 0;
    return fibonacci($n-1) + fibonacci($n-2);
}
[download]

This subroutine should work correctly if the subroutine is called with a positive integer, but a number of things could go wrong: what will happen if no parameter is passed to the subroutine? or if the parameter is a negative integer, say -3? or if the parameter is a positive number but not an integer, e.g. 3.14? or if the parameter is not a number but a string? (Note that there would also be a problem with a large integer, but that's a different story.)

For the above subroutine to be correct, you would need to add probably half a dozen boiler plate code lines to guard against invalid input, for example maybe something like this:

sub fibonacci {
    die "..." unless defined $_[0];
    my $n = shift;
    die "..." unless is_a_number($n); # the is_a_number function is to
+ be defined
    die "..." if $n < 0;
    die "..." if $n != int $n;
    # ...
}
[download]

With (non experimental) function signatures and proper typing, all you would need might just boil down to something like:

sub fibonacci (PositiveInt $n) {
    return 1 if $n <= 1;
    return fibonacci($n-1) + fibonacci($n-2);
}
[download]

I think this would look quite cleaner.

I hope the video of Ovid's talk will on-line soon.

Comments are welcome.

Update (Aug 23): ovid created a new meditation explaining his views with some details here: Recap: The Future of Perl 5.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.