TL;DR

I discovered unit sub MAIN (...); and I like it.

I read Mark Gardner’s Frenemies part 2: What a difference a (Perl) module makes (which I suggest people to read, too) and I was intrigued by this comment by Mark J. Reed:

For short programs with no other subroutines, I prefer using unit sub MAIN(signature here);, which treats the entire file as the body of the MAIN subroutine and saves you some curlies and an indentation level while still getting you the automatic argument parsing that comes from declaring a MAIN sub.

Indeed this is a nice way of getting out-of-the-box command line handling for simple (and not-so-simple maybe?) programs:

#!/usr/bin/env raku
use v6;
unit sub MAIN (:$this!, :$that = 'whatever');

put "this<$this>";
put "that<$that>";

It’s the good ol’ bunch of lines likely to grow untamed, which has a retro feeling I like at my age.

But then this caught my attention (emphasis mine):

For short programs with no other subroutines, I prefer […]

Wait, what?

This restriction can be loosened a bit. Raku allows having subs nested in other subs, so this works too:

#!/usr/bin/env raku
use v6;
unit sub MAIN (:$this!, :$that = 'whatever');

put "this<$this>";
put "that<$that>";

print-all($this, $that);

sub print-all (*@stuff) { .put for @stuff }

Then… of course there will probably be differences (like… does print-all have a fully qualified name at all?), but again this means that for simple programs it’s still possible to get organized with some modularity.

Alas, at the expense of that retro feeling. I’m getting too old for this…

Have -Ofun and stay safe people!!!