I like the idea here, check out Devel::Examine::Subs, which uses PPI to figure out where subs are. Not only that, it fetches the sub code and stuffs each sub into objects where you can spit them out individually. Works on any Perl file type.

I'm currently working AFK so I can't demo anything at the moment, but I'll see if I can get a chance a little later, but here's a quick and dirty example:

use strict;
use warnings;

use 5.10.0;

use Devel::Examine::Subs;

my $des = Devel::Examine::Subs->new(file => 'test.pl');

my $subs = $des->objects;

for my $sub (@$subs){
    say $sub->name;
    say "------";
    say $_ for @{ $sub->code };
    say "\n";
}
[download]

Input file:

use warnings;
use strict;

three(5);

sub three {
    return two(shift);
}
sub two {
    return one(_helper(shift));
}
sub one {
    my $num = calc(shift);
    display($num);
}
sub calc {
    my $num = shift;
    return $num ** 3;
}
sub display {
    my $num = shift;
    print "$num\n";
}
sub _helper {
    my $num = shift;
    return ++$num;
}
[download]

Output:

spek@scelia ~/scratch $ perl des.pl
display
------
sub display {
    my $num = shift;
    print "$num\n";
}


two
------
sub two {
    return one(_helper(shift));
}


three
------
sub three {
    return two(shift);
}


one
------
sub one {
    my $num = calc(shift);
    display($num);
}


calc
------
sub calc {
    my $num = shift;
    return $num ** 3;
}


_helper
------
sub _helper {
    my $num = shift;
    return ++$num;
}
[download]

Might help facilitate the separation with a bit more reliability :)