#!/usr/bin/perl

use v5.24;
use warnings;
use experimental 'signatures';

say "This is perl $]";

sub f :lvalue ($k) {
    state $href = {a => 10};
    $href->{$k};
}

sub g :lvalue ($k) {
    state $href = {b => 20};
    $href->{$k};
}

eval q{
    (f($_) || g($_))++ for qw(a b);
    1;
} or warn $@;

${\(f($_) // g($_))}++ for qw(a b);

say "f(a) = ", f('a');
say "g(b) = ", g('b');

__DATA__
Can't modify logical or (||) in postincrement (++) at (eval 5) line 2, near ")++"
This is perl 5.032001
f(a) = 11
g(b) = 21