use Algorithm::Loops qw( NestedLoop );

my $iter = NestedLoop([
   map { [ $_->() ] } @subs
]);

while ( my @items = $iter->() ) {
   ...
}

##</code><code>##

use Algorithm::Loops qw( NestedLoop );

my $iter = NestedLoop(\@subs);

while ( my @items = $iter->() ) {
   ...
}