That's exactly what Algorithm::Loops's NestedLoop does.

use Algorithm::Loops qw( NestedLoop );

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

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

Update: LanX points out the above can be simplified if the subs return the same thing each time they are called. They also need to return the values via a reference to an array.

use Algorithm::Loops qw( NestedLoop );

my $iter = NestedLoop(\@subs);

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