# I hope this works:
@foobar = reduce {@a ^+ @b} @foo, @bar, @baz, @etc;

# ... or this:
@foobar = reduce {@$a ^+ @$b} @foo, @bar, @baz, @etc;

# ... or possibly this:
@foobar = reduce {$a ^+ $b} @foo, @bar, @baz, @etc;