com.twitter.algebird
Some(5) - Some(3) == Some(2) Some(5) - Some(5) == None negate Some(5) == Some(-5) Note: Some(0) and None are equivalent under this Group
override this if there is a faster way to do this sum than reduceLeftOption on plus
Some(5) - Some(3) == Some(2) Some(5) - Some(5) == None negate Some(5) == Some(-5) Note: Some(0) and None are equivalent under this Group