Combines two T instances associatively.
Combines two T instances associatively.
result of combining l and r
Returns an instance of T calculated by summing all instances in
iter in one pass.
Returns an instance of T calculated by summing all instances in
iter in one pass. Returns None if iter is empty, else
Some[T].
None if iter is empty, else an option value containing the summed T
Override if there is a faster way to compute this sum than
iter.reduceLeftOption using plus.
Returns the identity element of T for plus.
Returns the identity element of T for plus.
Combine 12 groups into a product group