These are from algebra.Monoid
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.
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