These are from algebra.
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]
.
instances of T
to be combined
None
if iter
is empty, else an option value containing the summed T
Since Lists are mutable, this always makes a full copy. Prefer scala immutable Lists if you use scala immutable lists, the tail of the result of plus is always the right argument