Combines two T
instances associatively.
Combines two T
instances associatively.
result of combining l
and r
Returns the identity element of T
for plus.
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