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]
.
instances of T
to be combined
None
if iter
is empty, else an option value containing the summed T
Group: this is a monoid that also has subtraction (and negation): So, you can do (a-b), or -a (which is equal to 0 - a).