Return the identity element for this monoid.
Return the identity element for this monoid.
Given a sequence of as
, sum them using the monoid and return the total.
Given a sequence of as
, sum them using the monoid and return the total.
Given a sequence of as
, sum them using the semigroup and return the total.
Given a sequence of as
, sum them using the semigroup and return the total.
If the sequence is empty, returns None. Otherwise, returns Some(total).
Return a
combined with itself n
times.