Summers

TODO: Discuss what summers are, and improve the documentation below on StatefulSummer.

StatefulSummer

A Stateful summer is something that is potentially more efficient (a buffer, a cache, etc…) that has the same result as a sum:

Law 1: Semigroup.sumOption(items) ==
  (Monoid.plus(items.map { stateful.put(_) }.filter { _.isDefined }, stateful.flush) &&
    stateful.isFlushed)
Law 2: isFlushed == flush.isEmpty

Documentation Help

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• StatefulSummer.scala