MutableArithmetics: An API for mutable operations

Arithmetic operations defined in Julia do not modify their arguments. However, in many situations, a variable represents an ac-cumulator that can be modified in-place to contain the result, e.g., when summing the elements of an array. Moreover, for types that support mutation, mutating the value may have a significant performance benefit over creating a new instance. This paper presents an interface that allows algorithms to exploit mutability in arithmetic operations in a generic manner.