This is just a side note, but a problem with accumulate in this context is that is defined as doing `acc = op(acc, element)` for each element. This means that w

This is just a side note, but a problem with accumulate in this context is that is defined as doing `acc = op(acc, element)` for each element. This means that whatever allocation the accumulator had is going to be thrown away on each iteration of the loop. Had it been defined as `acc += element`, then allocation schemes such as doubling the allocated memory would have been more effective and greatly reduces the number of allocations (and copies).