Reduce (fold) for the imperatively minded

The reduce or fold function is a concept in functional programming languages which can be used to simulate looping behaviour without the need for a real loop, and in particularly without the need for any explicit variables. I believe it originated in the field of functional programming languages, where getting rid of any form of ‘state’ seems to be an overriding aim.

I suspect that, with suitable training, one may be able to grasp the meaning of a