Designing Accumulator-Style Functions

Section  illustrated with two examples the need for accumulating extra knowledge. In some cases, the accumulation makes it easier to understand a function; in others it is necessary for the function to work properly. In both cases, however, we first chose one of the available design recipes, inspected the function, and then revised or fixed it. Put more generally, adding an ACCUMULATOR, that is, a parameter that accumulates knowledge, is something that we add to a function after we have designed a function, not before.

The keys to the development of an accumulator-style function are:

1. to recognize that the function benefits from, or needs, an accumulator;
2. to understand what the accumulator represents.

• Recognizing the Need for an Accumulator
• Accumulator-Style Functions
• Transforming Functions into Accumulator-Style