Higher Order Imperative Programming

It is argued that a programming style based on higher order techniques the use of procedures that have other procedures as arguments and or results can be most e ectively employed if it is driven by abstraction from real algorithms rather than attempting to work with a xed set of functional forms and the use of imperative forms and mutative procedures is permitted even encour aged rather than restricting to a purely applicative style A sequence of examples is presented illustrating a number of higher order techniques operators iterators accumulation reduction parallel reduction and their e ective use in conjunction with mutative procedures The examples culminate with an interesting family of sorting algorithms illustrating how higher order techniques can lead naturally to new algorithms