Paul A Bristow writes:
Thanks for this further motivational example: it had previously seemed a bit of a sledge hammer to crack a nut, but I now see situations in which it could provide much more safety than I had imagined.
The difficulty with constructing a simple motivational example is that the true value may not become apparent until one faces a real-world problem that is much more complex than an example warrants. Thus, perhaps some imagination is required to extrapolate from the structure of the example to what one might normally encounter. It seems that you are beginning to make that leap. I would appreciate suggestions on how to make that leap easier so that people can appreciate the power of this abstraction. Thanks for your comments. I look forward to more detailed reviews and tests. Cheers, Brook