Was Dijkstra wrong? Is GOTO good for novice programmers?

.. programming education .. may by chance have thrown the baby out with the bathwater, just as the reform maths educators did with calculators in schools.

In the old days, before calculators, children had to learn to do long multiplication, for example 431 × 27, using pencil and paper. This was a bit of a chore, now largely dropped in favour of tapping the problem into a calculator, which gets the answer more reliably. However, it turns out that the children were learning a lot more by accident than how to multiply long numbers. They were learning to set out their working in an error-displaying form, essentially a twentieth century proof that their answer was correct. They had to be absolutely precise in their working, but if they made a mistake, they could check their working, find the mistake and correct it. Their teachers could periodically take in this work and confirm that their pupils were working accurately and in a proper error-displaying way. Not only all that, but children were intuitively learning something about the mathematical structure of numbers by working with them, so that when they came to polynomials they found that working out (4x² + 3x + 1) × (2x + 7) was not much different to working out 431 × 27. (In fact it’s a bit simpler, because there are fewer carries.) To someone with a calculator, they are entirely different.

I wonder if, in the way we try to teach programming nowadays, we may have fallen into some similar traps, by not realising what students accidentally learned in the past.

For example — and here’s a heretical thought — are languages with GOTO really as bad as we imagine for noviceprogrammers? Dijkstra claimed that “It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration”. But don’t forget this was just a claim: where’s the evidence? Dijkstra himself obviously first learned to program in a language with only GOTOs, as I did, and I’m fairly happy that it did us no lasting damage. In fact I think it forced us to think about our code and to work with it in a particular detailed way, and this earlier practice may have served us well later, even when we programed in structured languages.





Leave a comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.