←back to thread

Type checking is a symptom, not a solution

(programmingsimplicity.substack.com)
67 points mpweiher | 1 comments | 05 Sep 25 05:56 UTC | HN request time: 0.372s | source
Show context
crazygringo ◴[05 Sep 25 18:41 UTC] No.45142085[source]▶
> Why do we need type checking at all? The standard answer is scale. “Small programs don’t need types,” the reasoning goes, “but large programs become unmaintainable without them.”

No it's not.

Type checking is a first line of defense against bugs. That's all.

It's just making sure you're not accidentally passing invalid data or performing an invalid operation.

And since the article gets the premise wrong, its conclusion that reducing complexity will make type checking "largely irrelevant" is therefore also wrong.

replies(3): >>45142327 #>>45142430 #>>45145286 #
1. Agraillo ◴[06 Sep 25 00:21 UTC] No.45145286[source]▶
> It's just making sure you're not accidentally passing invalid data or performing an invalid operation.

To understand that this is a big deal, one sometimes needs to face the relaxed rules of their static language of choice. Delphi (and its ancestor Turbo Pascal) allows passing untyped pointers for parameters defined as typed. This behavior is actually controlled by a setting that is probably relaxed (allowed) by default. It seems it was done for convenience when using pointer arithmetic. At some point in the past, I also started logging categories of bugs (an ad-hoc taxonomy) and, if some kind of bug appeared more than once, to do something about it (like encouraging a new habit, rule, or something similar). So, after passing wrong pointers twice in a short period of time, I made it mandatory for all sources to have only typed pointers, which required some additional typing but saved me from similar bugs further on.