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0 pointsjolux4y ago0 comments

> That is the difference between fact and conjecture.

Yes, but I'm trying to make a formal statement of fact here, not an empirical one.

> I think the set of kinds of bugs that can be written in dynamic languages is a strict superset of the kinds of bugs that can be written in a static language.

Here I am attempting to make a formal statement about the set of runtime behaviors that can be exhibited under static type systems. What I'm saying is that there is a set of incorrect runtime behaviors that can only be exhibited in a dynamic type system, that is, the set of type errors. I'm not aware of any runtime errors that can only be exhibited under a static type system. I'm not well educated enough in the relevant fields to be able to formalize this with notation (I would do so if I was, I think notation communicates these things much more clearly than words) but I do believe it has a formal representation.

> A conjecture that we've tried to verify yet failed to see a large effect is a problematic conjecture.

I think we're somewhat talking past each other here. What I'm saying is that the set of possible incorrect runtime behaviors is smaller in a static language. This can't really be empirically verified, it should have a formal answer in type theory or programming language theory. It's possible I'm wrong about what the formal answer is, but I haven't seen you address it yet. It's also possible that this is true but not strongly related to the way that bugs evolve in typical software engineering practice, I've speculated upthread that the total number of bugs might be similar because programmers make a higher number of repeated mistakes from the more narrow set while programming in static languages (though personally this seems unlikely). It's further possible that this is just not a very significant effect, as you have conjectured. However it is my belief that if there is an effect on bugs overall that it derives from what I understand to be a formal character of the runtime behavior of statically typed programs, that there are fewer ways for them to "go wrong."

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pron4y ago

> What I'm saying is that there is a set of incorrect runtime behaviors that can only be exhibited in a dynamic type system, that is, the set of type errors. I'm not aware of any runtime errors that can only be exhibited under a static type system.

But that doesn't mean they have fewer bugs! They might well have more.

> What I'm saying is that the set of possible incorrect runtime behaviors is smaller in a static language.

Not exactly. For every program in an untyped language, you could write a typed program with the exact same behaviours.

The assertion that typed programs have fewer bugs is simply false in theory, and failed to be confirmed empirically.

> However it is my belief that if there is an effect on bugs overall that it derives from what I understand to be a formal character of the runtime behavior of statically typed programs, that there are fewer ways for them to "go wrong."

I understand that that is your belief, but it is supported by neither theory nor practice.

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