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"Types lead to fewer bugs when making changes to long-lived codebases" is not up for much of a debate in my opinion. Preventing regressions is arguably a lot mo

"Types lead to fewer bugs when making changes to long-lived codebases" is not up for much of a debate in my opinion. Preventing regressions is arguably a lot more important than writing a correct first pass, which is what you are evaluating when looking at non-evolving code. Concretely-speaking, an example of a bug being preventd by a typing system: Removing a field from an object in a large vanilla JavaScript project is inherently a minefield that has caused many bugs in the past, whereas the same alteration in a full Typescript project can be made with confidence.

mpweiher 3y ago
It’s no longer up for debate, true. But not in the way you fervently want to believe. Once again: people have tried to show the truth of this for a long time, and they have consistently failed.
- Chabsff 3y ago
  I'm arguing that the studies linked in that blog post are fundamentally flawed because they only take into account first-pass development, and fail to take long-term maintainability into consideration. And this is silly because that's where the main value of type systems reside. > This paper presents an empirical study with 49 subjects that studies the impact of a static type system for the development of a parser over 27 hours working time.
  - mpweiher 3y ago
    That is not true. There are some studies like that, but there are others as well. And remember that all these studies were trying to find a positive effect, but failed to do so.
    - Chabsff 3y ago
      Well... It is true of everything in that blog post. But I am wiling to have my mind changed. I would be really interested in seeing a study that failed to find a benefit of type systems for refactoring tasks in large projects. The example I posted in my initial comment seems pretty open-and-shut to me, so I'm curious.
      - mpweiher 3y ago
        > Well... It is true of everything in that blog post. That turns out not to be the case. > I would be really interested in seeing a study that failed to find a benefit of type systems for refactoring tasks in large projects. You're inverting the burden of proof here. People who claim that something is beneficial are the ones who have to show that it is. Making a claim and then shouting "prove me wrong!" is not how science works. Not even computer science.
        spion 3y ago
        https://www.bmj.com/content/363/bmj.k5094 https://www.bmj.com/content/363/bmj.k5094
        deleted 3y ago
        [deleted]
  - boxed 3y ago
    And yet, if the signal was that strong, it should be clear. It's not.
taeric 3y ago
It... should be up for debate? I'm fine taking it as a given in projects I'm running. But I do expect people that have the ability to do so, to debate it. Preferably to study it and find concrete evidence.
- Chabsff 3y ago
  Admittedly, that was a bit hyperbolic on my part. What I meant to convey is that the matter is settled enough from my point of view that there needs to be a very strong case being made for me to be willing to engage in that conversation. Thanks for pointing this out, I've amended the comment to clarify a bit.
  - mpweiher 3y ago
    > the matter is settled enough Based on what evidence? Apart from emotion?
    - taeric 3y ago
      Charity to the idea, when boots are on the ground to do the actual work is a terribly place for running that debate. :D Is why I'm in agreement enough for projects I'm working on. I am open to the idea that we find more evidence and/or change our minds for the next project, but "when in Rome" is a good reason to drop the debate and basically declaim what your driving idea is at the start.
nurple 3y ago
"Types let me make changes to code I haven't taken the time to understand" is hardly the proof you seem to think it it's. Removing a field in a data structure is such a big problem, even in typed systems, that the most ubiquitous serialization IDLs, and customer-facing API conventions, don't even allow it.
- Chabsff 3y ago
  And I would contend that anyone claiming "I am capable of taking everything about the code I am tasked to change into consideration" is delusional when it comes to non-trivial projects, including single-dev endeavors. As far as serialization IDLs and API conventions go, they have the very special constraint of having to provide both forward and backwards compatibility across multiple applications, making them a very poor universal example.
  - mpweiher 3y ago
    Is there anyone making that claim? Apart from straw-men? As an example, I was once refactoring a Java system. The compiler was happy after about a day, the unit tests after three days. So if you claim your type system is going to keep your refactoring safe, I'd say that I'm not the one being delusional. And of course unit tests also tend to, in practice, catch the errors that are caught by types. If you check that a value is equal to 10 rather than 9, you've also implicitly checked that it is not of type PinkElephant. Now I perfectly understand the feeling that people who are used to the safety-net that static typing appears to give have when encountering a code-base without types. I have the same feeling when encountering a code-base without reasonably comprehensive unit tests (that fail when I poke into the code-base). The feeling is absolute terror. I just contend, with reasonably good justification, that this feeling is not particularly justified in the case of static types, because the evidence is just not there. I haven't checked what the evidentiary status is for unit tests. But then again, I don't make these sorts of categorical claims for unit tests. I just make claims for my experience with unit tests.
    - Chabsff 3y ago

mpweiher 3y ago

It’s no longer up for debate, true. But not in the way you fervently want to believe. Once again: people have tried to show the truth of this for a long time, and they have consistently failed.

Chabsff 3y ago
I'm arguing that the studies linked in that blog post are fundamentally flawed because they only take into account first-pass development, and fail to take long-term maintainability into consideration. And this is silly because that's where the main value of type systems reside. > This paper presents an empirical study with 49 subjects that studies the impact of a static type system for the development of a parser over 27 hours working time.
- mpweiher 3y ago
  That is not true. There are some studies like that, but there are others as well. And remember that all these studies were trying to find a positive effect, but failed to do so.
  - Chabsff 3y ago
    Well... It is true of everything in that blog post. But I am wiling to have my mind changed. I would be really interested in seeing a study that failed to find a benefit of type systems for refactoring tasks in large projects. The example I posted in my initial comment seems pretty open-and-shut to me, so I'm curious.
    - mpweiher 3y ago
      > Well... It is true of everything in that blog post. That turns out not to be the case. > I would be really interested in seeing a study that failed to find a benefit of type systems for refactoring tasks in large projects. You're inverting the burden of proof here. People who claim that something is beneficial are the ones who have to show that it is. Making a claim and then shouting "prove me wrong!" is not how science works. Not even computer science.
      - spion 3y ago
        https://www.bmj.com/content/363/bmj.k5094 https://www.bmj.com/content/363/bmj.k5094
      - deleted 3y ago
        [deleted]
- boxed 3y ago
  And yet, if the signal was that strong, it should be clear. It's not.

taeric 3y ago

It... should be up for debate? I'm fine taking it as a given in projects I'm running. But I do expect people that have the ability to do so, to debate it. Preferably to study it and find concrete evidence.

Chabsff 3y ago
Admittedly, that was a bit hyperbolic on my part. What I meant to convey is that the matter is settled enough from my point of view that there needs to be a very strong case being made for me to be willing to engage in that conversation. Thanks for pointing this out, I've amended the comment to clarify a bit.
- mpweiher 3y ago
  > the matter is settled enough Based on what evidence? Apart from emotion?
  - taeric 3y ago
    Charity to the idea, when boots are on the ground to do the actual work is a terribly place for running that debate. :D Is why I'm in agreement enough for projects I'm working on. I am open to the idea that we find more evidence and/or change our minds for the next project, but "when in Rome" is a good reason to drop the debate and basically declaim what your driving idea is at the start.

nurple 3y ago

"Types let me make changes to code I haven't taken the time to understand" is hardly the proof you seem to think it it's. Removing a field in a data structure is such a big problem, even in typed systems, that the most ubiquitous serialization IDLs, and customer-facing API conventions, don't even allow it.

Chabsff 3y ago
And I would contend that anyone claiming "I am capable of taking everything about the code I am tasked to change into consideration" is delusional when it comes to non-trivial projects, including single-dev endeavors. As far as serialization IDLs and API conventions go, they have the very special constraint of having to provide both forward and backwards compatibility across multiple applications, making them a very poor universal example.
- mpweiher 3y ago
  Is there anyone making that claim? Apart from straw-men? As an example, I was once refactoring a Java system. The compiler was happy after about a day, the unit tests after three days. So if you claim your type system is going to keep your refactoring safe, I'd say that I'm not the one being delusional. And of course unit tests also tend to, in practice, catch the errors that are caught by types. If you check that a value is equal to 10 rather than 9, you've also implicitly checked that it is not of type PinkElephant. Now I perfectly understand the feeling that people who are used to the safety-net that static typing appears to give have when encountering a code-base without types. I have the same feeling when encountering a code-base without reasonably comprehensive unit tests (that fail when I poke into the code-base). The feeling is absolute terror. I just contend, with reasonably good justification, that this feeling is not particularly justified in the case of static types, because the evidence is just not there. I haven't checked what the evidentiary status is for unit tests. But then again, I don't make these sorts of categorical claims for unit tests. I just make claims for my experience with unit tests.
  - Chabsff 3y ago