5 ms·

No, static typing just gives a false sense of reliability to people who are not experts in reliability. There is even some research showing no correlation of st

by zzzcpan 10y ago

No, static typing just gives a false sense of reliability to people who are not experts in reliability. There is even some research showing no correlation of static typing vs dynamic typing to bugs [1]. People tend to ignore it though. [1] http://web.cs.ucdavis.edu/~filkov/papers/lang_github.pdf http://web.cs.ucdavis.edu/~filkov/papers/lang_github.pdf

zeptomu 10y ago
> No, static typing just gives a false sense of reliability That is not true, there are real benefits and classes of bugs, that can be avoided before runtime. Historically there was the drawback that inferring these bugs has been computational infeasible for some programs, but nowadays the situation is much better. IMHO the only positive aspect of dynamic languages is their syntactic beauty and existing large eco systems. I admire Elixir's and Erlang's approach to concurrency and think this model (do not share data and engineer for failures that will happen in distributed systems) is great, but could be combined with static typing.
- goatlover 10y ago
  Dynamic languages tend to let you express yourself more easily and cleanly with less code. Paul Graham years ago wrote about how Lisp let's you write more maintainable code by being able to express yourself close to the problem domain. The power of DSLs is that it's easy to read and write code for that particular sort of task. Another way to state the advantage of expressive languages is that the less code you have to right, the less bugs you will have. And the less code written, the less code needs to be maintained, the less needs to be read to understand what's going on. Of course this all depends on writing clean code, not obfuscated hacks or undocumented messes with needless complexity. But that goes for all programming.
  - lobster_johnson 10y ago
    There have been some advances in language theory since Lisp, though. In particular, modern type inference allows you to practically eliminate type declarations and approximate the terseness and expressiveness of dynamic languages. Recent languages such as Crystal and Nim have demonstrated that this is entirely feasible. (I mentioned Go earlier, but Go is, if anything, regressive when it comes to language theory, and not a good example of how to do things right.) The Lisp example is only convincing if you've not seen what a really impressive type system can do; Haskell and the ML family come to mind, and Rust and Swift both seem promising in that regard, as does Crystal. "Less code means less bugs" is a powerful meme, but it's a misleading metric in the context of type systems. Dynamic languages necessarily require less code since they eliminate information that otherwise allows you to fully reason at compile time about the program's future execution, thereby eliminating the ability to guarantee its safety; and the opposite is also true: "less information means more bugs". Ultimately, it's less logic we want — less decisions that can go wrong. In Lisp, or any other dynamically typed language, you can pass a variable of the wrong type to a function and won't know it's wrong until you run the program — how did fewer lines of code help you? The equivalent program in a statically typed language might be slightly longer (though it could also be the same size), but the additional type declarations have made your program less buggy, not more.
    - braveo 10y ago
      "less information means less bugs" is not the same thing as "less code means less bugs". Your entire argument there is a non-sequitur, no one who says "less code means less bugs" is talking about the mechanical aspect of typing out code. They're talking about a combination of using battle tested code and writing at a higher level of abstraction.
      - lobster_johnson 10y ago
        I wasn't talking about "the mechanical aspect". And I did not claim anything like what your first sentence implies.
        braveo 10y ago
        you treated the phrase literally.
    - kazinator 10y ago
      > won't know it's wrong until you run the program That's a big problem, indeed, if your goal is to ship code that was never executed.
      - lobster_johnson 10y ago
        But the whole point of type systems is that you can theoretically verify your code at a high level (though very few computer languages are able to approximate anything like a mathematical proof). I wrote about this in another comment, in the context of writing tests.
        kazinator 10y ago
        In theory, practice is the same as theory. In practice, it isn't. I've seen only toy examples of some non-trivial program properties being encoded in type systems. It nowhere constituted proof of an entire program. Nobody actually does that. A lot can remain wrong in code which passes type checks. There is no "if it compiles, ship it". Not to mention that compilers can have bugs, and that hidden performance and resource problems can lie latent in high level languages.
  - fghgfdfg 10y ago
    I've never understood what people actually mean when they say things like "dynamic languages let you express yourself more easily." I tend to find it significantly harder in dynamic languages. Yeah, there is way more flexibility in small decisions (like right now, is it easier to return a string or an integer or whatever) but it's not free. Your little decision interacts, directly or otherwise, with potentially the entire rest of the program that might ever exist. There is probably a best choice, and it's hard not to try to find it every single time. Doing the easiest thing right now might mean you need to go and adjust many other things. In order to know what is overall easier you need to keep the rest of the program in mind. I find dynamic languages kind of exhausting to write anything but one-off scripts in. I can't make good choices without holding far more of the program in my head than I would in a static language. Sometimes I don't even realize I'm making such a decision because I don't have a correct or full view of the rest of the program. To make matters worse those errors won't even show up as being a problem at the decision-site. I feel like I express myself much easier in a language with a strong static type system. I can write down clearly exactly what the model is, and then the compiler or types let me know when I try to stray from it. From there I can decide if it's better to adjust what I'm doing in the small or the large.
    - goatlover 10y ago
      Because languages like Lisp, Smalltalk, Ruby give you greater control over bending the language to more closely match the problem domain, instead of jumping through extra hoops to express what's needed, and the result is a more readable program, because it's expressed in terms of what the program's trying to accomplish. The entire history of computing is abstraction away from the machine, and offloading as much of the work to the machine, so that humans can focus on solving problems instead of worrying about lower level details. Dynamic languages tend to be better at that. Now if you Haskell is the comparison, then maybe not. But Haskell has an advanced type system with excellent composability, so it's quite capable of expressing high level abstractions and domain specific code. That's the general idea, but clearly not everyone agrees. Or perhaps, other concerns are considered more important.
- Rapzid 10y ago
  F#'s got the types and the beauty factor IMO. Lacks lisp macros, but otherwise is pretty fantastic. 4.1 will officially support .net core as well. I hope to be able to use it for work some day.
abrookewood 10y ago
From the conclusion in that paper: "The data indicates functional languages are better than procedural languages; it suggests that strong typing is better than weak typing; that static typing is better than dynamic; and that managed memory usage is better than unmanaged. Further, that the defect proneness of languages in general is not associated with software domains. Also, languages are more related to individual bug categories than bugs overall."
- zzzcpan 10y ago
  Yeah, that was a weird conclusion as their data suggests otherwise.
lobster_johnson 10y ago
This does not match my experience. It's also commonly accepted — and, in my opinion, true — that dynamically typed languages move the burden of verifying your program to tests. I waste a lot more time in Ruby tests throwing bad data at my code than in Go, whereas in Go I can concentrate on real use cases, because static typing eliminates a whole class of abuse. In other words, the language forces me to do my own type validation at runtime and in tests. Moreover, one big reason why static languages are more robust is that static typing changes one's entire approach to handling data. For example, in Ruby it's common to just do JSON.parse(raw_string) and then pluck out whatever it parsed (and again, the burden is on the programmer to verify that the parsed data structure is the correct one). The equivalent in Go is to declare a schema in the form a compile-time struct annotated with the field names that you expect as the input; the unmarshaler will catch type errors and blow up if something goes wrong. In other words, there's a completely different methodology: When Go has parsed your data, you know all the types are satisfied, whereas Ruby is stuck with duck typing. Maybe someone clever has written a strict JSON library for Ruby, but I don't know of one. Ruby libraries tend to be very un-strict. The dark side of duck typing is that anything you don't explicitly recognize can get ignored. If you have a method with "def foo(options = {})", and someone does "foo(non_existent: 42)", nobody will typically complain. This sort of thing is why ActiveSupport has "assert_valid_keys", and why Ruby now has proper keyword arguments (which only solves the problem of valid keys, not valid data). This stuff is hard to catch and leads to code rot, which is a big maintenance problem that exacerbated by the fact that if you change or remove an argument like this, you won't know if it fails until you run the code, and "grep" is the only tool you can use to find out who actually uses the code.
- zzzcpan 10y ago
  I understand where you are coming from, there are certainly cases where there is too much flexibility and there is a general need for better quality culture, always writing unit tests with good test coverage, etc. Not all languages do it well and many could benefit from some extra optional compiler strictness. However, you still have comparable bug rates for both very expressive dynamic high level languages and lower level ones, making quite a big difference in total number of bugs for the problems of the same complexity. Basically having to write say 3x less code in something like Perl than in Go, to solve the same problem leaves you with 3x less bugs and takes a lot less time.
deleted 10y ago
[deleted]

by zzzcpan 10y ago

zeptomu 10y ago

> No, static typing just gives a false sense of reliability That is not true, there are real benefits and classes of bugs, that can be avoided before runtime. Historically there was the drawback that inferring these bugs has been computational infeasible for some programs, but nowadays the situation is much better. IMHO the only positive aspect of dynamic languages is their syntactic beauty and existing large eco systems. I admire Elixir's and Erlang's approach to concurrency and think this model (do not share data and engineer for failures that will happen in distributed systems) is great, but could be combined with static typing.

goatlover 10y ago
Dynamic languages tend to let you express yourself more easily and cleanly with less code. Paul Graham years ago wrote about how Lisp let's you write more maintainable code by being able to express yourself close to the problem domain. The power of DSLs is that it's easy to read and write code for that particular sort of task. Another way to state the advantage of expressive languages is that the less code you have to right, the less bugs you will have. And the less code written, the less code needs to be maintained, the less needs to be read to understand what's going on. Of course this all depends on writing clean code, not obfuscated hacks or undocumented messes with needless complexity. But that goes for all programming.
- lobster_johnson 10y ago
  There have been some advances in language theory since Lisp, though. In particular, modern type inference allows you to practically eliminate type declarations and approximate the terseness and expressiveness of dynamic languages. Recent languages such as Crystal and Nim have demonstrated that this is entirely feasible. (I mentioned Go earlier, but Go is, if anything, regressive when it comes to language theory, and not a good example of how to do things right.) The Lisp example is only convincing if you've not seen what a really impressive type system can do; Haskell and the ML family come to mind, and Rust and Swift both seem promising in that regard, as does Crystal. "Less code means less bugs" is a powerful meme, but it's a misleading metric in the context of type systems. Dynamic languages necessarily require less code since they eliminate information that otherwise allows you to fully reason at compile time about the program's future execution, thereby eliminating the ability to guarantee its safety; and the opposite is also true: "less information means more bugs". Ultimately, it's less logic we want — less decisions that can go wrong. In Lisp, or any other dynamically typed language, you can pass a variable of the wrong type to a function and won't know it's wrong until you run the program — how did fewer lines of code help you? The equivalent program in a statically typed language might be slightly longer (though it could also be the same size), but the additional type declarations have made your program less buggy, not more.
  - braveo 10y ago
    "less information means less bugs" is not the same thing as "less code means less bugs". Your entire argument there is a non-sequitur, no one who says "less code means less bugs" is talking about the mechanical aspect of typing out code. They're talking about a combination of using battle tested code and writing at a higher level of abstraction.
    - lobster_johnson 10y ago
      I wasn't talking about "the mechanical aspect". And I did not claim anything like what your first sentence implies.
      - braveo 10y ago
        you treated the phrase literally.
  - kazinator 10y ago
    > won't know it's wrong until you run the program That's a big problem, indeed, if your goal is to ship code that was never executed.
    - lobster_johnson 10y ago
      But the whole point of type systems is that you can theoretically verify your code at a high level (though very few computer languages are able to approximate anything like a mathematical proof). I wrote about this in another comment, in the context of writing tests.
      - kazinator 10y ago
        In theory, practice is the same as theory. In practice, it isn't. I've seen only toy examples of some non-trivial program properties being encoded in type systems. It nowhere constituted proof of an entire program. Nobody actually does that. A lot can remain wrong in code which passes type checks. There is no "if it compiles, ship it". Not to mention that compilers can have bugs, and that hidden performance and resource problems can lie latent in high level languages.
- fghgfdfg 10y ago
  I've never understood what people actually mean when they say things like "dynamic languages let you express yourself more easily." I tend to find it significantly harder in dynamic languages. Yeah, there is way more flexibility in small decisions (like right now, is it easier to return a string or an integer or whatever) but it's not free. Your little decision interacts, directly or otherwise, with potentially the entire rest of the program that might ever exist. There is probably a best choice, and it's hard not to try to find it every single time. Doing the easiest thing right now might mean you need to go and adjust many other things. In order to know what is overall easier you need to keep the rest of the program in mind. I find dynamic languages kind of exhausting to write anything but one-off scripts in. I can't make good choices without holding far more of the program in my head than I would in a static language. Sometimes I don't even realize I'm making such a decision because I don't have a correct or full view of the rest of the program. To make matters worse those errors won't even show up as being a problem at the decision-site. I feel like I express myself much easier in a language with a strong static type system. I can write down clearly exactly what the model is, and then the compiler or types let me know when I try to stray from it. From there I can decide if it's better to adjust what I'm doing in the small or the large.
  - goatlover 10y ago
    Because languages like Lisp, Smalltalk, Ruby give you greater control over bending the language to more closely match the problem domain, instead of jumping through extra hoops to express what's needed, and the result is a more readable program, because it's expressed in terms of what the program's trying to accomplish. The entire history of computing is abstraction away from the machine, and offloading as much of the work to the machine, so that humans can focus on solving problems instead of worrying about lower level details. Dynamic languages tend to be better at that. Now if you Haskell is the comparison, then maybe not. But Haskell has an advanced type system with excellent composability, so it's quite capable of expressing high level abstractions and domain specific code. That's the general idea, but clearly not everyone agrees. Or perhaps, other concerns are considered more important.
Rapzid 10y ago
F#'s got the types and the beauty factor IMO. Lacks lisp macros, but otherwise is pretty fantastic. 4.1 will officially support .net core as well. I hope to be able to use it for work some day.

abrookewood 10y ago

From the conclusion in that paper: "The data indicates functional languages are better than procedural languages; it suggests that strong typing is better than weak typing; that static typing is better than dynamic; and that managed memory usage is better than unmanaged. Further, that the defect proneness of languages in general is not associated with software domains. Also, languages are more related to individual bug categories than bugs overall."

zzzcpan 10y ago
Yeah, that was a weird conclusion as their data suggests otherwise.

lobster_johnson 10y ago

This does not match my experience. It's also commonly accepted — and, in my opinion, true — that dynamically typed languages move the burden of verifying your program to tests. I waste a lot more time in Ruby tests throwing bad data at my code than in Go, whereas in Go I can concentrate on real use cases, because static typing eliminates a whole class of abuse. In other words, the language forces me to do my own type validation at runtime and in tests. Moreover, one big reason why static languages are more robust is that static typing changes one's entire approach to handling data. For example, in Ruby it's common to just do JSON.parse(raw_string) and then pluck out whatever it parsed (and again, the burden is on the programmer to verify that the parsed data structure is the correct one). The equivalent in Go is to declare a schema in the form a compile-time struct annotated with the field names that you expect as the input; the unmarshaler will catch type errors and blow up if something goes wrong. In other words, there's a completely different methodology: When Go has parsed your data, you know all the types are satisfied, whereas Ruby is stuck with duck typing. Maybe someone clever has written a strict JSON library for Ruby, but I don't know of one. Ruby libraries tend to be very un-strict. The dark side of duck typing is that anything you don't explicitly recognize can get ignored. If you have a method with "def foo(options = {})", and someone does "foo(non_existent: 42)", nobody will typically complain. This sort of thing is why ActiveSupport has "assert_valid_keys", and why Ruby now has proper keyword arguments (which only solves the problem of valid keys, not valid data). This stuff is hard to catch and leads to code rot, which is a big maintenance problem that exacerbated by the fact that if you change or remove an argument like this, you won't know if it fails until you run the code, and "grep" is the only tool you can use to find out who actually uses the code.

zzzcpan 10y ago
I understand where you are coming from, there are certainly cases where there is too much flexibility and there is a general need for better quality culture, always writing unit tests with good test coverage, etc. Not all languages do it well and many could benefit from some extra optional compiler strictness. However, you still have comparable bug rates for both very expressive dynamic high level languages and lower level ones, making quite a big difference in total number of bugs for the problems of the same complexity. Basically having to write say 3x less code in something like Perl than in Go, to solve the same problem leaves you with 3x less bugs and takes a lot less time.

deleted 10y ago

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