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Using a static language to manipulate complex types, particularly those sourced from a different type system (say complex nested Avro, SQL, or even complex JSON

Using a static language to manipulate complex types, particularly those sourced from a different type system (say complex nested Avro, SQL, or even complex JSON) is much more awkward when the types cannot be normalized into the language automatically as can be done with dynamic languages. Static languages require more a priori knowledge of data types, and are very awkward at handling collections with diverse type membership. Data has many forms in reality -- dynamic languages are much more effective at manipulating data on its own terms.

chowells 3y ago
You realize every single thing that dynamically-typed languages can do with data types, statically-typed languages can do too? Except when it matters, they can also choose to do things dynamically-typed languages can't. Lots of people assume static typing means creating domain types for the semantics of every single thing, and then complain that those types contain far more information than they need. Well, stop doing that. Create types that actually contain the information you need. Or use the existing ones. If you're deserializing JSON data, it turns out that the deserialization library already has a type for arbitrary JSON. Just use it, if all you're doing is translating that data to another format. Saying "this data is JSON I didn't bother to understand the internal content of" is a perfectly fine level to work at. Stop inventing work for yourself.
- belmont_sup 3y ago
  Reminds me of https://lexi-lambda.github.io/blog/2020/01/19/no-dynamic-type-systems-are-not-inherently-more-open/ https://lexi-lambda.github.io/blog/2020/01/19/no-dynamic-typ.... Always a fun revisit.
  - throwaway2037 3y ago
    Excellent blog post. I never saw it before. Thank you to share.
- bazoom42 3y ago
  You can’t do monkeypatching or dynamically modify the inheritance chain of an object in a statically typed language. But yes, you can have a JsonNode type, which is still better than having every type being “object”.
  - throwaway2037 3y ago
    About monkeypatching, perhaps we have difference definitions. From time to time, I need to modify a Java class from a dependency that I do not own/control. I copy the decompiled class into my project with the same package name. I make changes, then run. To me, this is monkeypatching for Java. Do you agree? If not, how is it different? I would like to learn. Honestly, I discovered that Java technique years ago by accident. Another technique: While the JVM is running with a debugger attached, it is possible to inject a new version of a class. IDEs usually make this seamless. It also works when remote debugging. Do you consider this monkeypatching also?
    - bazoom42 3y ago
      Monkeypatching is programatically adding a method to a class at runtime.
  - chowells 3y ago
    > You can’t do monkeypatching or dynamically modify the inheritance chain of an object in a statically typed language. There's no theoretical reason you can't. No languages that I know of provide that combination features, because monkey-patching is a terrible idea for software engineering... But there's no theoretical reason you couldn't make it happen. I think you've conflated static typing with a static language. They're not the same thing and can be analyzed separately.
    - bazoom42 3y ago
      So how would a statically typed language support conditionally adding methods at runtime? Lets say the code adds a method with name and parameters specified by user input at runtime. How could this possibly be checked at compile time?
brabel 3y ago
I love using "mixed" dynamic/static typed languages in these scenarios... you can do that data manipulation without types, but benefit from types everywhere else... my two favourite "mixed" languages are Groovy on the JVM, and Dart elsewhere... Dart now has a very good type system, but still supports `dynamic` which makes it as easy as Python to manipulate data.

chowells 3y ago

You realize every single thing that dynamically-typed languages can do with data types, statically-typed languages can do too? Except when it matters, they can also choose to do things dynamically-typed languages can't. Lots of people assume static typing means creating domain types for the semantics of every single thing, and then complain that those types contain far more information than they need. Well, stop doing that. Create types that actually contain the information you need. Or use the existing ones. If you're deserializing JSON data, it turns out that the deserialization library already has a type for arbitrary JSON. Just use it, if all you're doing is translating that data to another format. Saying "this data is JSON I didn't bother to understand the internal content of" is a perfectly fine level to work at. Stop inventing work for yourself.

belmont_sup 3y ago
Reminds me of https://lexi-lambda.github.io/blog/2020/01/19/no-dynamic-type-systems-are-not-inherently-more-open/ https://lexi-lambda.github.io/blog/2020/01/19/no-dynamic-typ.... Always a fun revisit.
- throwaway2037 3y ago
  Excellent blog post. I never saw it before. Thank you to share.
bazoom42 3y ago
You can’t do monkeypatching or dynamically modify the inheritance chain of an object in a statically typed language. But yes, you can have a JsonNode type, which is still better than having every type being “object”.
- throwaway2037 3y ago
  About monkeypatching, perhaps we have difference definitions. From time to time, I need to modify a Java class from a dependency that I do not own/control. I copy the decompiled class into my project with the same package name. I make changes, then run. To me, this is monkeypatching for Java. Do you agree? If not, how is it different? I would like to learn. Honestly, I discovered that Java technique years ago by accident. Another technique: While the JVM is running with a debugger attached, it is possible to inject a new version of a class. IDEs usually make this seamless. It also works when remote debugging. Do you consider this monkeypatching also?
  - bazoom42 3y ago
    Monkeypatching is programatically adding a method to a class at runtime.
- chowells 3y ago
  > You can’t do monkeypatching or dynamically modify the inheritance chain of an object in a statically typed language. There's no theoretical reason you can't. No languages that I know of provide that combination features, because monkey-patching is a terrible idea for software engineering... But there's no theoretical reason you couldn't make it happen. I think you've conflated static typing with a static language. They're not the same thing and can be analyzed separately.
  - bazoom42 3y ago
    So how would a statically typed language support conditionally adding methods at runtime? Lets say the code adds a method with name and parameters specified by user input at runtime. How could this possibly be checked at compile time?

brabel 3y ago

I love using "mixed" dynamic/static typed languages in these scenarios... you can do that data manipulation without types, but benefit from types everywhere else... my two favourite "mixed" languages are Groovy on the JVM, and Dart elsewhere... Dart now has a very good type system, but still supports `dynamic` which makes it as easy as Python to manipulate data.