4 ms·

In strongly typed languages, there are serialization/deserialization libraries that don't require you to type the entire JSON object - just the fields you care

In strongly typed languages, there are serialization/deserialization libraries that don't require you to type the entire JSON object - just the fields you care about.

sjy 7y ago
I’m not a very skilled Haskell programmer, but every time I’ve tried to parse JSON in it I’ve felt a strong urge to switch back to Python or JavaScript. There are libraries that make it easier but I think it’s always going to be hardly to get started with JSON APIs in a language with a powerful and strict type system. Of course, that extra up-front effort might be worth it in the long run due to the benefits of type safety, but as the grandparent said, sometimes programmers need the freedom to incur technical debt.
- yawaramin 7y ago
  Out of curiousity, what exactly was the difficulty with decoding JSON in Haskell/
  - june11 7y ago
    a quick search brings up a library, not sure why you would have trouble, other than maybe experience? https://github.com/bos/aeson https://github.com/bos/aeson
    - yawaramin 7y ago
      I was replying to someone who said they had trouble.
  - sjy 7y ago
    I was trying to use Aeson, which as noted in this excellent tutorial [1] (which didn’t exist when I first tried it) is “hopelessly magical for people who try to learn it by looking at provided examples, and existing tutorials don’t help that much.“ The rest of the tutorial should give you some idea of why I say that parsing JSON in Haskell is complex, at least if you’re used to doing it in JavaScript. [1]: https://artyom.me/aeson https://artyom.me/aeson
    - yawaramin 7y ago
      I'm interested in specifically what issues you had with JSON.
- the_gipsy 7y ago
  I've really come to love strict JSON parsing, because everytime an API call was not as expected, I get the error straight at it's source, not somewhere 20 layers deeps in my views or models, way too late, and only with this one specific combination of events.
- hopia 7y ago
  Aeson parsing seems straightforward to me, not sure it could be easier in any language. Serialization from your endpoint is automatic, based on your data types. The real benefit of using a well typed language here is that you only need to parse the data once at this point, after that the type system makes sure the data is of correct format everywhere else in your codebase.
  - marcosdumay 7y ago
    Aeson is not straightforward at all. Just try doing what the GP is saying he wants to do, you will discover you can't. It is a very good library if you control both sides of the communication, and have fit for purpose interfaces. Otherwise, you are better with any lower level library. Besides, what is it with the strictness of Haskell JSON libraries? There's nothing that will even accept Window's BOM.
    - hopia 7y ago
      Fair enough, you're probably right, I have only used it in contexts where I build both sides of the application.
    - platz 7y ago
      You don't have to define a type for Json data in Haskell if you don't want to. Defining a full type is only norm/preference. With Aeson, You always have the option work with a map directly and pull out properties by name. That is also especially useful when you can't predict what keys or shape the data will have
      - marcosdumay 7y ago
        I don't want to detract from Aeson. It's a great library. If you control both ends of your channel, it can be more convenient than the equivalent encoding and decoding on Javascript, and making a JSON library that is more convenient than JS is no small feat. But it's a very complex library. It may not show at your code interface, but that complexity is there at the documentation and type errors. It is also famous for generating bad runtime messages. There is even another library for fixing this, at the cost of even more complexity. If you fall outside of its optimum usage scenario, it won't afford you more functionality than a low level parser, so you are much better saving that complexity and going with the parser.
- deleted 7y ago
  [deleted]

In strongly typed languages, there are serialization/deserialization libraries that don't require you to type the entire JSON object - just the fields you care about.

sjy 7y ago

I’m not a very skilled Haskell programmer, but every time I’ve tried to parse JSON in it I’ve felt a strong urge to switch back to Python or JavaScript. There are libraries that make it easier but I think it’s always going to be hardly to get started with JSON APIs in a language with a powerful and strict type system. Of course, that extra up-front effort might be worth it in the long run due to the benefits of type safety, but as the grandparent said, sometimes programmers need the freedom to incur technical debt.

yawaramin 7y ago
Out of curiousity, what exactly was the difficulty with decoding JSON in Haskell/
- june11 7y ago
  a quick search brings up a library, not sure why you would have trouble, other than maybe experience? https://github.com/bos/aeson https://github.com/bos/aeson
  - yawaramin 7y ago
    I was replying to someone who said they had trouble.
- sjy 7y ago
  I was trying to use Aeson, which as noted in this excellent tutorial [1] (which didn’t exist when I first tried it) is “hopelessly magical for people who try to learn it by looking at provided examples, and existing tutorials don’t help that much.“ The rest of the tutorial should give you some idea of why I say that parsing JSON in Haskell is complex, at least if you’re used to doing it in JavaScript. [1]: https://artyom.me/aeson https://artyom.me/aeson
  - yawaramin 7y ago
    I'm interested in specifically what issues you had with JSON.
the_gipsy 7y ago
I've really come to love strict JSON parsing, because everytime an API call was not as expected, I get the error straight at it's source, not somewhere 20 layers deeps in my views or models, way too late, and only with this one specific combination of events.
hopia 7y ago
Aeson parsing seems straightforward to me, not sure it could be easier in any language. Serialization from your endpoint is automatic, based on your data types. The real benefit of using a well typed language here is that you only need to parse the data once at this point, after that the type system makes sure the data is of correct format everywhere else in your codebase.
- marcosdumay 7y ago
  Aeson is not straightforward at all. Just try doing what the GP is saying he wants to do, you will discover you can't. It is a very good library if you control both sides of the communication, and have fit for purpose interfaces. Otherwise, you are better with any lower level library. Besides, what is it with the strictness of Haskell JSON libraries? There's nothing that will even accept Window's BOM.
  - hopia 7y ago
    Fair enough, you're probably right, I have only used it in contexts where I build both sides of the application.
  - platz 7y ago
    You don't have to define a type for Json data in Haskell if you don't want to. Defining a full type is only norm/preference. With Aeson, You always have the option work with a map directly and pull out properties by name. That is also especially useful when you can't predict what keys or shape the data will have
    - marcosdumay 7y ago
      I don't want to detract from Aeson. It's a great library. If you control both ends of your channel, it can be more convenient than the equivalent encoding and decoding on Javascript, and making a JSON library that is more convenient than JS is no small feat. But it's a very complex library. It may not show at your code interface, but that complexity is there at the documentation and type errors. It is also famous for generating bad runtime messages. There is even another library for fixing this, at the cost of even more complexity. If you fall outside of its optimum usage scenario, it won't afford you more functionality than a low level parser, so you are much better saving that complexity and going with the parser.
deleted 7y ago
[deleted]