7 ms·

IMO it would also be really nice to have non-string keys in objects, like: { [1, 2]: "a", [3, 4]: "b" }

resonantjacket5 6y ago
it's usually a pretty bad idea to have a mutable object (the array) as a key. Though I guess if you consider it as a 'tuple' since when in json form it can't be modified I guess it'd be technically possible, though with some heavy caveats.
- chrisseaton 6y ago
  There’s no concept of mutability in JSON. A JSON parser could give you immutable arrays and maps if it wanted to.
  - resonantjacket5 6y ago
    Yes, but json by itself doesn't actually do anything. It'd always be used in context of javascript/python/ etc.. As I said you could interpret it as a tuple or I guess a frozen array for javascript? I don't think there is a native immmutable array in javascript. If it's a map I'm a bit more unsure how you'd check to find the object (quickly). You're basically getting into the how to store a struct/class as a map key. Either way its a bit more involved than just having json parser return an immutable array and map, and the more I think about it the more edges cases there are.
    - recursive 6y ago
      > I don't think there is a native immmutable array in javascript. I'm here to tell you that `Object.freeze()` works just fine on arrays.
      - resonantjacket5 6y ago
        Nice. Though I don't think that solves the rest of the issues I outlined sadly. I guess you could have this json+ convert into some custom javascript class that allows arrays/objects as map keys rather than the normal javascript object that only accepts strings as map keys.
        chrisseaton 6y ago
        > I guess you could have this json+ convert into some custom javascript class that allows arrays/objects as map keys rather than the normal javascript object that only accepts strings as map keys. Sure - why not? JSON doesn't have to map directly to JavaScript objects.
xpe 6y ago
You realize this would push outside of what JavaScript provides? 'Welcome to Node.js v15.7.0. Type ".help" for more information. > { [1, 2]: "a" } ({ [1, 2]: "a" }) ^ Uncaught SyntaxError: Unexpected token ',' Thar' be dragons! https://stackoverflow.com/questions/32660188/using-array-objects-as-key-for-es6-map https://stackoverflow.com/questions/32660188/using-array-obj...
- ledauphin 6y ago
  it's true JS doesn't support this, and it's also true that any JSON that supported it would therefore no longer be _JavaScript_ object notation. However, it's equally true that a better language and object notation would support non-string scalar keys.
  - kevingadd 6y ago
    JavaScript wouldn't be able to consume those resulting objects, so it would be pretty diminished as an alternative to JSON. Object keys are all strings.
    - wruza 6y ago
      Not that I find this idea useful for otherwise limited DTO format, which JSON is, but JS has Map, which may be used for such maps.
      - kevingadd 6y ago
        Sadly because arrays are not immutable you can't meaningfully use them as Map keys. You'd need a tuple type, which does not currently exist.
  - xpe 6y ago
    I can see why you want non-string scalar keys. In general, I do too. (I'm writing a data language that has them.) However, I don't think it is useful to prod JSON (or a variant) to go in this direction.
redisman 6y ago
Why?
- wruza 6y ago
  One of the uses is mapping values to objects instead of strings, so you don’t have to use ids: ob = {...} somemap[ob] = value // vs somemap[ob.id] = value In languages which allow weak keys in such maps, a garbage collector may even reclaim whole key-value pairs once ob falls out of existence. But to my opinion, in json it is barely useful for a number of reasons. It is more programming technique than data transfer format, and these features (and reference loops) should be encoded at a higher level than json.

it's usually a pretty bad idea to have a mutable object (the array) as a key. Though I guess if you consider it as a 'tuple' since when in json form it can't be modified I guess it'd be technically possible, though with some heavy caveats.

chrisseaton 6y ago
There’s no concept of mutability in JSON. A JSON parser could give you immutable arrays and maps if it wanted to.
- resonantjacket5 6y ago
  Yes, but json by itself doesn't actually do anything. It'd always be used in context of javascript/python/ etc.. As I said you could interpret it as a tuple or I guess a frozen array for javascript? I don't think there is a native immmutable array in javascript. If it's a map I'm a bit more unsure how you'd check to find the object (quickly). You're basically getting into the how to store a struct/class as a map key. Either way its a bit more involved than just having json parser return an immutable array and map, and the more I think about it the more edges cases there are.
  - recursive 6y ago
    > I don't think there is a native immmutable array in javascript. I'm here to tell you that `Object.freeze()` works just fine on arrays.
    - resonantjacket5 6y ago
      Nice. Though I don't think that solves the rest of the issues I outlined sadly. I guess you could have this json+ convert into some custom javascript class that allows arrays/objects as map keys rather than the normal javascript object that only accepts strings as map keys.
      - chrisseaton 6y ago
        > I guess you could have this json+ convert into some custom javascript class that allows arrays/objects as map keys rather than the normal javascript object that only accepts strings as map keys. Sure - why not? JSON doesn't have to map directly to JavaScript objects.

xpe 6y ago

You realize this would push outside of what JavaScript provides? 'Welcome to Node.js v15.7.0. Type ".help" for more information. > { [1, 2]: "a" } ({ [1, 2]: "a" }) ^ Uncaught SyntaxError: Unexpected token ',' Thar' be dragons! https://stackoverflow.com/questions/32660188/using-array-objects-as-key-for-es6-map https://stackoverflow.com/questions/32660188/using-array-obj...

ledauphin 6y ago
it's true JS doesn't support this, and it's also true that any JSON that supported it would therefore no longer be _JavaScript_ object notation. However, it's equally true that a better language and object notation would support non-string scalar keys.
- kevingadd 6y ago
  JavaScript wouldn't be able to consume those resulting objects, so it would be pretty diminished as an alternative to JSON. Object keys are all strings.
  - wruza 6y ago
    Not that I find this idea useful for otherwise limited DTO format, which JSON is, but JS has Map, which may be used for such maps.
    - kevingadd 6y ago
      Sadly because arrays are not immutable you can't meaningfully use them as Map keys. You'd need a tuple type, which does not currently exist.
- xpe 6y ago
  I can see why you want non-string scalar keys. In general, I do too. (I'm writing a data language that has them.) However, I don't think it is useful to prod JSON (or a variant) to go in this direction.

redisman 6y ago

Why?

wruza 6y ago
One of the uses is mapping values to objects instead of strings, so you don’t have to use ids: ob = {...} somemap[ob] = value // vs somemap[ob.id] = value In languages which allow weak keys in such maps, a garbage collector may even reclaim whole key-value pairs once ob falls out of existence. But to my opinion, in json it is barely useful for a number of reasons. It is more programming technique than data transfer format, and these features (and reference loops) should be encoded at a higher level than json.