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by zubspace 385 days ago
Wouldn't it just solve a whole lot of problems if we could just add optional type declarations to json? It seems so simple and obvious that I'm kinda dumbfounded that this is not a thing yet. Most of the time you would not need it, but it would prevent the parser from making a wrong guess in all those edge cases.

Probably there are types not every parser/language can accept, but at least it could throw a meaningful error instead of guessing or even truncating the value.
2 comments
ivanbakel 385 days ago
I doubt that would fix the issue. The real cause is that programmers mostly deal in fixed-size integers, and that’s how they think of integer values, since those are the concepts their languages provide. If you’re going to write a JSON library for your favourite programming language, you’re going to reach for whatever ints are the default, regardless of what the specs or type hints suggest.

Haskell’s Aeson library is one of the few exceptions I’ve seen, since it only parses numbers to ‘Scientific’s (essentially a kind of bigint for rationals.) This makes the API very safe, but also incredibly annoying to use if you want to just munge some integers, since you’re forced to handle the error case of the unbounded values not fitting in your fixed-size integer values.

Most programmers likely simply either don’t consider that case, or don’t want to have to deal with it, so bad JSON libraries are the default.

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movpasd 385 days ago
This is actually a deliberate design choice, which the breathtakingly short JSON standard explains quite well [0]. The designers deliberately didn't introduce any semantics and pushes all that to the implementors. I think this is a defensible design goal. If you introduce semantics, you're sure to annoy someone.

There's an element of "worse is better" here [1]. JSON overtook XML exactly because it's so simple and solves for the social element of communication between disparate projects with wildly different philosophies, like UNIX byte-oriented I/O streams, or like the C calling conventions.

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[0] https://ecma-international.org/publications-and-standards/st...

[1] https://en.wikipedia.org/wiki/Worse_is_better

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