4 ms·

per specifications, json parsing is not lenient, html parsing is lenient

taeric 4y ago
Right, and amusingly, more than a few json parsers are very lenient in this. That or folks abandon ship fairly quickly and go for another spec that is far more friendly.
- preseinger 4y ago
  well json definitely does not accept `{'test':'value'}` as valid input any parser that behaves otherwise is pretty clearly buggy json has many problems but parsing ambiguity is not really one of them
  - taeric 4y ago
    Me thinks you have never looked at the field. I'd as soon declare csv is an error free format. Only true if you ignore the proliferation of applications that get it wrong. In subtle ways, often. Still wrong.
    - preseinger 4y ago
      csv is wildly ambiguous, to the frustration of ~every data science engineer in industry json is not show me an application that parses `{'a':'b'}` as valid JSON, i'm actually interested, probably there are some which exist, but there is no ambiguity about those applications being wrong
      - taeric 4y ago
        https://news.ycombinator.com/item?id=12796556 https://news.ycombinator.com/item?id=12796556
        preseinger 4y ago
        fun doc! it lists many of the undefined behaviors of the spec, and many of the problems in common parsers afaict none of them permit keys or value strings to be expressed with single quotes
        taeric 4y ago
        Apologies for the, in retrospect, somewhat lazy posting of an article with no comment. I thought that article had a section about how many of them allow single quotes if you don't "enable strict." I am not seeing it on review, though; so either I made that up in my mind, or I'm remembering another article. Either way, apologies. I did find https://github.com/json5/json5 https://github.com/json5/json5 no a quick search that basically says what I asserted about people just jumping to another standard for things that you hand write. I was probably also thinking heavily about python's dict syntax. (And I confess, I still don't know when to use single versus double quotes in python...)
        preseinger 4y ago
        no worries mate
goto11 4y ago
To be pedantic, html parsing is not lenient, it is unambiguously specified.
- preseinger 4y ago
  if that were true then browsers would refuse to render text/html responses that didn't include a closing </html> tag, i guess
  - goto11 4y ago
    No, because the closing </html> tag can be omitted according to the current HTML spec. See https://html.spec.whatwg.org/#optional-tags https://html.spec.whatwg.org/#optional-tags
    - preseinger 4y ago
      this is exactly my point html is not precisely defined
      - 4rt 3y ago
        I think you're missing the point that it is defined, the current html5 spec says that <title> implies the existence of <head>, <body> implies the end of <head>, body tags imply the end of <head> and the start of <body> etc. HTML5 is not XHTML. <!DOCTYPE html> <title>Title <h1>Heading expands to <!DOCTYPE html> <head><title>Title</title></head> <body><h1>Heading</h1></body>
        preseinger 3y ago
        if `<title>A <h1>Heading` is equivalent to `<head><title>A</title></head> <body><h1>Heading</h1></body>` then this means the language is not precisely defined
      - goto11 3y ago
        Sorry I don't understand your argument. HTML is fully and unambiguously defined, as you can see if you follow the link. Some tags are optional in certain contexts, but this is also precisely defined.

Right, and amusingly, more than a few json parsers are very lenient in this. That or folks abandon ship fairly quickly and go for another spec that is far more friendly.

preseinger 4y ago
well json definitely does not accept `{'test':'value'}` as valid input any parser that behaves otherwise is pretty clearly buggy json has many problems but parsing ambiguity is not really one of them
- taeric 4y ago
  Me thinks you have never looked at the field. I'd as soon declare csv is an error free format. Only true if you ignore the proliferation of applications that get it wrong. In subtle ways, often. Still wrong.
  - preseinger 4y ago
    csv is wildly ambiguous, to the frustration of ~every data science engineer in industry json is not show me an application that parses `{'a':'b'}` as valid JSON, i'm actually interested, probably there are some which exist, but there is no ambiguity about those applications being wrong
    - taeric 4y ago
      https://news.ycombinator.com/item?id=12796556 https://news.ycombinator.com/item?id=12796556
      - preseinger 4y ago
        fun doc! it lists many of the undefined behaviors of the spec, and many of the problems in common parsers afaict none of them permit keys or value strings to be expressed with single quotes
        taeric 4y ago
        Apologies for the, in retrospect, somewhat lazy posting of an article with no comment. I thought that article had a section about how many of them allow single quotes if you don't "enable strict." I am not seeing it on review, though; so either I made that up in my mind, or I'm remembering another article. Either way, apologies. I did find https://github.com/json5/json5 https://github.com/json5/json5 no a quick search that basically says what I asserted about people just jumping to another standard for things that you hand write. I was probably also thinking heavily about python's dict syntax. (And I confess, I still don't know when to use single versus double quotes in python...)
        preseinger 4y ago
        no worries mate

goto11 4y ago

To be pedantic, html parsing is not lenient, it is unambiguously specified.

preseinger 4y ago
if that were true then browsers would refuse to render text/html responses that didn't include a closing </html> tag, i guess
- goto11 4y ago
  No, because the closing </html> tag can be omitted according to the current HTML spec. See https://html.spec.whatwg.org/#optional-tags https://html.spec.whatwg.org/#optional-tags
  - preseinger 4y ago
    this is exactly my point html is not precisely defined
    - 4rt 3y ago
      I think you're missing the point that it is defined, the current html5 spec says that <title> implies the existence of <head>, <body> implies the end of <head>, body tags imply the end of <head> and the start of <body> etc. HTML5 is not XHTML. <!DOCTYPE html> <title>Title <h1>Heading expands to <!DOCTYPE html> <head><title>Title</title></head> <body><h1>Heading</h1></body>
      - preseinger 3y ago
        if `<title>A <h1>Heading` is equivalent to `<head><title>A</title></head> <body><h1>Heading</h1></body>` then this means the language is not precisely defined
    - goto11 3y ago
      Sorry I don't understand your argument. HTML is fully and unambiguously defined, as you can see if you follow the link. Some tags are optional in certain contexts, but this is also precisely defined.