YAML: probably not so great after all (2017)

Post by pjmlp » Fri, Jun 22, 2018, 12:05 PM UTC

DonHopkins wrote: post #265

akavel wrote: post #246

Earlier quoted context omitted.

Interestingly, the Lua programming language actually evolved from configuration files: https://www.lua.org/history.html (and is still officially deemed useful for writing them)

That was also one of the rationales behind TCL's design. John Ousterhout explained in one of his early TCL papers that, as a "Tool Command Language" like the shell but unlike Lisp, arguments were treated as quoted literals by default (presuming that to be the common case), so you don't have to put quotes around most strings, and you have to use punctuation like ${}[] to evaluate expressions. TCL's syntax is optimized…

Post by webXL » Fri, Jun 22, 2018, 12:43 PM UTC

wildrhythms wrote: post #392

lysium wrote: post #380

Earlier quoted context omitted.

Do you need a time zone for dates?

Consider if I'm storing a user's (local) birthday on my server: {..., "birthday": "2018-03-25"} If my server is located in New York City, and the user is in Sydney, then my server isn't going to wish them happy birthday in time. So maybe we could do: {..., "birthday": "2018-03-25", "location": "Sydney/AU"} But at this point we might as well use a standardized time format (UTC) with a timezone offset. Maybe I'm thinki…

   Year:
      YYYY (eg 1997)
   Year and month:
      YYYY-MM (eg 1997-07)
   Complete date:
      YYYY-MM-DD (eg 1997-07-16)
   Complete date plus hours and minutes:
      YYYY-MM-DDThh:mmTZD (eg 1997-07-16T19:20+01:00)
   Complete date plus hours, minutes and seconds:
      YYYY-MM-DDThh:mm:ssTZD (eg 1997-07-16T19:20:30+01:00)
   Complete date plus hours, minutes, seconds and a decimal fraction of a second
      YYYY-MM-DDThh:mm:ss.sTZD (eg 1997-07-16T19:20:30.45+01:00)
  where:

     YYYY = four-digit year
     MM   = two-digit month (01=January, etc.)
     DD   = two-digit day of month (01 through 31)
     hh   = two digits of hour (00 through 23) (am/pm NOT allowed)
     mm   = two digits of minute (00 through 59)
     ss   = two digits of second (00 through 59)
     s    = one or more digits representing a decimal fraction of a second
     TZD  = time zone designator (Z or +hh:mm or -hh:mm)

Post by spiralx » Fri, Jun 22, 2018, 4:43 PM UTC

nojvek wrote: post #305

spankalee wrote: post #279

Earlier quoted context omitted.

JSON5 is also a great alternative: https://json5.org/ Supports comments, trailing commas, single quotes, multi-line strings, and more number formats.

I really wished json5 would support optional commas as well. If you have a new line, no comma needed. So you can do [ 1 2 3 ] New lines used by humans, computers should do a good job as well.

  'firstName'

  'lastName'

  "required": [

    "firstName",

    "lastName"

  ]

Post by spiralx » Fri, Jun 22, 2018, 5:09 PM UTC

jerrac wrote: post #384

erik_seaberg wrote: post #290

Earlier quoted context omitted.

YAML tags work this way. E.g., 2002-04-28 is a date (because it looks like one) but !!str 2002-04-28 is a string.

I had never heard of tags before. Thanks! So, would this work? ports: https: enabled: yes !!int port: 443 Then if someone is copy/pasting and tries to use "blah" as the value, the !!int tag would cause the yaml parser to throw an error. Right?

  ports:
    https:
      port: !!str 443

  {
    "ports": {
      "https": {
        "port": "443"
      }
    }
  }

Post by jgalt212 » Sat, Jun 23, 2018, 5:24 PM UTC

gpoore wrote: post #379

jgalt212 wrote: post #267

Our shop are heavy users of YAML, and we've sort of backed our way into a restricted subset of YAML. Some of them are config files, but others function closer to DSLs. I have not yet taken a look at strictyaml, but after years of use the spec definitely needs YAML, The Good Parts Treatment. One thing the author did not mention was how slow the out of box the Python YAML parser can be. This can be sped up with a call…

I suspect the speed issues are more a result of implementation details than of being in Python. Last year, I created a config language for my own use that supports some syntax very similar to YAML. My pure Python library can load simple dict/list/string data 10x as fast as PyYAML, and nearly within 1.5x the speed of libyaml ( https://bespon.org/#benchmarks ). That's while building an AST with source information to al…