Domain Specific Formats

[laktak]

Support for additional types and/or formats has been requested several times (hn/reddit/issues):

• NaN, Infinity, -Infinity for number type, Explicitly support NaN, Infinity, -Infinity for number type #27, Failure to handle infinity and NaN limits hjson's usefulness. #54
• Hexadecimal numbers, Hexadecimal numbers #36
• Date type (ISO_8601?, also Feature Request: Define a date literal #21)
• Intervals
• C++14 style numeric, How do you think about supporting C++14 style numeric format? #46
• etc.

I've not added new types in the past to keep the Hjson grammar small and because it's not easy to decide which types to add without blowing up the spec.

A possible solution to this problem could be Hjson's quoteless strings. The following is already possible with the current implementations:

{
  nan: NaN
  posInf: Inf
  negInf: -Inf
  hex: 0xff
  date: 2016-08-22
}

This allows formats that are not known by JSON/Hjson to be added without breaking current tools. Anything unknown will be treated as a string.

By using Domain Specific Formats, that can be selectively enabled by the application, we can allow new formats to be added where they are needed. For example

• math enables NaN, Infinity and -Infinity (should also support -0)
• date enables ISO_8601 dates
• hex enables hex numbers

math and date can output the same format when stringified. hex would revert to decimal (unless the desired format were to be stored with the type).

Other formats can be implemented in the application as required.

[laktak]

The JavaScript, Java and C# implementations were updated with experimental support for DSF.