UTILS Course

Data definition languages

A gathering of notes about easy to learn, and easy to master, data definition languages, such as JSON (and JSON5), or YAML.


You got 6 types in JSON: number (integer/float), object, array, boolean, null, and string.

  • Object ✨: {}, take a key and a value for each key
  "key": 1
  "key2": "an object"
  "key3": false
  "key4": {}
  "key5": { "key1": "another object" }
  "key6": []
  • Array πŸ€“: simply an array of values
  1, 2, "an array", true, false, null, { "key1": "another object" }, []

JSON5 is usually what most people use, but you may try JSON5 at your own "risks" πŸ˜ŽπŸš€.
Note: There are no comments in JSON, but you can use comments in JSON5
Note: There is no multiline string, so you must bear with it, unless you are using JSON5.


YAML is way more complex than JSON. In fact, JSON syntax is included in YAML. YAML is quite human-readable πŸš€, so in some cases, it may be better to use YAML rather than JSON.

  • List
- a
- b
- c

# same as
[a, b, c]
['a', 'b', 'c']
  • Keys
key1: value
key2: 5
key3: {}
key4: true
key5: ['a', 'b', 'c']
  - a
  - b
  - c
  • Long texts
short: This is a short text
long_text: This is a really really really
  long long text. 
  And this is still part of the text πŸš€.

You got way more things you can do, this is only a short preview 😱.


INI is a language that was previously only used on Windows for initialization/configuration files. This is a plain text file with key -> value. You can add sections if you want.

; a comment



You may use _, spaces, uppercase letters in the names. At least, if your parser is allowing them.