JSON

parse

parse(text: String) -> Result<Any, Error>
parse(text: String, options: {Atom: Bool}) -> Result<Any, Error>

Parses a JSON document, strictly.

The whole text must be one JSON value with nothing after it — trailing input is TrailingInput, not a silently ignored tail. Objects come back as maps with atom keys, arrays as lists, null as None.

Parameters

text

the JSON document

Returns the parsed value, or why it failed

Examples

JSON.parse("{\"a\": 1, \"b\": [true, null, 2.5]}")
# => Ok({ a: 1, b: [true, None, 2.5] })
JSON.parse("[1, 2")   # => Error(UnexpectedEnd(5))

Reading a config file

match JSON.parse(FS.File.read("config.json").or("")) do
  Ok(config) => IO.printLine(config)
  Error(e)   => IO.printError("config.json is not valid JSON: ${e}")
end

stringify

stringify(value: Any) -> String

Renders a Kex value as strict JSON text.

Maps become objects, lists become arrays, None becomes null, and strings are escaped. A map written with atom keys — the usual Kex spelling — renders with those names as strings, so { name: "Ada" } becomes {"name":"Ada"}. Object keys come out in canonical key order.

Anything the encoder does not recognise renders as null rather than failing, so this never raises.

Parameters

value

the value to render

Returns the JSON text

Examples

JSON.stringify({ name: "Ada", n: 1, ok: true })
# => '{"n":1,"name":"Ada","ok":true}'
JSON.stringify([1, 2, 3])
# => '[1,2,3]'

Writing a JSON file

FS.File.write("out.json", JSON.stringify(report))

A round trip

JSON.parse(JSON.stringify({ a: 1 }))   # => Ok({ a: 1 })