json

The json module parses JSON into navigable values, queries and edits JSON strings by key, merges and reshapes objects and arrays, pretty-prints or minifies, and streams large arrays or NDJSON one value at a time. Import it with import json.

Parsing and serialization

Function	Signature	Description
`valid`	`json.valid(s: string) → bool`	Whether `s` is valid JSON
`parse`	`json.parse(s: string) → any`	Parse into a navigable object/array/scalar tree
`stringify`	`json.stringify(v: any, indent?: string) → string`	Serialize a value; pass an indent for pretty output. Keys are sorted
`pretty`	`json.pretty(s: string) → string`	Re-indent existing JSON text with 2 spaces
`minify`	`json.minify(s: string) → string`	Strip whitespace from JSON text

Querying

These operate on a JSON string and read top-level keys.

Function	Signature	Description
`get`	`json.get(j: string, key: string) → string`	Value at `key` as a string; empty if missing/null
`getInt`	`json.getInt(j: string, key: string) → int`	Value at `key` as int; 0 if missing/non-numeric
`getBool`	`json.getBool(j: string, key: string) → bool`	Value at `key` as bool; false if missing
`has`	`json.has(j: string, key: string) → bool`	Whether `key` exists
`keys`	`json.keys(obj: any) → string[]`	Sorted field names of a parsed object or JSON string
`length`	`json.length(j: string) → int`	Object key count or array length
`arrayGet`	`json.arrayGet(j: string, idx: int) → string`	Element at `idx` of a JSON array

Editing

These return a new JSON string with the change applied.

Function	Signature	Description
`setString`	`json.setString(j: string, key: string, val: string) → string`	Set `key` to a string value
`setInt`	`json.setInt(j: string, key: string, val: int) → string`	Set `key` to an int value
`setBool`	`json.setBool(j: string, key: string, val: bool) → string`	Set `key` to a bool value
`delete`	`json.delete(j: string, key: string) → string`	Remove `key`
`merge`	`json.merge(j1: string, j2: string) → string`	Merge two objects; `j2` keys overwrite `j1`
`fromArray`	`json.fromArray(arr: string[]) → string`	Convert an array into a JSON array string

json.stream

Streams a JSON source one top-level value at a time, calling fn(value) for each. Handles both a JSON array (each element delivered separately) and concatenated values or NDJSON. The callback may return false to stop early. Returns the count of values delivered.

Function	Signature	Description
`parseString`	`json.stream.parseString(s: string, fn) → int`	Stream values from a JSON string
`parseFile`	`json.stream.parseFile(path: string, fn) → int`	Stream values from a JSON file

Example

import json

let doc = json.parse("{\"name\": \"alice\", \"age\": 30}")
print(doc.name)                         // alice

let updated = json.setInt("{\"age\": 30}", "age", 31)
print(updated)

json.stream.parseString("[1, 2, 3]", fn(v) {
    print(v)
    return true
})

Standard library · View as Markdown · llms-full.txt