available
io
File & Path I/O
Read and write files, stream large inputs, and work with paths. Blocking I/O can run on background threads.
- Whole-file read/write
- Streaming handles
- Background I/O
- Path helpers
Ecosystem
json
availableJSON Parse & Manipulate
Core Standard Library
Overview
The json module is what you use for config files, API payloads, and log lines. Parse a string into a mutable tree, change values, stringify back out. Nested keys are reachable with dot paths like user.address.city so you don't write three levels of bracket indexing.
merge combines two objects recursively (handy for default config + overrides), and clone copies a subtree without shared references.
- parse & stringify
- Dot-path access
- Deep merge
- Pretty-print
Import
import
import "json" |
Quick start
quick start
import "json" |
|
let data = json.parse('{"user": {"name": "Niao", "tags": ["fast"]}}') |
json.set(data, "user.tags.1", "lean") |
print(json.stringify(data, { pretty: true })) |
Capabilities
High-level overview of what json is for.
parse & stringify
Turn JSON text into Niao values and back. stringify accepts a pretty flag for indented output.
Nested path access
get and set by dot path, user.settings.theme instead of chaining ["user"]["settings"]["theme"].
Deep merge & clone
merge walks both objects and combines keys; clone duplicates a value tree for safe mutation.
Pretty-print
Indented stringify for configs and debug dumps you actually want to read.
API reference
15 functions and methods in json. Grouped by category from the standard library docs.
Namespace API (recommended)
| Signature | Description |
|---|---|
| json.parse(text) | Parse JSON string → value |
| json.stringify(value) | Compact JSON text |
| json.stringify_pretty(value, indent?) | Pretty-print (default indent `2`) |
| json.valid(text) | `true` if text is valid JSON |
| json.type(value) | `"null"`, `"bool"`, `"number"`, `"string"`, `"array"`, `"object"` |
| json.is_json(value) | Whether value can be serialized to JSON |
| json.keys(object) | Sorted key list |
| json.has(object, key) | Key exists |
| json.get(value, path) | Nested read - e.g. `"user.items[0].id"` |
| json.set(object, path, value) | Set nested field in place |
| json.merge(target, source) | Deep-merge objects into `target` |
| json.clone(value) | Deep copy |
| json.equal(a, b) | Deep equality |
| json.array_len(array) | Array length |
| json.object_len(object) | Object field count |
Related libraries
More from Core Standard Library.
available
time
Wall-Clock & Time Zones
Timestamps, formatting, parsing, and time zones. Built on chrono and chrono-tz, DST handled correctly.
- IANA time zones
- strftime formats
- Datetime values
- Date math
available
re
Regular Expressions
Regular expressions via Rust's regex crate. Match, split, replace, and compile patterns once for hot loops.
- Capture groups
- Search & replace
- Compiled patterns
- Unicode-aware