# Standard library overview

> Index of the Langoost standard library — text, data, encoding, math, collections, time, filesystem, OS, networking, crypto, data stores, and concurrency modules.

# Standard library

Langoost ships with a large standard library. Import any module by name with
`import modulename`, then call functions with dot syntax. Each module below has
its own reference page.

## Built-in functions

Always in scope, no import required:

`print`, `println`, `len`, `toString`, `toInt`, `toFloat`, `range`, `typeof`,
`append`, `read`, `exit`.

## Text & data

| Module | Purpose |
| --- | --- |
| [strings](/docs/stdlib/strings) | Search, slice, split, join, case, padding, formatting, builder |
| [regex](/docs/stdlib/regex) | Regular expressions: match, find, replace, capture groups |
| [types](/docs/stdlib/types) | Runtime type checks and conversions |
| [json](/docs/stdlib/json) | Parse, query, edit, and stream JSON |
| [yaml](/docs/stdlib/yaml) | Parse and serialize YAML |
| [xml](/docs/stdlib/xml) | Validate, query, and convert XML |
| [url](/docs/stdlib/url) | Parse and build URLs and query strings |
| [encode](/docs/stdlib/encode) | base64, hex, CSV, binary, JSON/XML |
| [serialize](/docs/stdlib/serialize) | msgpack and protobuf |
| [compress](/docs/stdlib/compress) | gzip, zlib, lz4, brotli |

## Math & collections

| Module | Purpose |
| --- | --- |
| [math](/docs/stdlib/math) | Arithmetic, trig, logs, random, bitwise, interpolation |
| [collections](/docs/stdlib/collections) | Stack, queue, set, map, heap, trie, ring, list, tuple |

## Time

| Module | Purpose |
| --- | --- |
| [time](/docs/stdlib/time) | Clock, dates, timers, durations, formatting |
| [date](/docs/stdlib/date) | Convenience date API over Unix timestamps |
| [timer](/docs/stdlib/timer) | setTimeout, setInterval, clear |

## System & I/O

| Module | Purpose |
| --- | --- |
| [io](/docs/stdlib/io) | Files, streams, and path helpers |
| [os](/docs/stdlib/os) | Environment, process, signals, permissions |
| [exec](/docs/stdlib/exec) | Run shell commands and programs |
| [signal](/docs/stdlib/signal) | POSIX signal handlers |
| [terminal](/docs/stdlib/terminal) | Raw mode, key input, ANSI colors and cursor |
| [runtime](/docs/stdlib/runtime) | Introspection and a process-global shared store |
| [memory](/docs/stdlib/memory) | Byte buffers, interning pools, GC stats |
| [logging](/docs/stdlib/logging) | Leveled logging with a debug toggle |

## Networking

| Module | Purpose |
| --- | --- |
| [net](/docs/stdlib/net) | TCP, UDP, TLS, DNS, and an HTTP client |
| [http](/docs/stdlib/http) | HTTP client (the built-in server is in [HTTP server](/docs/http-server)) |

## Crypto & data stores

| Module | Purpose |
| --- | --- |
| [crypto](/docs/stdlib/crypto) | Hashing, HMAC, AES, RSA, Ed25519, random, certs, TLS |
| [redis](/docs/stdlib/redis) | Redis client — key/value, lists, hashes, pub/sub |
| [sql](/docs/stdlib/sql) | SQLite, Postgres, and MySQL |
| [mongo](/docs/stdlib/mongo) | MongoDB client — insert, find, update, delete, count |

## Concurrency

The `thread` module (goroutines, channels, mutexes, futures, and more) is
covered on the **[concurrency](/docs/concurrency)** page. Shared state across
tasks lives in `runtime.core` — see the **[runtime](/docs/stdlib/runtime)** module.