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# Packages

C+ is **C plus packages**. The language core is small on purpose; capability comes from packages, **including the standard library**. `stdlib` is a vendored package like any other, not a language built-in.

## How a package works

Every package is a directory under `vendor/` with a `Cplus.toml` manifest, a `<package-name>.cplus` library entry, and in-package `#[test]` functions you can run with `cd vendor/<pkg> && cpc test`. To use one, add it to your manifest and import it:

```toml
[dependencies]
stdlib = "*"
json   = "*"
```

```cplus
import "stdlib/io" as io;
import "json/json" as json;
```

The driver walks one directory up from your project to resolve sibling vendor dependencies, so no per-package symlinks are needed beyond the canonical `vendor/` checkout.

You can populate `vendor/` by hand, or let [`cplus-pm`](/docs/package-manager), the standalone package manager, resolve and fetch dependencies for you (`cplus-pm install`).

## The standard library

- [stdlib](/docs/packages/stdlib) — I/O, collections, ownership wrappers, concurrency, files, and networking. The package you reach for first.

## GPU & numerics

C+ talks to GPUs and BLAS as a *consumer* of the vendor SDKs, through plain C FFI with `Drop`-managed handles. See [GPU & numerics](/docs/gpu-numerics) for the backend matrix and how to pick one.

- [metal](/docs/packages/metal) — typed Metal and MPS bindings for Apple GPU compute.
- [cuda](/docs/packages/cuda) — CUDA Runtime + cuBLAS bindings for NVIDIA GPUs.
- [accelerate](/docs/packages/accelerate) — Apple CPU numerics (BLAS, vDSP).
- [cblas](/docs/packages/cblas) — cross-platform CPU BLAS (OpenBLAS / Netlib / MKL).
- [simd](/docs/packages/simd) — portable `f32x4` math plus integer lane helpers.

## AI

- [llama_cpp](/docs/packages/llama_cpp) — bindings for llama.cpp with a safe `Session` facade for LLM inference.
- [coreai](/docs/packages/coreai) — a Swift bridge to Apple's CoreAI (macOS).

## Agent surface

Expose a C+ app to an external agent — described, driven, and observed over a consent-gated bridge. See [Agent surface](/docs/agent-surface) for the full story.

- [agent_core](/docs/packages/agent_core) — the framework-agnostic authorization brain.
- [agent_appkit](/docs/packages/agent_appkit) — the macOS GUI backend (live NSView tree → surface).
- [agent_mcp](/docs/packages/agent_mcp) — the JSON-RPC 2.0 / MCP bridge.

## Platform

- [appkit](/docs/packages/appkit) — typed Cocoa / AppKit bindings for native macOS apps.
- [uikit](/docs/packages/uikit) — typed UIKit bindings for native iOS apps.
- [jni](/docs/packages/jni) — minimal Java Native Interface bindings.

## Embedded

C+ cross-compiles to microcontrollers; see [Targets](/docs/targets) and [Embedded & ESP32](/docs/embedded).

- [espidf](/docs/packages/espidf) — ESP-IDF bindings (GPIO, timer, task, UART) for the `esp32-xtensa` target.

## Utilities

- [clap](/docs/packages/clap) — command-line argument parsing with a fluent builder.
- [json](/docs/packages/json) — a typed-enum JSON parser and serializer.
- [log](/docs/packages/log) — a leveled, zero-allocation structured logger.
- [uuid](/docs/packages/uuid) — RFC 4122 v4 UUIDs.
- [arena](/docs/packages/arena) — a growable bump-pointer arena.
- [static-arena](/docs/packages/static-arena) — a fixed-size, stack-resident arena.

## Real-time

- [rt](/docs/packages/rt) — lock-free primitives for the real-time contracts (`rt` and the platform `rt_darwin`).