> ## Documentation Index
> Fetch the complete documentation index at: https://docs.poly.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Libraries

> Standard library and pre-installed packages available to functions, including requests, jsonschema, and urllib3.

<Info>
  **This page requires Python familiarity.** PolyAI's function runtime executes Python in a managed cloud sandbox. Only the standard library and the packages listed below are available. You cannot install additional packages. If you need a library that is not listed, contact your PolyAI representative.
</Info>

## Execution environment

Functions run in a **sandboxed cloud environment**. This means:

* **No local file system access** – you cannot read or write files from your machine (e.g., CSV files, text files, or databases stored locally).
* **No package installation** – only the standard library and the pre-installed packages listed below are available.
* **Network access** – you can make outbound HTTP requests using the `requests` library to call external APIs or fetch hosted data.

If you need to use data from a file, host it externally (e.g., on a web server or cloud storage) and fetch it at runtime using `requests`.

## Standard library

Within functions you have access to the full [Python standard library](https://docs.python.org/3/library/index.html), including modules like `datetime`, `json`, `re`, `urllib`, and `hashlib`.

## Notable language features

The runtime supports modern Python language features, including:

* **Structural pattern matching** (`match`/`case`, Python 3.10+) – a cleaner alternative to long `if`/`elif` chains for branching on values or structures. See the [Python docs on match statements](https://docs.python.org/3/tutorial/controlflow.html#match-statements).
* **Parenthesized context managers** (Python 3.10+) – you can use parentheses to split multiple context managers across lines:
  ```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
  with (
      open("input.json") as infile,
      open("output.json", "w") as outfile,
  ):
      ...
  ```
* **Exception Groups and `except*`** (Python 3.11+) – handle multiple exceptions raised concurrently. Useful when your function makes parallel API calls. See [PEP 654](https://peps.python.org/pep-0654/).

## Pre-installed packages

The following packages are pre-installed and available for `import`:

| Library                                                                | Description                          |
| ---------------------------------------------------------------------- | ------------------------------------ |
| [requests](https://requests.readthedocs.io/en/stable/user/quickstart/) | HTTP library for making API requests |
| [urllib3](https://urllib3.readthedocs.io/en/stable/)                   | Low-level HTTP client                |
| [jsonschema](https://python-jsonschema.readthedocs.io/en/stable/)      | JSON schema validation               |

<Tip>
  The `requests` library is the recommended way to make external API calls from your functions. See the [requests quickstart guide](https://requests.readthedocs.io/en/stable/user/quickstart/) for usage examples.
</Tip>

If you encounter unexpected behavior with a library, contact your PolyAI representative.