---
title: erl
url: https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/
---

**Kind:** Module  
**Package:** compute-sdk-cpp 0.7.0  
**Path:** `fastly::erl`

## Classes

| Name | Summary |
| --- | --- |
| [ERL](https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/class.ERL/) |  |
| [ERLError](https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/class.ERLError/) | Errors that can arise during [ERL](https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/class.ERL/) operations. |
| [PenaltyBox](https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/class.PenaltyBox/) | A penalty box that can be used with the edge rate limiter or stand alone for adding and checking if some entry is in the data set. |
| [RateCounter](https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/class.RateCounter/) | A rate counter that can be used with an edge rate limiter or stand alone for counting and rate calculations |

## Enums

| Name | Summary |
| --- | --- |
| [CounterDuration](https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/enum.CounterDuration/) | To be used for picking the duration in a rate counter `lookup_count` call. |
| [ERLError::Code](https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/enum.ERLError-Code/) |  |
| [RateWindow](https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/enum.RateWindow/) | To be used for picking the window in a rate counter `lookup_rate` or a [ERL](https://www.fastly.com/documentation/reference/compute/sdks/cpp/fastly/erl/class.ERL/) `check_rate` call. |