# Chez Scheme

> R6RS Scheme compiler and run-time

**Wikidata**: [Q5094657](https://www.wikidata.org/wiki/Q5094657)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Chez_Scheme)  
**Source**: https://4ort.xyz/entity/chez-scheme

## Summary
Chez Scheme is an R6RS-compliant Scheme programming language implementation that serves as both a compiler and run-time environment.

## Key Facts
- Chez Scheme is an R6RS-compliant Scheme compiler and run-time
- Developed by Cisco (formerly Cadence Research Systems)
- Inception in 1985
- Licensed under the Apache Software License 2.0
- Available in multiple versions including 9.5.6 (2021), 9.6.2 (2023), and 10.0.0 (2024)
- Runs on BSD operating systems
- Considered free software
- Has an English-language user manual

## FAQs
### Q: What is Chez Scheme used for?
A: Chez Scheme is used as a programming language implementation that serves as both a compiler and run-time environment for R6RS-compliant Scheme code.

### Q: Who developed Chez Scheme?
A: Chez Scheme was developed by Cisco (formerly Cadence Research Systems).

### Q: What are the system requirements?
A: Chez Scheme runs on BSD operating systems and is available as packages for systems like FreeBSD, Ubuntu, and NetBSD.

### Q: Is Chez Scheme open source?
A: Yes, Chez Scheme is free software licensed under the Apache Software License 2.0.

## Why It Matters
Chez Scheme represents a significant implementation of the R6RS standard for the Scheme programming language. As both a compiler and run-time environment, it provides a comprehensive solution for developing and executing Scheme programs. The language's adherence to the R6RS standard ensures compatibility with other implementations while offering performance advantages through its compilation approach. Its long history since 1985 demonstrates sustained development and maintenance, making it a reliable choice for both academic and professional use cases.

## Notable For
- It's one of the few implementations that serves as both a compiler and run-time environment for Scheme
- Maintains compliance with the R6RS standard while offering performance optimizations
- Has been developed continuously since 1985 by Cisco (formerly Cadence Research Systems)
- Provides comprehensive documentation and user guides
- Available as free software under the Apache License 2.0

## Body
### Technical Overview
Chez Scheme implements the R6RS standard for the Scheme programming language. It functions as both a compiler and run-time environment, meaning it compiles Scheme code into machine code while also providing the runtime system to execute that code. The implementation was originally developed by R. Kent Dybvig and others at Cadence Research Systems in 1985 and has been maintained by Cisco since then.

### Development and Versions
The software has been continuously developed since its inception in 1985. Multiple versions have been released, with the most recent stable versions being 10.0.0 (released February 6, 2024), 9.6.4 (October 16, 2023), and 9.6.2 (August 29, 2023). Earlier versions include 9.5.8a (April 27, 2023), 9.5.8 (April 25, 2022), and 9.5.4 (August 31, 2020).

### Licensing and Distribution
Chez Scheme is distributed under the Apache Software License 2.0, making it free software. It's available through various package repositories including FreeBSD's lang/chez-scheme, Ubuntu's chezscheme package, and NetBSD's wip/chezscheme. The source code is hosted on GitHub at https://github.com/cisco/ChezScheme.

### System Requirements and Compatibility
Chez Scheme requires a BSD operating system and is designed to run on Unix-like systems. It has been ported to various platforms including FreeBSD, Ubuntu, and NetBSD. The implementation supports dynamic typing, latent typing, and strong typing as described in the R6RS standard.

### Documentation and Support
Comprehensive documentation is available through the official website at http://cisco.github.io/ChezScheme/. The user manual is available at http://cisco.github.io/ChezScheme/csug9.6/csug.html. Support and development are maintained by Cisco, with the community contributing through the GitHub repository.

## References

1. [Source](http://www.scheme.com/)
2. [Chez Scheme Version 9.5.6. 2021](https://github.com/cisco/ChezScheme/releases/tag/v9.5.6)
3. [Release 9.4. 2016](https://github.com/cisco/ChezScheme/releases/tag/v9.4)
4. [Release 9.5. 2017](https://github.com/cisco/ChezScheme/releases/tag/v9.5)
5. [Release 9.5.2. 2019](https://github.com/cisco/ChezScheme/releases/tag/v9.5.2)
6. [Release 9.5.4. 2020](https://github.com/cisco/ChezScheme/releases/tag/v9.5.4)
7. [Release 9.5.8. 2022](https://github.com/cisco/ChezScheme/releases/tag/v9.5.8)
8. [Release 9.5.8a. 2023](https://github.com/cisco/ChezScheme/releases/tag/v9.5.8a)
9. [Release 9.6.2. 2023](https://github.com/cisco/ChezScheme/releases/tag/v9.6.2)
10. [Release 9.6.4. 2023](https://github.com/cisco/ChezScheme/releases/tag/v9.6.4)
11. [Release 10.0.0](https://github.com/cisco/ChezScheme/releases/tag/v10.0.0)
12. [Release 10.1.0. 2024](https://github.com/cisco/ChezScheme/releases/tag/v10.1.0)
13. [Release 10.2.0. 2025](https://github.com/cisco/ChezScheme/releases/tag/v10.2.0)
14. [Release 10.3.0. 2025](https://github.com/cisco/ChezScheme/releases/tag/v10.3.0)