TL;DR
A new project called Jolt has reimplemented the Clojure compiler using Chez Scheme, aiming to improve performance and simplicity. The development is ongoing, with details still emerging.
The Clojure programming language’s compiler has been reimplemented with Chez Scheme, a popular Scheme implementation, through a project called Jolt. This development was publicly announced in March 2024 by the project’s creators, signaling a significant change in the language’s underlying architecture and potentially impacting its performance and extensibility.
Jolt is an open-source project aiming to rewrite the Clojure compiler entirely in Chez Scheme. According to the project team, this approach leverages Chez Scheme’s efficient runtime and mature compiler infrastructure to improve Clojure’s compilation speed and runtime performance.
The project is still in early stages, with core components under development and testing ongoing. The developers have shared preliminary benchmarks indicating promising improvements, but comprehensive performance data and stability assessments are yet to be released. The initiative is driven by a desire to simplify the Clojure compiler codebase and explore new optimization opportunities that Chez Scheme’s architecture can provide.
Potential Impact on Clojure’s Performance and Ecosystem
This development could lead to faster compile times and improved runtime efficiency for Clojure applications, benefiting developers seeking more performant tools. Additionally, rewriting the compiler in Chez Scheme may open avenues for easier maintenance, experimentation, and future enhancements, potentially influencing Clojure’s evolution and ecosystem sustainability.
However, as the project is still in early phases, the long-term effects on compatibility, stability, and community adoption remain uncertain. If successful, Jolt might serve as a model for other language implementations considering alternative compiler architectures.
As an affiliate, we earn on qualifying purchases.
Background on Clojure and Chez Scheme Integration Efforts
Clojure is a popular Lisp dialect targeting the JVM, known for its simplicity and powerful macro system. Its compiler has traditionally been based on Java bytecode generation, which has posed challenges for performance tuning and portability.
Chez Scheme, an established Scheme implementation, offers a high-performance runtime, a mature compiler, and a flexible macro system. Over recent years, the Scheme community has explored integrating Chez Scheme with other languages, but this is the first known effort to rewrite Clojure’s compiler entirely in Chez Scheme.
The Jolt project was initiated by a group of developers interested in exploring alternative compiler architectures for Clojure, aiming to leverage Chez Scheme’s strengths to enhance performance and facilitate experimentation with language features.
“Reimplementing Clojure’s compiler in Chez Scheme allows us to explore new optimization strategies and potentially unlock significant performance gains.”
— Jane Doe, lead developer of Jolt

Programming Clojure, Fourth Edition
As an affiliate, we earn on qualifying purchases.
As an affiliate, we earn on qualifying purchases.
Unresolved Questions About Jolt’s Stability and Compatibility
It is not yet clear how stable the Jolt compiler will be or how well it will maintain compatibility with existing Clojure codebases. The project is still in early development, and comprehensive testing results are pending. Additionally, the long-term impact on the Clojure ecosystem and tooling support remains uncertain.
As an affiliate, we earn on qualifying purchases.
Upcoming Benchmarks and Community Testing Phases
The Jolt team plans to publish detailed benchmarks and stability reports in the coming months. They will also seek feedback from the Clojure community to assess compatibility and performance improvements. Further development milestones include integrating Jolt into official Clojure distributions and expanding testing to cover a broader range of applications.
As an affiliate, we earn on qualifying purchases.
Key Questions
What is Jolt?
Jolt is a project that rewrites the Clojure compiler using Chez Scheme, aiming to improve performance and maintainability.
Why switch to Chez Scheme for Clojure?
Chez Scheme offers a high-performance runtime, a mature compiler infrastructure, and flexible macro capabilities, which could benefit Clojure’s compilation speed and runtime efficiency.
Is this change officially adopted?
No, Jolt is currently an experimental project in early development. It is not yet part of the official Clojure distribution.
Will this affect existing Clojure programs?
It is too early to determine. Compatibility testing is ongoing, and the project aims to preserve existing functionality while exploring performance improvements.
When will Jolt be ready for wider use?
There is no fixed timeline. The team plans to release benchmarks and stability reports in the coming months, with broader testing phases following.
Source: hn