Cheshire
A fast and feature-rich JSON and SMILE encoding/decoding library for Clojure.
What is Cheshire?
Cheshire is a Clojure library for fast JSON and SMILE encoding and decoding. It solves the need for high-performance JSON handling in Clojure applications while supporting extended data types like Date, UUID, and sets that aren't natively covered by basic JSON libraries.
Clojure developers who need efficient JSON serialization/deserialization with support for Clojure-specific and Java types, especially those working on web APIs, data pipelines, or performance-sensitive applications.
Developers choose Cheshire for its combination of speed (built on Jackson) and rich feature set, including SMILE support, custom encoders, and seamless handling of Clojure data structures without sacrificing performance.
Overview
Clojure JSON and JSON SMILE (binary json format) encoding/decoding
Use Cases
Best For
- High-performance JSON serialization in Clojure web services
- Encoding Clojure data structures with Date, UUID, or Set types to JSON
- Working with the binary SMILE format for compact data exchange
- Adding custom encoding logic for specific Java or Clojure classes
- Streaming JSON encoding/decoding to handle large datasets efficiently
- Parsing JSON with lazy sequences to reduce memory overhead
Not Ideal For
- Projects that require JSON schema validation or other advanced JSON standards beyond basic encoding/decoding
- Teams in mixed JVM environments aiming to minimize Jackson dependencies due to conflicts or licensing
- Applications that only handle standard JSON types and don't use Clojure-specific extensions like sets or symbols
Pros & Cons
Pros
Benchmarked as approximately twice as fast as data.json, leveraging Jackson's optimized core for speed-critical applications.
Natively encodes Clojure symbols, sets, queues, and Java types like Date and UUID, which are not covered by basic JSON libraries.
Supports the SMILE binary JSON format for compact data representation, useful in network-efficient or storage-sensitive scenarios.
Allows defining custom encoders for arbitrary classes while maintaining performance, with helpers for common encoding actions.
Cons
Built on Jackson, which can introduce dependency conflicts, increase artifact size, and tie you to Jackson's update cycle and potential issues.
The README admits custom encoders are 'slightly slower' than the fast encoder, so performance may drop for custom types in high-throughput use cases.
Specifically designed for Clojure, making it less suitable for projects using other JVM languages without Clojure interoperability layers.
Frequently Asked Questions
Related Projects
FastjsonFASTJSON 2.0.x has been released, faster and more secure, recommend you upgrade.
JacksonMain Portal page for the Jackson project
KryoJava binary serialization and cloning: fast, efficient, automatic
Ffjsonfaster JSON serialization for Go
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