Releases

Releases

This page indexes Hydra's published releases and package registries. All Hydra packages in a release share a single version number.

For release engineering policy and publish procedure, see Release process. For release notes, see CHANGELOG.md.

This page follows the same broad separation used by Apache TinkerPop's download page: published package locations are listed separately from historical releases and release verification. Hydra is not yet an Apache project, so source-release signing and Apache mirror verification are future work under #441.

Published packages

Current package registries used by Hydra:

• Hackage (Haskell): hydra, hydra-kernel, hydra-haskell
• Maven Central (Java): hydra-kernel, hydra-java, hydra-pg, hydra-rdf; historical artifacts: hydra-ext, hydra
• PyPI (Python): hydra-kernel, hydra-python, hydra-pg, hydra-rdf
• conda-forge (Python): hydra-kernel, hydra-python, hydra-pg, hydra-rdf

The package set has changed over time. Older releases were usually represented by the Hackage hydra package and, later, by Java artifacts. Hydra 0.15 introduced per-package Java and Python distributions. On Maven Central, hydra-java is available back to 0.2.0 and hydra-ext back to 0.7.0.

Release verification

Hydra release verification currently happens through the project release workflow. See Release process for maintainer procedure.

Apache-style source-release signatures, checksums, and mirror/archive instructions are future #441 work.

0.15

0.15.0 — 2026-04-29. GitHub tag. CHANGELOG.

Structural cleanup release: the repository moved to the packages/ / heads/ / dist/ layout, Java and Python shifted to per-package published artifacts, and JSON kernel format v1 was formalized.

Published package links:

• Hackage: hydra-0.15.0
• Maven Central: hydra-kernel, hydra-java, hydra-pg, hydra-rdf
• PyPI: hydra-kernel, hydra-python, hydra-pg, hydra-rdf
• conda-forge: hydra-kernel, hydra-python, hydra-pg, hydra-rdf

0.14

0.14.1 — 2026-03-30. GitHub tag. CHANGELOG.

Patch release regenerating all implementations after a group-eval primitive fix.

0.14.0 — 2026-03-29. GitHub tag. CHANGELOG.

Major release adding Scala, Clojure, Common Lisp, and Scheme as complete implementations, with Avro bidirectional coding and new demos.

Published package links:

• Hackage: hydra-0.14.1, hydra-0.14.0
• Maven Central: 0.14.1 hydra-java, hydra-ext; 0.14.0 hydra-java, hydra-ext

0.13

0.13.0 — 2026-02-27. GitHub tag. CHANGELOG.

Major release completing Hydra-Python and Hydra-Java as self-hosting implementations and demonstrating mutual self-hosting across Haskell, Java, and Python.

Published package links:

• Hackage: hydra-0.13.0
• Maven Central: hydra-java, hydra-ext

0.12

0.12.0 — 2025-08-28. GitHub tag. CHANGELOG.

Consolidation release with significant Python progress, kernel cleanup, and bookkeeping closures for Java module ports.

Published package links:

• Hackage: hydra-0.12.0
• Maven Central: hydra-java, hydra-ext

0.11

0.11.0 — 2025-03-16. GitHub tag. CHANGELOG.

Type-inference rebase release aligning inference internals with Algorithm W.

Historical note:

• Documented in CHANGELOG.md.
• Maven Central: hydra-java, hydra-ext

0.10

0.10.0 — 2025-02-19. GitHub tag. CHANGELOG.

Added initial Hydra-Python completion, GraphSON coding, provisional Hydra-Go, and dot-separated namespaces.

Historical note:

• Documented in CHANGELOG.md.
• Maven Central: hydra-java, hydra-ext

0.9

0.9.0 — 2025-01-06. GitHub tag. CHANGELOG.

Bootstrapped Hydra-Python and the JSON Schema coder; added a fluent Java DSL for flows.

Historical note:

• Documented in CHANGELOG.md.
• Maven Central: hydra-java, hydra-ext

0.8

0.8.1 — 2024-09-24. GitHub tag. CHANGELOG.

Patch release generalizing property-graph merging.

0.8.0 — 2024-09-09. GitHub tag. CHANGELOG.

Added C# support, Graphviz DOT coding, term accessors, and a Java error-handling change for Spark.

Published package links:

• Hackage: hydra-0.8.1, hydra-0.8.0
• Maven Central: 0.8.1 hydra-java, hydra-ext; 0.8.0 hydra-java, hydra-ext

0.7

0.7.0 — 2024-08-21. GitHub tag. CHANGELOG.

Major module-organization release establishing DNS-style namespaces in hydra-ext and promoting property-graph models into hydra.pg.

Published package links:

• Hackage: hydra-0.7.0
• Maven Central: hydra-java, hydra-ext

0.6

0.6.0 — 2024-08-19. GitHub tag. CHANGELOG.

Type-system improvement release with System F type abstraction/application, expanded language support, and revamped annotations.

Published package links:

• Hackage: hydra-0.6.0
• Maven Central: hydra-java

0.5

0.5.3 — 2024-08-06. GitHub tag. CHANGELOG.

Patch release preserving map/set ordering during JSON serialization.

0.5.1 — 2024-08-01. GitHub tag. CHANGELOG.

Patch release with dependency updates and minor improvements after the 0.5.0 Hydra Core overhaul.

0.5.0 — 2024-07-26. GitHub tag. CHANGELOG.

Major Hydra Core overhaul replacing polymorphic core types with explicit type schemes and revamping Let term encoding.

Historical note:

• Documented in CHANGELOG.md.
• Maven Central: hydra-java

0.4

0.4.0 — 2024-07-10. GitHub tag. CHANGELOG.

Added null checks to generated Java, the Gremlin model, and Protobuf annotation refinements.

Historical note:

• Documented in CHANGELOG.md.
• Maven Central: hydra-java

0.3

0.3.0 — 2024-06-05. GitHub tag. CHANGELOG.

Added an OpenCypher parser, KQL model and serializer, Delta Parquet model, and early property-graph query support.

Historical note:

• Documented in CHANGELOG.md.
• Maven Central: hydra-java

0.2

0.2.0 — 2024-01-10. GitHub tag. CHANGELOG.

Hydra-Java release with major Java tooling, Protobuf bidirectional coding, property-graph validation, JSON support, and early OpenCypher support.

Published package links:

• Hackage: hydra-0.2.0
• Maven Central: hydra-java

0.1

0.1.1 — 2022-12-04. GitHub tag. CHANGELOG.

Patch release with README polish.

0.1.0 — 2022-12-04. GitHub tag. CHANGELOG.

First packaged Hydra release. Included the core language, graph/module models, type inference, adapters, coders, and early language support.

Published package links:

• Hackage: hydra-0.1.1, hydra-0.1.0