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Welcome to the Hydra wiki!

Where docs live. This wiki is for user-facing documentation that explains Hydra's design as it is: conceptual framing, the LambdaGraph data model, property-graph and RDF design, release policy. Procedural recipes, implementation-level details, build-system mechanics, and troubleshooting live in docs/. Provisional material — sketches, in-flight proposals — belongs in issues or branch plans, not here.

Documentation

• Main README - Project overview and getting started
• Concepts - Core concepts, type system, and design principles
• Packaging - The packaging model: packages, modules, definitions, and entity metadata
• Inference - Type inference and checking: HM together with elaboration to System F
• DSL guide - Comprehensive guide to Hydra's domain-specific languages
• Implementation - Detailed implementation guide covering type modules, DSLs, primitives, and coders
• Coding style - Guiding principles and coding conventions
• Code organization - The packages/, heads/, dist/ layout used across Hydra packages
• Developer Recipes - Step-by-step guides for common development tasks
• Property graphs - Property graph data model, GraphSON, GQL, mapping language
• RDF - RDF, SHACL, and OWL support
• Testing - Common test suite and language-specific testing
• Wiki pages (see sidebar) - Release process and feature documentation

Package documentation

• Hydra-Kernel - Language-independent kernel types, terms, and DSL sources
• Hydra-Haskell - Haskell coder (DSL sources + generated Haskell coder output)
• Hydra-Java - Java coder DSL sources (Haskell-based)
• Hydra-Python - Python coder DSL sources (Haskell-based)
• Hydra-Scala - Scala coder DSL sources + sbt build
• Hydra-Lisp - Lisp coder DSL sources (Clojure, Scheme, Common Lisp, Emacs Lisp)
• Hydra-Ext - Extension coders (Avro, Protobuf, GraphQL, C++, Go, Rust, TypeScript, ...)
• Hydra-PG - Property graph models and coders
• Hydra-RDF - RDF, SHACL, and OWL models
• Hydra-Coq - Coq code generation
• Hydra-TypeScript - TypeScript coder DSL sources (full implementation, #126)
• Hydra-Go - Go coder DSL sources (head bud — generator works, runtime partial; not yet test-suite green)
• Hydra-Wasm - WebAssembly target (in progress)
• Hydra-Bench - Synthetic workloads for cross-host inference benchmarking

Runtime heads

• heads/haskell/ - Haskell runtime, exec binaries, sync scripts
• heads/java/ - Java runtime (primitives, DSL, utils)
• heads/python/ - Python runtime (primitives, DSL, pyproject.toml)
• heads/scala/ - Scala runtime (primitives, bootstrapping host)
• heads/lisp/ - Per-dialect Lisp runtimes (clojure, scheme, common-lisp, emacs-lisp)
• heads/typescript/ - TypeScript runtime (#126)
• heads/go/ - Go runtime (head bud)
• heads/wasm/ - WebAssembly runtime (in progress)

Generated output

• dist/json/ - JSON kernel modules (always checked in; canonical interchange format)
• dist/haskell/ - Generated Haskell kernel and per-package coders (hydra-haskell, hydra-java, hydra-python, hydra-scala, hydra-lisp, hydra-pg, hydra-rdf, hydra-ext, hydra-coq, hydra-typescript, hydra-wasm, ...)
• dist/java/ - Generated Java kernel
• dist/python/ - Generated Python kernel
• dist/scala/ - Generated Scala kernel
• dist/typescript/ - Generated TypeScript kernel
• dist/go/ - Generated Go kernel (head bud — kernel only)
• dist/clojure/, dist/scheme/, dist/common-lisp/, dist/emacs-lisp/ - Per-dialect Lisp kernels

Only dist/json/ and dist/haskell/ are tracked in git; the rest are regenerated from dist/json/ on demand via bin/sync.sh.