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semantic is a Haskell library and command line tool for parsing, analyzing, and comparing source code.
In a hurry? Check out our documentation of example uses for the semantic command line tool.
| Table of Contents |
|---|
| Usage |
| Language support |
| Development |
| Technology and architecture |
| Licensing |
Run semantic --help for complete list of up-to-date options.
Usage: semantic parse [--sexpression | (--json-symbols|--symbols) |
--proto-symbols | --show | --quiet] [FILES...]
Generate parse trees for path(s)
Available options:
--sexpression Output s-expression parse trees (default)
--json-symbols,--symbols Output JSON symbol list
--proto-symbols Output protobufs symbol list
--show Output using the Show instance (debug only, format
subject to change without notice)
--quiet Don't produce output, but show timing stats
-h,--help Show this help text
| Language | Parse | AST Symbols† | Stack graphs |
|---|---|---|---|
| Ruby | ✅ | ✅ | |
| JavaScript | ✅ | ✅ | |
| TypeScript | ✅ | ✅ | 🚧 |
| Python | ✅ | ✅ | 🚧 |
| Go | ✅ | ✅ | |
| PHP | ✅ | ✅ | |
| Java | 🚧 | ✅ | |
| JSON | ✅ | ⬜️ | ⬜️ |
| JSX | ✅ | ✅ | |
| TSX | ✅ | ✅ | |
| CodeQL | ✅ | ✅ | |
| Haskell | 🚧 | 🚧 |
† Used for code navigation on github.com.
- ✅ — Supported
- 🔶 — Partial support
- 🚧 — Under development
- ⬜ - N/A ️
semantic requires at least GHC 8.10.1 and Cabal 3.0. We strongly recommend using ghcup to sandbox GHC versions, as GHC packages installed through your OS's package manager may not install statically-linked versions of the GHC boot libraries. semantic currently builds only on Unix systems; users of other operating systems may wish to use the Docker images.
We use cabal's Nix-style local builds for development. To get started quickly:
git clone [email protected]:github/semantic.git cd semantic script/bootstrap cabal v2-build all cabal v2-run semantic:test cabal v2-run semantic:semantic -- --help
You can also use the Bazel build system for development. To learn more about Bazel and why it might give you a better development experience, check the build documentation.
git clone [email protected]:github/semantic.git cd semantic script/bootstrap-bazel bazel build //...
stack as a build tool is not officially supported; there is unofficial stack.yaml support available, though we cannot make guarantees as to its stability.
Architecturally, semantic:
- Generates per-language Haskell syntax types based on tree-sitter grammar definitions.
- Reads blobs from a filesystem or provided via a protocol buffer request.
- Returns blobs or performs analysis.
- Renders output in one of many supported formats.
Throughout its lifecycle, semantic has leveraged a number of interesting algorithms and techniques, including:
- Myers' algorithm (SES) as described in the paper An O(ND) Difference Algorithm and Its Variations
- RWS as described in the paper RWS-Diff: Flexible and Efficient Change Detection in Hierarchical Data.
- Open unions and data types à la carte.
- An implementation of Abstracting Definitional Interpreters extended to work with an à la carte representation of syntax terms.
Contributions are welcome! Please see our contribution guidelines and our code of conduct for details on how to participate in our community.
Semantic is licensed under the MIT license.