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|
|Technology and architecture|
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|
† Used for code navigation on github.com.
✅— Supported 🔶— Partial support 🚧— Under development ⬜- N/A ️
semantic requires at least GHC 8.8.1 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.
cabal's Nix-style local builds for development. To get started quickly:
git clone firstname.lastname@example.org:github/semantic.git cd semantic script/bootstrap cabal v2-build all cabal v2-test cabal v2-run 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 documentation at
git clone email@example.com: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.
Technology and architecture
- Reads blobs.
- Generates parse trees for those blobs with tree-sitter (an incremental parsing system for programming tools).
- Assigns those trees into a generalized representation of syntax.
- Performs analysis, computes diffs, or just returns parse trees.
- Renders output in one of many supported formats.
Semantic leverages a number of interesting algorithms and techniques:
- 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.
Semantic is licensed under the MIT license.