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Parsing, analyzing, and comparing source code across many languages
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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
Language support
Technology and architecture


Run semantic --help for complete list of up-to-date options.


Usage: semantic parse ([--sexpression] | [--json] | [--json-graph] | [--symbols]
                      | [--dot] | [--show] | [--quiet]) [FILES...]
  Generate parse trees for path(s)

Available options:
  --sexpression            Output s-expression parse trees (default)
  --json                   Output JSON parse trees
  --json-graph             Output JSON adjacency list
  --symbols                Output JSON symbol list
  --dot                    Output DOT graph parse trees
  --show                   Output using the Show instance (debug only, format
                           subject to change without notice)
  --quiet                  Don't produce output, but show timing stats


Usage: semantic diff ([--sexpression] | [--json] | [--json-graph] | [--toc] |
                     [--dot] | [--show]) [FILE_A] [FILE_B]
  Compute changes between paths

Available options:
  --sexpression            Output s-expression diff tree (default)
  --json                   Output JSON diff trees
  --json-graph             Output JSON diff trees
  --toc                    Output JSON table of contents diff summary
  --dot                    Output the diff as a DOT graph
  --show                   Output using the Show instance (debug only, format
                           subject to change without notice)


Usage: semantic graph ([--imports] | [--calls]) [--packages] ([--dot] | [--json]
                      | [--show]) ([--root DIR] [--exclude-dir DIR]
                      DIR:LANGUAGE | FILE | --language ARG (FILES... | --stdin))
  Compute a graph for a directory or from a top-level entry point module

Available options:
  --imports                Compute an import graph (default)
  --calls                  Compute a call graph
  --packages               Include a vertex for the package, with edges from it
                           to each module
  --dot                    Output in DOT graph format (default)
  --json                   Output JSON graph
  --show                   Output using the Show instance (debug only, format
                           subject to change without notice)
  --root DIR               Root directory of project. Optional, defaults to
                           entry file/directory.
  --exclude-dir DIR        Exclude a directory (e.g. vendor)
  --language ARG           The language for the analysis.
  --stdin                  Read a list of newline-separated paths to analyze
                           from stdin.

Language support

Priority Language Parse Assign Diff ToC Symbols Import graph Call graph Control flow graph
1 Ruby 🚧
2 JavaScript 🚧
3 TypeScript 🚧
4 Python 🚧
5 Go 🚧
Java 🔶
Haskell 🔶
Markdown 🔶 N/A N/A N/A  
  • — Supported
  • 🔶 — Partial support
  • 🚧 — Under development


semantic requires at least GHC 8.6.4 and Cabal 2.4. 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.

We use cabal's Nix-style local builds for development. To get started quickly:

git clone
cd semantic
cabal new-build
cabal new-test
cabal new-run semantic -- --help

stack as a build tool is not officially supported; there is an unofficial stack.yaml available, though we cannot make guarantees as to its stability.

Technology and architecture

Architecturally, semantic:

  1. Reads blobs.
  2. Generates parse trees for those blobs with tree-sitter (an incremental parsing system for programming tools).
  3. Assigns those trees into a generalized representation of syntax.
  4. Performs analysis, computes diffs, or just returns parse trees.
  5. Renders output in one of many supported formats.

Semantic leverages a number of interesting algorithms and techniques:


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.

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