如何可视化Cabal项目的包依赖图？

Got it, I totally get the frustration with ghc-pkg dot—it’s great for inspecting the global/user GHC package database, but it doesn’t reflect the per-project dependency tree you’re actually working on with Cabal. Here are the most reliable tools and workflows to generate accurate dependency graphs tailored to your Cabal project:

1. Use cabal-plan (The Go-To Tool) #

cabal-plan is purpose-built to parse Cabal’s build plans and generate dependency graphs that match your project’s exact constraints and resolved versions. It’s the gold standard for this use case.

• First, install it (if you haven’t already):

  cabal install cabal-plan
  

• Generate a DOT file of your project’s full dependency graph:

  cabal-plan dot > project-deps.dot
  

• Convert the DOT file to a visual image (you’ll need Graphviz installed—most package managers offer it as graphviz):

  # Generate a PNG for quick viewing
  dot -Tpng project-deps.dot -o project-deps.png
  # Or an SVG for sharper, scalable output
  dot -Tsvg project-deps.dot -o project-deps.svg
  

• Pro Tip: If the full graph is too cluttered, focus only on your project and its direct dependencies (prune transitive ones):

  cabal-plan dot --prune=none --focus=your-project-name > focused-deps.dot
  

  Replace your-project-name with the name of your Cabal package (from your .cabal file).

2. If You Use Stack: stack dot #

If your Cabal project is managed with Stack, it has a built-in command to generate dependency graphs without extra tools:

• Generate the DOT file, focusing only on project-specific dependencies:

  stack dot --project-only > project-deps.dot
  

• Convert to a visual with Graphviz using the same commands as above.

3. Bonus: Nix Users Can Use nix-deps-graph #

If you’re using Nix to manage your Cabal project’s dependencies, nix-deps-graph can generate a detailed graph that includes Nix-specific dependency details:

nix-build -A haskellPackages.your-project-name.dependencyGraph

This will output a DOT file you can render with Graphviz.

Quick Graphviz Tweaks for Better Readability #

• Use different layout engines to reduce clutter:

  # Neato for a force-directed, compact layout
  dot -Tsvg -Kneato project-deps.dot -o project-deps-neato.svg
  # FDP for another force-directed style that handles dense graphs well
  dot -Tsvg -Kfdp project-deps.dot -o project-deps-fdp.svg
  

内容的提问来源于stack exchange，提问作者Cigarette Smoking Man