Awesome

duffer

This is a learning exercise and an API for git, in that order. Please do not use this code in production. Instead I would recommend Vincent Hanquez's excellent and very educational hs-git.

I gave a presentation on this project.

What this library does

• Reads and writes loose blobs, trees, commits, and tags.
• Reads full packfiles.
• Reads and writes git refs.

Some things this library does not do (yet)

• Generate a packfile index from a packfile.
• Support arbitrary backends besides file storage.
• Read .git/index
• Diffs (you can get surprisingly far without them!)
• Provide Functor, Applicative, or Monad instances for a repository, whatever that means.

Goals

Although this is primarily a way for me to learn both Haskell and git at the same time, there a couple of (I think) cool things I would like to do with this library:

• Use git as a NoSQL store, i.e. using git data formats to persist data for an application. Irmin is exactly this for OCaml but I don't know of an equivalent in Haskell (although filestore comes close). This means eventually supporting pluggable backends like Irmin and libgit2 do so that you're not limited to a filesystem backend.
• A GraphQL/other query language interface to a git repository's commits. If commits form a beautiful acyclic directed graph, there has to be a better way of querying them than git log.

Getting Started

1. Set up stack if you haven't already.
2. Clone this repository: git clone git@github.com:vaibhavsagar/duffer.git
3. cd duffer
4. stack test
5. Tests should all pass. If they don't, please open an issue.