Githack: A Persistent Object Store for Lisp Based on Git

Git has a built-in persistent store for objects based on Merkle trees. It is tailored to store files and directories, but these are just specializations of trees of blobs. There is no reason it couldn't be used to store Lisp objects. Githack is a Lisp object store that uses Git as its backend. It is a simple library that provides persistent objects for Lisp and a transactional interface for manipulating them. Simple atomic objects are stored as blobs and composite objects are stored as trees. Standard composite Lisp objects, such as lists, vectors, and hash tables, are supported. Custom composite objects can be created through DEFINE-PERSISTENT-STRUCT or DEFCLASS with a :STANDARD-PERSISTENT-METACLASS. WITH-REPOSITORY is used to specify which repository to use for storing objects. WITH-TRANSACTION sets up a transaction for manipulating objects and retrieves the root object. You use standard slot accessors to walk the object tree. When you are done, you commit the transaction, and…