Git's core is C. This has the packfile and object store code, the diffing and patching code, reflog code, generic commit-walking libraries, etc. I read it a few

Git's core is C. This has the packfile and object store code, the diffing and patching code, reflog code, generic commit-walking libraries, etc. I read it a few years ago when making a Git packfile reader, and the C code is very understandable. I grokked it much quicker than HG's core, the only other one I read. Most of Git's functionality is built with scripts. Lots of jobs, like octopus merging, are done in Bash scripts that dispatch all of the real work to the C libraries. The Git source distribution has a contrib section that has Python, elisp, and Perl (among others). It also includes a few subprojects like Gitweb, each done in random languages. All of this causes the overall source tree feel very unorganized.