Pijul is a free and open source (GPL2) distributed version control system. Its distinctive feature is to be based on a theory of patches, while still being fast and scalable. This makes it easy to learn and use, without any compromise on power or features.
Why?
Commutation
In Pijul, independent changes can be applied in any order without changing the result or the version’s identifier. This makes Pijul significantly simpler than workflows using git rebase or hg transplant. Pijul has a branch-like feature called “channels”, but these are not as important as in other systems. For example, so-called feature branches are often just changes in Pijul. Keeping your history clean is the default.
Merge correctness
Pijul guarantees a number of strong properties on merges. The most important one is that the order between lines is always preserved. This is unlike 3-way merge, which may sometimes shuffle lines around. When the order is unknown (for example in the case of concurrent edits), this is a conflict, which contrasts with systems with “automatic” or “no conflicts” merges.
First-class conflicts
In Pijul, conflicts are not modelled as a “failure to merge”, but rather as the standard case. Specifically, conflicts happen between two changes, and are solved by one change. The resolution change solves the conflict between the same two changes, no matter if other changes have been made concurrently. Once solved, conflicts never come back.
Partial clones
Commutation makes it possible to clone only a small subset of a repository: indeed, one can only apply the changes related to that subset. Working on a partial clone produces changes that can readily be sent to the large repository.
