Tvix

Tvix is a new implementation of the Nix language and package manager. See the announcement post for information about the background of this project.

Tvix is developed by TVL in our monorepo, the depot, at //tvix. Code reviews take place on Gerrit, bugs are filed in our issue tracker.

For more information about Tvix, feel free to reach out. We are interested in people who would like to help us review designs, brainstorm and describe requirements that we may not yet have considered.

Most of the discussion around development happens on our IRC channel, which you can join in several ways documented on tvl.fyi, or on our mailing list.

Contributions to Tvix follow the TVL review flow and contribution guidelines.

WARNING: Tvix is not ready for use in production. None of our current APIs should be considered stable in any way.

WARNING: Any other instances of this project or repository are josh-mirrors. We do not accept code contributions or issues outside of the tooling and communication methods outlined above.

Components

This folder contains the following components:

• //tvix/eval - an implementation of the Nix programming language
• //tvix/nix-compat - library functions for compatibility with C++ Nix
• //tvix/cli - preliminary REPL & CLI implementation for Tvix
• //tvix/serde - Rust library for using the Nix language for app configuration
• //tvix/store - implementation of a file store for Tvix

Some additional folders with auxiliary things exist and can be explored at your leisure.

Building the CLI

The CLI can also be built with standard Rust tooling (i.e. cargo build), as long as you are in a shell with the right dependencies.

• If you cloned the full monorepo, it can be provided by mg shell //tvix:shell.
• If you cloned the tvix workspace only (git clone https://code.tvl.fyi/depot.git:workspace=views/tvix.git), nix-shell provides it.

If you're in the TVL monorepo, you can also run mg build //tvix/cli (or mg build from inside that folder) for a more incremental build.

Please follow the depot-wide instructions on how to get mg and use the depot tooling.

Compatibility

Important note: We only use and test Nix builds of our software against Nix 2.3. There are a variety of bugs and subtle problems in newer Nix versions which we do not have the bandwidth to address, builds in newer Nix versions may or may not work.

Rust projects, crate2nix

Some parts of Tvix are written in Rust. To simplify the dependency management on the Nix side of these builds, we use crate2nix in a single Rust workspace in //tvix to maintain the Nix build configuration.

When making changes to Cargo dependency configuration in any of the Rust projects under //tvix, be sure to run mg run //tvix:crate2nixGenerate -- in //tvix itself and commit the changes to the generated Cargo.nix file. This only applies to the full TVL checkout.

License structure

All code implemented for Tvix is licensed under the GPL-3.0, with the exception of the protocol buffer definitions used for communication between services which are available under a more permissive license (MIT).

The idea behind this structure is that any direct usage of our code (e.g. linking to it, embedding the evaluator, etc.) will fall under the terms of the GPL3, but users are free to implement their own components speaking these protocols under the terms of the MIT license.