tvl-depot/tvix/eval
Vincent Ambo 878dc6c227 fix(tvix/eval): aggressively fix a borrow error in nix_eq
When comparing Nix values for equality, an issue can occur where
recursive values contain thunks to themselves which causes borrow
errors when forcing them for comparison later down the line.

To work around this we clone the values for now. There might be some
optimisations possible like checking for thunk equality directly and
short-circuiting on that (we have to check what Nix does).

Change-Id: I7e75c992ea68f100058f52b4b46168da7d671994
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7314
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
2022-11-21 15:26:56 +00:00
..
benches refactor(tvix/eval): use Clap for arg+env parsing 2022-09-18 22:08:43 +00:00
builtin-macros feat(tvix/eval): Add docstrings as documentation for builtins 2022-11-08 13:42:37 +00:00
docs docs(tvix/eval): document abandoned thread-local vm 2022-11-08 08:41:04 +00:00
proptest-regressions/value test(tvix/eval): Add tests for the Eq laws of Value 2022-09-18 17:57:09 +00:00
src fix(tvix/eval): aggressively fix a borrow error in nix_eq 2022-11-21 15:26:56 +00:00
tests feat(tvix/eval): Allow adding strings to paths 2022-10-10 20:23:41 +00:00
.skip-subtree feat(tvix/tests): check in Nix' language test suite 2022-08-24 21:25:41 +00:00
build.rs feat(tvix/eval): implement builtins.currentSystem 2022-10-24 12:20:01 +00:00
Cargo.lock feat(tvix/eval): Add a proc-macro for defining builtins 2022-11-08 13:42:37 +00:00
Cargo.toml feat(tvix/eval): Add a proc-macro for defining builtins 2022-11-08 13:42:37 +00:00
default.nix feat(tvix/eval): Add a proc-macro for defining builtins 2022-11-08 13:42:37 +00:00
README.md docs(tvix/eval): explain where to find the site-specific mg tool 2022-10-13 18:41:02 +00:00

Tvix Evaluator

This project implements an interpreter for the Nix programming language. You can experiment with an online version of the evaluator: tvixbolt.

The interpreter aims to be compatible with nixpkgs, on the foundation of Nix 2.3.

Important note: The evaluator is not yet feature-complete, and while the core mechanisms (compiler, runtime, ...) have stabilised somewhat, a lot of components are still changing rapidly.

Please contact TVL with any questions you might have.

Building the evaluator

If you are in a full checkout of the TVL depot, you can simply run mg build in this directory (or mg build //tvix/eval from anywhere in the repo). The mg command is found in /tools/magrathea.

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.

The evaluator can also be built with standard Rust tooling (i.e. cargo build).

If you would like to clone only the evaluator and build it directly with Rust tooling, you can do:

git clone https://code.tvl.fyi/depot.git:/tvix/eval.git tvix-eval

cd tvix-eval && cargo build

Nix test suite

C++ Nix implements a language test suite in the form of Nix source code files, and their expected output. The coverage of this test suite is not complete, but we intend to be compatible with it.

We have ported the test suite to Tvix, but do not run it by default as we are not yet compatible with it.

You can run the test suite by enabling the nix_tests feature in Cargo:

cargo test --features nix_tests

rnix-parser

Tvix is written in memory of jD91mZM2, the author of rnix-parser who sadly passed away.

Tvix makes heavy use of rnix-parser in its bytecode compiler. The parser is now maintained by Nix community members.