Step-by-Step Guide to Updating a Package on Nix for Your Project
Table of Contents:
- Introduction
- Understanding the Issue
- Analyzing the Current Version of Milton
- Finding a Recent Tag of Milton on GitHub
- Using Niv to Pin Nix Packages
- Initializing Niv and Pinning Nix Packages
- Getting Milton into a Shell
- Importing Milton into Shell.nix
- Modifying the Milton Configuration
- Testing the Updated Milton Version
- Updating the Package Online
- Conclusion
Introduction
In this article, we will explore how to update a package in Nix, specifically focusing on a package called Milton. Milton is a standard ML compiler that has an outdated version in the Nix packages repository. We will go through the step-by-step process of updating it, from understanding the issue to testing the updated version. If you're new to Nix or interested in learning how to update packages, this article is for you.
Understanding the Issue
The first step in updating a package is to understand the issue at hand. In this case, we have identified that the current version of Milton in the Nix packages repository is outdated. To verify this, we can use the Nix REPL and check the default.nix file associated with Milton. Upon inspection, we find that the revision is from 2018, which is quite old. Our goal is to obtain the most recent version of Milton and compile it.
Analyzing the Current Version of Milton
To find the most recent version of Milton, we need to explore the available options on GitHub. Milton has a repository called "mlton" on GitHub, and by examining the tags, we can identify a recent tag. It is important to note that the master branch is not building, so we should avoid using that. After some research, we find a suitable tag from January of this year. Although it is still relatively old, it is a significant improvement compared to the 2018 version.
Finding a Recent Tag of Milton on GitHub
To find the recent tag of Milton on GitHub, we can navigate to the "mlton" repository. Once there, we can browse through the tags and identify the most recent one. In this case, we find a tag from January of this year that seems suitable for our purposes. It is crucial to verify that the tag is not on the master branch, as the master branch is not building. We can make note of the commit hash associated with the tag as well.
Using Niv to Pin Nix Packages
To update the package, we need to pin our Nix packages using Niv. Niv is a tool that simplifies the process of pinning Nix packages. By initializing Niv and specifying the branch as "nixpkgs-unstable," we can generate a sources.json file that contains the most recent Nix packages unstable.
Initializing Niv and Pinning Nix Packages
To initialize Niv and pin the Nix packages, we can use the "niv init" command followed by "-b nixpkgs-unstable." This command will fetch the branch "nixpkgs-unstable" and generate the sources.json file. It is important to note that this step requires an internet connection.
Getting Milton into a Shell
To get Milton into a shell, we need to modify our shell.nix file. By importing the necessary sources from Nix and adding callPackage, we can create a shell that includes Milton. We should ensure that the buildInputs include Milton so that it is included in the shell.
Importing Milton into Shell.nix
To import Milton into shell.nix, we need to modify the configuration. We can copy the code from the default.nix file and make the necessary adjustments. This includes updating the revision and version based on the recent tag we found on GitHub. Additionally, we may need to add a fake sha256 hash temporarily to resolve any errors.
Modifying the Milton Configuration
In the Milton configuration, we need to update the revision and version based on the recent tag we found on GitHub. This ensures that the correct version of Milton is fetched. We also need to remove any references to the meta.nix file, as it is not necessary for our purposes.
Testing the Updated Milton Version
After modifying the Milton configuration, we can test the updated version to ensure that it works as expected. By running Milton, we can verify that we are using the correct release and hash. It is important to conduct thorough testing, especially with a compiler like Milton.
Updating the Package Online
If we want to make the updated Milton version available online, we can make the necessary changes in the Nix packages repository. This involves cloning the repository, adding a new version of Milton, and pushing the changes. The Nix packages maintainers are usually responsive and helpful, so reaching out to them for guidance is recommended.
Conclusion
Updating packages in Nix can be a complex process, but with the right steps, it is achievable. In this article, we explored how to update a package called Milton, starting from understanding the issue to testing the updated version. By following the steps outlined in this article, you can update packages in Nix effectively and contribute to the Nix packages repository.
🔍 Resources:
Highlights:
- Updating an outdated package in Nix can be done by following a step-by-step process.
- Milton, a standard ML compiler, serves as an example in this article.
- Niv is a helpful tool for pinning Nix packages and simplifying the update process.
- Modifying the package configuration and conducting thorough testing are crucial steps.
- Contributing changes to the Nix packages repository is optional but appreciated.
FAQ:
Q: Can I update any package in Nix using the same process?
A: Yes, the process can be applied to any package in the Nix packages repository.
Q: Is it necessary to push the updated package to the Nix packages repository?
A: It is not mandatory, but contributing the changes is encouraged to benefit the wider community.
