purs-nix

purs-nix is a project which aims to allow you to use the entire PureScript ecosystem with nothing but Nix. It has been designed to take full advantage of Nix flakes but works with Nix stable as well. For help, you can reach out on the FP/Nix Zulips.

This project is currently unstable, however, it is built to be 100% pure, so your projects should never break out from under you.

Gettings Started (flakes)

• Setup nix.
• Run nix flake init -t github:ursi/purs-nix in a new directory to initialize a new project.
• Run nix develop to enter a Nix shell with the purs-nix command added to your PATH.
• Run purs-nix run to see the output of the default project.

Getting Started (Nix stable)

• Install Nix
• Copy the template from templates/default, and then replace flake.nix with templates/shell.nix.
• Run nix-shell to enter a Nix shell with the purs-nix command added to your PATH.
• Run purs-nix run to see the output of the default project.

Documentation

Packages

purs-nix has it's own package set, which is an extension of the the official package set with the following differences:

• Package namespaces: We have package namespaces.
• No global module namespace: All packages are not required to compile with each other.
• Single source of truth for package info: You can define the version and dependencies of your package in its home repository and import it here. Nix is lazy so you will only ever download the information for the packages you need.
• Easy modification: Using a modified version of the package set is as easy as forking it and changing the input of your flake ("github:ursi/purs-nix" -> "github:<your-username>/purs-nix"). If you put in a PR to add your package, using your fork of the package set is just as easy as using the official one, so you don't have to wait for the PR to be accepted to use your normal workflow.
• Get package info: Since package info can be imported from a foreign repository, we need a way to view the info of a package easily.
  • To view the info of a non-namespaced package, use nix run github:ursi/purs-nix#package-info.<pacakge-name>.
  • To view the info or a namespaced package, use nix run github:ursi/purs-nix#package-info-ns.<namespace>.<package-name>.

TODO

This is an incomplete list of things that are currently planned.

• FAQ/How To's: I'd like to have an FAQ, but first I see which Qs are FA'd.
• Packaging foreign dependencies: Being able to add dependencies that rely on npm packages without needing to use npm yourself would be a huge QoL upgrade.
• Package replacing: I'd like to have an easy API for replacing one package with another, so instead of having to use a forked version of the package set, you can add your version of a package in your namespace, and then just replace the official version with yours inside your project. Something like: replace-package tuple ursi.tuple dependencies.
• Module renaming: Since there is no more global module namespace, you may find that two packages have the same module name and cannot compile together. I think arbitrary module renaming should be possible, so I plan to explore this as a solution. Something like: html-module.rename-module "Html" "HtmlModule.Html". I'd also like to add opt-in module name prefixing for indirect dependencies, to guarantee they never collide.