# Lambdalog

## Sean Seefried's programming blog

1 Sep 2018

Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. It provides atomic upgrades and rollbacks, side-by-side installation of multiple versions of a package, multi-user package management and easy setup of build environments.

I like Nix because it allows me to:

• create reproducible development environments that do not interfere with other software installed on my computer
• specify the entire stack of software dependencies that my project has, including system libraries and build tools, using a single language: Nix expressions.

Nix has the advantage that it doesn’t just tame Haskell’s dependency hell but also that of the entire system. Unfortunately, there is quite a lot to learn about Nix before one can use it effectively. Fortunately, Gabriel Gonzales has written a great guide on how to use Nix for Haskell development. I’ve also included a link to an addendum Gabriel is going to add to the original guide.

• Nix and Haskell in production. This is a detailed guide on how to use Cabal + Nix to create completely reproducible builds.

• How to fetch Nixpkgs with an empty NIX PATH. A short addendum on how to remove impure references to NIX_PATH, this making your builds even more reproducible.

• NixOS in production. This post is not Haskell specific but shows you how to build a source free Nix binary closure on a build machine and then deploy it to a production machine. This is fantastic workflow for space/computing-limited production machines e.g. t2.micro instances on Amazon AWS.

Tagged as: Haskell, Nix, build systems.