Advanced Haskell Development with Nix

A workshop at Haskell eXchange 2017 hosted by:

• Peter Simons
• Bas van Dijk

This repository contains the workshop materials.

Abstract

This workshop introduces Haskell developers to the purely functional package manager Nix through a series of interactive practical examples. The first hour of the workshop focuses on practical use of Nix as a tool for Haskell developers: we'll examine how to create declarative reproducible development environments for advanced Haskell hacking, how to extend and customize the Nix package set with our own libraries, and how to integrate external system libraries into our build processes.

The second hour looks at Nix as a tool for Haskell application deployment: we'll use Nix to manage the development, continuous integration, and deployment of a non-trivial GHCJS web application with a Haskell back-end and a PostgreSQL database. (See the nixtodo repo).

We assume no prior knowledge of Nix, but we do assume that participants have a basic understanding of basic Haskell development with Cabal, cabal-install, or stack. All examples used in this workshop live in the Git repository https://github.com/basvandijk/nix-workshop. We encourage participants to clone that repository and to make sure they have access to a working Nix installation before the event starts. We provide a Docker image for these purposes that users can enter by running the docker-run.sh script found in the nix-workshop repository. Participants who can't or don't want to use Docker should please install Nix by other means as explained on the page https://nixos.org/nix/download.html.

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Get Access to Nix

• Install Nix:

  • Run ./docker-run.sh in checkout of https://github.com/basvandijk/nix-workshop.

  • curl https://nixos.org/nix/install | sh

  • https://nixos.org/nix/download.html

• Install NixOS:

  • https://nixos.org/nixos/download.html

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Get Access to Nixpkgs

$ git clone git://github.com/NixOS/nixpkgs.git

$ git clone git://github.com/NixOS/nixpkgs-channels.git

$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable nixpkgs
$ nix-channel --update

$ nix-channel --add https://nixos.org/channels/nixos-17.09 nixpkgs
$ nix-channel --update

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Popular Nix Commands

$ nix-env --install --dry-run ghc cabal-install
$ nix-env -qaP --description Hackage

$ nix-channel --list

$ nix-shell --pure -p ghc
$ nix-shell "<nixpkgs>" -A ghc

$ nix-build --no-out-link "<nixpkgs>" -A ghc

$ nix-instantiate "<nixpkgs>" -A stdenv

$ nix-collect-garbage --delete-older-than 30d