/haskell-nix-template

batteries-included haskell.nix project template

Primary LanguageNixBSD 3-Clause "New" or "Revised" LicenseBSD-3-Clause

Template for Haskell + Nix projects.

A simplified Haskell + Nix project template and tutorial forked from template-haskell.

Uses IOG's haskell.nix for setting up an environment containing ghc, cabal, hoogle, and haskell-language-server.

Nix Flakes Overview

A flake is a source tree (such as a Git repository) containing a file named flake.nix in the root directory, which provides a standardized interface to Nix packages. Flakes can have dependencies on other flakes, with a flake.lock file pinning those dependencies to exact revisions to ensure reproducibility.

Install Nix

Start by installing Nix for your operating system.

Install Flakes & Set Up Binary Cache

  1. Install nixFlakes in your environment with the following command: 
    $ nix-env -iA nixpkgs.nixFlakes
  2. Edit either /etc/nix/nix.conf, or if you are a trusted user, ~/.config/nix/nix.conf, and add the following lines: 
    # Enable `nix` command and flakes
experimental-features = nix-command flakes

# Binary Cache for Haskell.nix
trusted-public-keys = [...] hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= [...]
substituters = [...] https://cache.iog.io [...]

Note: if you installed Nix in multi-user mode in the previous section, you'll need to restart the nix-daemon:

$ sudo systemctl restart nix-daemon

Reference

Create Repository from Template

  1. Click the green Use this template button at the top right of this repository page, name your project, and click Create repository from template.
  2. Click the Code dropdown button on your repository page and copy the HTTPS link.
  3. In a terminal window, enter the directory where you'd like your project to be stored and enter the following, pasting in your repository URL: 
    $ git clone https://github.com/<your github username>/<your project name>.git

Run Wizard to Configure Project

  1. In your terminal, enter your project directory (i.e. $ cd <your project name>/) and run the following command to start the wizard script: 
    $ ./wizard.sh
  2. Respond to the prompts as follows:
  • Package name [<your project name>]: hit ENTER to accept the default.
  • Author name [<your name>]: hit ENTER to accept the default.
  • Author email [<your email>]: hit ENTER to accept the default.
  • Reinitialize git history? [Y/n]? type n and ENTER.
  1. Stage, commit and push your changes: 
    $ git add -A
$ git commit -m "Set up project"
$ git push