Haskell Template

Get up & running with production-ready haskell in no time! This "project stump" can be forked, allowing you to get going faster. This project stump expects you to use nix and vscodium/vscode, and has a ridiculous amount of batteries included:

• Relude included via a cabal mixin
• A nix development environment accessible though nix develop, featuring:
  • formatters for haskell, cabal files, nix, nixpkgs, markdown, json, yaml and many more.
  • language servers for haskell & nix
  • hlint
  • cabal
• Scripts for launching vscode/vscodiumin the nix development environment. Call ./launch-code.shor ./launch-codium.sh from anywhere and pick up where you left off!
• A list of recommended extensions for formatting, LSP support & file-watch cabal test.
• Project-specific settings.json that run cabal test every time a haskell file changes. Check Output > File Watcher for test results
• Intellisense that just works, in /src, /app, /test & /benchmark folders.

Forking this repo

Launch vscode in the nix development environment by using ./launch-code.shor ./launch-codium.sh, and:

1. Fork this repo and clone it to your local machine. Set the name to your new project name by adding the directory name as the second parameter: git clone https://github.com/jonathanmoregard/haskell-template.git "${myNewProjectName}"
2. rename the internal project files by running ./rename-template.sh "${myNewProjectName}"
3. Open the project using ./launch-code.shor ./launch-codium.sh.
4. The first time you do this, nix will do nix stuff for a long time. The second time it's faster.
5. Install the extensions recommended by the workspace
6. Open a terminal and run cabal update hackage.haskell.org,2022-03-14T23:55:49Z
7. Pick any license you want and put it in LICENSE.md
8. Replace everything in this readme up until this point with new info. The points below will be needed for users of your new project.

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One Time Tooling Set-Up

1. Install prerequisites

You need the following software:

• nix!
• vscodium! (note: use vscode if you like getting spied on)

2. Configure Nix

Configure nix to enable:

• nix flake commands (you won't be able to do anything without these)
• Cached binaries for ghc (If you don't do this, you will have to build GHC multiple times!)

Nix settings can be found in /etc/nix/nix.conf or, if you are a trusted user, ~/.config/nix/nix.conf.

Add the following to nix.conf:

trusted-public-keys = [...] hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= [...]
substituters = [...] https://hydra.iohk.io [...]

experimental-features = nix-command flakes
allow-import-from-derivation = true

(The [...] denotes previous entries in the list of trusted-public-keys & substituters)

If you run into issues (= end up building GHC), check out the troubleshooting guide.

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Thanks to

This project is based on output from Kowainik's "Summoner".
This project is built using IOHK's "Haskell.nix".