3.1 KiB
3.1 KiB
haskell-template
Get a Haskell development environment up and running quickly, as long as Nix is available on your system1.
This repository is a Haskell project template that is optimized for a fully reproducible and friendly development environment. It is based on:
- Nix + Flakes (via
github:srid/haskell-flake
) + GHC 9 - VSCode + HLS
- fourmolu autoformatting
- Relude as Prelude.
.hlint.yaml
is from relude
Getting Started
First-time setup:
- Install Nix (>= 2.8) & enable Flakes (Using Windows? See footnote1)
- Run
nix develop -c haskell-language-server
to sanity check your environment - Open as single-folder workspace in Visual Studio Code
- When prompted by VSCode, install the workspace recommended extensions
- Ctrl+Shift+P to run command "Nix-Env: Select Environment" and then select
shell.nix
.- The extension will ask you to reload VSCode at the end. Do it.
To run the program with auto-recompile:
- Press Ctrl+Shift+B in VSCode, or run
bin/run
in terminal, to launch Ghcid running your program.
Open Main.hs
, and expect all HLS IDE features like hover-over tooltip to work out of the box. Try changing the source, and expect Ghcid to re-compile and re-run the app in the terminal below.
Renaming the project:
# First, click the green "Use this template" button on GitHub to create your copy.
git clone <your-clone-url>
cd your-project
NAME=myproject
git mv haskell-template.cabal ${NAME}.cabal
nix run nixpkgs#sd -- haskell-template ${NAME} * */*
git add . && git commit -m rename
Tips
- Run
nix flake update
to update all flake inputs. - Run
treefmt
in nix shell to autoformat the project. This uses treefmt, which uses./treefmt.toml
(where fourmolu and nixpkgs-fmt are specified). - Run
bin/hoogle
to start Hoogle with packages in your cabal file. - Run the application without installing:
nix run github:srid/haskell-template
(ornix run .
from checkout)
Alternatives
-
On Windows, you may install Nix under WSL2 and use the Remote - WSL extension to connect from the native VSCode. This runs your project under Linux while providing a near-native development experience on Windows. ↩︎