57 lines
3.1 KiB
Markdown
57 lines
3.1 KiB
Markdown
# haskell-template
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Get a Haskell development environment up and running quickly, as long as Nix is available on your system[^windows].
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[^windows]: On Windows, you may install Nix [under WSL2](https://nixos.wiki/wiki/Nix_Installation_Guide#Windows_Subsystem_for_Linux_.28WSL.29) and use the [Remote - WSL extension](https://marketplace.visualstudio.com/items?itemName=ms-vscode-remote.remote-wsl) to connect from the native VSCode. This runs your project under Linux while providing a near-native development experience on Windows.
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This repository is a Haskell project template that is optimized for a fully reproducible and friendly development environment. It is based on:
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- [Nix](https://srid.ca/haskell-nix) + [Flakes](https://serokell.io/blog/practical-nix-flakes) (via [`github:srid/haskell-flake`](https://github.com/srid/haskell-flake)) + GHC 9
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- VSCode + [HLS](https://github.com/haskell/haskell-language-server)
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- [fourmolu](https://github.com/fourmolu/fourmolu) autoformatting
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- [Relude](https://github.com/kowainik/relude#relude) as Prelude.
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- `.hlint.yaml` is [from relude](https://github.com/kowainik/relude/blob/main/.hlint.yaml)
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## Getting Started
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First-time setup:
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- [Install Nix](https://nixos.org/download.html) (>= 2.8) & [enable Flakes](https://nixos.wiki/wiki/Flakes) (Using Windows? See footnote[^windows])
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- Run `nix develop -i -c haskell-language-server` to sanity check your environment
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- [Open as single-folder workspace](https://code.visualstudio.com/docs/editor/workspaces#_singlefolder-workspaces) in Visual Studio Code
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- When prompted by VSCode, install the [workspace recommended](https://code.visualstudio.com/docs/editor/extension-marketplace#_workspace-recommended-extensions) extensions
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- <kbd>Ctrl+Shift+P</kbd> to run command "Nix-Env: Select Environment" and then select `shell.nix`.
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- The extension will ask you to reload VSCode at the end. Do it.
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To run the program with auto-recompile:
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- Press <kbd>Ctrl+Shift+B</kbd> in VSCode, or run `bin/run` in terminal, to launch Ghcid running your program.
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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.
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---
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Renaming the project:
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```sh
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# First, click the green "Use this template" button on GitHub to create your copy.
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git clone <your-clone-url>
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cd your-project
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NAME=myproject
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git mv haskell-template.cabal ${NAME}.cabal
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nix run nixpkgs#sd -- haskell-template ${NAME} * */*
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git add . && git commit -m rename
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```
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## Tips
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- Run `nix flake update` to update all flake inputs.
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- Run `treefmt` in nix shell to autoformat the project. This uses [treefmt](https://github.com/numtide/treefmt), which uses `./treefmt.toml` (where fourmolu and nixpkgs-fmt are specified).
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- Run `bin/hoogle` to start Hoogle with packages in your cabal file.
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- Run `bin/test` to run the test suite.
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- Run the application without installing: `nix run github:srid/haskell-template` (or `nix run .` from checkout)
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## Discussions
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Got questions? Ideas? Suggestions? Post them here: https://github.com/srid/haskell-template/discussions
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