PureLint

A PureScript linter inspired by hlint, providing suggestions for cleaner, more idiomatic PureScript code.

Features

PureLint currently ships with 81 lint rules, covering common PureScript refactors and simplifications.

For a complete list, see lib/purslint/src/Purslint/Rules/.

Installation

$3

``bash
npm install -g purslint

CLI


purelint --help
`

$3

- PureScript compiler (purs)
- Spago package manager
- Go 1.19+
- psgo - PureScript to Go compiler

$3

`bash


Install dependencies

spago install

Build CLI

purs compile --codegen corefn 'lib//.purs' 'bin/purslint-cli//.purs' '.spago/*/.purs'
psgo output/*/corefn.json
cp output/Main/Main.go main_cli.go
go build -o purelint main_cli.go

Build LSP

purs compile --codegen corefn 'lib//.purs' 'bin/purslint-lsp//.purs' '.spago/*/.purs'
psgo output/*/corefn.json
cp output/Main/Main.go main_lsp.go
go build -o purelint-lsp main_lsp.go

Build and run tests

purs compile --codegen corefn 'lib//.purs' 'test//.purs' '.spago/*/.purs'
psgo output/*/corefn.json
cp output/Test.Main/Test_Main.go test_main.go
go build -o test-runner test_main.go
./test-runner
`

Usage

$3

`bash


Lint a single file

./purelint src/Main.purs

Lint multiple files

./purelint src/*.purs

Lint with config file (optional)

./purelint --config purelint.json src/*.purs
`

$3

The LSP binary (purelint-lsp) provides IDE integration. It communicates via stdio using the standard LSP protocol.

#### Zed Editor

A Zed extension is available in the zed-extension/ directory. To install:

1. Open Zed
2. Go to Extensions (Cmd+Shift+X)
3. Click "Install Dev Extension"
4. Select the zed-extension/ directory

The extension will automatically use the purelint-lsp binary.

#### Neovim (nvim-lspconfig)

After building purelint-lsp (see build steps below), you can configure Neovim like this:

`lua
require("lspconfig").purelint = {
default_config = {
cmd = { "/path/to/purelint-lsp" },
filetypes = { "purescript" },
root_dir = require("lspconfig.util").root_pattern(".git", "spago.yaml", "package.json"),
},
}

require("lspconfig").purelint.setup({})
`

If you prefer to run the bundled JS directly:

`lua
cmd = { "node", "/path/to/dist/purelint-lsp.js" }
`

Configuration

Create a purelint.json file in your project root:

`json
{
"disabledRules": ["LetToWhere", "EtaReduce"]
}
`

Architecture

PureLint is written in PureScript and compiled to Go using psgo (purescript-native). This allows:

- Full access to the PureScript CST parser (purescript-language-cst-parser)
- Native binary performance
- Easy distribution without runtime dependencies

$3

`
purelint/
├── lib/purslint/src/ # Core library
│ └── Purslint/
│ ├── Rules/ # Lint rules
│ ├── Runner.purs # Rule runner
│ ├── Types.purs # Core types
│ └── Imports.purs # Import checking
├── bin/
│ ├── purslint-cli/ # CLI application
│ └── purslint-lsp/ # LSP server
├── test/ # Test suite
└── zed-extension/ # Zed editor extension
`

Development

$3

Publishing is handled by GitHub Actions. Add an NPM_TOKEN secret with an
automation or granular token that has publish rights for purslint, then
create a GitHub Release to trigger the workflow. You can also run it manually
via the workflow dispatch.

$3

1. Create a new file in lib/purslint/src/Purslint/Rules/
2. Implement the rule using the CST traversal API
3. Export the rule from Purslint.Rules
4. Add tests in test/Test/Main.purs
5. Rebuild and test

$3

- purescript-language-cst-parser - PureScript CST parser
- purescript-lsp` - LSP protocol implementation (Go FFI)

License

MIT