purescript-tidy

A syntax tidy-upper (formatter) for PureScript.

Install

$ npm install -g purs-tidy

Also available for Nix via Nixpkgs 22.11+ and Easy PureScript Nix

Usage

You can use purs-tidy to format files in place or via STDIN / STDOUT (which is useful for editor integration):

Formatting a collection of files in place:

$ purs-tidy format-in-place "src/**/*.purs"

Using STDIN to format a file:

$ purs-tidy format < MyFile.purs

You can also use purs-tidy to verify whether files have already been formatted. This is often useful to verify, in continuous integration, that all project files are formatted according to the configuration. Files that would be changed by running format-in-place are listed out.

Verifying files are formatted

$ purs-tidy check "src/**/*.purs"
All files are formatted.

Configuration

You can see all configuration that purs-tidy accepts using the --help flag for the command you are using:

$ purs-tidy format-in-place --help

Some common options include:

• --indent to set the number of spaces used in indentation, which defaults to 2 spaces
• --arrow-first or --arrow-last to control whether type signatures put arrows first on the line or last on the line (purty-style), which defaults to arrow-first.

You can generate a .tidyrc.json using the generate-config command. If a .tidyrc.json file is found, it will be used in lieu of CLI arguments.

Operator Precedence

To support correct operator precedence without having to parse your entire source tree (potentially for a single file), purs-tidy uses a pre-baked operator precedence table. By default, purs-tidy ships with a table built from the core and contrib organizations. If you need support for more operators, you can generate your own table using the generate-operators command.

$ spago sources | xargs purs-tidy generate-operators > .tidyoperators
$ purs-tidy generate-config --arrow-first --unicode-never --operators .tidyoperators

Editor Support

• Spacemacs
• Vim
• VS Code

Spacemacs

Spacemacs' Purescript layer supports formatting using purs-tidy out of the box.

You can run the formatter manually with either M-x spacemacs/purescript-format or with the shortcut SPC m =.

To enable automatic formatting of the buffer on save, enable purescript-fmt-on-save in your spacemacs config:

  (setq-default dotspacemacs-configuration-layers '(
    (purescript :variables
                purescript-fmt-on-save t)))

Vim

via ALE

Add to your other fixers .vimrc or $XDG_CONFIG_HOME/neovim/init.vim

let b:ale_fixers = { 'purescript': [ 'purstidy' ] }
" suggested to fix on save
let g:ale_fix_on_save = 1

via Neoformat

Add to your .vimrc or $XDG_CONFIG_HOME/neovim/init.vim

let g:neoformat_enabled_purescript = ['purstidy']

VS Code

via PureScript IDE

The PureScript IDE plugin for VS Code supports purs-tidy as a built-in formatter in versions after 0.25.1. Choose purs-tidy from the list of supported formatters in the settings, or add this to your settings.json:

"purescript.formatter": "purs-tidy"

Development

Requirements

• purs: 0.15
• spago: 0.20
• node: 14
• esbuild: 0.14

Running bin

For local development pointing to the output directory:

$ npm run build
$ ./bin/index.dev.js --help

For a local production build pointing to the bundle directory:

$ npm run bundle
$ ./bin/index.js --help

If you would like to use your local build of purs-tidy in your editor, use path to bin/index.js instead of the purs-tidy binary in your settings. For example, instead of setting the format command to purs-tidy format, set it to $TIDY_DIR/bin/index.js format where $TIDY_DIR is the location of your checkout of this repository.

Running test

To accept snapshot tests:

$ npm run test -- -a "--accept"

Generating the built-in operator table

$ npm run generate-default-operators