ghcid

# ghcid [![Hackage version](https://img.shields.io/hackage/v/ghcid.svg?label=Hackage)](https://hackage.haskell.org/package/ghcid) [![Stackage version](https://www.stackage.org/package/ghcid/badge/nightly?label=Stackage)](https://www.stackage.org/package/ghcid) [![Build status](https://img.shields.io/github/actions/workflow/status/ndmitchell/ghcid/ci.yml?branch=master)](https://github.com/ndmitchell/ghcid/actions)

Either "GHCi as a daemon" or "GHC + a bit of an IDE". To a first approximation, it opens `ghci` and runs `:reload` whenever your source code changes, formatting the output to fit a fixed height console. Unlike other Haskell development tools, `ghcid` is intended to be _incredibly simple_. In particular, it doesn't integrate with any editors, doesn't provide access to the `ghci` it starts, doesn't depend on GHC the library and doesn't start web servers.

_Acknowledgements:_ This project incorporates significant work from [JPMoresmau](https://github.com/JPMoresmau), who is listed as a co-author.

### Using it

Run `stack install ghcid`, `brew install ghcid` or `cabal update && cabal install ghcid` to install it as normal. Then run `ghcid "--command=ghci Main.hs"`. The `command` is how you start your project in `ghci`. If you omit `--command` then it will default to `stack ghci` if you have the `stack.yaml` file and `.stack-work` directory, default to `ghci` if you have a `.ghci` file in the current directory, and otherwise default to `cabal repl`.

Personally, I always create a `.ghci` file at the root of all my projects, which usually [reads something like](https://github.com/ndmitchell/ghcid/blob/master/.ghci):

    :set -fwarn-unused-binds -fwarn-unused-imports
    :set -isrc
    :load Main

After that, resize your console and make it so you can see it while working in your editor. On Windows you may wish to pass `--topmost` so the console will sit on top of all other windows. On Linux, you probably want to use your window manager to make it topmost or use a [tiling window manager](http://xmonad.org/).

### What you get

On every save you'll see a list of the errors and warnings in your project. It uses `ghci` under the hood, so even relatively large projects should update their status pretty quickly. As an example:

    Main.hs:23:10:
        Not in scope: `verbosit'
        Perhaps you meant `verbosity' (imported from System.Console.CmdArgs)
    Util.hs:18:1: Warning: Defined but not used: `foo'

Or, if everything is good, you see:

    All good

Please [report any bugs](https://github.com/ndmitchell/ghcid/issues) you find.

### Editor integration

There are a few plugins that integrate Ghcid into editors, notably:

* [VS Code](https://marketplace.visualstudio.com/items?itemName=ndmitchell.haskell-ghcid)
* [nvim](plugins/nvim/)
* [vim](https://github.com/aiya000/vim-ghcid-quickfix)
* [Emacs](plugins/emacs/)

### Usage tips

* If you have a `.ghcid` file in the current folder, or a parent folder, the contents of that file will be used