Integration point for [ghcide](https://github.com/haskell/ghcide) and [haskell-ide-engine](https://github.com/haskell/haskell-ide-engine). One IDE to rule
- Code evaluation codelens (inspired by [Dante](https://github.com/jyp/dante#-reploid)). You can evaluate code by writing it in a comment of the form -- >>>
- Type information and documentation on hover. Note that currently, in order for docs to be displayed for dependencies, they must have been built with GHC's `-haddock` flag:
- For cabal:
- Add to your global config file (e.g. `~/.cabal/config`):
```
program-default-options
ghc-options: -haddock
```
- Or, for a single project, run `cabal configure --ghc-options=-haddock`
- For stack, add to global `$STACK_ROOT\config.yaml`, or project's `stack.yaml`:
```
ghc-options:
"$everything": -haddock
```
This will cause compilation errors if a dependency contains invalid Haddock markup, though in a future version of GHC (hopefully 8.12), [these will be demoted to warnings](https://gitlab.haskell.org/ghc/ghc/-/merge_requests/2377).
- For standalone `.hs`/`.lhs` files, [ghc](https://www.haskell.org/ghc/) must be installed and on the PATH. The easiest way to install it is with [ghcup](https://www.haskell.org/ghcup/) or [Chocolatey](https://www.haskell.org/platform/windows.html) on Windows.
- For Cabal based projects, both ghc and [cabal-install](https://www.haskell.org/cabal/) must be installed and on the PATH. It can also be installed with [ghcup](https://www.haskell.org/ghcup/) or [Chocolatey](https://www.haskell.org/platform/windows.html) on Windows.
- For Stack based projects, [stack](http://haskellstack.org) must be installed and on the PATH.
If you are using [`ghcup`](https://www.haskell.org/ghcup/) to manage your installations, you can install the latest version of `haskell-language-server` with
If you are using Visual Studio Code, the [Haskell extension](https://marketplace.visualstudio.com/items?itemName=haskell.haskell) will automatically download and install `haskell-language-server` for you.
There are pre-built binaries available from the [releases page](https://github.com/haskell/haskell-language-server/releases) for Linux, Windows and macOS.
To install, download the `haskell-language-server-wrapper` executable for your platform as well as any `haskell-language-server` executables for the GHC versions you plan on working with, and either put them on your PATH or point your client to them.
In order to avoid problems with long paths on Windows you can do either one of the following:
1. Clone the `haskell-language-server` to a short path, for example the root of your logical drive (e.g. to
`C:\hls`). Even if you choose `C:\haskell-language-server` you could hit the problem. If this doesn't work or you want to use a longer path, try the second option.
2. If the `Local Group Policy Editor` is available on your system, go to: `Local Computer Policy -> Computer Configuration -> Administrative Templates -> System -> Filesystem` set `Enable Win32 long paths` to `Enabled`. If you don't have the policy editor you can use regedit by using the following instructions [here](https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#enable-long-paths-in-windows-10-version-1607-and-later). You also need to configure git to allow longer paths by using unicode paths. To set this for all your git repositories use `git config --system core.longpaths true` (you probably need an administrative shell for this) or for just this one repository use `git config core.longpaths true`.
In addition make sure `haskell-language-server.exe` is not running by closing your editor, otherwise in case of an upgrade the executable can not be installed.
**For a full explanation of possible configurations, refer to [hie-bios/README](https://github.com/mpickering/hie-bios/blob/master/README.md).**
haskell-language-server has some limited support via hie-bios to detect automatically
your project configuration and set up the environment for GHC.
The plan is to improve it to handle most use cases.
However, for now, the more reliable way is using a `hie.yaml` file in the root
of the workspace to **explicitly** describe how to setup the environment.
For that you need to know what *components* have your project and the path
associated with each one. So you will need some knowledge about
[stack](https://docs.haskellstack.org/en/stable/build_command/#components) or [cabal](https://cabal.readthedocs.io/en/latest/cabal-commands.html?#cabal-v2-build) components.
Note to editor integrators: there is a `haskell-language-server-wrapper` executable, which is installed alongside the `haskell-language-server` executable. When this is invoked in the project root directory, it attempts to work out the GHC version used in the project, and then launch the matching `haskell-language-server` executable.
All of the editor integrations assume that you have already installed `haskell-language-server` (see above) and that the installation script put the `haskell-language-server` and `haskell-language-server-wrapper` binaries in your `PATH` (usually `~/.local/bin` or `~/.cabal/bin` on Linux and macOS, `%APPDATA%\local\bin` or `%APPDATA%\cabal\bin` on Windows).
[the VSCode marketplace](https://marketplace.visualstudio.com/items?itemName=haskell.haskell), or manually from the repository [vscode-haskell](https://github.com/haskell/vscode-haskell).
The `haskell-language-server` and `haskell-language-server-wrapper` binaries will be automatically downloaded on an ad-hoc basis, but if you have them already installed on your PATH then it will just use them instead.
and issuing a `:PlugInstall` command within Neovim or Vim.
##### Clone the LanguageClient-neovim repo
As an alternative to using [vim-plug](https://github.com/junegunn/vim-plug) shown above, clone [LanguageClient-neovim](https://github.com/autozimu/LanguageClient-neovim)
into `~/.vim/pack/XXX/start/`, where `XXX` is just a name for your "plugin suite".
##### Sample `~/.vimrc`
```vim
set rtp+=~/.vim/pack/XXX/start/LanguageClient-neovim
let g:LanguageClient_serverCommands = { 'haskell': ['haskell-language-server-wrapper', '--lsp'] }
```
You'll probably want to add some mappings for common commands:
The plugin ide-haskell-hie is designed to work with haskell-ide-engine by default, so you will have to put the path to haskell-language-server-wrapper in the configuration option `Absolute path to hie executable`.
The project includes a [`.editorconfig`](https://editorconfig.org) [file](https://github.com/haskell/haskell-language-server/blob/master/.editorconfig) with the editor basic settings used by the project.
However, most editors will need some action to honour those settings automatically.
For example vscode needs to have installed a specific [extension](https://marketplace.visualstudio.com/items?itemName=EditorConfig.EditorConfig).
Please, try to follow those basic settings to keep the codebase as uniform as possible.
