This project aims to be the universal interface to a growing number of Haskell tools, providing a full-featured and easy to query backend for editors and IDEs that require Haskell-specific functionality.

We are currently focusing on using the Language Server Protocol as the interface via which we talk to clients.

• Haskell IDE Engine
  • Features
  • Installation
    • Installation with stack or Nix
    • ArchLinux
  • Configuration
  • Editor Integration
    • Using HIE with VS Code, Sublime Text, Vim/Neovim, Atom, Oni, Emacs, Spacemacs or Spacemacs+Nix
  • Docs on hover/completion
  • Contributing
    • Planned Features
    • This is not yet another ghc-mod or ide-backend project
    • It's time to join the project!
  • Architecture
    • 1. BIOS layer
    • 2. Plugin layer
    • 3. IDE interfacing layer
  • Documentation
  • Troubleshooting

• Supports plain GHC projects, cabal projects(sandboxed and non sandboxed) and stack projects

• Fast due to caching of compile info

• Uses LSP, so should be easy to integrate with a wide selection of editors

• Diagnostics via hlint and GHC warnings/errors

  

• Code actions and quick fixes via apply-refact

  

• Type information and documentation(via haddock) on hover

  

• Jump to definition

  

• List all top level definitions

  

• Highlight references in document

  

• Completion

  

• Formatting via brittany

  

• Renaming via HaRe

  

• Add packages to cabal and hpack package files

  

• Typo quick fixes

  

• Add missing imports (via hsimport)

  

Note: The version on branch hie-0.1.0.0 supports GHC 8.0.2. This is not supported in master.

On linux derivatives you will need to do the equivalent of before building

sudo apt install libicu-dev libtinfo-dev

HIE builds from source code, so first,

$ git clone https://github.com/haskell/haskell-ide-engine --recursive
$ cd haskell-ide-engine

HIE builds from source code, so first,

$ git clone https://github.com/haskell/haskell-ide-engine
$ cd haskell-ide-engine
$ git checkout hie-0.1.0.0
$ git submodule update --init

To install HIE, you need Stack version >= 1.7.1

In order to support both stack and cabal, hie requires cabal-install as well.

If it is not already installed, install it and update its package list. One of the ways is:

stack install cabal-install
cabal update

To install all supported GHC versions, name them as expected by the VS Code plugin, and also build a local hoogle database, you need the make tool (on Windows, see the further advice below). Use the command:

make build-all

Then add

"languageServerHaskell.useCustomHieWrapper": true,
"languageServerHaskell.useCustomHieWrapperPath": "hie-wrapper",

to VS Code user settings.

Otherwise, do one of the following.

Using master

stack install

Using master

stack --stack-yaml=stack-<VERSION>.yaml install

where <VERSION> correlates to one of the yaml files in the hie directory.

Note that GHC 8.0.2 is only available via branch hie-0.1.0.0 and not master, but otherwise the instructions above are the same.

The Makefile doesn't work on Windows due to several UNIX-specific things, such as the cp command or extensionless executable names. Instead, a PowerShell script is provided specifically for this purpose:

Under PowerShell run:

./build-all.ps1

Under cmd.exe run:

powershell -ExecutionPolicy RemoteSigned -c ./build-all.ps1

In order to avoid problems with long paths on Windows you can do the following:

1. Edit the group policy: set "Enable Win32 long paths" to "Enabled". Works only for Windows 10

2. Clone the haskell-ide-engine to the root of your logical drive (e.g. to E:\hie)

Download the pre-built binaries from the releases page, and copy/symlink them into /usr/local/bin (or somewhere else in your $PATH):

ln -s hie-bin-dir/hie* /usr/local/bin/

Alternatively, you can install from source with make build.

Follow the instructions at https://github.com/domenkozar/hie-nix

An haskell-ide-engine-git package is available on the AUR.

Using Aura:

# aura -A haskell-ide-engine-git

There are some settings that can be configured via a settings.json file:

{
    "languageServerHaskell": {
        "hlintOn": Boolean,
        "maxNumberOfProblems": Number
    }
}

• VS Code: These settings will show up in the settings window
• LanguageClient-neovim: Create this file in $projectdir/.vim/settings.json or set g:LanguageClient_settingsPath

Note to editor integrators: there is now a hie-wrapper executable, which is installed alongside the hie 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 hie executable.

All of the editor integrations assume that you have already installed HIE (see above) and that stack put the hie binary in your path (usually ~/.local/bin on linux and macOS).

Install from the VSCode marketplace, or manually from the repository vscode-hie-server.

.config/nixpkgs/config.nix sample:

with import <nixpkgs> {};

let
  hie = (import (fetchFromGitHub {
                   owner="domenkozar";
                   repo="hie-nix";
                   rev="e3113da";
                   sha256="05rkzjvzywsg66iafm84xgjlkf27yfbagrdcb8sc9fd59hrzyiqk";
                 }) {}).hie84;
in
{
  allowUnfree = true;
  packageOverrides = pkgs: rec {

    vscode = pkgs.vscode.overrideDerivation (old: {
      postFixup = old.postFixup + ''
        wrapProgram $out/bin/code --prefix PATH : ${lib.makeBinPath [hie]}
      '';
    });

  };
}

• Make sure HIE is installed (see above) and that the directory stack put the hie binary in is in your path
  • (usually ~/.local/bin on unix)
• Install LSP using Package Control
• From Sublime Text, press Command+Shift+P and search for Preferences: LSP Settings
• Paste in these settings. Make sure to change the command path to your hie

{
"clients": {
  "haskell-ide-engine": {
    "command": ["hie"],
    "scopes": ["source.haskell"],
    "syntaxes": ["Packages/Haskell/Haskell.sublime-syntax"],
    "languageId": "haskell",
  },
},
}

Now open a haskell project with Sublime Text. You should have these features available to you:

1. Errors are underlined in red
2. LSP: Show Diagnostics will show a list of hints and errors
3. LSP: Format Document will prettify the file

As above, make sure HIE is installed. These instructions are for using the LanguageClient-neovim client.

If you use vim-plug, then you can do this by e.g. including the following line in the Plug section of your init.vim:

Plug 'autozimu/LanguageClient-neovim', {
    \ 'branch': 'next',
    \ 'do': './install.sh'
    \ }

and issuing a :PlugInstall command within neovim.

Clone LanguageClient-neovim into ~/.vim/pack/XXX/start/, where XXX is just a name for your "plugin suite".

set rtp+=~/.vim/pack/XXX/start/LanguageClient-neovim
let g:LanguageClient_serverCommands = { 'haskell': ['hie-wrapper'] }

You'll probably want to add some mappings for common commands:

nnoremap <F5> :call LanguageClient_contextMenu()<CR>
map <Leader>lk :call LanguageClient#textDocument_hover()<CR>
map <Leader>lg :call LanguageClient#textDocument_definition()<CR>
map <Leader>lr :call LanguageClient#textDocument_rename()<CR>
map <Leader>lf :call LanguageClient#textDocument_formatting()<CR>
map <Leader>lb :call LanguageClient#textDocument_references()<CR>
map <Leader>la :call LanguageClient#textDocument_codeAction()<CR>
map <Leader>ls :call LanguageClient#textDocument_documentSymbol()<CR>

Use Ctrl+xCtrl+o (<C-x><C-o>) to open up the auto-complete menu, or for asynchronous auto-completion, follow the setup instructions on LanguageClient.

If you'd like diagnostics to be highlighted, add a highlight group for ALEError/ALEWarning/ALEInfo, or customize g:LanguageClient_diagnosticsDisplay:

hi link ALEError Error
hi Warning term=underline cterm=underline ctermfg=Yellow gui=undercurl guisp=Gold
hi link ALEWarning Warning
hi link ALEInfo SpellCap

If you're finding that the server isn't starting at the correct project root, it may also be helpful to also specify root markers:

let g:LanguageClient_rootMarkers = ['*.cabal', 'stack.yaml']

Make sure HIE is installed, then install the two Atom packages atom-ide-ui and ide-haskell-hie,

$ apm install language-haskell atom-ide-ui ide-haskell-hie

Install HIE along with the following emacs packages:

lsp-mode lsp-ui lsp-haskell

Make sure to follow the instructions in the README of each of these packages.

Install HIE, and then add the following to your .spacemacs config,

(defun dotspacemacs/layers ()
  "..."
  (setq-default
   ;; ...
   dotspacemacs-configuration-layers
   '(
     lsp
     (haskell :variables ;; Or optionally just haskell without the variables.
              haskell-completion-backend 'ghci
              haskell-process-type 'stack-ghci)
     )
   dotspacemacs-additional-packages '(
      (lsp-haskell :location (recipe :fetcher github :repo "emacs-lsp/lsp-haskell"))
      )
    ;; ...
    ))

and then activate lsp-haskell in your user-config section,

(defun dotspacemacs/user-config ()
  "..."
  (require 'lsp-haskell)
  (add-hook 'haskell-mode-hook #'lsp-haskell-enable)
  )

Now you should be able to use HIE in Spacemacs. I still recommend checking out lsp-ui and lsp-mode.

If you use HIE with spacemacs on nix-built haskell projects, you may want to try out this spacemacs layer. It has installation instructions which includes a nix expression to install everything that hie needs in your environment. It wraps the hie binary calls to use nix-sandbox to find the closest ancestor directory that has nixfiles.

It is still pretty new and may change drastically as the author understands the lsp, lsp-ui, lsp-haskell, hie stack a bit better. PRs and feedback are very welcome on the layer's repo if you find it useful and/or lacking in some way.

Oni (a Neovim GUI) added built-in support for HIE, using stack, in #1918. If you need to change the configuration for HIE, you can overwrite the following settings in your ~/.config/oni/config.tsx file (accessible via the command palette and Configuration: Edit User Config),

export const configuration = {
  "language.haskell.languageServer.command": "stack",
  "language.haskell.languageServer.arguments": ["exec", "--", "hie"],
  "language.haskell.languageServer.rootFiles": [".git"],
  "language.haskell.languageServer.configuration": {},
}

HIE supports fetching docs from haddock on hover. It will fallback on using a hoogle db(generally located in ~/.hoogle on linux) if no haddock documentation is found.

To generate haddock documentation for stack projects:

$ cd your-project-directory
$ stack haddock --keep-going

To enable documentation generation for cabal projects, add the following to your ~/.cabal/config

documentation: True

To generate a hoogle database that hie can use

$ cd haskell-ide-engine
$ stack --stack-yaml=<stack.yaml you used to build hie> exec hoogle generate

Or you can set the environment variable HIE_HOOGLE_DATABASE to specify a specific database.

• Multiproject support
• Project wide references
• Cross project find definition
• New-build support
• HaRe refactorings
• More code actions
• Cross project/dependency Find Definition
• Case splitting, type insertion etc.

Both the ghc-mod and ide-backend maintainers have agreed to contribute code to this new repository and then rebase the old repos on this. The reason we're using a new repo instead of modifying one of the existing ones is so that the existing projects experience no disruption during this migration process. If this was a new set of people starting a new project without support from existing projects, I'd agree with you. But Alan's reached out to existing players already, which is an important distinction.

This project is not started from scratch:

1. See why we should supersede previous tools
2. Check the list of existing tools and functionality
3. See more other tools and IDEs for inspiration

❤️ Haskell tooling dream is near, we need your help! ❤️

• Register in our google group mailing list.
• Join our IRC channel at #haskell-ide-engine on freenode.
• Fork this repo and hack as much as you can.
• Ask @alanz or @hvr to join the project.

Below you find a short overview of the main architectural layers of haskell-ide-engine. For more info have a look in the docs folder at the root of this project, especially:

• The Architecture discussion
• The Protocol discussion
• The Design discussion

ghc-mod stays an AGPL project, and is used for its "awesome sauce" in terms of the BIOS functions that it does so well. This interface is straightforward to use, and if a license-constrained user wants to do something else it is also easy to replace, if there is strong control of the operating environment.

A layer providing a point to integrate tools and existing functions, probably including ghci.

The focus is currently on LSP as the protocol we use to interface with IDEs.

Existing transports are still functional for the time being.

All the documentation is in the docs folder at the root of this project.

Rename the file at ~/.stack/programs/x86_64-osx/ghc-8.4.3/lib/ghc-8.4.3/integer-gmp-1.0.2.0/HSinteger-gmp-1.0.2.0.o to a temporary name. Should be fixed in GHC 8.8.1.

Make sure that you are running the correct version of hie for your version of ghc, or check out hie-wrapper.

Delete any .ghc.environment* files in your project root and try again. (At the time of writing, cabal new-style projects are not supported with ghc-mod)

Try running cabal update.