Introduction

In this document I list all editors/IDEs I've personally used and the way to configure them to work with Haskell to have features like:

• auto complete
• syntax highlighting
• linting
• formatting

I will try to keep these instructions up-to-date. However, feel free to send PR requests if you spot anything wrong or out-of-date.

IDE/Editor Configuration

Spacemacs - for full keyboard operation

VIM/Neovim - for full keyboard operaton

Visual Studio Code - easiest to get started and works reasonably well

Haskell Tools

The tools you'll need:

• GHC (the compiler)
• Build tools, Stack or Cabal
• HLS (Haskell Language Server, this is the only IDE engine you need)
• other tools like hlint, stylish-haskell, hasktags, hoogle etc, choose whatever you need.

The easiest way to get started with Haskell is to use GHCup.

Installation (GHCup)

Automated GHCup install

Use haskell/install.sh to install GHCUP, cabal, stack and HLS in one command.

You can edit the env vars in the script to change what you wanna install.

haskell/install.sh

Manual GHCup install

Install GHCup on Unix-like systems:

curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | sh

Frequently run this command to upgrade GHCup:

ghcup upgrade

List available tools you can install and have installed:

ghcup list

Install GHC

# latest
ghcup install ghc

# or a specific version
ghcup install ghc 8.10.7

Install build tools.

ghcup install stack
ghcup install cabal

Install haskell-language-server, this is what will provide IDE capabilities in your editor (VSCode, VIM, Emacs etc)

ghcup install hls

All versions of binaries will be installed in ~/.ghcup/bin. Please browse this directory to get familiar with how files are organised, and make sure the relevant version is under your $PATH env var for easy access.

Installation (Stack)

The wrong way

A lot of people use stack install to install tools like hlint and stylish-haskell, which by default puts the binaries into ~/.local/bin. This is a very bad idea because these "globally" installed tools only work with a specific version of GHC. If you have multiple projects that use multiple versions of GHC, then your editor won't work with all the projects; or if you later upgrade to a higher version of GHC these tools will simply stop working.

The right way

Install these tools per project, which means going into each project's directory and doing something like this

stack build hlint

Doing this for every project takes time because each time they have to be downloaded and built. Fortunately there's a way to only build these tools once for each version of GHC on your system. Simply pass --copy-compiler-tool when building them like the following

## Faster for subsequent builds for a specific GHC version
stack build --copy-compiler-tool stylish-haskell

Tools to consider

• haskell-language-server - one IDE to rule them all
• stylish-haskell - code fomatter
• hlint - linter
• apply-refact - required by hlint-refactor
• hasktags - produces ctags "tags" and etags TAGS files for Haskell programs
• hoogle - provides api doc lookup
• Hasklig - ligrature for pretty operators

Putting it all together

Apart from Hasklig which requires manual download, I usually install them like this:

stack build --copy-compiler-tool hlint apply-refact stylish-haskell hasktags hoogle