It follows the UNIX philosophy of [do one thing and do it well](https://en.wikipedia.org/wiki/Unix_philosophy#Do_One_Thing_and_Do_It_Well). Similar in scope to [rustup](https://github.com/rust-lang-nursery/rustup.rs), [pyenv](https://github.com/pyenv/pyenv) and [jenv](http://www.jenv.be).
If you want to know what these scripts do, check out the [source code at the repository](https://github.com/haskell/ghcup-hs/tree/master/scripts/bootstrap). Advanced users may want to perform a [manual installation](#manual-installation) and GPG verify the binaries.
GHCup has two main channels for every tool: **recommended** and **latest**. By default, it installs *recommended*.
*latest* follows the latest release of every tool, while *recommended* is at the discretion of the GHCup maintainers and based on community adoption (hackage libraries, tools like HLS, stackage support, etc.) and known bugs.
Also see [tags and shortcuts](../guide/#tags-and-shortcuts) for more information.
You need the following packages: curl g++ gcc gmp make ncurses realpath xz-utils. Consult your distro documentation on the exact names of those packages.
On OS X, in the course of running ghcup you will be given a dialog box to install the command line tools. Accept and the requirements will be installed for you. You will then need to run the command again.
On Darwin M1 you might also need a working llvm installed (e.g. via brew) and have the toolchain exposed in PATH.
On Windows, msys2 should already have been set up during the installation, so most users should just proceed. If you are installing manually, make sure to have a working mingw64 toolchain and shell.
- choose a base directory for installation, e.g. `C:\` that has sufficient space
- then create the directory, e.g. `C:\ghcup\bin`
- download the binary: https://downloads.haskell.org/~ghcup/x86_64-mingw64-ghcup.exe
- place it as `ghcup.exe` into e.g. `C:\ghcup\bin`
2. Install MSYS2
- download https://repo.msys2.org/distrib/msys2-x86_64-latest.exe and execute it
- remember the installation destination you choose (default is `C:\msys64`)
- finish the installation
* Add environment variables and update `Path`
- open search bar and type in "Edit the system environment variables", then open it
- click on "Environment Variables..." at the near bottom
- in the upper half, select `Path` variable and double click on it
- in the new window, click "New", type in `C:\ghcup\bin` (depending on step 1.) and press enter
- click "OK" at the bottom
- in the upper half, click on "New..."
- enter `GHCUP_MSYS2` under "Variable name" and the installation destination from step 2. under "Variable value"
- click "OK" at the bottom
- in the upper half, click on "New..."
- enter `GHCUP_INSTALL_BASE_PREFIX` under "Variable name" and based on the installation destination from step 1. enter the device directory (default `C:\`)
- click "OK" at the bottom
- in the upper half, click on "New..."
- enter `CABAL_DIR` under "Variable name" and based on the installation destination from step 1. enter the device directory + `cabal` subdir (default `C:\cabal`)
- click "OK" at the bottom
- click "OK" at the bottom
- click "OK" at the bottom
3. Install tools
- open powershell
- run `ghcup install ghc --set recommended`
- run `ghcup install cabal latest`
- run `ghcup install stack latest`
- run `ghcup install hls latest`
- run `cabal update`
4. Update msys2
- run `ghcup run -m -- pacman --noconfirm -Syuu`
- run `ghcup run -m -- pacman --noconfirm -Syuu`
- run `ghcup run -m -- pacman --noconfirm -S --needed curl autoconf mingw-w64-x86_64-pkgconf`
- run `ghcup run -m -- pacman --noconfirm -S ca-certificates`
5. Update cabal config
- go to e.g. `C:\cabal` (based on device you picked in 1.)
- open file `config`
- uncomment `extra-include-dirs` (the `-- `) and add the value (depending on installation destination you chose in 2.), e.g. `C:\msys64\mingw64\include`... so the final line should be `extra-include-dirs: C:\msys64\mingw64\include`
- uncomment `extra-lib-dirs` and do the same, adding `C:\msys64\mingw64\lib`
- uncomment `extra-prog-path` and set it to `C:\ghcup\bin, C:\cabal\bin, C:\msys64\mingw64\bin, C:\msys64\usr\bin`, depending on your install destinations from 1. and 2.
6. Set up msys2 shell
- run `ghcup run -m -- sed -i -e 's/db_home:.*$/db_home: windows/' /etc/nsswitch.conf` to make the HOME in your msys2 shell match the one from windows
- make a desktop shortcut from `C:\msys64\msys2_shell.cmd`, which will allow you to start a proper msys2 shell
- run `ghcup run -m -- sed -i -e 's/#MSYS2_PATH_TYPE=.*/MSYS2_PATH_TYPE=inherit/' /c/msys64/msys2.ini`
- run `ghcup run -m -- sed -i -e 's/rem set MSYS2_PATH_TYPE=inherit/set MSYS2_PATH_TYPE=inherit/' /c/msys64/msys2_shell.cmd`
All set. You can run `cabal init` now in an empty directory to start a project.
The developers of the Haskell Language Server offer an [extension](https://github.com/haskell/vscode-haskell) tightly integrated with the [Haskell Language Server](https://github.com/haskell/haskell-language-server). To get started:
1. Install GHCup. During installation, opt in to install the Haskell Language Server (HLS).
2. Install the extension (from VSCode: Ctrl + P and then `ext install haskell.haskell`).
3. Make sure your project uses the GHC version installed from GHCup (otherwise HLS is likely to fail on launch):
- instructions for [stack](https://docs.haskellstack.org/en/stable/yaml_configuration/#system-ghc)
On Linux, some users have reported an issue when VSCode is not launched from a terminal ("cannot find ghc version"). A solution is to [let HLS know about your GHCup on $PATH](https://github.com/haskell/vscode-haskell#stackcabalghc-can-not-be-found).
