# Developing on windows # On Windows, Stack comes with an installation of [msys2](https://www.msys2.org/). Msys2 will be used by Stack to provide a unix-like shell for Stack. This may be necessary for installing some Haskell packages, such as those which use `configure` scripts. No matter which terminal you choose (cmd.exe, powershell, git bash or any other) you can use this environment too by executing all programs through `stack exec -- program`. This is especially useful if your project needs some additional tools during the build phase. Executables and libraries can be installed with Pacman. All tools can be found [in the package list](https://github.com/msys2/msys2/wiki/Packages). A [list of commands](https://github.com/msys2/msys2/wiki/Using-packages) that work with Pacman is also available. Just remember that pacman—like all other tools—should be started with `stack exec -- pacman`. ## Setup.hs ## `Setup.hs` is automatically run inside the stack environment. So when you need to launch another tool you don't need to prefix the command with `stack exec --` within the custom `Setup.hs` file. ## Pacman packages to install for common Haskell packages ## The following lists Pacman packages known to allow the installation of some common Haskell packages on Windows. Feel free to submit additional entries via a pull request. * For [text-icu](https://github.com/bos/text-icu) install `mingw64/mingw-w64-x86_64-icu` ## Cmake ## Cmake has trouble finding other tools even if they are available on the `PATH`. Likely this is not a cmake problem but one of the environment not fully integrating. For example GHC comes with a copy of GCC which is not installed by msys itself. If you want to use this GCC you can provide a full path to it, or find it first with `System.Directory.findExecutable` if you want to launch GCC from a Haskell file such as `Setup.hs`. Experience tells that the `mingw-w64` versions of make and cmake are most likely to work. Though there are other versions available through pacman, so have a look to see what works for you. Both tools can be installed with the commands: ``` stack exec -- pacman -S mingw-w64-x86_64-make stack exec -- pacman -S mingw-w64-x86_64-cmake ``` Even though make and cmake are then both installed into the same environment. Cmake still seems to have trouble to find make. To help cmake find GCC and make supply the following flags: ``` -DCMAKE_C_COMPILER=path -DCMAKE_MAKE_PROGRAM=path ```