Developing on Windows¶
On Windows, Stack comes with an installation of MSYS2.
MSYS2 will be used by Stack to provide a Unix-like shell and environment for
Stack. This may be necessary for installing some Haskell packages, such as those
configure scripts, or if your project needs some additional tools
during the build phase.
No matter which terminal software you choose (Windows Terminal, Console Windows
Host, Command Prompt, PowerShell, Git bash or any other) you can use this
environment too by executing all programs through
stack exec -- <program_name>.
Executables and libraries can be installed with the MSYS2 package manager
pacman. All tools can be found in the
package list. A list of
commands that work with
pacman is also available. Just remember that
pacman — like all other
tools — should be started with
stack exec -- pacman.
stack path --bin-path to see the PATH in the Stack environment. On
Windows, it includes the
directories of the Stack-supplied MSYS2. If your executable depends on files
(for example, dynamic-link libraries) in those directories and you want ro run
it outside of the Stack environment, you will need to ensure copies of those
files are on the PATH.
The Stack-supplied MSYS2 can itself be updated with the Stack-supplied
See the MSYS2 guide
'III. Updating packages'. If
pacman has a version that is 22.214.171.12403 or greater (see
stack exec -- pacman --version) then the command to update is simply:
stack exec -- pacman -Syuu
This command may need to be run more than once, until everything is reported by
pacman as 'up to date' and 'nothing to do'.
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
Pacman packages to install for common Haskell packages¶
The following lists MSYS2 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 install
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
MSYS2 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
Experience tells that the
mingw-w64 versions of Make and CMake are most
likely to work. Though there are other versions available through
have a look to see what works for you. Both tools can be installed with the
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: