Setting_up_Ghc_with_MSYS2

Intro

My own notes on how to setup a GHC environment on windows with MSYS2. I was put on the right track by following “Building GHC On Windows”.

Installing MSYS2

Grab the installer from [http://msys2.github.io/]
Grab either the 32 or 64 bit version. I would suggest the 32 bit version since I still ran into some troubles with 64 bit GHC 7.8.4
Don’t install it to a path with spaces in it.
Follow the steps on the installer’s site in particular
- Update the core MSYS first by running pacman -Syu from the MSYS shell and then restart the shell.
Some things to note about the installation
- In the install directory there are three .bat files to run 3 different shells (MSYS, MINGW32, MINGW64). Most of the time you will run one of the MINGW shells (mingw32_shell.bat if using MSYS2 32 bit)
- Your home directory would be INSTALLATION_DIRECTORY\home\USER_NAME
- From within the shell you have a posix like file system in particular
  - C: drive is /c (drives don’t show up in root but can all be accessed similarly)
  - Home directory is ~
  - You can get the windows path from a shell path by doing pwd -W
Next install some tools needed for development
- From the MINGW shell pacman -Sy git tar binutils autoconf make libtool automake python2 p7zip patch man wget
- Note do not install a compiler tool chain (i.e. gcc) we will use the one that comes with GHC
Optionally setup public cryptography for use with github etc (openssh should be installed, if not run pacman -Sy openssh)
- if you already have a public and a private key copy them to ~/.ssh (windows does not like making directories with periods do it from the shell cd ~; mkdir .ssh
- Otherwise generate RSA keys by doing ssh-keygen .
  - Private key will be ~/.ssh/id_rsa
  - Public key will be ~/.ssh/id_rsa.pub
- Setup ssh agent to load the keys when starting the shell.
  - Edit the following file ```~/.bashrc
  - Add the following line to run the ssh agent eval `ssh-agent -s`
  - Add the following line to add your keys ssh-add

Install GHC

Grab pre-built binaries for Windows from [https://www.haskell.org/ghc/]
At the current time I would suggest 32 bit GHC 7.8.3 [https://www.haskell.org/ghc/dist/7.8.3/ghc-7.8.3-i386-unknown-mingw32.tar.xz]
I suggest installing GHC in such a way so that it is easy to switch between distributions
Make a directory where you would extract GHC (e.g. c:\ghc_all)
Extract the versioned GHC folder to that directory (e.g. after extraction you have c:\ghc_all\ghc-7.8.3
Create a junction called ghc_current to point at the versioned GHC
- From the Windows command line and not from the MSYS/MINGW shell.
- CD to the where the versioned directory was extracted (e.g. `cd c:\ghc_all)
- Create a junction called ghc_current to the versioned directory (e.g. mklink /J ghc_current ghc-7.8.3 )
- You should now have a folder ghc_current that points to the specific GHC.
Now modify the .bashrc file so that the MSYS/MINGW shell will know about GHC and use the gcc that came with your GHC version.
- Edit the file ~/.bashrc to add GHC, GHC and cabal to the path by appending
  - Add GHC : export PATH=/c/ghc_all/ghc_current/bin:$PATH
  - Add GCC that comes with GHC : export PATH=/c/ghc_all/ghc_current/mingw/bin:$PATH
  - Add cabal default binary install directory: export PATH=/c/Users/$USER/AppData/Roaming/cabal/bin:$PATH
Get the Windows binaries for Cabal from [https://www.haskell.org/cabal/download.html]
- Extract the binary the versioned GHC binary directory (e.g. c:\ghc_all\ghc-7.8.3\bin
- The name of the newer built binaries include the full version of cabal so rename it to cabal for easy access.
- If you install a newer cabal using cabal it will detect and use that one.
- Update Cabal, from MINGW shell cabal update
- Edit your Cabal config file to ensure library profiling is enabled
  - Edit the file ```/c/Users/$USER/AppData/Roaming/cabal/config
  - Make sure the file contains the line library-profiling: True (your probably just have to uncomment it)