UMBC CMSC331-01&04, Programming Languages, Fall 2022

Running Haskell Programs

On GL (default option)

On Windows 10

Steps:

1. First make sure that WSL is enabled on your Windows system. From the Start Menu, search for "Turn Windows features on or off". Click on the Control Panel result from that search. This brings up a window with a bunch of checkboxes. Scroll to the bottom and see if the box for "Windows Subsystem for Linux" is checked. If not, check that box, click "OK" and reboot your machine.

2. Go to the Microsoft Store and search for "WSL". Choose one of the Linux distributions available. Either "Ubuntu" or "Debian" is recommended.

3. After Debian or Ubuntu is installed, launch the app. This will bring up a terminal window. Allow the system to do some housekeeping after the first launch. This could take a few minutes. You will be asked to create a super-user account and password. Remember this password! You will need the password to install packages.

4. When the Linux distribution is ready, first update the packages:

      sudo apt update
      

5. Next, install GHC and the PCRE module

      sudo apt install ghc libghc-regex-pcre-dev
      

6. You will also want to install some Linux tools that might not be already installed, such as emacs, vim, openssh-client, rsync, ... These can be easily installed using the sudo apt install command.

On MacOS

Updated 2022-09-02

MacOS is Unix underneath. So, you just need to install the GHC package. Since MaCOS does not come with its own package manager, you have to first install a package manager. The recommended package manager is Homebrew. If you already have another package manager installed (e.g., Macports or Fink), you can also install GHC using those package managers.

MacOS installation is complicated by three things:

1. The steps vary a bit depending on which shell you use. The Unix command to install Homebrew on their website works for sh, bash and zsh. If you are using csh or tcsh, you should fire up zsh (the default MacOS shell these days) to run the Homebrew installation command. Also, for csh and tcsh, each time you install something using Homebrew, you should issue a rehash command to make the new command available to you.
2. The steps vary a bit depending on which version of MacOS you have. The following has been tested on Monterey (MacOS 12.5) and Big Sur (MacOS 11.6). Mojave (MacOS 10.14) is not supported by Homebrew. I have not checked Catalina (MacOS 10.15).
3. None of Homebrew, MacPorts or Fink have the PCRE package for Haskell as a library install. We have to use Cabal, the native Haskell package manager to get the Text.Regex.PCRE module.

1. Go to the Homebrew web page and copy the Unix command under the heading "Install Homebrew". The command starts with

      /bin/bash -c "$(curl -fsSL ...
      

2. Launch the MacOS Terminal app. (Drop into zsh if you are using csh or tcsh.) Paste the command at the Unix prompt. Wait for Homebrew to finish installing.

3. After Homebrew is done with its installation, check if the brew command is available. If not, follow the instructions to add the path to the commands installed by Homebrew to your PATH environment variable.

   The actual path might vary depending on versions. It might be /opt/homebrew/bin or /usr/local/bin.

   If you are using csh or tcsh, manually add the path in your .cshrc or .tcshrc file instead of using the instructions provided by the Homebrew installer.

   Logout and log back in and check if the brew command is available.

4. Next, you can use Homebrew to install GHC:

      brew install ghc
      

In addition to ghc, you need to install the PCRE module (Perl Compatible Regular Expressions) for Haskell. This is somewhat more complicated on MacOS since Homebrew does not supply the binaries and we need to use cabal to download and install the package. This means we need to install cabal and some system tools:

brew install cabal-install
brew install pkg-config
brew install pcre

Depending on which shell you use, you may need to issue the rehash command to see the newly installed utilities. Then, we can use cabal to install Text.Regex.PCRE:

cabal update
cabal install --lib regex-pcre

import Text.Regex.PCRE

On Android (not recommended)

1. First, on your Android device, go to the F-Droid site and download the F-Droid .apk file. Then, using your favorite Android file manager, install the .apk file. You may need to change your system settings to allow your file manager to install apps. (You can change it back after installing F-Droid.)

2. Run the F-Droid app. Go to the updates panel. Update F-Droid itself, if available. You may need to change your system settings to allow F-Droid to install and update apps.

3. In the F-Droid app, search for "Termux". Install the Termux app.

4. Launch Termux. There are some housekeeping commands you need to issue:
   • First, update Termux itself

           pkg update
           

   • Second, allow Termux to access the Android file system

           termux-setup-storage      
           

     Your Android files are linked under storage or you can go directly to /sdcard.
   • Next, install any Linux utilities that you like using the pkg install command. Termux has many but not all Linux packages in its repository. In particular, it does not have GHC. Hence the next step.

5. Now we can install Ubuntu inside Termux. Still in Termux:

         pkg install proot-distro
         

   When that is done

         proot-distro install ubuntu
         

6. Now you can switch over to Ubuntu:

         proot-distro login ubuntu
         

   Inside Ubuntu, you should first update the distro:

         apt update 
         

   Then you can install GHC and the PCRE module

         apt install ghc libghc-regex-pcre-dev 
         

   If your PATH environment variable is set up properly, you can run many Termux utilities from Ubuntu. Some installations like LaTeX will not work, because the directories are in the wrong places. You can install additional Ubuntu specific utilities using the apt install command, as usual.

7. You can access Ubuntu files from Termux and vice versa. The Termux files are located in:

      /data/data/com.termux/files/home
      

   The Ubuntu files are in:

      /data/data/com.termux/files/usr/var/lib/proot-distro/installed-rootfs/ubuntu/root
      

   You can also access your Android files from Ubuntu using /sdcard.