how to use this file?

1. Install nix package manager
2. Enable Flake options by running the following code in bash

   mkdir -p ~/.config/nix
   echo "experimental-features = nix-command flakes" > ~/.config/nix/nix.conf

3. Put the flake.nix file inside the project folder
4. Make flake.nix tracked by git by running git add flake.nix
5. In the project shell, type either nix develop .#haskell or nix develop .#java to enter respective development environment.