Building the project on a fresh machine

[Boarders]

Currently our project can be very painful to build on a fresh machine if it is not easy to grab the correct versions of GHC and cabal. Nix is a package manager for both mac and linux that should, in theory, make this a bit easier as it can grab the relevant version of the compiler for you. We should test whether this makes it easy to build on a fresh machine. The instructions to do so are:

First install nix: this can be done via: curl https://nixos.org/nix/install | sh though the website here also offers tarballs and a way to securely verify the installation.

After that is installed (and perhaps after restarting the shell) one should then be able to run (within the pcg directory):

nix-shell --packages haskell.compiler.ghc881 --run 'cabal install'

This is assuming the version of the compiler we wish to build with is ghc-8.8.1 but can be changed as appropriate so long as the compiler is available from the nix package repository.