From a fresh Ubuntu:

  $ sudo add-apt-repository ppa:hvr/ghc
  $ sudo apt-get update
  $ sudo apt-get install ghc-8.2.2

Build steps:

  $ git submodule update --init --recursive
  $ stack build

Execution:

  $ stack exec atva-demo elf.exe


Note for MacOS users:
  The input language of macaw is Elf, which is not a format of object file format supported by OS X (Mach-O).

  To generate Elf file on MacOS, we cross-compile to a linux target.
  1) set gcc target to be a linux machine:

  $ gcc -fno-stack-protector -foptimize-sibling-calls -target x86_64-unknown-linux-gnu -c -o foo.o foo.c

  2) use a linker configured for that target-triple. Follow the instructions on
  https://stackoverflow.com/questions/39059597/how-to-create-an-elf-executable-on-mac-os-x before running: 

  $ ~/.local/binutils/x86_64-unknown-linux-gnu/bin/ld -static -o foo.exe foo.o