Install Stack.
$ curl -sSL https://get.haskellstack.org/ | sh
$ stack setup
Install Unison from source.
$ git clone --recursive https://github.com/unisonweb/unison.git
$ cd unison
$ stack install
Change into a temporary directory and initialse a new Unison codebase.
$ mkdir ~/unison_project
$ cd ~/unison_project
$ unison -codebase . init
$ unison -codebase .
Inside the Unison shell install the base prelude.
.> pull https://github.com/unisonweb/base .base