1. download the binary for linux
$ wget https://github.com/purescript/purescript/releases/download/v0.11.5/linux64.tar.gz - /opt/purescriptw
  1. smylink the executable
$ ln -s /opt/purescript/purs /usr/local/bin/purs
  1. install libtinfo
$ gpg --keyserver pgp.mit.edu --recv-keys F7E48EDB # needed for the folloing package
$ pacaur -S ncurses5-compat-libs
$ pacaur -S libtinfo

see here