Download the community version from JetBrains web site or install it from the distro repository:

# pacman -S intellij-idea-community-edition

At the first time it is executed:

  • Customize any configurations.

  • Install the official scala plug-in.

  • Install the additional plug-in scalariform.

  • After the initial setup, go to File -> Settings -> Keymap and search for scalariform and change its shortcut to Ctrl+Shift+S.