Step by step introduction for xtext, combined calculator, defun and if statement.
Based on eclipse oxygen, download and install it.
Then select these additional plugins to run as product org.eclipse.platform.ide
org.eclipse.equinox.ds
org.eclipse.equinox.event
org.apache.felix.scr
org.eclipse.core.net
org.eclipse.ui.ide.application
Don't forget to click add required plugins