So do some real analysis...
I took two quarters of real analysis as an undergraduate, but I never took complex analysis.
Swift also makes extensive use of variables whose values cannot be changed. These are known as constants
What am I missing here?
and the only substance harder is natural and synthetic diamond.
I hate to be the one to break the news to you, but there are substances haeder than corundum yet softer than diamond. SiC and BN come to mind