The "Compiler Design" course at my university was the hardest CS course I've ever taken -- and it was generally taken your very last semester (and was infamous

The "Compiler Design" course at my university was the hardest CS course I've ever taken -- and it was generally taken your very last semester (and was infamous for being a common cause of many senior CS students not graduating on time). Had it been optional, I would have been sorely tempted to skip it. But, taking it was probably good for me in the long run :)