The lucky kids of JavaSchools are never going to get weird segfaults trying to implement pointer-based hash tables. They're never going to go stark, raving mad trying to pack things into bits. They'll never have to get their head around how, in a purely functional program, the value of a variable never changes.
T. Omori, and K. Maruyama. MSR '08: Proceedings of the 2008 international workshop on Mining software repositories, page 31--34. New York, NY, USA, ACM, (May 2008)