The type system hasn't been published yet. We don't have monkey-patching. We've been burned too much by JavaScript and the like. Cyclic structures: think abou

The type system hasn't been published yet. We don't have monkey-patching. We've been burned too much by JavaScript and the like. Cyclic structures: think about trying to teach graph algorithms. Let's say you believe it's important to write tests. Many graph algorithms aren't inherently mutational. But you need mutation just to create examples of your data. The graph construct gets around this problem entirely, so mutation and graph algorithms become orthogonal topics. In general, I'm a big believer in eliminating unnecessary curricular dependencies. Having taught graph algorithms this way for a few years now, I can't imagine going back. See the notes on graphs in PAPL (papl.cs.brown.edu/2013/).