@seanmor5 - This is a great book so far… I’m enjoying reading and coding along with it! Quick question, though - since “evaluate” goes to the trouble of calling the “fitness_function” and generating an updated list of Chromosomes with the new calculated “fitness” values in the struct, instead of en…

Good catch! I think that’s the result of me forgetting to update the call to sort_by after I added in the fitness calculation for each chromosome. I’ll make sure that gets fixed. I thought a lot about whether or not to include some examples of Genetic Programing and other tree-type methods. Ultimat…