One oft-repeated fact is that in the Scala language, immutable Vectors are implemented using a 32-way trees. This makes many operations take O(log32(n)) time, and given a maximum size of 2^31 elements, it never takes more than 6 steps to perform a given operation. They call this "effectively constant" time. This fact has found its way into books, blog posts, StackOverflow answers, and even the off