There are a lot of such. When Larry Wall wrote the map operation for Perl, he just took the grep operation, added the function call, and added a resize if it w

There are a lot of such. When Larry Wall wrote the map operation for Perl, he just took the grep operation, added the function call, and added a resize if it was needed. The result is that the common "turn a list into a hash with map" operation was quadratic because it did the resize on every input element. I fixed that. I later noticed that unshift did the same thing for a different reason and fixed that. And then I looked at Ruby's source code and saw all the same performance mistakes. Exactly as the blog says, n^2 is fast enough to make it into production and slow enough to fall over once there. We focus on making it right, and only return to making it fast when there is need. And most of the time the cause is a hidden n^2 that we never thought about.