Visual explanation of why we prepend instead of appending


Anybody wondering why it’s a bad idea to append to lists, when using immutable data? I took a crack at explaining it visually on the Hello World Show Live, recorded at DevConf Poland. Check out that section at and let me know what you think. I’m intending to make it a much better lightning talk I can do at meetups, conferences, etc. (This one was almost totally unrehearsed due to time constraints.)

(Yes it’s static for a while at the start. Hang on. Had a bit of a momentary snag with the slides later in, but got past it. And no, that’s not me in the preview.)