See, this is because you don't deal with data and statistics on a regular basis, which I do. And if you figure out how to fit a generalised additive model in c

See, this is because you don't deal with data and statistics on a regular basis, which I do. And if you figure out how to fit a generalised additive model in clojure with one line of code, please let me know :) So, in DS/stats you end up needing mutability because the datasets are really large, and the models take a long time to run, so copying is generally bad.