John Carmack on mutable variables

Clojure also makes it very easy, it'd require too much discipline to do such a thing in Python. Even Carmack, who I think still does python mostly by himself instead of a team, is having issues there.

> it'd require too much discipline to do such a thing in Python

Is Python that different from JavaScript? Because it's easy in JavaScript. Just stop typing var and let, and start typing const. When that causes a problem, figure out how to deal with it. If all else fails: "Dear AI, how can I do this thing while continuing to use const? I can't figure it out."

I agree that Python is not too different and in general I treat my Python variables as const. One thing, however, where I resort to mutating variables more often than I'd like is when building lists & dictionaries. Lambdas in Python have horrible DX (no multi-line, no type annotations, bad type checker support even in obvious cases), which is why the functional approach to build your list, using map() and filter() is much more cumbersome than in JS. As a result, whenever a list comprehension becomes too long, you end up building your list the old-fashioned way, using a for loop and the_list.append().

In python there's no let, var nor const. So yes.

Javascript only enforces reassignments to const. So this,

  const arr = []
  arr.push(“grape nuts”]

is just peachy in JS and requires the programmer to avoid using it.

More importantly, because working immutably in JS is not enforced, trying to use it consistently either limits which libraries you can use and/or requires you to wrap them to isolate their side effects. ImmerJS can help a lot here, since immutability is its whole jam. I’d rather work in a language where I get these basic benefits by default, though.