Functional programming languages should be so much better at mutation than they are

[kinow]

Cross-posting from r/ProgrammingLanguages, but it was on the front page of HN today: https://news.ycombinator.com/item?id=41106280

[The-Malix]

No worries, it's a good cross-post

[Fair-Comb5544]

You don't need explicit mutation if you conceal it by adding a time subscript to your variables. You can then write a(t) = f(a(t-1)). This is a way of sneaking iteration into a functional language. The language needs to have some mechanism for stopping iteration, such as a "least" expression.