The StringBuilder example is just that-- an example that many software developers should be familiar with. The deeper idea is that in Flix one can write a pure function that internally use mutation and imperative programming.
Plus that you regretted having `+` as a concatenation operator.
However, I believe an even better design choice would be to forgo string concatenation and instead rely entirely on string interpolation. String interpolation is a much more powerful and elegant solution to the problem of building complex strings.
