but I dont think you have to be a either pure/func...

# language-proposals

[groostav]

but I dont think you have to be a either pure/functional/monadic programmer or a mutable/old-school/imperitive programmer. I'm using ANTLR a fair bit, and the way they have you define AST visitors is with a plethora of mutable state. But because "walks" and "visits" are the idiomatic way to use that state, you can wrap all your mutability up into a neat referentially-transparent package.