Comment by jorkadeen

That's right. Locally scoped mutable memory in Flix is very similar to the ST Monad. The two major differences are: (a) Flix is in direct-style vs. monadic style and (b) we use a type and effect system.

Note that there is no requirement that all mutation must occur within a single function. The requirement is that once you leave the lexical scope then all mutable memory associated with that scope become unreachable. Mutation can certainly span over multiple functions.