I suspect the syntax of `<-` (or lack thereof) will be a common topic of discussion. Let's see how various audiences respond to this change and then discuss if we'd like to restore `<-` for mutation. Personally, I don't use a ton of mutations in my code so I have less at stake and if there's anything we can do to appeal to a wider audience, I'm inclined to give it a shot.
Maybe I'm too used to Ocaml to comment but I think using `=` for mutation is a bit misleading because it might make it appear that `x.mutablefield = bla` and `let x = bla` are the same thing, which is the case for typical imperative languages (but definitely not for Ocaml).
BTW, one thing that I do find awkward about Ocaml's syntax is the difference between := and <-. Dunno if its possible to unify them in a sane manner though.
F# doesn't unify them, but it makes := largely redundant by letting you do "let mutable ...", and then assign to it with "<-" - so you simply don't need to use refs if you just need some mutable data (you still need them if you want to have a closure mutate something it closed over).
`ref` and `mutable` were unified in F# 4.0. You no longer need to use a `ref` when closing over a mutable value, you can use `let mutable` in all cases and the compiler will figure it out for you. The generated code is the same as before, it's just that there's a unified syntax now.
There is an optional warning one can enable which emits when a `let mutable` is converted to a `ref` behind the scenes - for those who want to by hyper-aware of hidden allocations.
