- val a = 1;

val a = 1 : int

- fun f() = a;

val f = fn : unit -> int

- f();

val it = 1 : int

- val a = 2;

val a = 2 : int

- f();

val it = 1 : int // a is still bound to 1 as far as f() is concerned

Now in Javascript:

> var a = 1;

undefined

> function f(){return a};

undefined

> f();

1

> a = 2;

2

> f();

2

>

If you bind a val, then you define a function that references that val, then you later shadow the val binding, then call the function again, the function still sees the earlier val binding, because it's a closure of the environment at the point where the function was defined, not at the point where it was called. This is unlike variable assignment in imperative languages.