Null handling

All expressions can have a null value.

For instance:

let x: int = null

Although x is an int, its value is actually null.

To check if an expression has value null, use:

let
    x: int = null
in
    Nullable.IsNull(x) // true

... while:

let
    x: int = 2
in
    Nullable.IsNull(x) // false