E4040

The type constructor expects a different number of arguments than provided.

Erroneous Example

let a : Option = Some(3)

The example above tries to create an instance of the Option type. The Option type is a generic type that expects a single type argument, but the example does not provide any type arguments, giving the following error on line 1:

The type constructor Option expects 1 argument(s), but is here given 0 argument(s).

Suggestion

Make sure to provide the correct number of type arguments:

let a : Option[Int] = Some(3)