Menu
I wonder if I can write something like this in my code:
None[String] 
741
None is a subtype of Option type. This may cause calling programs to crash if it doesn't properly handle null. Scala's best practices advise us to wrap the return value in the Option type in cases where the function may not have a return value.
In Scala, using null to represent nullable or missing values is an anti-pattern: use the type Option instead. The type Option ensures that you deal with both the presence and the absence of an element. Thanks to the Option type, you can make your system safer by avoiding nasty NullPointerException s at runtime.
The Option in Scala is referred to a carrier of single or no element for a stated type. When a method returns a value which can even be null then Option is utilized i.e, the method defined returns an instance of an Option, in place of returning a single object or a null.
Scala's Option is particularly useful because it enables management of optional values in two self-reinforcing ways: Type safety – We can parameterize our optional values. Functionally aware – The Option type also provides us with a set of powerful functional capabilities that aid in creating fewer bugs.
I am surprised that nobody mentioned the existence of Option.empty:
scala> Option.empty[String] res0: Option[String] = None Note that in many cases simply using None where an Option[String] is expected will work fine. Or in other words, (as shown by Aleksey Izmailov), the following is corrrect:
def f(o: Option[String]) = ...; f(None) This is because None extends Option[Nothing], so by virtue of Option being covariant (and Nothing being a sub-type of every other type), None is always a compatible with Option[T] for any T.
This is also why type ascription is also a fine alternative (for the cases where you do need to be explicit on the type of options, by example if it is needed to drive type inference):
scala> None: Option[String] res0: Option[String] = None If you want to specify the type of Option you could use:
None:Option[String]
The colon is an explicit type annotation.
35
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
