So it's my understanding there are two types of Algebraic Data Types (ADTs). For the case of Option[T] in Scala or Optional<T> in Java, would this be an example of a sum type or a product type?
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uh_big_mike_boi
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2I'm pretty sure you can figure it out if you consider that an `Optional
` is either a `T` or no `T`. – molbdnilo Nov 26 '17 at 02:40 -
Because it is fixed ok – uh_big_mike_boi Nov 26 '17 at 02:45
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Defining the Option[T] type in Haskell makes it clear that it's a sum type.
data Option t = None | Some t
Values of type Option t can be one of 2 things:
NoneSome t
So Option[T] and Optional<T> both take a type T and then add 1 more possible value (None).
For fun, we can also translate this ADT into an algebraic equation:
Option(t) = 1 + t
To see why, see this question: Abusing the algebra of algebraic data types - why does this work?
4castle
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