#Scala enum code#

However you could still want to gracefully handle the removal of a case from your public API, such as special casing deprecated cases. Deprecation of Enum CasesĪs a library author, you may want to signal that an enum case is no longer intended for use. You must use an indirect reference, such as demonstrated with Earth. The fields referenced by Mercury are not visible, and the fields referenced by Venus may not be referenced directly (using import Planet.*).

Scalaz features for everyday usage part 3: State Monad, Writer Monad and lenses

. Scalaz features for everyday usage part 2: Monad Transformers and the Reader Monad

Private final val (earthMass, earthRadius) = (5.976e+24, 6.37814e6) The following articles are currently available in this series: Scalaz features for everyday usage part 1: Typeclasses and Scala extensions. Private final val (mercuryMass, mercuryRadius) = (3.303e+23, 2.4397e6)Ĭase Mercury extends Planet(mercuryMass, mercuryRadius) // Not foundĬase Venus extends Planet(venusMass, venusRadius) // illegal referenceĬase Earth extends Planet(Planet.earthMass, Planet.earthRadius) // ok The advantage of enum classes is that they can be serialized and deserialized out of the. Since those classes can be object declarations, we can use sealed classes to a certain degree instead of enums, but not the other way around. So as you can see enumeration in Swift and sealed case classes/traits in Scala have very similar purpose and ergonomics.Enum Planet(mass: Double, radius: Double): It aims to be similar enough to Scalas built in Enumeration to be easy-to-use and understand while offering more flexibility, type-safety (see this blog post describing erasure on Scalas Enumeration), and richer enum values without having to maintain your own collection of values. Enum classes represent a concrete set of values, while sealed classes represent a concrete set of classes. This article will discuss the usage of enumerations in the Scala programming language.

to add convenience methods and infix operators. See how easy it is to use Scala 3 extension methods, e.g. Get a refresher on the Functor and Monad laws. In the process, have a tiny bit of fun with Scala 3 enums. To create an enumeration within your script, you’ll have to extend your desired class from Enumeration class in Scala. Explore a terser definition of the Option Monad that uses a Scala 3 enum as an Algebraic Data Type. This group consists of similar types of values. The result of AND is 1 only if both bits are 1. An enumeration in Scala is a group of named constants. Following are the bitwise operators : Bitwise AND (&): Takes two numbers as operands and does AND on every bit of two numbers. Armed with native enums, developers no longer have to rely on extending classes to create an enumeration before it. Incredibly basic conceptually, enums allow developers to group related, constant values. Scala will issue a soft warning for exhaustive check failure. In Scala, there are 7 bitwise operators which work at bit level or used to perform bit by bit operations. According to 86 of developers surveyed by Scala, the most exciting Scala 3 development is the introduction of enums.

This lets us and the compiler know the finite possible values of an enumeration.ĭef toString(c:Color) : String = c match ' enum E: case A inline def headParamsT<:NonEmptyTuple:String inline erasedValueT match case : (t : ts) > val mp summonInlineMirror.ProductOft constValuemp.MirroredLabel main def psvm:Unit val ms summonInlineMirror.SumOfE // works when called directly on Tuple.

The trait should be sealed so that all implementors are defined in the same file. Simple enumeration like this can be implemented using a sealed trait and case objects in Scala. If the switch statement misses any color the compiler will throw error. If youre defining message types or enums that you anticipate will be widely used outside of.

#Scala enum code#

Swift is very strict about exhaustive matching. proto files that reside outside of a specific projects code base. Despite their outward differences they really have similar goals.Ī basic enumeration in Swift goes like this. Case classes in Scala and enumaration in Swift are two long lost cousins.