avail/avail.descriptor.types/TypeTag/Modifier/Variant

Variant

abstract class Variant(val name: String, val traverse: A_Type.() -> A_Type) : TypeTag.Modifier

The mechanism for expressing covariant and contravariant relationships for types. Each TypeTag that represents a region of the type lattice can define Covariant and Contravariant relations that apply to types that have that TypeTag.

Constructors

Variant

fun Variant(name: String, traverse: A_Type.() -> A_Type)

Functions

applyTo

abstract fun applyTo(typeTag: TypeTag)

Adjust the TypeTag to accommodate this modifier.

Properties

name

val name: String

The symbolic name of the variant, for descriptive purposes.

traverse

val traverse: A_Type.() -> A_Type

A function that extracts a co-/contravariant type from the original type, where this Variant is applicable. For example, given something with the tag SET_TYPE_TAG (the TypeTag for set types), the set type's element type can be extracted by running the traverse function of the "element" covariant type parameter.

Inheritors

Contra