avail/avail.descriptor.types/TypeTag/Modifier/Contra

Contra

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

A Contravariant relationship. When a TypeTag declares such a relationship, then for all A and B having that TypeTag, if A ⊆ B, then traverse(B) ⊆ traverse(A), where traverse is a function provided by the Contra instance.

Constructors

Contra

constructor(name: String, traverse: A_Type.() -> A_Type)

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.

Functions

applyTo

open override fun applyTo(typeTag: TypeTag)

Adjust the TypeTag to accommodate this modifier.