scala3-compiler-bootstrapped/dotty.tools/dotty.tools.dotc/dotty.tools.dotc.core/Types/HKTypeLambda

HKTypeLambda

dotty.tools.dotc.core.Types.HKTypeLambda

See theHKTypeLambda companion class

object HKTypeLambda extends TypeLambdaCompanion[HKTypeLambda]

Attributes

Companion: class
Graph
Supertypes: class TypeLambdaCompanion[HKTypeLambda]

class LambdaTypeCompanion[TypeName, TypeBounds, HKTypeLambda]

class Object

trait Matchable

class Any
Self type: HKTypeLambda.type

Members list

Value members

Concrete methods

Distributes Lambda inside type bounds. Examples:

    type T[X] = U        becomes    type T = [X] =>> U
    type T[X] <: U       becomes    type T >: Nothing <: ([X] =>> U)
    type T[X] >: L <: U  becomes    type T >: ([X] =>> L) <: ([X] =>> U)

The variances of regular TypeBounds types, as well as of match aliases and of opaque aliases are always determined from the given parameters params. The variances of other type aliases are determined from the given parameters only if one of these parameters carries a + or - variance annotation. Type aliases without variance annotation are treated structurally. That is, their parameter variances are determined by how the parameter(s) appear in the result type.

Examples:

  type T[X] >: A              // X is invariant
  type T[X] <: List[X]        // X is invariant
  type T[X] = List[X]         // X is covariant (determined structurally)
  opaque type T[X] = List[X]  // X is invariant
  opaque type T[+X] = List[X] // X is covariant
  type T[A, B] = A => B       // A is contravariant, B is covariant (determined structurally)
  type T[A, +B] = A => B      // A is invariant, B is covariant