Packages

sealed abstract class Leibniz[-L, +H >: L, A >: L <: H, B >: L <: H] extends AnyRef

Leibnizian equality: a better =:=

This technique was first used in Typing Dynamic Typing (Baars and Swierstra, ICFP 2002).

It is generalized here to handle subtyping so that it can be used with constrained type constructors.

Leibniz[L,H,A,B] says that A = B, and that both of its types are between L and H. Subtyping lets you loosen the bounds on L and H.

If you just need a witness that A = B, then you can use A===B which is a supertype of any Leibniz[L,H,A,B]

The more refined types are useful if you need to be able to substitute into restricted contexts.

Source
Leibniz.scala
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Abstract Value Members

  1. abstract def subst[F[_ >: L <: H]](p: F[A]): F[B]

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##: Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. def andThen[L2 <: L, H2 >: H, C >: L2 <: H2](that: Leibniz[L2, H2, B, C]): Leibniz[L2, H2, A, C]
  5. def apply(a: A): B
  6. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  7. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
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    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @native()
  8. def compose[L2 <: L, H2 >: H, C >: L2 <: H2](that: Leibniz[L2, H2, C, A]): Leibniz[L2, H2, C, B]
  9. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  10. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  11. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable])
  12. def flip: Leibniz[L, H, B, A]
  13. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  14. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  15. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  16. def liskov: Liskov[A, B]

    A === B implies A <~< B.

  17. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  18. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  19. final def notifyAll(): Unit
    Definition Classes
    AnyRef
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    @native()
  20. def onContra[FA](fa: FA)(implicit U: AuxA[Contravariant, FA, A]): (U)#M[B]
  21. def onCov[FA](fa: FA)(implicit U: AuxA[Functor, FA, A]): (U)#M[B]
  22. def onF[X](fa: (X) => A): (X) => B
  23. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
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  24. def toString(): String
    Definition Classes
    AnyRef → Any
  25. final def wait(): Unit
    Definition Classes
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    Annotations
    @throws(classOf[java.lang.InterruptedException])
  26. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
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    @throws(classOf[java.lang.InterruptedException])
  27. final def wait(arg0: Long): Unit
    Definition Classes
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    @throws(classOf[java.lang.InterruptedException]) @native()

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