=:=

sealed abstract class =:=[From, To] extends <:<[From, To] with Serializable

An instance of A =:= B witnesses that the types A and B are equal. It also acts as a A <:< B, but not a B <:< A (directly) due to restrictions on subclassing.

In case of any confusion over which method goes in what direction, all the "Co" methods (including apply) go from left to right in the type ("with" the type), and all the "Contra" methods go from right to left ("against" the type). E.g., apply turns a From into a To, and substituteContra replaces the Tos in a type with Froms.

From: a type which is proved equal to To
To: a type which is proved equal to From

Annotations: @implicitNotFound("Cannot prove that ${From} =:= ${To}.")
Source: typeConstraints.scala
See also: <:< for expressing subtyping constraints

Linear Supertypes

<:<[From, To], java.io.Serializable, (From) => To, AnyRef, Any

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=:=
<:<
Serializable
Function1
AnyRef
Any

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by UnliftOps
by any2stringadd
by StringFormat
by Ensuring
by ArrowAssoc

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Abstract Value Members

abstract def substituteBoth[F[_, _]](ftf: F[To, From]): F[From, To]
Substitute To for From and From for To in the type F[To, From], given that F is a type constructor of two arguments.
Substitute To for From and From for To in the type F[To, From], given that F is a type constructor of two arguments. Essentially swaps To and From in ftf's type.
Equivalent in power to each of substituteCo and substituteContra.
This method is impossible to implement without throwing or otherwise "cheating" unless From = To, so it ensures that this really represents a type equality.
returns
ftf, but with a (potentially) different type
Definition Classes
=:= → <:<

Concrete Value Members

final def !=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
returns
true if !(this == that), false otherwise.
Definition Classes
AnyRef → Any
final def ##(): Int
Equivalent to x.hashCode except for boxed numeric types and null.
Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.
returns
a hash value consistent with ==
Definition Classes
AnyRef → Any
def +(other: String): String
Implicit
This member is added by an implicit conversion from =:=[From, To] toany2stringadd[=:=[From, To]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd
def ->[B](y: B): (=:=[From, To], B)
Implicit
This member is added by an implicit conversion from =:=[From, To] toArrowAssoc[=:=[From, To]] performed by method ArrowAssoc in scala.Predef.This conversion will take place only if To is a subclass of Option[Nothing] (To <: Option[Nothing]).
Definition Classes
ArrowAssoc
Annotations
@inline()
final def ==(arg0: Any): Boolean
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
def andThen[C](r: =:=[To, C]): =:=[From, C]
If From = To and To = C, then From = C (equality is transitive)
def andThen[C](r: <:<[To, C]): <:<[From, C]
If From <: To and To <: C, then From <: C (subtyping is transitive)
If From <: To and To <: C, then From <: C (subtyping is transitive)
Definition Classes
<:<
def andThen[C](r: (To) => C): (From) => C
Composes two instances of Function1 in a new Function1, with this function applied first.
Composes two instances of Function1 in a new Function1, with this function applied first.
returns
a new function f such that f(x) == g(apply(x))
Definition Classes
<:< → Function1
def apply(f: From): To
Coerce a From into a To.
Coerce a From into a To. This is guaranteed to be the identity function.
This method is often called implicitly as an implicit A =:= B doubles as an implicit view A => B.
f
some value of type From
returns
f, but with a (potentially) different type
Definition Classes
=:= → <:< → Function1
final def asInstanceOf[T0]: T0
Cast the receiver object to be of type T0.
Cast the receiver object to be of type T0.
Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.
returns
the receiver object.
Definition Classes
Any
Exceptions thrown
ClassCastException if the receiver object is not an instance of the erasure of type T0.
def clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
returns
a copy of the receiver object.
Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
Note
not specified by SLS as a member of AnyRef
def compose[C](r: =:=[C, From]): =:=[C, To]
If From = To and C = From, then C = To (equality is transitive)
def compose[C](r: <:<[C, From]): <:<[C, To]
If From <: To and C <: From, then C <: To (subtyping is transitive)
If From <: To and C <: From, then C <: To (subtyping is transitive)
Definition Classes
<:<
def compose[C](r: (C) => From): (C) => To
Composes two instances of Function1 in a new Function1, with this function applied last.
Composes two instances of Function1 in a new Function1, with this function applied last.
returns
a new function f such that f(x) == apply(g(x))
Definition Classes
<:< → Function1
def ensuring(cond: (=:=[From, To]) => Boolean, msg: => Any): =:=[From, To]
Implicit
This member is added by an implicit conversion from =:=[From, To] toEnsuring[=:=[From, To]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: (=:=[From, To]) => Boolean): =:=[From, To]
Implicit
This member is added by an implicit conversion from =:=[From, To] toEnsuring[=:=[From, To]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean, msg: => Any): =:=[From, To]
Implicit
This member is added by an implicit conversion from =:=[From, To] toEnsuring[=:=[From, To]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean): =:=[From, To]
Implicit
This member is added by an implicit conversion from =:=[From, To] toEnsuring[=:=[From, To]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
final def eq(arg0: AnyRef): Boolean
Tests whether the argument (that) is a reference to the receiver object (this).
Tests whether the argument (that) is a reference to the receiver object (this).
The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:
- It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.
- For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
- null.eq(null) returns true.
When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).
returns
true if the argument is a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
def equals(arg0: AnyRef): Boolean
The equality method for reference types.
The equality method for reference types. Default implementation delegates to eq.
See also equals in scala.Any.
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
def finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.
Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
Note
not specified by SLS as a member of AnyRef
def flip: =:=[To, From]
If From = To then To = From (equality is symmetric)
def formatted(fmtstr: String): String
Returns string formatted according to given format string.
Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).
Implicit
This member is added by an implicit conversion from =:=[From, To] toStringFormat[=:=[From, To]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@inline()
final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
Returns the runtime class representation of the object.
returns
a class object corresponding to the runtime type of the receiver.
Definition Classes
AnyRef → Any
Annotations
@native()
def hashCode(): Int
The hashCode method for reference types.
The hashCode method for reference types. See hashCode in scala.Any.
returns
the hash code value for this object.
Definition Classes
AnyRef → Any
Annotations
@native()
final def isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object is T0.
Test whether the dynamic type of the receiver object is T0.
Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.
returns
true if the receiver object is an instance of erasure of type T0; false otherwise.
Definition Classes
Any
def liftCo[F[_]]: =:=[F[From], F[To]]
Lift this evidence over any type constructor F.
Lift this evidence over any type constructor F.
Definition Classes
=:= → <:<
def liftContra[F[_]]: =:=[F[To], F[From]]
Lift this evidence over the type constructor F, but flipped.
Lift this evidence over the type constructor F, but flipped.
Definition Classes
=:= → <:<
final def ne(arg0: AnyRef): Boolean
Equivalent to !(this eq that).
Equivalent to !(this eq that).
returns
true if the argument is not a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
final def notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
final def notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
def substituteCo[F[_]](ff: F[From]): F[To]
Substitute the From in the type F[From], where F is any type constructor, for To.
Substitute the From in the type F[From], where F is any type constructor, for To.
Equivalent in power to each of substituteBoth and substituteContra.
This method is impossible to implement without throwing or otherwise "cheating" unless From = To, so it ensures that this really represents a type equality.
returns
ff, but with a (potentially) different type
Definition Classes
=:= → <:<
def substituteContra[F[_]](ft: F[To]): F[From]
Substitute the To in the type F[To], where F is any type constructor, for From.
Substitute the To in the type F[To], where F is any type constructor, for From.
Equivalent in power to each of substituteBoth and substituteCo.
This method is impossible to implement without throwing or otherwise "cheating" unless From = To, so it ensures that this really represents a type equality.
returns
ft, but with a (potentially) different type
Definition Classes
=:= → <:<
final def synchronized[T0](arg0: => T0): T0
Definition Classes
AnyRef
def toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
returns
a String representation of the object.
Definition Classes
Function1 → AnyRef → Any
def unlift: PartialFunction[From, B]
Converts an optional function to a partial function.
Converts an optional function to a partial function.
Implicit
This member is added by an implicit conversion from =:=[From, To] toUnliftOps[From, B] performed by method UnliftOps in scala.Function1.This conversion will take place only if To is a subclass of Option[B] (To <: Option[B]).
Definition Classes
UnliftOps
Example:
1. Unlike Function.unlift, this UnliftOps.unlift method can be used in extractors.
  val of: Int => Option[String] = { i => if (i == 2) { Some("matched by an optional function") } else { None } } util.Random.nextInt(4) match { case of.unlift(m) => // Convert an optional function to a pattern println(m) case _ => println("Not matched") }
final def wait(): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long, arg1: Int): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()

Deprecated Value Members

def →[B](y: B): (=:=[From, To], B)
Implicit
This member is added by an implicit conversion from =:=[From, To] toArrowAssoc[=:=[From, To]] performed by method ArrowAssoc in scala.Predef.This conversion will take place only if To is a subclass of Option[Nothing] (To <: Option[Nothing]).
Definition Classes
ArrowAssoc
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use -> instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

Packages

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Avoid Blocking

=:=

sealed abstract class =:=[From, To] extends <:<[From, To] with Serializable

Abstract Value Members

Concrete Value Members

Deprecated Value Members

Inherited from <:<[From, To]

Inherited from java.io.Serializable

Inherited from (From) => To

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion UnliftOps from=:=[From, To] to UnliftOps[From, B]

Inherited by implicit conversion any2stringadd from=:=[From, To] to any2stringadd[=:=[From, To]]

Inherited by implicit conversion StringFormat from=:=[From, To] to StringFormat[=:=[From, To]]

Inherited by implicit conversion Ensuring from=:=[From, To] to Ensuring[=:=[From, To]]

Inherited by implicit conversion ArrowAssoc from=:=[From, To] to ArrowAssoc[=:=[From, To]]

Ungrouped

Packages

Package structure

Automatic imports

Guide

Common Imports

Specifying Durations

Using Futures For Non-blocking Computation

Avoid Blocking

=:=

sealed abstract class =:=[From, To] extends <:<[From, To] with Serializable

Abstract Value Members

Concrete Value Members

Deprecated Value Members

Inherited from <:<[From, To]

Inherited from java.io.Serializable

Inherited from (From) => To

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion UnliftOps from=:=[From, To] to UnliftOps[From, B]

Inherited by implicit conversion any2stringadd from=:=[From, To] to any2stringadd[=:=[From, To]]

Inherited by implicit conversion StringFormat from=:=[From, To] to StringFormat[=:=[From, To]]

Inherited by implicit conversion Ensuring from=:=[From, To] to Ensuring[=:=[From, To]]

Inherited by implicit conversion ArrowAssoc from=:=[From, To] to ArrowAssoc[=:=[From, To]]

Ungrouped

=:=