Scala Compiler2.12.18 < Back
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# Packages

-  package root

  The Scala compiler and reflection APIs.

  The Scala compiler and reflection APIs.

  Definition Classes
    root
-  package scala
  Definition Classes
    root
-  package tools
  Definition Classes
    scala
-  package nsc
  Definition Classes
    tools
-  package transform
  Definition Classes
    nsc
-  package patmat
  Definition Classes
    transform
-  trait Interface extends TreeDSL
  Definition Classes
    patmat
- CODE
- MatchMonadInterface
- TypedSubstitution
- vpmName

t

scala.tools.nsc.transform.patmat.Interface

# MatchMonadInterface 

###

#### trait MatchMonadInterface extends AnyRef

Interface with user-defined match monad? if there's a `__match` in scope, we use this as the match strategy, assuming it conforms to MatchStrategy as defined below:

    type Matcher[P[_], M[+_], A] = {
      def flatMap[B](f: P[A] => M[B]): M[B]
      def orElse[B >: A](alternative: => M[B]): M[B]
    }

    abstract class MatchStrategy[P[_], M[+_]] {
      // runs the matcher on the given input
      def runOrElse[T, U](in: P[T])(matcher: P[T] => M[U]): P[U]

      def zero: M[Nothing]
      def one[T](x: P[T]): M[T]
      def guard[T](cond: P[Boolean], then: => P[T]): M[T]
    }

P and M are derived from one's signature (`def one[T](x: P[T]): M[T]`)

if no `__match` is found, we assume the following implementation (and generate optimized code accordingly)

    object __match extends MatchStrategy[({type Id[x] = x})#Id, Option] {
      def zero = None
      def one[T](x: T) = Some(x)
      // NOTE: guard's return type must be of the shape M[T], where M is the monad in which the pattern match should be interpreted
      def guard[T](cond: Boolean, then: => T): Option[T] = if(cond) Some(then) else None
      def runOrElse[T, U](x: T)(f: T => Option[U]): U = f(x) getOrElse (throw new MatchError(x))
    }

Source
  PatternMatching.scala

Linear Supertypes
AnyRef, Any
Known Subclasses
TypedSubstitution, MatchAnalyzer, MatchApproximator, CodegenCore, OptimizedCodegen, PureCodegen, PureMatchMonadInterface, CommonSubconditionElimination, MatchOptimizer, SwitchEmission, MatchTranslator, TreeMakers, OptimizingMatchTranslator, PureMatchTranslator
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Ordering

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2. By Inheritance

Inherited

1. MatchMonadInterface
2. AnyRef
3. Any

Implicitly

1. by any2stringadd
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

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Visibility

1. Public
2. All

### Abstract Value Members

1.  abstract val typer: (analyzer)#Typer

### Concrete Value Members

1.  final def !=(arg0: Any): Boolean
   Definition Classes
     AnyRef → Any
2.  final def ##(): Int
   Definition Classes
     AnyRef → Any
3.  def +(other: String): String
   Implicit
     This member is added by an implicit conversion from MatchMonadInterface to any2stringadd[MatchMonadInterface] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
4.  def ->[B](y: B): (MatchMonadInterface, B)
   Implicit
     This member is added by an implicit conversion from MatchMonadInterface to ArrowAssoc[MatchMonadInterface] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
5.  final def ==(arg0: Any): Boolean
   Definition Classes
     AnyRef → Any
6.  final def asInstanceOf[T0]: T0
   Definition Classes
     Any
7.  def clone(): AnyRef
   Attributes
     protected[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws( ... ) @native()
8.  def ensuring(cond: (MatchMonadInterface) ⇒ Boolean, msg: ⇒ Any): MatchMonadInterface
   Implicit
     This member is added by an implicit conversion from MatchMonadInterface to Ensuring[MatchMonadInterface] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
9.  def ensuring(cond: (MatchMonadInterface) ⇒ Boolean): MatchMonadInterface
   Implicit
     This member is added by an implicit conversion from MatchMonadInterface to Ensuring[MatchMonadInterface] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
10.  def ensuring(cond: Boolean, msg: ⇒ Any): MatchMonadInterface
    Implicit
      This member is added by an implicit conversion from MatchMonadInterface to Ensuring[MatchMonadInterface] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
11.  def ensuring(cond: Boolean): MatchMonadInterface
    Implicit
      This member is added by an implicit conversion from MatchMonadInterface to Ensuring[MatchMonadInterface] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
12.  final def eq(arg0: AnyRef): Boolean
    Definition Classes
      AnyRef
13.  def equals(arg0: Any): Boolean
    Definition Classes
      AnyRef → Any
14.  def finalize(): Unit
    Attributes
      protected[lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( classOf[java.lang.Throwable] )
15.  final def getClass(): Class[_]
    Definition Classes
      AnyRef → Any
    Annotations
      @native()
16.  def hashCode(): Int
    Definition Classes
      AnyRef → Any
    Annotations
      @native()
17.  final def isInstanceOf[T0]: Boolean
    Definition Classes
      Any
18.  val matchOwner: Global.Symbol
19.  final def ne(arg0: AnyRef): Boolean
    Definition Classes
      AnyRef
20.  final def notify(): Unit
    Definition Classes
      AnyRef
    Annotations
      @native()
21.  final def notifyAll(): Unit
    Definition Classes
      AnyRef
    Annotations
      @native()
22.  def pureType(tp: Global.Type): Global.Type
23.  def reportMissingCases(pos: Global.Position, counterExamples: List[String]): Unit
24.  def reportUnreachable(pos: Global.Position): Unit
25.  final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
      AnyRef
26.  def toString(): String
    Definition Classes
      AnyRef → Any
27.  final def wait(): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
28.  final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
29.  final def wait(arg0: Long): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... ) @native()
30.  def →[B](y: B): (MatchMonadInterface, B)
    Implicit
      This member is added by an implicit conversion from MatchMonadInterface to ArrowAssoc[MatchMonadInterface] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Deprecated Value Members

1.  def formatted(fmtstr: String): String
   Implicit
     This member is added by an implicit conversion from MatchMonadInterface to StringFormat[MatchMonadInterface] performed by method StringFormat in scala.Predef.
   Definition Classes
     StringFormat
   Annotations
     @deprecated @inline()
   Deprecated

     (Since version 2.12.16) Use `formatString.format(value)` instead of `value.formatted(formatString)`, or use the `f""` string interpolator. In Java 15 and later, `formatted` resolves to the new method in String which has reversed parameters.

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd from MatchMonadInterface to any2stringadd[MatchMonadInterface]

### Inherited by implicit conversion StringFormat from MatchMonadInterface to StringFormat[MatchMonadInterface]

### Inherited by implicit conversion Ensuring from MatchMonadInterface to Ensuring[MatchMonadInterface]

### Inherited by implicit conversion ArrowAssoc from MatchMonadInterface to ArrowAssoc[MatchMonadInterface]

### Ungrouped