Scala Compiler2.12.21 < Back
 

# 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
 
Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. MatchMonadInterface
2. AnyRef
3. Any

Implicitly

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

1. Hide All
2. Show All

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