scala
trait PartialFunction

[source: `scala/PartialFunction.scala`]

`` `trait` PartialFunction[-A, +B]
  `extends` (A) => B

  A partial function of type `PartialFunction[A, B]` is a unary function where the domain does not include all values of type `A`. The function `isDefinedAt` allows to test dynamically, if a value is in the domain of the function.

Author
  Martin Odersky
Version
  1.0, 16/07/2003

Direct Known Subclasses:
  Seq, Map, MutableList

Method Summary
`override def` | andThen [C](k : (B) => C) : PartialFunction[A, C] (f andThen g)(x) = g(f(x))
`abstract def` | isDefinedAt (x : A) : Boolean Checks if a value is contained in the functions domain.
`def` | orElse [A1 <: A, B1 >: B](that : PartialFunction[A1, B1]) : PartialFunction[A1, B1]

Methods inherited from Function1
apply (abstract), toString, compose

Methods inherited from AnyRef
getClass, hashCode, equals, clone, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized

Methods inherited from Any
==, !=, isInstanceOf, asInstanceOf

Method Details

`abstract` `def` isDefinedAt(x : A) : Boolean

  Checks if a value is contained in the functions domain.

Parameters
  `x -` the value to test
Returns
  true, iff `x` is in the domain of this function.

`` `def` orElse[A1 <: A, B1 >: B](that : PartialFunction[A1, B1]) : PartialFunction[A1, B1]

`override` `def` andThen[C](k : (B) => C) : PartialFunction[A, C]

  (f andThen g)(x) = g(f(x))

Overrides
  Function1.andThen