Scala single method interface implementation

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Scala has experimental support for SAMs starting with 2.11, under the flag -Xexperimental:

Welcome to Scala version 2.11.0-RC3 (OpenJDK 64-Bit Server VM, Java 1.7.0_51).
Type in expressions to have them evaluated.
Type :help for more information.

scala> :set -Xexperimental

scala> val r: Runnable = () => println("hello world")
r: Runnable = $anonfun$1@7861ff33

scala> new Thread(r).run
hello world

Edit: Since 2.11.5, this can also be done inline:

scala> new Thread(() => println("hello world")).run
hello world

The usual limitations about the expected type also apply:

  • it must define a single abstract method,
  • its primary constructor (if any) must be public, no-args, not overloaded,
  • the abstract method must take a single argument list,
  • the abstract method must be monomorphic.

According to the original commit by Adriaan, some of those restrictions may be lifted in the future, especially the last two.

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