Hand Rolled Pattern Matcher

roll-your-own-pattern-matcher.scala

object Match {
  trait Matchable[A] { 
    def `match`[B](cases: PartialFunction[A, B]*): B
  }
  
  implicit def anyToMatchable[A](a: A): Matchable[A] = new Matchable[A]{
    def `match`[B](cases: PartialFunction[A, B]*) = {
      cases.toList match {
        case Nil => throw new MatchError(a)
        case x :: _ if x.isDefinedAt(a) => x(a)
        case _ :: xs => a `match` (xs : _*) 
      }
    }
  }
}


import Match._
import Stream._

(Stream(1), Stream(2)) `match` (
  {case (Stream.Empty, Stream.Empty) => None},
  {case (l #:: ls, rs) => None}
)