// use case in function args for pattern matching. (xs zip ys) map { case (x,y) => x*y } // GOOD (xs zip ys) map( (x,y) => x*y ) // BAD // "v42" is interpreted as a name matching any Int value, and "42" is printed. // BAD val v42 = 42 Some(3) match { case Some(v42) => println("42") case _ => println("Not 42") } // "`v42`" with backticks is interpreted as the existing val v42, and “Not 42” is printed. // GOOD val v42 = 42 Some(3) match { case Some(`v42`) => println("42") case _ => println("Not 42") } // UppercaseVal is treated as an existing val, rather than a new pattern variable, because it starts with an uppercase letter. // Thus, the value contained within UppercaseVal is checked against 3, and “Not 42” is printed. // GOOD val UppercaseVal = 42 Some(3) match { case Some(UppercaseVal) => println("42") case _ => println("Not 42") } // Creating an alias for a match // This will maintain the original value passed into the match function, using the '@' symbol, and print "Matched Some(3)" Some(3) match { case foundSome @ Some(_) => println("Matched " + foundSome) case _ => println("Matched nothing") } // Case Classes // This method allows you to match on any combination of properties of a case class case class Example(a: Int, b: String, c: Boolean) Example(1, "word", true) match { case Example(3, _, _) => println("Matches any Example where a = 3") case Example(_, "foo", _) => println("Matches any Example where b = foo") case Example(_, _, false) => println("Matches any Example where c = false") case Example(1, "word", true) => println("Matches our Example") case Example(_, _, _) => println("Matches any other Example") }