cheat.sheets/sheets/_scala/PatternMatching

// 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")
}