mirror of
https://github.com/chubin/cheat.sheets
synced 2024-11-03 15:40:17 +00:00
47 lines
1.7 KiB
Plaintext
47 lines
1.7 KiB
Plaintext
// 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")
|
|
}
|