Pattern Matching in Scala
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The document discusses pattern matching in Scala, focusing on user accounts which can be either PayPal or Bitcoin. It includes examples of case classes for users and accounts, as well as methods for identifying account types. Additionally, it showcases advanced pattern matching techniques to extract specific information from user objects.
Pattern Matching in Scala
- 1. Pa$ern Matching in Scala
- 2. First, an example • Users have accounts • Accounts are either Paypal or Bitcoin • Paypal accounts have an email • Bitcoin accounts have a key
- 3. case class User(name: String, account: Account) sealed class Account case class Paypal(email: String) extends Account case class Bitcoin(key: String) extends Account
- 4. Iden@fy account type private String whatis(Object obj) { if(obj instanceof User) { User user = (User) obj; if(user.account instanceof Paypal) { Paypal paypal = (Paypal) user.account; return "Paypal for email " + paypal.email; } else if(user.account instanceof Bitcoin) { Bitcoin bitcoin = (Bitcoin) user.account; return "Bitcoin with key " + bitcoin.key; } else { return "Unknown account type" } } else { return "Unknown object type"; } }
- 5. Iden@fy account type def whatis(obj: Any) { obj match { case User(name, Paypal(email)) => "Paypal for email " + email case User(name, Bitcoin(key)) => "Bitcoin with key " + key case _ => "Unknown object type" } }
- 6. Lots more power def whatis(obj: Any) { obj match { case User(name, Paypal("[email protected]")) if(!name.isEmpty) => "Bilbo's got Paypal" ... } }
- 7. Pa$erns on val crea@on def getTuple: (User, Account) = ... // Decompose the tuple, no need for _1 and _2 accessors val (user,account) = getTuple