Senior Software Developer and Lead Trainer Alejandro Lujan explains pattern matching, a very powerful and elegant feature of Scala, using a series of examples. Learn more about this topic and find more presentation on Scala at:

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("bilbo@shire.com"))
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