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Instance Methods are Curried Functions in Swift

An instance method in Swift is just a type method that takes the instance as an argument and returns a function which will then be applied to the instance.

class BankAccount {
    var balance: Double = 0.0

    func deposit(amount: Double) {
        balance += amount
    }
}

We can obviously create an instance of this class and call the deposit() method on that instance:

let account = BankAccount()
account.deposit(100) // balance is now 100

So far, so simple. But we can also do this:

let depositor = BankAccount.deposit
depositor(account)(100) // balance is now 200

Ole Begemann

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