Currying in Swift

Currying in Swift

• 1.
  Currying in Swift A tale of state encapsulation Maxim Zaks @iceX33
• 2.
  Every presentation needsa theme
• 3.
  func amountWithVat(vat:Float, amount:Float) -> Float { return roundf((1 + vat) * amount) } let amount1 = amountWithVat(0.19, 100) let amount2 = amountWithVat(0.19, 200) let amount3 = amountWithVat(0.2, 300)
• 4.
  func amountWithVat(vat:Float)(amount: Float)-> Float { return roundf((1 + vat) * amount) } let addGermanVatTo = amountWithVat(0.19) let addUKVatTo = amountWithVat(0.2) let amount1 = addGermanVatTo(amount: 100) let amount2 = addGermanVatTo(amount: 200) let amount3 = addUKVatTo(amount: 300)
• 5.
  func amountWithVat( vat: Float, roundFunction : (Float)->Float = roundf) (amount: Float) -> Float { return roundFunction((1 + vat) * amount) } let addGermanVatTo = amountWithVat(0.19){ roundf($0 * 100) / 100 } let addUKVatTo = amountWithVat(0.2) let amount1 = addGermanVatTo(amount: 101) let amount2 = addGermanVatTo(amount: 200) let amount3 = addUKVatTo(amount: 300)
• 6.
  Should we consider currying as a revelation?
• 7.
  func amountWithVat(vat:Float)(amount: Float)-> Float { return roundf((1 + vat) * amount) } let addGermanVatTo = amountWithVat(0.19) let addUKVatTo = amountWithVat(0.2) let amount1 = addGermanVatTo(amount: 100) let amount2 = addGermanVatTo(amount: 200) let amount3 = addUKVatTo(amount: 300)
• 8.
  func amountWithVat(vat:Float) ->Float -> Float { return { (amount:Float) -> Float in return roundf((1 + vat) * amount) } } let addGermanVatTo = amountWithVat(0.19) let addUKVatTo = amountWithVat(0.2) let amount1 = addGermanVatTo(100) let amount2 = addGermanVatTo(200) let amount3 = addUKVatTo(300)
• 9.
  typedef float (^FloatToFloat)(float); FloatToFloat (^amountWithVat)(float) = ^FloatToFloat (float vat) { return ^(float amount){ return roundf((1 + vat) * amount); }; }; FloatToFloat addGermanVatTo = amountWithVat(.19); FloatToFloat addUKVatTo = amountWithVat(0.2); float amount1 = addGermanVatTo(100); float amount2 = addGermanVatTo(200); float amount3 = addUKVatTo(300);
• 10.
  Interesting application offunction currying found out by Ole Begemann (http://oleb.net/blog/2014/07/swift-instance-methods-curried-functions/)
• 11.
  class BankAccount { var balance: Double = 0.0 func deposit(amount: Double) { balance += amount } } let account = BankAccount() account.deposit(100) // balance is now 100 let depositor = BankAccount.deposit depositor(account)(100) // balance is now 200
• 12.
  So every methodis implemented internaly through function currying
• 13.
  One More Thing
• 14.
  Who knows thename of the show I used for the theme
• 16.
  Thank you MaximZaks @iceX33