Scala Currying
Examples
A configurable multiplier as a curried function
def multiply(factor: Int)(numberToBeMultiplied: Int): Int = factor * numberToBeMultiplied
val multiplyBy3 = multiply(3)_ // resulting function signature Int => Int
val multiplyBy10 = multiply(10)_ // resulting function signature Int => Int
val sixFromCurriedCall = multiplyBy3(2) //6
val sixFromFullCall = multiply(3)(2) //6
val fortyFromCurriedCall = multiplyBy10(4) //40
val fortyFromFullCall = multiply(10)(4) //40Multiple parameter groups of different types, currying parameters of arbitrary positions
def numberOrCharacterSwitch(toggleNumber: Boolean)(number: Int)(character: Char): String =
if (toggleNumber) number.toString else character.toString
// need to explicitly specify the type of the parameter to be curried
// resulting function signature Boolean => String
val switchBetween3AndE = numberOrCharacterSwitch(_: Boolean)(3)('E')
switchBetween3AndE(true) // "3"
switchBetween3AndE(false) // "E"Currying a function with a single parameter group
def minus(left: Int, right: Int) = left - right
val numberMinus5 = minus(_: Int, 5)
val fiveMinusNumber = minus(5, _: Int)
numberMinus5(7) // 2
fiveMinusNumber(7) // -2