playground.swift

import UIKit


// Runnable -> no input, no output
// Callable -> no input -> Producer
// Function -> input, output
// Consumer

// **Higher order function**

func runnable() {
    print("this is some lambda")
}

func consumer(a: String) {
    print(a)
}

func producer() -> String {
    return "a"
}

func producer2() -> String {
    return "b"
}


func functional(a: String) -> String {
    return a.uppercased()
}
 

func anotherFunction(randomFunction:()->String) {
    print(randomFunction())
}

func newFunction(r: (String)-> String) { // r is functional
    print(r("Gello1")) // print(functional("hello"))
}

func ViewCreate(clickHandler:()->()) {

    // framework view clicked
    clickHandler()
}




anotherFunction(randomFunction: producer)
newFunction(r: functional)

// Lambda - only this is required
newFunction { a in
    return a.lowercased()
}


//anotherFunction(randomFunction: producer2)

func unit_test(setup:()->(), teardown:()->()) {
    setup()
    // unit test code
    teardown()
}



let f1: ()->() = runnable
let f2: (String) -> () = consumer
let f3: ()-> (String) = producer
let f4: (String)->(String) = functional
let f5 = producer // type inference


// f1...f5-> storing function in a variable
// int, function


print(f3()) // function call
print(f5()) // print(producer())