/*
* The map and fold function and lambda
* map returns a new list where the items in the original list have been
* transformed by the lambda
* fold returms a single thing that results from combining the list
* according to the lambda
* There are other functions like map and fold
* @author ggtowell
* @created Aug 3, 2021
 */
fun main() {
    val aa = listOf(1,2,3,4,5,6,7,8,9)
    println(aa)
    // create an anonymous function to square items
    val f2 = fun(av:Int):Int { return av*av}
    val f2l = { av:Int -> av*av*av }
    // use map with the anonyous func
    println(aa.map(f2))
    println(aa.map(f2l))

    // map with lambda to double items
    val aa2 = aa.map({av -> av*2 })
    println(aa2)
    // map with labmda to turn items into strings with []
    val aaS = aa.map({aq -> String.format("<<%d>>", aq)})
    println(aaS)
    // map to turn list into list of lists 
    println("AAA" + aa.map({aq -> listOf(aq*aq)}))
    
    // fold to compute sum   
    // the arguement in parens is the initial value
    println(aa.fold(0){sum, vl -> sum+vl})
    // fold to build a string representation
    println(aa.fold("aa"){sum, vl -> String.format("%s %d ", sum, vl)})
}