FindIndex in DataWeave

findIndex.dwl

fun indexOf<T>(array: Array<T>, elem: T, carry: Number = 0): Number =
    array match {
        case [] -> -1
        case [head ~ tail] ->
            if(head == elem)
                carry
            else
                findIndex(tail, elem, carry + 1)
    }

var HelloWorld = "Hello World!" splitBy ''

---

HelloWorld findIndex 'H' // 0
HelloWorld findIndex 'o' // 4
HelloWorld findIndex 'aaaaa' // -1

fun indexOf <T>(array: Array<T>, elem: T, carry: Number = 0): Number =
    array match {
        case [] -> -1
        case [head ~ tail] ->
            if(head == elem)
                carry
            else
                indexOf(tail, elem, carry + 1)
    }

var HelloWorld = "Hello World!" splitBy ''

---
[
  HelloWorld indexOf 'H', // 0
  HelloWorld indexOf 'o', // 4
  HelloWorld indexOf 'aaaaa' // -1
]