module arrays

// index_of_first returns the index of the first element of `array`, for which the predicate fn returns true.
// If predicate does not return true for any of the elements, then index_of_first will return -1.
// Example: assert arrays.index_of_first([4,5,0,7,0,9], fn(idx int, x int) bool { return x == 0 }) == 2
pub fn index_of_first[T](array []T, predicate fn (idx int, elem T) bool) int {
    for i, e in array {
        if predicate(i, e) {
            return i
        }
    }
    return -1
}

// index_of_last returns the index of the last element of `array`, for which the predicate fn returns true.
// If predicate does not return true for any of the elements, then index_of_last will return -1.
// Example: assert arrays.index_of_last([4,5,0,7,0,9], fn(idx int, x int) bool { return x == 0 }) == 4
pub fn index_of_last[T](array []T, predicate fn (idx int, elem T) bool) int {
    for i := array.len - 1; i >= 0; i-- {
        e := array[i]
        if predicate(i, e) {
            return i
        }
    }
    return -1
}