Accessing array index variable from bash shell script loop

I want to access the array index variable while looping thru an array in my bash shell script.

myscript.sh

#!/bin/bash
AR=('foo' 'bar' 'baz' 'bat')
for i in ${AR[*]}; do
  echo $i
done

The result of the above script is:

foo
bar
baz
bat

The result I seek is:

0
1
2
3

How do I alter my script to achieve this?