Using bash to implement recursion-based reduce

reduce.sh

#!/bin/bash

function testRecurse {

  ONE=${1:0}
  TWO=("${@:1}")

  if [[ $# -eq 1 ]]; then
    echo Final answer $ONE
  else
    echo \|${TWO[1]}\|
    let ACC=ONE+TWO[1]
    ARR=("${TWO[@]:2}")
    echo recursion $ACC - $ARR
    testRecurse $ACC ${ARR[@]}
  fi
}

testRecurse
testRecurse 10
testRecurse 10 1 2 3 4