Check if a value is in an array in Bash

array_contains.sh

##
# Determine if a given element exists in an array.
#
# Based on:
# https://stackoverflow.com/a/11525897/4342230
#
# @param  string    $1
#   The value to look for (the "needle").
# @param  string... $2...
#   The array of values to search (the "haystack").
#
# @return int
#   Either success (0) if the needle was found in the haystack; or, 1 if it was
#   not.
#
array_contains() {
  local needle="${1}"; shift
  local haystack=( "${@}" )

  for current_element in "${haystack[@]}"; do
    if [[ "${current_element}" == "${needle}" ]]; then
      return 0
    fi
  done

  return 1
}