create/use map in shell script

map.sh

#!/usr/bin/env bash

# put a key/value in map
# usage: map_put map_name key value
map_put() {
  [ "$#" != 3 ] && exit 1
  alias "${1}$2"="$3"
}

# get a value from map
# usage: map_get map_name key
map_get() {
  [ "$#" != 2 ] && exit 1
  if map_has_key $1 $2; then
    alias "${1}$2" | awk -F"'" '{ print $2; }'  
  fi
}

# get all keys from map
# returns array of keys
# usage: map_keys map_name 
map_keys() {
  [ "$#" != 1 ] && exit 1
  alias -p | grep $1 | cut -d'=' -f1 | awk -F"$1" '{print $2; }'
}

# check if map has a key
# usage: map_has_key map_name key
map_has_key() {
  [ "$#" != 2 ] && exit 1
  if alias ${1}$2 2>/dev/null>/dev/null; then
    return 0
  fi

  return 1
}