#!/bin/zsh

TAGS=( $(herbstclient tag_status 0 | tr ":\!.+#" " ") )
FOO=$(for i in "${TAGS[@]}"; do echo $i; done | dmenu)

if [[ "${TAGS[@]}" != *"$FOO"* ]]; then
    herbstclient add $FOO
fi

herbstclient use $FOO