autoload -U compinit
compinit
#zmodload zsh/files
bindkey -e
prompt='%h %n@%m%(#.#.$) '

make_p () {
    local x i
    x="$1"

    [ -f $x ] || return 0

    for i; do
        [ -f $i -a $i -nt $x ] && return 0
    done

    return 1
}

cache_hosts_file="$HOME/.cache_hosts"
known_hosts_file="$HOME/.ssh/known_hosts"

print_cache_hosts () {
    if [ -f $known_hosts_file ]; then
        awk '{ if (split($1, a, ",") > 1) for (i in a) { if (a[i] ~ /^[a-z]/) print a[i] } else print $1 }' $known_hosts_file
    fi
}

update_cache_hosts () {
    print_cache_hosts | sort -u > $cache_hosts_file
}

make_p $cache_hosts_file $known_hosts_file && update_cache_hosts

_cache_hosts=( $(cat $cache_hosts_file) )