fish_prompt.zsh

fish_path() {
        setopt localoptions rcquotes nullglob
        local result part; local -a tree expn; local -i i
        (
                tree=(${(s:/:)${1-${PWD/#$HOME/\~}}})
                if [[ $tree[1] == \~* ]] {
                        cd -q ${~tree[1]}
                        result=$tree[1]; shift tree
                } else { cd -q / }
                for dir in $tree; {
                        if (( $#tree == 1 )) {
                                result+="/$tree" && break
                        }
                        expn=(a b); part=''; i=0
                        until [[ (( ${#expn} == 1 )) || $dir = $expn || $i -gt 99 ]] do
                                (( i++ )); part+=$dir[$i]; expn=($(part*(-/))) && break
                        done
                        result+="/$part"; cd -q $dir && shift tree
                }
                print -n ${result:-/}
        )
}
setopt promptsubst
if (( EUID == 0 || UID == 0 )) then
    PS1='%n@%m %F{red}$(fish_path)%f# '
else
    PS1='%n@%m %F{green}$(fish_path)%f> '
fi