My version of http://k0kubun.hatenablog.com/entry/2014/07/06/033336

peco-find-file.zsh

function peco-find-file() {
    local source_files
    if git rev-parse 2> /dev/null; then
        source_files=$(git ls-files)
    else
        source_files=$(find . -type f)
    fi
    local selected_files=$(echo $source_files | peco --prompt "[find file]")

    LBUFFER="${LBUFFER% } $(echo ${selected_files} | tr '\n' ' ')"
    zle redisplay
}
zle -N peco-find-file
bindkey '^u^f' peco-find-file