vectorio is a library for Go (aka "golang") to implement the writev(2), and in the future, readv(2) system calls. This enables a list of byte slices to be efficiently written to a file without first copying them to an intermediate buffer. Go's built-in bufio library is the standard approach to buffered I/O, but vectorio can be a replacement to achieve the same goal but without copying data.
// Create a temp file to use
f, _ := ioutil.TempFile("", "vectorio")
defer f.Close()
data1 := []byte("foobarbaz")
data2 := []byte("foobazbar")
w, _ := vectorio.NewBufferedWritev(f)
w.Write(data2)
w.WriteIovec(syscall.Iovec{&data1[0], 9})
nw, _ := w.Flush()
fmt.Println("Wrote", nw, "bytes to file!")