nice!

nice hack using length of source as maxlength

Also,

strings.Split(s, " ") is equvalent to string.Fields(s)

I'd say the proper way is:

import "unicode/utf8"

utf8.RuneCountInString()

Seen this on Go blog.
Cheers :)

This solutions doesn't account for unicode characters!
E.g. len("→") => 2
Use len([]rune("→") => 1