What's the advantage of doing everything in the same process? Your article said this is nicer but I don't see what the advantages are and there are some disadvantages I listed (ABI issues, security).
Well, spawn() and pctl() are actually more like a finer-grained fork(), without the necessity of, for example, O_CLOEXEC, or anything in fcntl. Between pctl() and Limbo's channels (on which Go's are patterned), a lot of what is required for security in "vanilla" Unix is unnecessary.
What I was trying to convey in the article (sorry if it was a bit vague) was that using functions available to the shell was the nice part, the actual advantage over regular Unix. That is to say, if a user passes '*[0-9]?.gz', you can call functions within the shell to handle the glob rather than having to implement them yourself, for example. The shell is also designed as a library, in other words. This includes things such as parsing sh's syntax, even.
