Tooting my own horn here, but I'm working on a book covering the Go Standard Library. Still in progress, and not at the sync package yet, but it's coming along. Check it out if you feel inclined.

http://thestandardlibrary.com/go.html

You know what'd be cool? To take arbitrary code in a language, pattern match on the implementation in that language of each std lib function, and actively recommend substitutes for duplicated code.

That would be very cool. I wonder how hard it would be though. At least in Go I know that the standard lib contains lots of duplicate code (primarily so that things that should be small don't require larger things as dependencies. I think the time package's String() functions use reimplemented fmt package functionality for example, since fmt is a much larger dependency than time should have.)

Yes, but outside the Go standard libraries, adding a dependency on a standard library isn't a big deal and won't add a cycle.

Yes. What I mean though is that if you are reimplementing, say, fmt.Printf, such a suggestion system might correctly suggest you use fmt.Printf instead, but also suggest you can use func (m Month) String() string from time, or something equally silly.

Since the standard libs in Go duplicate code, you would have to be careful that your suggestion system isn't picking up false positives. I think the idea has a lot of promise though.

Looks interesting (thanks). Will certainly check it out.