[enneff]

Sorry, I missed the blog post. The Go code in the post is garbage. It doesn't check errors, which all good Go code does. (His plan to "add error handling only if the compiler told [him] to" is a bad idea.) I talk about the Go philosophy of error handling here: https://www.youtube.com/watch?v=dKGmK_Z1Zl0#t=27m10s

json.Unmarshal only returns an error value, so it never "returns an empty list". Instead you provide it with a []byte of the JSON data you want decoded and a pointer to the data structure into which to put the decoded data. If you don't check the error value returned by json.Unmarshal then you don't know if it decoded anything or not. That's why the author is left with an empty list.

In reality you'd add two lines to get the following code, which does not proceed past the failure in json.Unmarshal: http://play.golang.org/p/rYfwncjU2f

An aside: os.Getenv doesn't return an error value because it's a convenience that is mostly used in contexts where you don't care if the variable is set or not (in the shell you usually don't care either, you just test for != ""). If you actually care you can inspect the environment with os.Environ. But in this case it doesn't matter.