It looks to be a custom function for parsing JSON arrays: https://github.com/haifengl/smile/blob/5bf4075b2978af68b31c7...
The benefit is that the type will be known to be JSArray without need for runtime casting (at least, outside the scope of the function). For comparison, `json` returns a JSObject.
I honestly haven't seen this before working with Scala, and it's defined just for the smile repository.
I'm curious, now: can a Scala person (this is Scala, right?) explain what the difference is between these two things?