And exactly that was what I meant 
When calling an API that extracts some value from an opaque type, we don’t care if this value is extracted/returned just by patternmatching a tuple, fetching some state from another process or even from the “outside world” via ports. And since the type is opaque and we are all well behaving programmers, we don’t even care if we pass a tuple, a pid or something else around.
We are aware though that some function called with the same set of data may return different values on multiple calls. Try to make this understandable and comfortable to a Haskeller without using the “M” word
