In general it’s not, although for a number of languages (e.g. java, ruby, go) it kinda is. Here the dictionary is supposed to hold Item values, not Optional[It

In general it’s not, although for a number of languages (e.g. java, ruby, go) it kinda is. Here the dictionary is supposed to hold Item values, not Optional[Item], so None would be the signal of a missing item. Think Lookup k -> Map k a -> Maybe a Not sure how that came about tho, as the article specifically argues against returning a None for missing entries?