90% of the time you don't need to check the value for null, because it won't be null and that will be reflected in the type. In langauges where all types contai

90% of the time you don't need to check the value for null, because it won't be null and that will be reflected in the type. In langauges where all types contain null, there is no way for a function to communicate that it always returns a non-null value, which forces the caller to make redundant checks. If the value can be null, then they are at risk of NullReferenceExceptions if they fail to check. In cases where the value could be missing, the type is change to Maybe and the caller is forced to handle the null case. They can still avoid explicit checks using various combinators (>>=, fmap, liftA2 etc.) which propagate empty Maybe values. Explicit matching on Maybe is fairly uncommon in languages which support it.