I personally think nobody should emit null values ...

# rx

[thomasnield]

I personally think nobody should emit null values if they can help it. What is problematic is some libraries (like JavaFX) do yield null values for things like controls with no values. That will mess up my RxJavaFX project when it's carried over. I may copy what Tomas Mikula did with ReactFX and have "notNull()" variants of factories.