And more importantly, if a function has [WifiResult] as the defined return type, you can be absolutely definitely sure that you get a list back. This is not so

And more importantly, if a function has [WifiResult] as the defined return type, you can be absolutely definitely sure that you get a list back. This is not something inherently unique to Haskell. Any strictly typed language could easily have chosen to not let null be a member of all classes. Or at the very least add some "non-nullable" qualifier to types.