Sir Anthony Hoare calls the null reference his billion dollar mistake because it has led to "innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years." Whether the order of magnitude is true remains to be proven by the scientific community but I think it's fair to say that null references are one of the leading causes of sleep deprivation for developers about to release. Thankfully most programming languages have been extended with alternate ways to handle "the absence of value" that lead to more expressive code, less room for errors and better sleep.

In this talk we will explore the Nullability possibilities that C#8 and 9 provide, the alternate ways that other languages like Python, Kotlin or F# have picked and techniques such as Railway-Oriented Programming or the Null-Object-Pattern that can help if the language of choice does not provide an option. Finally we'll look at migration options for older code bases.