Slide 36
Slide 36 text
The Nothing Type
https://en.wikipedia.org/wiki/Bottom_type
" In type theory, a theory within mathematical logic,
the bottom type is the type that has no values. It is also
called the zero or empty type, and is sometimes denoted
with falsum (⊥).
A function whose return type is bottom cannot return any
value. In the Curry–Howard correspondence, the bottom
type corresponds to falsity. "