Enums: Mention sum types / discriminated unions

Author: dbrgn

sections/reading_rust.tex

@@ -198,7 +198,7 @@ \section{Reading Rust}
 \end{columns}
   \begin{itemize}
     \item<1-> In its simplest form similar to C/C++ (but type safe)
-	\item<1-> Data that is one of several possible variants
+    \item<1-> Data that is one of several possible variants (sum type, discriminated union)
     \item<2> We can match (switch) on enums
     \item<2> We \emph{must} match all variants
   \end{itemize}