tex: add stuff on dhall

tex/references.bib

@@ -79,6 +79,14 @@
 	note={{Available from: \url{https://dhall-lang.org}. [viewed 2023-05-17]}},
 }
 
+@misc{dhallprelude,
+	howpublished = {[online]},
+	title = {{Prelude-v23.0.0}},
+	author = {{The Dhall Language Contributors}},
+	year = 2023,
+	note={{Available from: \url{https://store.dhall-lang.org/Prelude-v23.0.0/}. [viewed 2023-05-24]}},
+}
+
 @misc{dhallnorm,
 	howpublished = {[online]},
 	title = {{Safety Guarantees}},

tex/text.tex

@@ -612,7 +612,27 @@ Figure~\ref{fig:dhallschema}. The \texttt{let} statement declares a variable
 called \texttt{Schema} and assigns it the result of the expression on the right
 side of the equals sign, which has for practical reasons been trimmed and is
 displayed without the \emph{default} block, which is instead shown in its own
-Figure~\ref{fig:dhallschemadefault}.
+Figure~\ref{fig:dhallschemadefaults}.
+
+The main configuration is comprised of both raw attributes and child records,
+which allows for grouping of related functionality. For instance, configuration
+settings pertaining mailserver setup are grouped in a record named
+\textbf{Mailer}. Its attribute \textbf{Enabled} is annotated as \textbf{Bool},
+which was deemed appropriate for a on-off switch-like functionality, with the
+only permissible values being either \emph{True} or \emph{False}. Do note that
+in Dhall \[true != True\], since \textbf{True} is internally a Bool constant,
+which is built into Dhall (check out ``The Prelude''~\cite{dhallprelude}),
+while \textbf{true} is evaluated as an \emph{unbound} variable, that is, a
+variable \emph{not} defined in the current \emph{scope} and thus not
+\emph{present} in the current scope.
+
+Another one of specialties of Dhall is that $==$ and $!=$ equality operators
+only work on values of type \texttt{Bool}, which for example means that
+variables of type \texttt{Natural} (\texttt{uint}) or \texttt{Text}
+(\texttt{string}) cannot be compared directly as in other languages, which
+either leaves the work for a higher-level language (such as Go), or from the
+perspective of the Dhall authors, \emph{enums} are promoted when the value
+matters.
 
 \begin{figure}[h]
   \begin{varwidth}