a little progress

book.tex

@@ -6971,6 +6971,7 @@ for $R_6$.
 \label{fig:interp-R6}
 \end{figure}
 
+\clearpage
 
 \section{The $R_7$ Language: Untyped Racket}
 \label{sec:r7-lang}
@@ -6989,8 +6990,10 @@ for $R_6$.
      &\mid& (\itm{cmp}\;\Exp\;\Exp) \mid \IF{\Exp}{\Exp}{\Exp} \\
      &\mid& (\key{vector}\;\Exp^{+}) \mid
       (\key{vector-ref}\;\Exp\;\Exp) \\
-  &\mid& (\key{vector-set!}\;\Exp\;\Exp\;\Exp) \mid (\key{void}) \\
-  &\mid& (\Exp \; \Exp^{*}) \mid (\key{lambda}\; (\Var^{*}) \; \Exp) \\
+     &\mid& (\key{vector-set!}\;\Exp\;\Exp\;\Exp) \mid (\key{void}) \\
+     &\mid& (\Exp \; \Exp^{*}) \mid (\key{lambda}\; (\Var^{*}) \; \Exp) \\
+     & \mid & (\key{boolean?}\;\Exp) \mid (\key{integer?}\;\Exp)\\
+     & \mid & (\key{vector?}\;\Exp) \mid (\key{procedure?}\;\Exp) \mid (\key{void?}\;\Exp) \\
   \Def &::=& (\key{define}\; (\Var \; \Var^{*}) \; \Exp) \\
 R_7  &::=& (\key{program} \; \Def^{*}\; \Exp)
 \end{array}
@@ -7061,7 +7064,7 @@ Figure~\ref{fig:interp-R7}.
           ((interp-r7 new-env) body)]
          [else (error "interp-r7, expected function, not" f-val)])])))
 \end{lstlisting}
-\caption{Interpreter for the $R_7$ language.}
+\caption{Interpreter for the $R_7$ language. UPDATE ME -Jeremy}
 \label{fig:interp-R7}
 \end{figure}
 
@@ -7073,7 +7076,7 @@ Figure~\ref{fig:interp-R7}.
 %% Most of the compiler passes only require straightforward changes.  The
 %% interesting part is in instruction selection.
 
-\section{Shrink}
+\section{Shrinking $R_6$}
 \label{sec:shrink-r6}
 
 In the \code{shrink} pass we recommend compiling \code{project} into
@@ -7081,10 +7084,11 @@ an explicit \code{if} expression that uses three new operations:
 \code{tag-of-any}, \code{value-of-any}, and \code{exit}.  The
 \code{tag-of-any} operation retrieves the type tag from a tagged value
 of type \code{Any}.  The \code{value-of-any} retrieves the underlying
-value from a tagged value.
-
-\code{exit}...
-
+value from a tagged value. Finally, the \code{exit} operation ends the
+execution of the program by invoking the operating system's
+\code{exit} function. So the translation for \code{project} is as
+follows. (We have ommitted the \code{has-type} AST nodes to make this
+output more readable.)
 
 \begin{tabular}{lll}
 \begin{minipage}{0.3\textwidth}
@@ -7105,9 +7109,10 @@ $\Rightarrow$
 \end{minipage}
 \end{tabular}  \\
 
+Similarly, we recommend translating the type predicates
+(\code{boolean?}, etc.) into uses of \code{tag-of-any} and \code{eq?}.
 
-
-\section{Instruction Selection}
+\section{Instruction Selection for $R_6$}
 \label{sec:select-r6}
 
 \paragraph{Inject}