added exercises for chapters 7 and 8

book.tex

@@ -6401,7 +6401,7 @@ _mainconclusion:
 \end{figure}
 
 \begin{exercise}\normalfont
-Expand your compiler to handle $R_4$ as outlined in this section.
+Expand your compiler to handle $R_4$ as outlined in this chapter.
 Create 5 new programs that use functions, including examples that pass
 functions and return functions from other functions and including
 recursive functions. Test your compiler on these new programs and all
@@ -6874,6 +6874,12 @@ $\Downarrow$
 Figure~\ref{fig:R5-passes} provides an overview of all the passes needed
 for the compilation of $R_5$.
 
+\begin{exercise}\normalfont
+Expand your compiler to handle $R_5$ as outlined in this chapter.
+Create 5 new programs that use \key{lambda} functions and make use of
+lexical scoping. Test your compiler on these new programs and all of
+your previously created test programs.
+\end{exercise}
 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -7405,6 +7411,13 @@ of type \code{Any} in the same way that it treats variables of type
   to the root stack instead of the normal procedure call stack.
 \end{itemize}
 
+\begin{exercise}\normalfont
+Expand your compiler to handle $R_6$ as discussed in the last few
+sections.  Create 5 new programs that use the \code{Any} type and the
+new operations (\code{inject}, \code{project}, \code{boolean?},
+etc.). Test your compiler on these new programs and all of your
+previously created test programs.
+\end{exercise}
 
 \section{Compiling $R_7$ to $R_6$}
 \label{sec:compile-r7}
@@ -7550,6 +7563,19 @@ $\Rightarrow$
 \label{fig:compile-r7-r6}
 \end{figure}
 
+
+\begin{exercise}\normalfont
+Expand your compiler to handle $R_7$ as outlined in this chapter.
+Create tests for $R_7$ by adapting all of your previous test programs
+by removing type annotations. Add 5 more tests programs that
+specifically rely on the language being dynamically typed. That is,
+they should not be legal programs in a statically typed language, but
+nevertheless, they should be valid $R_7$ programs that run to
+completion without error.
+\end{exercise}
+
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \chapter{Gradual Typing}
 \label{ch:gradual-typing}