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book.tex

@@ -1070,12 +1070,12 @@ Appendix~\ref{appendix:utilities}.\\
 \chapter{Integers and Variables}
 \label{ch:int-exp}
 
-This chapter is about compiling the subset of Racket that includes
-integer arithmetic and local variable binding, which we name $R_1$, to
-x86-64 assembly code~\citep{Intel:2015aa}.  Henceforth we refer
-to x86-64 simply as x86.  The chapter begins with a description of the
-$R_1$ language (Section~\ref{sec:s0}) followed by a description of x86
-(Section~\ref{sec:x86}). The x86 assembly language is large, so we
+This chapter is about compiling a subset of Racket named $R_1$, that
+includes integer arithmetic and local variable binding, to x86-64
+assembly code~\citep{Intel:2015aa}.  Henceforth we refer to x86-64
+simply as x86.  The chapter begins with a description of the $R_1$
+language (Section~\ref{sec:s0}) followed by a description of x86
+(Section~\ref{sec:x86}). The x86 assembly language is large so we
 discuss only what is needed for compiling $R_1$. We introduce more of
 x86 in later chapters. Once we have introduced $R_1$ and x86, we
 reflect on their differences and come up with a plan to break down the
@@ -1085,10 +1085,9 @@ chapter give detailed hints regarding each step
 (Sections~\ref{sec:uniquify-s0} through \ref{sec:patch-s0}).  We hope
 to give enough hints that the well-prepared reader, together with a
 few friends, can implement a compiler from $R_1$ to x86 in a couple
-weeks while at the same time leaving room for some fun and creativity.
-To give the reader a feeling for the scale of this first compiler, the
-instructor solution for the $R_1$ compiler is less than 500 lines of
-code.
+weeks.  To give the reader a feeling for the scale of this first
+compiler, the instructor solution for the $R_1$ compiler is
+approximately 500 lines of code.
 
 \section{The $R_1$ Language}
 \label{sec:s0}
@@ -1241,7 +1240,7 @@ provide open recursion in the form of method overriding\index{method
 $R_1$ and $R_2$ using the
 \href{https://docs.racket-lang.org/guide/classes.html}{\code{class}}
 \index{class} feature of Racket.  We define one class for each
-language and place a method for interpreting expressions inside each
+language and define a method for interpreting expressions inside each
 class. The class for $R_2$ inherits from the class for $R_1$ and the
 method \code{interp-exp} for $R_2$ overrides the \code{interp-exp} for
 $R_1$. Note that the default case in \code{interp-exp} for $R_2$ uses
@@ -1404,7 +1403,7 @@ The goal for this chapter is to implement a compiler that translates
 any program $P_1$ written in the $R_1$ language into an x86 assembly
 program $P_2$ such that $P_2$ exhibits the same behavior when run on a
 computer as the $P_1$ program interpreted by \code{interp-R1}.  That
-is, they both output the same integer $n$. We depict this correctness
+is, they output the same integer $n$. We depict this correctness
 criteria in the following diagram.
 \[
 \begin{tikzpicture}[baseline=(current  bounding  box.center)]
@@ -2600,11 +2599,9 @@ Adapt the partial evaluator from Section~\ref{sec:partial-evaluation}
 (Figure~\ref{fig:pe-arith}) so that it applies to $R_1$ programs
 instead of $R_0$ programs. Recall that $R_1$ adds \key{let} binding
 and variables to the $R_0$ language, so you will need to add cases for
-them in the \code{pe-exp} function. Also, note that the \key{program}
-form changes slightly to include an $\itm{info}$ field.  Once
-complete, add the partial evaluation pass to the front of your
-compiler and make sure that your compiler still passes all of the
-tests.
+them in the \code{pe-exp} function. Once complete, add the partial
+evaluation pass to the front of your compiler and make sure that your
+compiler still passes all of the tests.
 \end{exercise}
 
 The next exercise builds on Exercise~\ref{ex:pe-R1}.