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@@ -22,7 +22,7 @@
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\def\racketEd{0}
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\def\pythonEd{1}
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-\def\edition{0}
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+\def\edition{1}
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% material that is specific to the Racket edition of the book
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\newcommand{\racket}[1]{{\if\edition\racketEd{#1}\fi}}
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@@ -1815,8 +1815,10 @@ we define many interpreters, one for each of language that we
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study. Because each language builds on the prior one, there is a lot
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of commonality between these interpreters. We want to write down the
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common parts just once instead of many times. A naive approach would
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-be for the interpreter of \LangVar{} to handle the cases for variables
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-and \racket{\code{let}}\python{assignment} but dispatch to \LangInt{}
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+be for the interpreter of \LangVar{} to handle the
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+\racket{cases for variables and \code{let}}
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+\python{case for variables}
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+but dispatch to \LangInt{}
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for the rest of the cases. The following code sketches this idea. (We
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explain the \code{env} parameter soon, in
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Section~\ref{sec:interp-Lvar}.)
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@@ -1986,8 +1988,11 @@ y = 10
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print(-y)
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\end{lstlisting}
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\fi}
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-\noindent We can invoke the \code{interp\_exp} method for \LangVar{} on this
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-expression, call it \code{e0}, by creating an object of the \LangVar{} class
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+\noindent We can invoke the \code{interp\_exp} method for \LangVar{}
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+\racket{on this expression,}
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+\python{on the \code{-y} expression,}
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+%
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+call it \code{e0}, by creating an object of the \LangVar{} class
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and calling the \code{interp\_exp} method.
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{\if\edition\racketEd
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\begin{lstlisting}
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@@ -2058,7 +2063,7 @@ interpreter for \LangVar{} adds two new \key{match} cases for
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variables and \racket{\key{let}}\python{assignment}. For
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\racket{\key{let}}\python{assignment} we need a way to communicate the
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value bound to a variable to all the uses of the variable. To
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-accomplish this, we maintain a mapping from variables to values,
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+accomplish this, we maintain a mapping from variables to values
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called an \emph{environment}\index{subject}{environment}.
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%
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We use%
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Jeremy Siek