starting on dynamic for python

book.tex

@@ -25,7 +25,7 @@
 
 \def\racketEd{0}
 \def\pythonEd{1}
-\def\edition{0}
+\def\edition{1}
 
 % material that is specific to the Racket edition of the book
 \newcommand{\racket}[1]{{\if\edition\racketEd{#1}\fi}}
@@ -16036,20 +16036,26 @@ and used in Chez Scheme version 1~\citep{Dybvig:2006aa}.
 \label{ch:Ldyn}
 \index{subject}{dynamic typing}
 
-\if\edition\racketEd
-
-In this chapter we discuss the compilation of \LangDyn{}, a dynamically
-typed language that is a subset of Racket. This is in contrast to the
-previous chapters, which have studied the compilation of Typed
-Racket. In dynamically typed languages such as \LangDyn{}, a given
-expression may produce a value of a different type each time it is
-executed. Consider the following example with a conditional \code{if}
-expression that may return a Boolean or an integer depending on the
-input to the program.
+In this chapter we discuss the compilation of \LangDyn{}, a
+dynamically typed language. This is in contrast to the previous
+chapters, which have studied the compilation of statically typed
+languages. In dynamically typed languages such as \LangDyn{}, a
+particular expression may produce a value of a different type each
+time it is executed. Consider the following example with a conditional
+\code{if} expression that may return a Boolean or an integer depending
+on the input to the program.
 % part of  dynamic_test_25.rkt
+{\if\edition\racketEd
+\begin{lstlisting}
+(not (if (eq? (read) 1) #f 0))
+\end{lstlisting}
+\fi}
+{\if\edition\pythonEd
 \begin{lstlisting}
-   (not (if (eq? (read) 1) #f 0))
+not (False if input_int() == 1 else 0)
 \end{lstlisting}
+\fi}
+
 Languages that allow expressions to produce different kinds of values
 are called \emph{polymorphic}, a word composed of the Greek roots
 ``poly'', meaning ``many'', and ``morph'', meaning ``shape''.  There
@@ -16061,17 +16067,28 @@ that arises in dynamically typed languages.
 
 Another characteristic of dynamically typed languages is that
 primitive operations, such as \code{not}, are often defined to operate
-on many different types of values. In fact, in Racket, the \code{not}
-operator produces a result for any kind of value: given \code{\#f} it
-returns \code{\#t} and given anything else it returns \code{\#f}.
+on many different types of values.  In fact, in
+\racket{Racket}\python{Python}, the \code{not} operator produces a
+result for any kind of value: given \FALSE{} it returns \TRUE{} and
+given anything else it returns \FALSE{}.
+
 Furthermore, even when primitive operations restrict their inputs to
 values of a certain type, this restriction is enforced at runtime
-instead of during compilation. For example, the following vector
-reference results in a run-time contract violation because the index
-must be in integer, not a Boolean such as \code{\#t}.
+instead of during compilation. For example, the following tuple read
+operation results in a run-time error because it requires a tuple, not
+a Boolean such as \TRUE{}.
+%
+{\if\edition\racketEd
 \begin{lstlisting}
-   (vector-ref (vector 42) #t)
+(vector-ref #t 0)
 \end{lstlisting}
+\fi}
+%
+{\if\edition\pythonEd
+\begin{lstlisting}
+True[0]
+\end{lstlisting}
+\fi}
 
 \begin{figure}[tp]
 \centering
@@ -16101,7 +16118,7 @@ must be in integer, not a Boolean such as \code{\#t}.
 \]
 \end{minipage}
 }
-\caption{Syntax of \LangDyn{}, an untyped language (a subset of Racket).}
+\caption{Syntax of \LangDyn{}, an untyped language (a subset of \racket{Racket}\python{Python}).}
 \label{fig:r7-concrete-syntax}
 \end{figure}
 
@@ -16111,6 +16128,7 @@ must be in integer, not a Boolean such as \code{\#t}.
 \fbox{
   \begin{minipage}{0.96\textwidth}
     \small
+{\if\edition\racketEd
 \[
 \begin{array}{lcl}
   \Exp &::=& \INT{\Int} \MID \VAR{\Var} \MID \LET{\Var}{\Exp}{\Exp} \\
@@ -16123,6 +16141,10 @@ must be in integer, not a Boolean such as \code{\#t}.
   \LangDynM{} &::=& \PROGRAMDEFSEXP{\code{'()}}{\LP\Def\ldots\RP}{\Exp} 
 \end{array}
 \]
+\fi}
+{\if\edition\pythonEd
+UNDER CONSTRUCTION
+\fi}
 \end{minipage}
 }
 \caption{The abstract syntax of \LangDyn{}.}
@@ -16130,17 +16152,19 @@ must be in integer, not a Boolean such as \code{\#t}.
 \end{figure}
 
 
-The concrete and abstract syntax of \LangDyn{}, our subset of Racket, is
-defined in Figures~\ref{fig:r7-concrete-syntax} and
-\ref{fig:r7-syntax}.
+The concrete and abstract syntax of \LangDyn{}, our subset of
+\racket{Racket}\python{Python}, is defined in
+Figures~\ref{fig:r7-concrete-syntax} and \ref{fig:r7-syntax}.
 %
 There is no type checker for \LangDyn{} because it is not a statically
 typed language (it's dynamically typed!).
 
+UNDER CONSTRUCTION
+
 The definitional interpreter for \LangDyn{} is presented in
-Figure~\ref{fig:interp-Rdyn} and its auxiliary functions are defined i
+Figure~\ref{fig:interp-Rdyn} and its auxiliary functions are defined in
 Figure~\ref{fig:interp-Rdyn-aux}. Consider the match case for
-\code{(Int n)}.  Instead of simply returning the integer \code{n} (as
+\INT{n}.  Instead of simply returning the integer \code{n} (as
 in the interpreter for \LangVar{} in Figure~\ref{fig:interp-Lvar}), the
 interpreter for \LangDyn{} creates a \emph{tagged value}\index{subject}{tagged
   value} that combines an underlying value with a tag that identifies
@@ -16337,6 +16361,7 @@ in greater detail.
 \fbox{
   \begin{minipage}{0.96\textwidth}
     \small
+{\if\edition\racketEd
 \[
 \begin{array}{l}
   \gray{\LintOpAST} \\ \hline
@@ -16361,6 +16386,10 @@ in greater detail.
 \end{array}
 \end{array}
 \]
+\fi}
+{\if\edition\pythonEd
+UNDER CONSTRUCTION
+\fi}
 \end{minipage}
 }
 \caption{The abstract syntax of \LangAny{}, extending \LangLam{} (Figure~\ref{fig:Rlam-syntax}).}
@@ -16863,6 +16892,7 @@ of an integer, as in \LangCVec{} (Figure~\ref{fig:c2-syntax}).
 \fbox{
 \begin{minipage}{0.96\textwidth}
 \small
+{\if\edition\racketEd
 \[
 \begin{array}{lcl}
 \Exp &::= & \ldots
@@ -16880,6 +16910,10 @@ of an integer, as in \LangCVec{} (Figure~\ref{fig:c2-syntax}).
 \LangCAnyM{} & ::= & \gray{ \PROGRAMDEFS{\itm{info}}{\LP\Def\ldots\RP} }
 \end{array}
 \]
+\fi}
+{\if\edition\pythonEd
+UNDER CONSTRUCTION
+\fi}
 \end{minipage}
 }
 \caption{The abstract syntax of \LangCAny{}, extending \LangCLam{} (Figure~\ref{fig:c4-syntax}).}
@@ -17125,7 +17159,7 @@ for the compilation of \LangDyn{}.
 
 % Further Reading
 
-\fi % racketEd
+
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 {\if\edition\pythonEd