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@@ -6553,12 +6553,11 @@ checking and define a type checker for \LangIf{}
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language \LangCVar{} into \LangCIf{} (Section~\ref{sec:Cif}) and
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\LangXInt{} into \LangXIf{} (Section~\ref{sec:x86-if}).}
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%
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-The remaining sections of this chapter discuss how the addition of
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-Booleans and conditional control flow to the language requires changes
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-to the existing compiler passes and the addition of new ones. In
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-particular, we introduce the \code{shrink} pass to translates some
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-operators into others, thereby reducing the number of operators that
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-need to be handled in later passes.
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+The remaining sections of this chapter discuss how Booleans and
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+conditional control flow require changes to the existing compiler
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+passes and the addition of new ones. We introduce the \code{shrink}
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+pass to translates some operators into others, thereby reducing the
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+number of operators that need to be handled in later passes.
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%
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The main event of this chapter is the \code{explicate\_control} pass
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that is responsible for translating \code{if}'s into conditional
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@@ -6590,7 +6589,7 @@ respectively. The \LangIf{} language includes all of
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rule for all of them. This means that the grammar no longer checks
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whether the arity of an operators matches the number of
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arguments. That responsibility is moved to the type checker for
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- \LangIf{}, which we introduce in Section~\ref{sec:type-check-Lif}.}
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+ \LangIf{} (Section~\ref{sec:type-check-Lif}).}
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\newcommand{\LifGrammarRacket}{
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@@ -6615,6 +6614,7 @@ respectively. The \LangIf{} language includes all of
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}
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\newcommand{\LintOpAST}{
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\begin{array}{rcl}
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+ \Type &::=& \key{Integer} \\
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\itm{op} &::= & \code{read} \MID \code{+} \MID \code{-}\\
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\Exp{} &::=& \INT{\Int} \MID \PRIM{\itm{op}}{\Exp\ldots}
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\end{array}
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@@ -6926,10 +6926,11 @@ for the below expression {\if\edition\racketEd
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not (10 + -(12 + 20))
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\end{lstlisting}
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\fi}
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-The subexpression
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-\racket{\code{(+ 10 (- (+ 12 20)))}}\python{\code{(10 + -(12 + 20))}}
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-has type \INTTY{} but the type checker enforces the rule that the argument of
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-\code{not} must be an expression of type \BOOLTY{}.
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+\noindent The subexpression
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+\racket{\code{(+ 10 (- (+ 12 20)))}}
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+\python{\code{(10 + -(12 + 20))}}
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+has type \INTTY{} but the type checker enforces the rule that the
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+argument of \code{not} must be an expression of type \BOOLTY{}.
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We implement type checking using classes and methods because they
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provide the open recursion needed to reuse code as we extend the type
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@@ -6948,8 +6949,7 @@ of the support code.
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%
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Each type checker is a structurally recursive function over the AST.
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Given an input expression \code{e}, the type checker either signals an
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-error or returns \racket{an expression and} its type (\INTTY{} or
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-\BOOLTY{}).
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+error or returns \racket{an expression and} its type.
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%
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\racket{It returns an expression because there are situations in which
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we want to change or update the expression.}
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@@ -7205,13 +7205,13 @@ class TypeCheckLif(TypeCheckLvar):
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\label{fig:type-check-Lif}
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\end{figure}
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-We shift our focus to Figure~\ref{fig:type-check-Lif}, the type
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-checker for \LangIf{}.
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+The type checker for \LangIf{} is defined in
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+Figure~\ref{fig:type-check-Lif}.
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%
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The type of a Boolean constant is \BOOLTY{}.
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%
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\racket{The \code{operator-types} function adds dictionary entries for
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- the other new operators.}
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+ the new operators.}
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%
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\python{Logical not requires its argument to be a \BOOLTY{} and
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produces a \BOOLTY{}. Similarly for logical and and logical or. }
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Jeremy Siek