sunet/doc/latex/toothless.tex

\chapter{Evaluating expression in ``safe'' environments}
%
\begin{description}
\item[Used files:] none, defined in modules.scm
\item[Name of the package:] loser, toothless, toothless-eval \\
  (you want the last one)
\end{description}
%

\section{Overview}
\FIXME{Is toothless really R5RS, too?}
These modules define an environment that is \RnRS without features that
could examine or effect the file system. You can also use it as a
model of how to execute code in other protected environments in \scm.

\section{The \protect{\texttt{loser}} package}
The \ex{loser} package exports only one procedure:

\begin{defundesc}{loser}{name}{nothing}
  Raises an error like ``Illegal call \var{name}''.
\end{defundesc}

\section{The \protect{\texttt{toothless}} package}
The \ex{toothless} package contains everything of \RnRS except
that following procedure cause an error if called:
\begin{itemize}
\item \ex{call-with-input-file}
\item \ex{call-with-output-file}
\item \ex{load}
\item \ex{open-input-file}
\item \ex{open-output-file}
\item \ex{transcript-on}
\item \ex{with-input-from-file}
\item \ex{with-input-to-file}
\item \ex{eval}
\item \ex{interaction-environment}
\item \ex{scheme-report-environment}
\end{itemize}

So, \ex{toothless} creates an environment as described in
\emph{Overview} above.

\section{The \protect{\texttt{toothless-eval}} package}

\begin{defundesc}{eval-safely} {expression} {any result}
  Creates a brand new package, imports the \ex{toothless} structure,
  and evaluates \semvar{expression} in it. When the evaluation is
  done, the environment is thrown away, so \semvar{expression}'s
  side-effects don't persist from one \ex{eval\=safely} call to the
  next. If \semvar{expression} raises an error exception, we abort and
  return \sharpf.
\end{defundesc}

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