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Code for non-local exits

This commit is contained in:
2020-10-02 01:22:21 +01:00
parent 313b8a7779
commit fe255ba70e
2 changed files with 40 additions and 1 deletions

View File

@@ -330,7 +330,10 @@
% UNIX example
\newcommand{\OSname}[0]{Tiny UNIX}
\newcommand{\Uexit}{\dec{exit}}
\newcommand{\exit}{\dec{exit}}
\newcommand{\Exit}{\dec{Exit}}
\newcommand{\Status}{\dec{Status}}
\newcommand{\status}{\dec{status}}
\newcommand{\basicIO}{\dec{basicIO}}
\newcommand{\Putc}{\dec{Putc}}
\newcommand{\putc}{\dec{putc}}

View File

@@ -2121,6 +2121,42 @@ We can now write some contents to the file and observe the effects.
\subsection{Exceptions: non-local exits}
\label{sec:tiny-unix-exit}
\[
\Status \defas \{\Exit : \Int \opto \Zero\}
\]
\[
\bl
\exit : \Int \to \alpha \eff \Status\\
\exit~n \defas \Absurd\;(\Do\;\Exit~n)
\el
\]
\[
\bl
\status : (\UnitType \to \alpha \eff \Status) \to \Int\\
\status~m \defas
\ba[t]{@{~}l}
\Handle\;m\,\Unit\;\With\\
~\ba{@{~}l@{~}c@{~}l}
\Return\;\_ &\mapsto& 0\\
\Exit~n~\_ &\mapsto& n
\ea
\ea
\el
\]
\[
\ba{@{~}l@{~}l}
&\bl
\basicIO\,(\lambda\Unit.
\status\,(\lambda\Unit.
\fwrite\,\Record{\stdout;\texttt{"dead"}};\exit~1;\fwrite\,\Record{\stdout;\texttt{"code"}}))
\el\\
\reducesto^+& \Record{1;\texttt{"dead"}} : \Record{\Int;\UFile}
\ea
\]
\subsection{Dynamic binding: user-specific environments}
\label{sec:tiny-unix-env}