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47
thesis.bib
47
thesis.bib
@@ -1319,6 +1319,19 @@
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year = {1988}
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year = {1988}
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}
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}
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@inproceedings{FelleisenWFD88,
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author = {Matthias Felleisen and
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Mitchell Wand and
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Daniel P. Friedman and
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|
Bruce F. Duba},
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|
title = {Abstract Continuations: {A} Mathematical Semantics for Handling Full
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|
Jumps},
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|
booktitle = {{LISP} and Functional Programming},
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pages = {52--62},
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publisher = {{ACM}},
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year = {1988}
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}
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|
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# Control and prompt
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# Control and prompt
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@article{SitaramF90,
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@article{SitaramF90,
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author = {Dorai Sitaram and
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author = {Dorai Sitaram and
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@@ -1440,6 +1453,17 @@
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month = aug
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month = aug
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}
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}
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|
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# Constraining call/cc
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@inproceedings{FriedmanH85,
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author = {Daniel P. Friedman and
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|
Christopher T. Haynes},
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title = {Constraining Control},
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booktitle = {{POPL}},
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pages = {245--254},
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|
publisher = {{ACM} Press},
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|
year = {1985}
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|
}
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|
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# Splitter
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# Splitter
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@inproceedings{QueinnecS91,
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@inproceedings{QueinnecS91,
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author = {Christian Queinnec and
|
author = {Christian Queinnec and
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@@ -1966,3 +1990,26 @@
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publisher = {Schloss Dagstuhl - Leibniz-Zentrum f{\"{u}}r Informatik},
|
publisher = {Schloss Dagstuhl - Leibniz-Zentrum f{\"{u}}r Informatik},
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year = {2019}
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year = {2019}
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}
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}
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|
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|
# Original report and paper on continuations
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@techreport{StracheyW74,
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author = {Christopher Strachey and
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|
Christopher P. Wadsworth},
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|
title = {Continuations: {A} Mathematical Semantics for Handling Full Jumps},
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|
institution = {Programming Research Group, University of Oxford},
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|
number = {PRG-11},
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|
type = {Technical Monograph},
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|
month = jan,
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|
year = 1974
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|
}
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|
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|
@article{StracheyW00,
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|
author = {Christopher Strachey and
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|
Christopher P. Wadsworth},
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|
title = {Continuations: {A} Mathematical Semantics for Handling Full Jumps},
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|
journal = {High. Order Symb. Comput.},
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|
volume = {13},
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|
number = {1/2},
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|
pages = {135--152},
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|
year = {2000}
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|
}
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198
thesis.tex
198
thesis.tex
@@ -568,6 +568,42 @@ the translation preserve typeability.
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\citet{Shan04} shows that dynamic delimited control and static
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\citet{Shan04} shows that dynamic delimited control and static
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delimited control is macro-expressible in an untyped setting.
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delimited control is macro-expressible in an untyped setting.
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|
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|
\paragraph{A language for understanding control}
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|
%
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|
To look at control we will a simply typed fine-grain call-by-value
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|
calculus. The calculus is essentially the same as the one used in
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|
Chapter~\ref{ch:handlers-efficiency}, except that here we will have an
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|
explicit invocation form for continuations. Although, in practice most
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|
systems disguise continuations as first-class functions, but for a
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|
theoretical examination it is convenient to treat them specially such
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|
that continuation invocation is a separate reduction rule from
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|
ordinary function application. Figure~\ref{fig:pcf-lang-control}
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|
depicts the syntax of types and terms in the calculus.
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|
%
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|
\begin{figure}
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|
\centering
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|
\begin{syntax}
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|
\slab{Types} & A,B &::=& \UnitType \mid \Zero \mid A \to B \mid A + B \mid A \times B \mid \Cont\,\Record{A;B} \smallskip\\
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|
\slab{Values} & V,W &::=& x \mid \lambda x^A.M \mid V + W \mid \Record{V;W} \mid \Unit \mid \cont_\EC\\
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|
\slab{Computations} & M,N &::=& \Return\;V \mid \Let\;x \revto M \;\In\;N \mid \Let \Record{x;y} = V \;\In\; N \\
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|
& &\mid& \Absurd^A\;V \mid V\,W \mid \Continue~V~W \smallskip\\
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|
\slab{Evaluation\textrm{ }contexts} & \EC &::=& [\,] \mid \Let\;x \revto \EC \;\In\;N
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|
\end{syntax}
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|
\caption{Types and term syntax}\label{fig:pcf-lang-control}
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|
\end{figure}
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|
%
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|
The types are the standard simple types with the addition of the empty
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|
type $\Zero$ and the continuation object type $\Cont\,\Record{A;B}$,
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|
which is parameterised by an argument type and a result type,
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|
respectively. The static semantics is standard as well, except for the
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|
continuation invocation primitive $\Continue$.
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|
%
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|
\begin{mathpar}
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|
\inferrule*
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|
{\typ{\Gamma}{V : A} \\ \typ{\Gamma}{W : \Cont\,\Record{A;B}}}
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|
{\typ{\Gamma}{\Continue~W~V : B}}
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|
\end{mathpar}
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|
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\section{Classifying continuations}
|
\section{Classifying continuations}
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|
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% \citeauthor{Reynolds93} has written a historical account of the
|
% \citeauthor{Reynolds93} has written a historical account of the
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@@ -678,7 +714,7 @@ Downward and upward use of continuations.
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\section{Controlling continuations}
|
\section{Controlling continuations}
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Table~\ref{tbl:classify-ctrl} provides a classification of a
|
Table~\ref{tbl:classify-ctrl} provides a classification of a
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non-exhaustive list of first-class control operators.
|
non-exhaustive list of first-class control operators.
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|
%
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\begin{table}
|
\begin{table}
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\centering
|
\centering
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\begin{tabular}{| l | l | l | l |}
|
\begin{tabular}{| l | l | l | l |}
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@@ -718,8 +754,9 @@ non-exhaustive list of first-class control operators.
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\end{tabular}
|
\end{tabular}
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\caption{Classification of first-class sequential control operators.}\label{tbl:classify-ctrl}
|
\caption{Classification of first-class sequential control operators.}\label{tbl:classify-ctrl}
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\end{table}
|
\end{table}
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|
%
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|
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\subsection{Undelimited operators}
|
\subsection{Undelimited control operators}
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%
|
%
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The early inventions of undelimited control operators were driven by
|
The early inventions of undelimited control operators were driven by
|
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the desire to provide a `functional' equivalent of jumps as provided
|
the desire to provide a `functional' equivalent of jumps as provided
|
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@@ -744,7 +781,7 @@ composable variant of callcc appeared. Moreover, every operator,
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except for \citeauthor{Landin98}'s J operator, capture the current
|
except for \citeauthor{Landin98}'s J operator, capture the current
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continuation.
|
continuation.
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|
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\paragraph{Reynolds' escape} The escape operator was introduced by
|
\paragraph{\citeauthor{Reynolds98a}' escape} The escape operator was introduced by
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\citeauthor{Reynolds98a} in 1972~\cite{Reynolds98a} to make
|
\citeauthor{Reynolds98a} in 1972~\cite{Reynolds98a} to make
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statement-oriented control mechanisms such as jumps and labels
|
statement-oriented control mechanisms such as jumps and labels
|
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programmable in an expression-oriented language.
|
programmable in an expression-oriented language.
|
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@@ -817,7 +854,7 @@ plugged into the context. The \slab{Resume} discards the current
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context $\EC$ and installs the captured context $\EC'$ with the
|
context $\EC$ and installs the captured context $\EC'$ with the
|
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argument $V$ plugged in.
|
argument $V$ plugged in.
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|
|
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\paragraph{Sussman and Steele's catch}
|
\paragraph{\citeauthor{SussmanS75}'s catch}
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%
|
%
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The catch operator originated in Lisp as an exception handling
|
The catch operator originated in Lisp as an exception handling
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construct. It had a companion throw operation, which would unwind the
|
construct. It had a companion throw operation, which would unwind the
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@@ -1022,14 +1059,16 @@ evaluation context.
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|
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\paragraph{\FelleisenC{} and \FelleisenF{}}
|
\paragraph{\FelleisenC{} and \FelleisenF{}}
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%
|
%
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The C operator is a variation of callcc, where capture mechanism
|
The C operator is a variation of callcc that provides control over the
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aborts the current continuation after capture. It was introduced by
|
whole continuation as it aborts the current continuation after
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\citeauthor{FelleisenFKD86} in two papers in
|
capture, whereas callcc implicitly invokes the current continuation on
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1986~\cite{FelleisenF86,FelleisenFKD86}. The year after
|
the value of its argument. The C operator was introduced by
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|
\citeauthor{FelleisenFKD86} in two papers during
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|
1986~\cite{FelleisenF86,FelleisenFKD86}. The following year,
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\citet{FelleisenFDM87} introduced the F operator which is a variation
|
\citet{FelleisenFDM87} introduced the F operator which is a variation
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of C, where the captured continuation is composable.
|
of C, whose captured continuation is composable.
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|
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Both operators are values.
|
In our framework both operators are value forms.
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%
|
%
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\[
|
\[
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V,W \in \ValCat ::= \cdots \mid \FelleisenC \mid \FelleisenF
|
V,W \in \ValCat ::= \cdots \mid \FelleisenC \mid \FelleisenF
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@@ -1077,7 +1116,7 @@ $\FelleisenC$.
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%
|
%
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\citet{FelleisenFDM87} also postulate that $\FelleisenC$ cannot express $\FelleisenF$.
|
\citet{FelleisenFDM87} also postulate that $\FelleisenC$ cannot express $\FelleisenF$.
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|
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\paragraph{Landin's J operator}
|
\paragraph{\citeauthor{Landin98}'s J operator}
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%
|
%
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The J operator was introduced by Peter Landin in 1965 (making it the
|
The J operator was introduced by Peter Landin in 1965 (making it the
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world's \emph{first} first-class control operator) as a means for
|
world's \emph{first} first-class control operator) as a means for
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@@ -1222,20 +1261,105 @@ syntactically embedded using callcc.
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\dhil{I am sort of torn between whether to treat continuations as
|
\dhil{I am sort of torn between whether to treat continuations as
|
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first-class functions\dots}
|
first-class functions\dots}
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|
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\subsection{Delimited operators}
|
\subsection{Delimited control operators}
|
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%
|
%
|
||||||
A delimited control operator captures only a designated segment of the
|
The main problem with undelimited control is that it is the
|
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evaluation stack. Typically, a delimited control operator is a pair
|
programmatic embodiment of the proverb \emph{all or nothing} in the
|
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consisting of a \emph{delimiter} and \emph{capture operation}. The
|
sense that an undelimited continuation always represent the entire
|
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delimiter delimits the extent of the continuation captured by the
|
residual program from its point of capture. With undelimited control
|
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capture operation.
|
there is no middle that allows some segments of the evaluation context
|
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|
to be reified.
|
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%
|
%
|
||||||
The first delimited control operator was introduced by
|
Delimited control rectifies this problem by associating each control
|
||||||
\citet{Felleisen88} with prompt and control, where prompt is the
|
operator with a control delimiter such that designated segments of the
|
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delimiter and control is the capture operation. Shortly after
|
evaluation context can be captured individually without interfering
|
||||||
\citet{DanvyF89} introduced their shift and reset as an alternative
|
with the context beyond the delimiter. This provides a powerful and
|
||||||
capture operation and delimiter, respectively. Since then a whole
|
modular programmatic tool that enables programmers to isolate the
|
||||||
variety of delimited control operators have been invented.
|
control flow of specific parts of their programs, and thus enables
|
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|
local reasoning about the behaviour of control infused program
|
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|
segments.
|
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|
%
|
||||||
|
One may argue that delimited control to an extent is more first-class
|
||||||
|
than undelimited control, because it provides fine-grain control over
|
||||||
|
the evaluation context.
|
||||||
|
%
|
||||||
|
Essentially, delimited control adds the excluded middle: \emph{all,
|
||||||
|
some, or nothing}.
|
||||||
|
|
||||||
|
In 1988 \citeauthor{Felleisen88} introduced the first control
|
||||||
|
delimiter known as `prompt', as a companion to the composable control
|
||||||
|
operator F (alias control)~\cite{Felleisen88}.
|
||||||
|
%
|
||||||
|
In \citeauthor{Felleisen88}'s line of work that led to the invention
|
||||||
|
of prompt was driven by a dynamic understanding of composable
|
||||||
|
continuations in terms of algebraic manipulation of continuations in
|
||||||
|
the control string of abstract machines. In context of abstract
|
||||||
|
machines a continuation is defined as a sequence of frames, whose end
|
||||||
|
is marked by a prompt, and the composition of continuations is defined
|
||||||
|
as concatenation of their
|
||||||
|
sequences~\cite{Felleisen87,FelleisenF86,FelleisenWFD88}.
|
||||||
|
%
|
||||||
|
This understanding of composable continuations ultimately led to the
|
||||||
|
control phenomenon known as \emph{dynamic delimited control}.
|
||||||
|
|
||||||
|
The following year, \citet{DanvyF89} introduced an alternative pair of
|
||||||
|
operators known as `shift' and `reset'. Their line of work were driven
|
||||||
|
by a static understanding of composable continuations in terms of
|
||||||
|
continuation passing style~\cite{DanvyF89,DanvyF90,DanvyF92}.
|
||||||
|
%
|
||||||
|
In this context a continuation is a compositional function in the
|
||||||
|
sense of \citeauthor{StracheyW74}'s denotational continuation
|
||||||
|
semantics~\cite{StracheyW74,StracheyW00}.
|
||||||
|
%
|
||||||
|
Their understanding of composable continuations ultimately led to the
|
||||||
|
control phenomenon known as \emph{static delimited control}.
|
||||||
|
|
||||||
|
|
||||||
|
% \citeauthor{Felleisen88}'s line of work
|
||||||
|
% that led to the invention of prompt was driven by motivation to
|
||||||
|
% provide a modular basis for programming with composable continuations,
|
||||||
|
% or `functional' jumps, which represent a shift in focus from abortive
|
||||||
|
% continuations, or `imperative' jumps, which had motivated undelimited
|
||||||
|
% control.
|
||||||
|
%
|
||||||
|
|
||||||
|
|
||||||
|
% The early inventions of delimited operators were driven by a desire to
|
||||||
|
% provide a modular and compositional basis for implementing various
|
||||||
|
% control phenomena such as exceptions, coroutines,
|
||||||
|
% engines~\cite{HaynesF84}, etc.
|
||||||
|
% %
|
||||||
|
% Whilst \citet{FriedmanH85} were arguing that undelimited control must be
|
||||||
|
% constrained, because the integrity of control phenomena embedded using
|
||||||
|
% undelimited is easily destroyed control are brittle and interact
|
||||||
|
% poorly with the environment.
|
||||||
|
|
||||||
|
% observed that control abstractions implemented in
|
||||||
|
% terms of unrestricted undelimited control, as provided by callcc, is
|
||||||
|
% brittle and inappropriate use can easily destroy the integrity of the
|
||||||
|
% embedded abstractions. They suggested to impose several ad-hoc, and
|
||||||
|
% rather complicated, restrictions on callcc and its continuations to
|
||||||
|
% make them modular.
|
||||||
|
% %
|
||||||
|
|
||||||
|
% \citeauthor{Felleisen88} wanted to develop a principled mechanism for
|
||||||
|
% capturing and composing continuations. The initial ideas towards
|
||||||
|
% delimited control were developed in \citeauthor{Felleisen87}'s PhD
|
||||||
|
% dissertation~\cite{Felleisen87} and related
|
||||||
|
% papers~\cite{FelleisenF86,FelleisenFDM87} with the design of the
|
||||||
|
% operator F.
|
||||||
|
% % A delimited control operator captures only a designated segment of the
|
||||||
|
% % evaluation stack. Typically, a delimited control operator is a pair
|
||||||
|
% % consisting of a \emph{delimiter} and \emph{capture operation}. The
|
||||||
|
% % delimiter delimits the extent of the continuation captured by the
|
||||||
|
% % capture operation.
|
||||||
|
% %
|
||||||
|
% The first delimited control operator was introduced by
|
||||||
|
% \citet{Felleisen88} with prompt and control, where prompt is the
|
||||||
|
% delimiter and control is the capture operation. Shortly after
|
||||||
|
% \citet{DanvyF89} introduced their shift and reset as an alternative
|
||||||
|
% capture operation and delimiter, respectively. Since then a whole
|
||||||
|
% variety of delimited control operators have been invented.
|
||||||
|
|
||||||
% Delimited control: Control delimiters form the basis for delimited
|
% Delimited control: Control delimiters form the basis for delimited
|
||||||
% control. \citeauthor{Felleisen88} introduced control delimiters in
|
% control. \citeauthor{Felleisen88} introduced control delimiters in
|
||||||
@@ -1258,7 +1382,7 @@ variety of delimited control operators have been invented.
|
|||||||
\paragraph{\citeauthor{Felleisen88}'s control and prompt}
|
\paragraph{\citeauthor{Felleisen88}'s control and prompt}
|
||||||
%
|
%
|
||||||
Control and prompt were introduced by \citeauthor{Felleisen88} in
|
Control and prompt were introduced by \citeauthor{Felleisen88} in
|
||||||
1988~\cite{Felleisen88}. The capture operation `control' is a
|
1988~\cite{Felleisen88}. The control operator `control' is a
|
||||||
rebranding of the F operator. Although, the name `control' was first
|
rebranding of the F operator. Although, the name `control' was first
|
||||||
introduced a little later by \citet{SitaramF90}. A prompt acts as a
|
introduced a little later by \citet{SitaramF90}. A prompt acts as a
|
||||||
control-flow barrier that delimits different parts of a program,
|
control-flow barrier that delimits different parts of a program,
|
||||||
@@ -1318,7 +1442,7 @@ typing judgement as $\FelleisenF$.
|
|||||||
%
|
%
|
||||||
|
|
||||||
The dynamic semantics for control and prompt consist of three rules:
|
The dynamic semantics for control and prompt consist of three rules:
|
||||||
1) to handle return through a prompt, 2) continuation capture, and 3)
|
1) handle return through a prompt, 2) continuation capture, and 3)
|
||||||
continuation invocation.
|
continuation invocation.
|
||||||
%
|
%
|
||||||
\begin{reductions}
|
\begin{reductions}
|
||||||
@@ -1364,11 +1488,11 @@ few simple examples.
|
|||||||
The continuation captured by the application of $\Control$ is
|
The continuation captured by the application of $\Control$ is
|
||||||
oblivious to the continuation $1 + [\,]$ of $\Prompt$. Since the
|
oblivious to the continuation $1 + [\,]$ of $\Prompt$. Since the
|
||||||
captured continuation is composable it returns to its call site. The
|
captured continuation is composable it returns to its call site. The
|
||||||
first invocation of $k$ returns the value 2, which is provided as the
|
first invocation of the continuation $k$ returns the value 2, which is
|
||||||
argument to the second invocation of $k$, resulting in the value
|
provided as the argument to the second invocation of $k$, resulting in
|
||||||
$4$. The prompt gets eliminated after its computation constituent has
|
the value $4$. The prompt $\Prompt$ gets eliminated when the
|
||||||
been fully reduced. Technically, the prompt is eliminated by applying
|
computation constituent of $\Prompt$ has been reduced to the value
|
||||||
the continuation of $\Prompt$ with the value $4$.
|
$4$, which is (implicitly) supplied to the continuation of $\Prompt$.
|
||||||
|
|
||||||
Let us consider a slight variation of the previous example.
|
Let us consider a slight variation of the previous example.
|
||||||
%
|
%
|
||||||
@@ -1417,11 +1541,11 @@ discarded, because the continuation $k'$ is never invoked.
|
|||||||
%
|
%
|
||||||
|
|
||||||
%
|
%
|
||||||
\begin{reductions}
|
% \begin{reductions}
|
||||||
% \slab{Value} & \reset{V} &\reducesto& V\\
|
% % \slab{Value} & \reset{V} &\reducesto& V\\
|
||||||
\slab{Capture} & \reset{\EC[\shift\,k.M]} &\reducesto& M[\cont_{\reset{\EC}}/k]\\
|
% \slab{Capture} & \reset{\EC[\shift\,k.M]} &\reducesto& M[\cont_{\reset{\EC}}/k]\\
|
||||||
% \slab{Resume} & \Continue~\cont_{\reset{\EC}}~V &\reducesto& \reset{\EC[V]}\\
|
% % \slab{Resume} & \Continue~\cont_{\reset{\EC}}~V &\reducesto& \reset{\EC[V]}\\
|
||||||
\end{reductions}
|
% \end{reductions}
|
||||||
%
|
%
|
||||||
|
|
||||||
\paragraph{\citeauthor{PlotkinP09}'s effect handlers}
|
\paragraph{\citeauthor{PlotkinP09}'s effect handlers}
|
||||||
@@ -1562,7 +1686,7 @@ implementation strategies.
|
|||||||
\hline
|
\hline
|
||||||
OchaCaml & shift/reset & Virtual machine\\
|
OchaCaml & shift/reset & Virtual machine\\
|
||||||
\hline
|
\hline
|
||||||
Racket & callcc, callcc$^{\ast}$, cupto, fcontrol, prompt/control, shift/reset, splitter, spawn & Continuation marks\\
|
Racket & callcc, callcc$^{\ast}$, cupto, fcontrol, control/prompt, shift/reset, splitter, spawn & Continuation marks\\
|
||||||
\hline
|
\hline
|
||||||
Rhino JavaScript & JI & Interpreter \\
|
Rhino JavaScript & JI & Interpreter \\
|
||||||
\hline
|
\hline
|
||||||
@@ -1570,7 +1694,7 @@ implementation strategies.
|
|||||||
\hline
|
\hline
|
||||||
SML/NJ & callcc & CPS\\
|
SML/NJ & callcc & CPS\\
|
||||||
\hline
|
\hline
|
||||||
Wasm/k & prompt/control & ?? \\
|
Wasm/k & control/prompt & ?? \\
|
||||||
\hline
|
\hline
|
||||||
\end{tabular}
|
\end{tabular}
|
||||||
\caption{Some languages and their implementation strategies for first-class control.}\label{tbl:ctrl-operators-impls}
|
\caption{Some languages and their implementation strategies for first-class control.}\label{tbl:ctrl-operators-impls}
|
||||||
|
|||||||
Reference in New Issue
Block a user