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{Programming,Constraining} continuations WIP

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2020-11-30 22:39:21 +00:00
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commit de7074a1da
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@@ -1474,6 +1474,17 @@
year = {1985} year = {1985}
} }
@article{HaynesF87,
author = {Christopher T. Haynes and
Daniel P. Friedman},
title = {Embedding Continuations in Procedural Objects},
journal = {{ACM} Trans. Program. Lang. Syst.},
volume = {9},
number = {4},
pages = {582--598},
year = {1987}
}
# Splitter # Splitter
@inproceedings{QueinnecS91, @inproceedings{QueinnecS91,
author = {Christian Queinnec and author = {Christian Queinnec and
@@ -2246,3 +2257,13 @@
pages = {687--730}, pages = {687--730},
year = {2007} year = {2007}
} }
# Sitaram's phd dissertation
@phdthesis{Sitaram94,
author = {Dorai Sitaram},
title = {Models of Control and Their Implications for Programming Language Design},
school = {Rice University, Houston, Texas, {USA}},
month = apr,
year = {1994}
}

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@@ -2097,16 +2097,16 @@ Shallow handlers can be used to simulate control0 and prompt0.
\slab{Resume} & \Continue~\cont_{\EC}~V &\reducesto& \EC[V] \slab{Resume} & \Continue~\cont_{\EC}~V &\reducesto& \EC[V]
\end{reductions} \end{reductions}
\subsection{Second-class control operators} % \subsection{Second-class control operators}
Coroutines, async/await, generators/iterators, amb. % Coroutines, async/await, generators/iterators, amb.
Backtracking: Amb~\cite{McCarthy63}. % Backtracking: Amb~\cite{McCarthy63}.
Coroutines~\cite{DahlDH72} as introduced by Simula % Coroutines~\cite{DahlDH72} as introduced by Simula
67~\cite{DahlMN68}. The notion of coroutines was coined by Melvin % 67~\cite{DahlMN68}. The notion of coroutines was coined by Melvin
Conway, who used coroutines as a code idiom in assembly % Conway, who used coroutines as a code idiom in assembly
programs~\cite{Knuth97}. Canonical reference for implementing % programs~\cite{Knuth97}. Canonical reference for implementing
coroutines with call/cc~\cite{HaynesFW86}. % coroutines with call/cc~\cite{HaynesFW86}.
\section{Programming continuations} \section{Programming continuations}
%Blind vs non-blind backtracking. Engines. Web %Blind vs non-blind backtracking. Engines. Web
@@ -2118,17 +2118,65 @@ jumps, such as \citeauthor{Landin98}'s modelling of \Algol{} labels
and gotos using the J and gotos using the J
operator~\cite{Landin65,Landin65a,Landin98,Reynolds93}. operator~\cite{Landin65,Landin65a,Landin98,Reynolds93}.
Backtracking is another early and prominent use of Backtracking is another early and prominent use of continuations. For
continuations. \citet{Burstall69} used the J operator to implement a example, \citet{Burstall69} used the J operator to implement a
backtracking mechanism to facilitate tree-based search. heuristic-driven search procedure with continuation-backed
backtracking for tree-based search.
%
Somewhat related to backtracking, \citet{FriedmanHK84} posed the
\emph{devils and angels problem} as an example that has no direct
solution in a programming language without first-class control. Any
solution to the devils and angels problem involves extensive
manipulation of control to jump both backwards and forwards to resume
computation.
Meta-programming~\cite{LawallD94,KameyamaKS11,OishiK17,Yallop17}. If the reader ever find themselves in a quiz show asked to single out
a canonical example of continuation use, then implementation of
cooperative concurrency would be a qualified guess. Various forms of
coroutines as continuations occur so frequently in the literature and
in the wild that they have become routine.
%
\citet{HaynesFW86} published one of the first implementations of
coroutines using first-class control. \citet{HiebD90} demonstrated how
to implement engines. An engine is a kind of scheduler for
computations running on a time budget~\cite{HaynesF84}.
%
Various other forms of schedulers were developed by \citet{GanzFW99}.
Continuations have also been used in meta-programming to speed up
partial evaluation and
multi-staging~\cite{LawallD94,KameyamaKS11,OishiK17,Yallop17}. Let
insertion is a canonical example of use of continuations in
multi-staging~\cite{Yallop17}.
The aforementioned applications of continuations is by no means
exhaustive, however, the diverse application spectrum underlines the
versatility of continuations.
\section{Constraining continuations} \section{Constraining continuations}
\citet{FriedmanH85} argued in favour of constraining the power of
continuations~\cite{HaynesF87}. Although, they were concerned with
callcc and undelimited continuations many of their arguments are
applicable to other control operators and delimited continuations.
For example callec is a variation of callcc where the continuation For example callec is a variation of callcc where the continuation
only can be invoked during the dynamic extent of only can be invoked during the dynamic extent of
callec~\cite{Flatt20}. callec~\cite{Flatt20}.
Dynamic-wind\dots
To avoid resource leakage the implementation of effect handlers in
Multicore OCaml provides both a \emph{continue} primitive for
continuing a given continuation and a \emph{discontinue} primitive for
aborting a given continuation~\cite{DolanWSYM15,DolanEHMSW17}. The
latter throws an exception at the operation invocation site to clean
up resources.
%
A similar approached is used by \citet{Fowler19}, who uses a
substructural type system to statically enforce the use of
continuations, either by means of a continue or a discontinue.
\section{Implementing continuations} \section{Implementing continuations}
Table~\ref{tbl:ctrl-operators-impls} lists some programming languages Table~\ref{tbl:ctrl-operators-impls} lists some programming languages
with support for first-class control operators and their with support for first-class control operators and their
@@ -2178,7 +2226,7 @@ implementation strategies.
\paragraph{Continuation passing style} \paragraph{Continuation passing style}
\paragraph{Interpreter} \paragraph{Abstract and virtual machines}
\paragraph{Segmented stacks} \paragraph{Segmented stacks}