-\section{\acrlong{TOP}}
-\subsection{\gls{iTasks}}
+\section{iTasks}
\gls{TOP} is a recent programming paradigm implemented as
\gls{iTasks}\cite{achten_introduction_2015} in the pure lazy functional
language \gls{Clean}\cite{brus_cleanlanguage_1987}. \gls{iTasks} is a
\gls{EDSL} to model workflow tasks in the broadest sense. A \CI{Task} is just
-a function that, given some state, returns the observable \CI{TaskValue}. The
+a function that --- given some state --- returns the observable \CI{TaskValue}. The
\CI{TaskValue} of a \CI{Task} can have different states. Not all state
transitions are possible as shown in Figure~\ref{fig:taskvalue}. Once a value
is stable it can never become unstable again. Stability is often reached
filled in and therefore the \CI{TaskValue} remains \CI{Unstable}. In the third
image all fields are entered and the \CI{TaskValue} transitions to the
\CI{Unstable} state. When the user presses \emph{Continue} the value becomes
-\CI{Stable} and can not be changed any further.
+\CI{Stable} and cannot be changed any further.
\begin{figure}[H]
\centering
specialization instances for these functions and show an according interface.
Generated interfaces can be modified with decoration operators.
-\subsection{Combinators}
+\section{Combinators}
\Glspl{Task} can be combined using so called \gls{Task}-combinators.
Combinators describe relations between \glspl{Task}. \Glspl{Task} can be
combined in parallel, sequenced and their result values can be converted to
-\glspl{SDS}. Moreover, a very important combinator is the step combinator that
-starts a new task according to the \CI{TaskValue}. The type signatures of the
-basic combinators are shown in Listing~\ref{lst:combinators}.
+\glspl{SDS}. Moreover, a very important combinator is the step combinator which
+starts a new task according to specified predicates on the \CI{TaskValue}.
+Type signatures of the basic combinators are shown in
+Listing~\ref{lst:combinators}.
\begin{itemize}
\item Step:
The step combinator is used to start \glspl{Task} when a predicate on
- the \CI{TaskValue} holds or an action has been taken place. The bind
+ the \CI{TaskValue} holds or an action has taken place. The bind
operator can be written as a step combinator.
\begin{lstlisting}[language=Clean]
(>>=) infixl 1 :: (Task a) (a -> (Task b)) -> (Task b) | iTask a & iTask b
onValue (Value a _) = Just (f a)
onValue _ = Nothing
- onStable (Value a True) = Just (f a)
- onStable _ = Nothing
+ onStable (Value a True) = Just (f a)
+ onStable _ = Nothing
\end{lstlisting}
\item Parallel:
(-&&-) infixr 4 :: (Task a) (Task b) -> Task (a,b) | iTask a & iTask b
\end{lstlisting}
-\subsection{\acrlongpl{SDS}}
+\section{\acrlongpl{SDS}}
+\Glspl{SDS} are an abstraction over resources that are available in the world
+or in the \gls{iTasks} system. The shared data can be a file on disk, it can be
+the time, a random integer or just some data stored in memory. The actual
+\gls{SDS} is just a record containing functions on how to read and write the
+source. In these functions the \CI{*World} is available and therefore it can
+interact with the outside world. The \CI{*IWorld} is also available and
+therefore the functions can also access other shares, possibly combining them.
+
+The basic operations for \glspl{SDS} are get, set and update. The signatures
+for these functions are shown in Listing~\ref{lst:shares}. All of the
+operations are atomic in the sense that during reading no other tasks are
+executed.
+
+\begin{lstlisting}[%
+ language=Clean,label={lst:shares},caption={\Gls{SDS} functions}]
+get :: (ReadWriteShared r w) -> Task r | iTask r
+set :: w (ReadWriteShared r w) -> Task w | iTask w
+upd :: (r -> w) (ReadWriteShared r w) -> Task w | iTask r & iTask w
+\end{lstlisting}
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