add a bit about combinators

diff --git a/methods.top.tex b/methods.top.tex
index 9777db5..174a783 100644 (file)
--- a/methods.top.tex
+++ b/methods.top.tex
@@ -67,4 +67,55 @@ specialization instances for these functions and show an according interface.
 Generated interfaces can be modified with decoration operators.
 
 \subsection{Combinators}
-\todo{Stukje over combinators, in ieder geval bind en paralel}
+\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}.
+
+\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
+               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
+(>>=) ta f = ta >>* [OnAction "Continue" onValue, OnValue onStable]
+    where
+        onValue (Value a _)     = Just (f a)
+        onValue _               = Nothing
+
+               onStable (Value a True) = Just (f a)
+               onStable _              = Nothing
+               \end{lstlisting}
+       \item Parallel:
+
+               The parallel combinator allows for concurrent \glspl{Task}. The
+               \glspl{Task} combined with these operators will appear at the same time
+               in the web browser of the user and the results are combined as the type
+               dictates.
+\end{itemize}
+
+\begin{lstlisting}[language=Clean,%
+       caption={\Gls{Task}-combinators},label={lst:combinators}]
+//Step combinator
+(>>*)  infixl 1 :: (Task a) [TaskCont a (Task b)] -> Task b     | iTask a & iTask b
+(>>=)  infixl 1 :: (Task a) (a -> Task b)         -> Task b   | iTask a & iTask b
+:: TaskCont a b
+       =     OnValue             ((TaskValue a)  -> Maybe b)
+       |     OnAction    Action  ((TaskValue a)  -> Maybe b)
+       | E.e: OnException         (e              -> b)       & iTask e
+       |     OnAllExceptions     (String         -> b)
+:: Action = Action String
+
+//Parallel combinators
+(-||-) infixr 3 :: (Task a) (Task a)              -> Task a     | iTask a
+(||-)  infixr 3 :: (Task a) (Task b)              -> Task b     | iTask a & iTask b
+(-||)  infixl 3 :: (Task a) (Task b)              -> Task a     | iTask a & iTask b
+(-&&-) infixr 4 :: (Task a) (Task b)              -> Task (a,b) | iTask a & iTask b
+\end{lstlisting}
+
+\subsection{\acrlongpl{SDS}}
+