methods.top.tex

   1 \section{\acrlong{TOP}}
   2 \subsection{\gls{iTasks}}
   3 \gls{TOP} is a recent new programming paradigm implemented as
   4 \gls{iTasks}\cite{achten_introduction_2015} in the pure lazy functional
   5 language \gls{Clean}\cite{brus_cleanlanguage_1987}. \gls{iTasks} is a
   6 \gls{EDSL} to model workflow tasks in the broadest sense. A \CI{Task} is just
   7 a function that, given some state, returns the observable \CI{TaskValue}. The
   8 \CI{TaskValue} of a \CI{Task} can have different states. Not all state
   9 transitions are possible as shown in Figure~\ref{fig:taskvalue}. Once a value
  10 has gone stable it can never become unstable again. Stability is often reached
  11 by pressing a confirmation button or for \glspl{Task} that offer a constant
  12 value. A simple example is shown in Listing~\ref{lst:taskex} accompanied with
  13 Figure~\ref{fig:taskex1},~\ref{fig:taskex2} and~\ref{fig:taskex3}. In this
  14 example the first image in is the \CI{NoValue} state, the second and third
  15 image are in the \CI{Unstable} state. When the user presses \emph{Continue} the
  16 value becomes \CI{Stable}.
  17
  18 \begin{figure}[H]
  19         \centering
  20         \includegraphics[width=.5\linewidth]{fig-taskvalue}
  21         \caption{The states of a \CI{TaskValue}}\label{fig:taskvalue}
  22 \end{figure}
  23
  24 \begin{lstlisting}[language=Clean,label={lst:taskex},%
  25         caption={An example \gls{Task} for entering a name}]
  26 :: Name         = { firstname :: String
  27                   , lastname  :: String
  28                                   }
  29
  30 derive class iTask Name
  31
  32 enterInformation :: String [EnterOption m] -> (Task m) | iTask m
  33
  34 enterName :: Task Name
  35 enterName = enterInformation "Enter your name" []
  36 \end{lstlisting}
  37
  38 \begin{figure}[H]
  39         \begin{subfigure}{.25\textwidth}
  40                 \centering
  41                 \includegraphics[width=.9\linewidth]{taskex1}
  42                 \caption{Initial interface}\label{fig:taskex1}
  43         \end{subfigure}
  44         \begin{subfigure}{.25\textwidth}
  45                 \centering
  46                 \includegraphics[width=.9\linewidth]{taskex2}
  47                 \caption{Incomplete entrance}\label{fig:taskex2}
  48         \end{subfigure}
  49         \begin{subfigure}{.25\textwidth}
  50                 \centering
  51                 \includegraphics[width=.9\linewidth]{taskex3}
  52                 \caption{Complete entry}\label{fig:taskex3}
  53         \end{subfigure}
  54         \caption{Example of a generated user interface}
  55 \end{figure}
  56
  57 For a type to be suitable it must have instances for a collection of generic
  58 functions that are captured in the class \CI{iTask}. Basic types have
  59 specialization instances for these functions and show an according interface.
  60 Generated interfaces can be modified with decoration operators.
  61
  62 \subsection{Combinators}
  63 \todo{Stukje over combinators, in ieder geval bind en paralel}