update conclusion and add mTask stuff

[msc-thesis1617.git] / methods.mtask.tex

diff --git a/methods.mtask.tex b/methods.mtask.tex
index 837933d..a0ec96b 100644 (file)
--- a/methods.mtask.tex
+++ b/methods.mtask.tex
@@ -1,15 +1,14 @@
-\section{mTask}

 The \gls{mTask}-\gls{EDSL} is the basis on which the system is built. The
 The \gls{mTask}-\gls{EDSL} is the basis on which the system is built. The

-\gls{mTask} was created by Koopman et al.\ to support several views such as an
-\gls{iTasks} simulation and a \gls{C}-code generator. The \gls{EDSL} was
-designed to generate a ready to compile \gls{TOP}-like system for
+\gls{mTask}-\gls{EDSL} was created by Koopman et al.\ to support several views
+such as an \gls{iTasks} simulation and a \gls{C}-code generator. The \gls{EDSL}
+was designed to generate a ready to compile \gls{TOP}-like system for

 microcontrollers such as the Arduino\cite{koopman_type-safe_nodate}%
 \cite{plasmeijer_shallow_2016}.
 
 The \gls{mTask}-\gls{EDSL} is a shallowly embedded class based \gls{EDSL} and
 therefore it is very suitable to have a new backend that partly implements the
 microcontrollers such as the Arduino\cite{koopman_type-safe_nodate}%
 \cite{plasmeijer_shallow_2016}.
 
 The \gls{mTask}-\gls{EDSL} is a shallowly embedded class based \gls{EDSL} and
 therefore it is very suitable to have a new backend that partly implements the

-given classes. The following subsections show the details of the \gls{EDSL}
-that are used in the extension. The parts of the \gls{EDSL} that are not used
+given classes. The following sections show the details of the \gls{EDSL}
+that are used in this extension. The parts of the \gls{EDSL} that are not used

 will not be discussed and the details of those parts can be found in the cited
 literature.
 
 will not be discussed and the details of those parts can be found in the cited
 literature.
 


@@ -36,15 +35,15 @@ instance isExpr Upd
 instance isExpr Expr
 \end{lstlisting}
 
 instance isExpr Expr
 \end{lstlisting}
 

-\subsection{Expressions}
+\section{Expressions}

 Expressions in the \gls{mTask}-\gls{EDSL} are divided into two types, namely
 boolean expressions and arithmetic expressions. The class of arithmetic
 language constructs also contains the function \CI{lit} that lifts a
 host-language value in to the \gls{EDSL} domain. All standard arithmetic
 Expressions in the \gls{mTask}-\gls{EDSL} are divided into two types, namely
 boolean expressions and arithmetic expressions. The class of arithmetic
 language constructs also contains the function \CI{lit} that lifts a
 host-language value in to the \gls{EDSL} domain. All standard arithmetic

-functions are included but are omitted for brevity. Moreover the class
-restrictions are only shown in the first functions and are later omitted. Both
-the boolean expression and arithmetic expression classes are shown in
-Listing~\ref{lst:arithbool}.
+functions are included in the \gls{EDSL} but are omitted in the example for
+brevity. Moreover, the class restrictions are only shown in the first functions
+and omitted in subsequent funcitons. Both the boolean expression and arithmetic
+expression classes are shown in Listing~\ref{lst:arithbool}.

 
 \begin{lstlisting}[language=Clean,label={lst:arithbool},
        caption={Basic classes for expressions}]
 
 \begin{lstlisting}[language=Clean,label={lst:arithbool},
        caption={Basic classes for expressions}]


@@ -60,10 +59,28 @@ class boolExpr v where
   (==.) infix 4 :: (v a p) (v a q) -> v Bool Expr       | ==, toCode a & ...
 \end{lstlisting}
 
   (==.) infix 4 :: (v a p) (v a q) -> v Bool Expr       | ==, toCode a & ...
 \end{lstlisting}
 

-\subsection{Control flow}
-\todo{Write this}
+\section{Control flow}
+Looping of \glspl{Task} happens because \glspl{Task} are executed after waiting
+a specified amount of time or when they are launched by another task or even
+themselves. Therefore there is no need for loop control flow functionality such
+as \emph{while} or \emph{for} constructions. The main control flow is the
+sequence operator and the \emph{if} statement. Both are shown in
+Listing~\ref{lst:control}. The first class of \emph{If} statements describe the
+regular \emph{if} statement. The expressions given can have any role. The
+functional dependency on \CI{s} determines the return type of the statement.
+The sequence operator is very straightforward and just ties the two expressions
+together in sequence.

 
 

-\subsection{Input/Output and class extensions}
+\begin{lstlisting}[%
+       language=Clean,label={lst:control},caption={Control flow operators}]
+class If v q r ~s where
+  If :: (v Bool p) (v t q) (v t r) -> v t s | ...
+
+class seq v where
+  (:.) infixr 0 :: (v t p) (v u q) -> v u Stmt | ...
+\end{lstlisting}
+
+\section{Input/Output and class extensions}

 All expressions that have an \CI{Upd} role can be assigned to. Examples of such
 expressions are \glspl{SDS} and \gls{GPIO}. Moreover, class extensions can be
 created for specific peripherals such as user LEDs. The classes facilitating
 All expressions that have an \CI{Upd} role can be assigned to. Examples of such
 expressions are \glspl{SDS} and \gls{GPIO}. Moreover, class extensions can be
 created for specific peripherals such as user LEDs. The classes facilitating


@@ -95,7 +112,7 @@ class assign v where
 \end{lstlisting}
 
 A way of storing data in \glspl{mTask} is using \glspl{SDS}. \glspl{SDS} serve
 \end{lstlisting}
 
 A way of storing data in \glspl{mTask} is using \glspl{SDS}. \glspl{SDS} serve

-as variables in the \gls{mTask} and will keep their value across executions.
+as variables in the \gls{mTask} and maintain their value across executions.

 The classes associated with \glspl{SDS} are listed in
 Listing~\ref{lst:sdsclass}. The \CI{Main} class is introduced to box an
 \gls{mTask} and make it recognizable by the type system.
 The classes associated with \glspl{SDS} are listed in
 Listing~\ref{lst:sdsclass}. The \CI{Main} class is introduced to box an
 \gls{mTask} and make it recognizable by the type system.


@@ -109,24 +126,79 @@ class sds v where
   sds :: ((v t Upd)->In t (Main (v c s))) -> (Main (v c s)) | ...
 \end{lstlisting}
 
   sds :: ((v t Upd)->In t (Main (v c s))) -> (Main (v c s)) | ...
 \end{lstlisting}
 

-\subsection{Example \gls{mTask}}
-\todo{Also explain semantics about running tasks}
-Some example \glspl{mTask} using almost all of the functionality are show in
+\section{Semantics}
+The \gls{C}-backend of the \gls{mTask}-system has an engine that is generated
+alongside the code for the \glspl{Task}. This engine will execute the
+\glspl{mTask} according to certain rules and semantics.
+\glspl{mTask} do not behave like functions but more like
+\gls{iTasks}-\glspl{Task}. An \gls{mTask} is queued when either his timer runs
+out or when it is started by another \gls{mTask}. When an \gls{mTask} is
+queued it does not block the execution but it will return immediately while
+the actual \gls{Task} will be executed some time in the future.
+
+The \gls{iTasks}-backend simulates the \gls{C}-backend and thus uses the same
+semantics. This engine expressed in pseudocode is listed as
+Algorithm~\ref{lst:engine}. All the \glspl{Task} are inspected on their waiting
+time. When the waiting time has not passed the delta is subtracted and they are
+pushed to the end of the queue. When the waiting has has surpassed they are
+executed. When a \gls{mTask} wants to queue another \gls{mTask} it can just
+append it to the queue.
+
+\begin{algorithm}[H]
+       \KwData{\textbf{queue} queue, \textbf{time} $t, t_p$}
+
+       $t\leftarrow\text{now}()$\;
+       \Begin{
+               \While{true}{
+                       $t_p\leftarrow t$\;
+                       $t\leftarrow\text{now}()$\;
+                       \If{notEmpty$($queue$)$}{
+                               $task\leftarrow \text{queue.pop}()$\;
+                               $task$.wait $\leftarrow task$.wait $-(t-t_p)$\;
+                               \eIf{$task.wait>t_0$}{
+                                       queue.append$(task)$\;
+                               }{
+                                       run\_task$(task)$\;
+                               }
+                       }
+               }
+       }
+       \caption{Engine pseudocode for the \gls{C}- and
+               \gls{iTasks}-backend}\label{lst:engine}
+\end{algorithm}
+
+To achieve this in the \gls{EDSL} a \gls{Task} clas are added that work in a
+similar fashion as the \texttt{sds} class. This class is listed in
+Listing~\ref{lst:taskclass}. \glspl{Task} can have an argument and always have
+to specify a delay or waiting time. The type signature of the \CI{mtask} is
+rather arcane and therefore an example is given. The aforementioned Listing
+shows a simple specification containing one task that increments a value
+indefinitely every one seconds.
+
+\begin{lstlisting}[language=Clean,label={lst:taskclass},%
+       caption={The classes for defining tasks}]
+class mtask v a where
+  task :: (((v delay r) a->v MTask Expr)->In (a->v u p) (Main (v t q))) -> Main (v t q) | ...
+
+count = task \count = (\n.count (lit 1000) (n +. One)) In {main = count (lit 1000) Zero}
+\end{lstlisting}
+
+\section{Example mTask}
+Some example \glspl{mTask} using almost all of the functionality are shown in

 Listing~\ref{lst:exmtask}. The \glspl{mTask} shown in the example do not belong
 to a particular view and therefore are of the type \CI{View t r}. The
 Listing~\ref{lst:exmtask}. The \glspl{mTask} shown in the example do not belong
 to a particular view and therefore are of the type \CI{View t r}. The

-\CI{blink} \gls{mTask} show the classic \emph{Arduino} \emph{Hello World!}
-application that blinks a certain LED every interval. The \CI{thermostat}
-\gls{mTask} will enable a digital pin powering a cooling fan when the analog
+\CI{blink} \gls{mTask} show the classic \gls{Arduino} \emph{Hello World!}
+application that blinks a certain LED every second. The \CI{thermostat}
+expression will enable a digital pin powering a cooling fan when the analog

 pin representing a temperature sensor is too high. \CI{thermostat`} shows the
 pin representing a temperature sensor is too high. \CI{thermostat`} shows the

-same program but now using the assignment style \gls{GPIO}.
+same expression but now using the assignment style \gls{GPIO} technique.

 
 \begin{lstlisting}[%
        language=Clean,label={lst:exmtask},caption={Some example \glspl{mTask}}]
 
 \begin{lstlisting}[%
        language=Clean,label={lst:exmtask},caption={Some example \glspl{mTask}}]

-blink :: Main (View Int Stmt)
-blink = sds \x=1 In sds \led=LED1 In {main =
-  IF (x ==. lit 1) (ledOn led) (ledOff led) :.
-  x =. lit 1 -. x
-  }
+blink = task \blink=(\x.
+               IF (x ==. lit True) (ledOn led) (ledOff led) :.
+               blink (lit 1000) (Not x)
+       In {main=blink (lit 1000) True}

 
 thermostat :: Main (View () Stmt)
 thermostat = {main =
 
 thermostat :: Main (View () Stmt)
 thermostat = {main =