-The \gls{mTask}-\gls{EDSL} is the basis on which the system is built. The
-\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 \gls{Arduino}~\cite{koopman_type-safe_nodate}%
+The \gls{mTask}-\gls{EDSL} is the language used for the proposed system. The
+\gls{mTask}-\gls{EDSL} was created by Koopman et al.\ and supports 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 program
+for microcontrollers such as the \gls{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
classes given. 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
+is 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.
-A view for the \gls{mTask}-\gls{EDSL} is a type with kind \CI{*->*->*}%
-\footnote{A type with two free type variables.} that implements some of the
-classes given. The types do not have to be present as fields in the higher
-kinded view and can, and will most often, be exclusively phantom types. A view
-is of the form \CI{v t r}. The first type variable will be the type of the
+A view for the \gls{mTask}-\gls{EDSL} is a type with two free type
+variables\footnote{kind \CI{*->*->*}.} that implements some of the classes
+given. The types do not have to be present as fields in the view and can, and
+will most often, be exclusively phantom types. Thus, views are of the
+form:\\\CI{:: v t r = ...}. The first type variable will be the type of the
view. The second type variable will be the type of the \gls{EDSL}-expression
and the third type variable represents the role of the expression. Currently
the role of the expressions form a hierarchy. The three roles and their
host-language value into the \gls{EDSL} domain. All standard arithmetic
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}.
+and are omitted in subsequent functions. Both the boolean expression and
+arithmetic expression classes are shown in Listing~\ref{lst:arithbool}.
\begin{lstlisting}[label={lst:arithbool},
caption={Basic classes for expressions}]
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 listing includes examples of implementations that illustrate this
-dependency.
+dependency. A special \emph{If} statement --- only used for statements --- is
+also added under the name \CI{IF}, of which the \CI{?} is a conditional
+statement to execute.
-The sequence operator is very straightforward and its only function is to tie
-the together in sequence.
+The sequence operator is straightforward and its only function is to tie
+two expressions together. The left expression is executed first, followed by
+the right expression.
\begin{lstlisting}[%
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 IF v where
+ IF :: (v Bool p) (v t q) (v s r) -> v () Stmt | ...
+ (?) infix 1 :: (v Bool p) (v t q) -> v () Stmt | ...
+
instance If Code Stmt Stmt Stmt
instance If Code e Stmt Stmt
instance If Code Stmt e Stmt
Values can be assigned to all expressions that have an \CI{Upd} role. Examples
of such expressions are \glspl{SDS} and \gls{GPIO} pins. Moreover, class
extensions can be created for specific peripherals such as built-in
-\glspl{LED}. The classes facilitating this are shown in
+\glspl{LED}. The classes facilitating this are shown in
Listing~\ref{lst:sdsio}. In this way the assignment is the same for every
assignable entity.
(=.) infixr 2 :: (v t Upd) (v t p) -> v t Expr | ...
\end{lstlisting}
-A way of storing data in \glspl{mTask} is using \glspl{SDS}. \glspl{SDS} serve
-as variables in the \gls{mTask} and maintain their value across executions.
-The classes associated with \glspl{SDS} are listed in
+One way of storing data in \gls{mTask}-\glspl{Task} is using \glspl{SDS}.
+\glspl{SDS} serve as variables in \gls{mTask} and maintain their value across
+executions. \glspl{SDS} can be used by multiple \glspl{Task} and can be used
+to share data. The classes associated with \glspl{SDS} are listed in
Listing~\ref{lst:sdsclass}. The \CI{Main} type is introduced to box an
-\gls{mTask} and make it recognizable by the type system.
+\gls{mTask} and make it recognizable by the type system by separating programs
+and decorations such as \glspl{SDS}.
\begin{lstlisting}[%
label={lst:sdsclass},caption={\glspl{SDS} in \gls{mTask}}]
\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{mTask}-\glspl{Task} according to certain rules and semantics.
+\gls{mTask}-\glspl{Task} do not behave like functions but more like
\gls{iTasks}-\glspl{Task}. An \gls{mTask} is queued when either its timer runs
out or when it is launched by another \gls{mTask}. When an \gls{mTask} is
-queued it does not block the execution and it will return immediately while
-the actual \gls{Task} will be executed anytime in the future.
+queued it does not block the execution and it will return immediately while the
+actual \gls{Task} will be executed anytime 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 the
\gls{Task} gets pushed to the end of the queue. When the waiting has surpassed
-they are executed. When an \gls{mTask} wants to queue another \gls{mTask} it
+they are executed. When an \gls{mTask} opts to queue another \gls{mTask} it
can just append it to the queue.
+~\\
\begin{algorithm}[H]
\KwData{\textbf{queue} queue, \textbf{time} $t, t_p$}
}
}
\caption{Engine pseudocode for the \gls{C}- and
- \gls{iTasks}-backend}\label{lst:engine}
+ \gls{iTasks}-view}\label{lst:engine}
\end{algorithm}
+~\\
To achieve this in the \gls{EDSL} a \gls{Task} class is added that work in a
similar fashion as the \texttt{sds} class. This class is listed in
\end{lstlisting}
\section{Example mTask}
-Some example \glspl{mTask} using almost all of their 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
-\CI{blink} \gls{mTask} show the classic \gls{Arduino} \emph{Hello World!}
-application that blinks a certain \gls{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 same
-expression but now using the assignment style \gls{GPIO} technique.
+Some example \gls{mTask}-\glspl{Task} using almost all of their functionality
+are shown in Listing~\ref{lst:exmtask}. The \gls{mTask}-\glspl{Task} 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 \gls{Arduino}
+blinking led application that blinks a certain \gls{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 same expression but now using the assignment style
+\gls{GPIO} technique. The \CI{thermostat} example also shows that it is not
+necessary to run everything as a \CI{task}. The main program code can also just
+consist of the contents of the root \CI{main} itself.
\begin{lstlisting}[%
- label={lst:exmtask},caption={Some example \glspl{mTask}}]
+ label={lst:exmtask},caption={Some example \gls{mTask}-\glspl{Task}}]
blink = task \blink=(\x.
IF (x ==. lit True) (ledOn led) (ledOff led) :.
blink (lit 1000) (Not x)
repositories / msc-thesis1617.git / blobdiff