X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;f=methods.mtask.tex;h=38930c5bc762c6fd47182bcca9377003583a0563;hb=36d2564cca6ffab6506198f13545e5d02cf2b5cc;hp=67f4b4e264522312dc5ee6ecbf54c08638e8957e;hpb=d11a7941da4024ec8ff9ef6afaebb6eb9d2c6ed4;p=msc-thesis1617.git diff --git a/methods.mtask.tex b/methods.mtask.tex index 67f4b4e..38930c5 100644 --- a/methods.mtask.tex +++ b/methods.mtask.tex @@ -1,32 +1,32 @@ -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 -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 +classes given. The following sections show the details of the \gls{EDSL} that +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, solely be phantom types. A view is 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 hierarchy are -shown in Listing~\ref{lst:exprhier}. This implies that everything is a -statement, only a \CI{Upd} and a \CI{Expr} are expressions. The \CI{Upd} +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 higher kinded 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 +hierarchy are shown in Listing~\ref{lst:exprhier}. This implies that everything +is a statement, only a \CI{Upd} and a \CI{Expr} are expressions. The \CI{Upd} restriction describes updatable expressions such as \gls{GPIO} pins and \glspl{SDS}. \begin{lstlisting}[% - language=Clean,label={lst:exprhier},caption={Expression role hierarchy}] + label={lst:exprhier},caption={Expression role hierarchy}] :: Upd = Upd :: Expr = Expr :: Stmt = Stmt @@ -40,13 +40,13 @@ instance isExpr Expr 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 +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}[language=Clean,label={lst:arithbool}, +\begin{lstlisting}[label={lst:arithbool}, caption={Basic classes for expressions}] class arith v where lit :: t -> v t Expr @@ -62,24 +62,31 @@ class boolExpr v where \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 operators -are the sequence operator and the \emph{if} statement. Both are shown in -Listing~\ref{lst:control}. The first class of \emph{If} statements describes +a specified amount of time or when they are launched by another \gls{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 +operators are the sequence operator and the \emph{if} statement. Both are shown +in Listing~\ref{lst:control}. The first class of \emph{If} statements describes 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. +functional dependency on \CI{s} determines the return type of the statement. +The listing includes examples of implementations that illustrate this +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 just ties -the two expressions 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}[% - language=Clean,label={lst:control},caption={Control flow operators}] + 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 @@ -92,12 +99,13 @@ class seq v where \section{Input/Output and class extensions} 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 builtin \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. +extensions can be created for specific peripherals such as built-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. \begin{lstlisting}[% - language=Clean,label={lst:sdsio},caption={Input/Output classes}] + label={lst:sdsio},caption={Input/Output classes}] :: DigitalPin = D0 | D1 | D2 | D3 | D4 | D5 |D6 | D7 | D8 | D9 | D10 | D11 | D12 | D13 :: AnalogPin = A0 | A1 | A2 | A3 | A4 | A5 :: UserLED = LED1 | LED2 | LED3 @@ -120,14 +128,16 @@ class assign v where (=.) 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}[% - language=Clean,label={lst:sdsclass},caption={\glspl{SDS} in \gls{mTask}}] + label={lst:sdsclass},caption={\glspl{SDS} in \gls{mTask}}] :: In a b = In infix 0 a b :: Main a = {main :: a} @@ -138,21 +148,22 @@ class sds v where \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. +\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. 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 -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 can just -append it to the queue. +\gls{Task} gets pushed to the end of the queue. When the waiting has surpassed +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} $t, t_p$} @@ -173,19 +184,20 @@ append it to the queue. } } \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} clas are added that work in a +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 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 complex and therefore an example is given. The aforementioned Listing -shows a simple specification containing one task that increments a value +shows a simple specification containing one \gls{Task} that increments a value indefinitely every one seconds. -\begin{lstlisting}[language=Clean,label={lst:taskclass},% - caption={The classes for defining tasks}] +\begin{lstlisting}[label={lst:taskclass},% + caption={The classes for defining \glspl{Task}}] 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) | ... @@ -193,17 +205,20 @@ count = task \count = (\n.count (lit 1000) (n +. One)) In {main = count (lit 100 \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 -\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}[% - language=Clean,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) @@ -211,7 +226,7 @@ blink = task \blink=(\x. thermostat :: Main (View () Stmt) thermostat = {main = - IF (analogRead A0 >. 50) + IF (analogRead A0 >. lit 50) ( digitalWrite D0 (lit True) ) ( digitalWrite D0 (lit False) ) } @@ -219,5 +234,5 @@ thermostat = {main = thermostat` :: Main (View () Stmt) thermostat` = let a0 = aIO A0 - d0 = dIO D0 in {main = IF (a0 >. 50) (d0 =. lit True) (d0 =. lit False) } + d0 = dIO D0 in {main = IF (a0 >. lit 50) (d0 =. lit True) (d0 =. lit False) } \end{lstlisting}