X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;f=methods.mtask.tex;h=6d1284872909509ff6e0b3196f18a487815d3f1c;hb=a4d108b9046bfd1d94e8b986a00c00090391d7b6;hp=4e61d97642d598f3222e46346b2abce7daf0ab91;hpb=c7fa2f10a5c049e2ae70405630857c7873778899;p=msc-thesis1617.git diff --git a/methods.mtask.tex b/methods.mtask.tex index 4e61d97..6d12848 100644 --- a/methods.mtask.tex +++ b/methods.mtask.tex @@ -1,22 +1,22 @@ -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 @@ -43,8 +43,8 @@ language constructs also contains the function \CI{lit} that lifts a 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}] @@ -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 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 @@ -93,7 +100,7 @@ class seq v where 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. @@ -121,11 +128,13 @@ 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}[% label={lst:sdsclass},caption={\glspl{SDS} in \gls{mTask}}] @@ -139,21 +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{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} $t, t_p$} @@ -174,19 +184,20 @@ can just 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} 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}[label={lst:taskclass},% - caption={The classes for defining tasks}] + 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) | ... @@ -194,17 +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 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)