mtask.io.tex

   1 Values can be assigned to all expressions that have an \CI{Upd} role. Examples
   2 of such expressions are \glspl{SDS} and \gls{GPIO} pins. Moreover, class
   3 extensions can be created for specific peripherals such as built-in
   4 \glspl{LED}. The classes facilitating this are shown in
   5 Listing~\ref{lst:sdsio}. In this way the assignment is the same for every
   6 assignable entity.
   7
   8 \begin{lstlisting}[language=Clean,%
   9         label={lst:sdsio},caption={Input/Output classes}]
  10 :: DigitalPin = D0 | D1 | D2 | D3 | D4 | D5 |D6 | D7 | D8 | D9 | D10 | D11 | D12 | D13
  11 :: AnalogPin    = A0 | A1 | A2 | A3 | A4 | A5
  12 :: UserLED = LED1 | LED2 | LED3
  13
  14 class dIO v where dIO :: DigitalPin -> v Bool Upd
  15 class aIO v where aIO :: AnalogPin -> v Int Upd
  16 class analogRead v where
  17         analogRead :: AnalogPin -> v Int Expr
  18         analogWrite :: AnalogPin (v Int p) -> v Int Expr
  19 class digitalRead v where
  20         digitalRead :: DigitalPin -> v Bin Expr
  21         digitalWrite :: DigitalPin (v Bool p) -> v Int Expr
  22
  23 :: UserLED = LED1 | LED2 | LED3
  24 class userLed v where
  25         ledOn   :: (v UserLED q) -> (v () Stmt)
  26         ledOff :: (v UserLED q) -> (v () Stmt)
  27
  28 class assign v where
  29         (=.) infixr 2 :: (v t Upd) (v t p) -> v t Expr | ...
  30 \end{lstlisting}
  31
  32 One way of storing data in \gls{mTask}-\glspl{Task} is using \glspl{SDS}.
  33 \glspl{SDS} serve as global variables in \gls{mTask} and maintain their value
  34 across executions. \glspl{SDS} can be used by multiple \glspl{Task} and can be
  35 used to share data. The classes associated with \glspl{SDS} are listed in
  36 Listing~\ref{lst:sdsclass}. The \CI{Main} type is introduced to box an
  37 \gls{mTask} and make it recognizable by the type system by separating programs
  38 and decorations such as \glspl{SDS}. The type signature is complex and uses
  39 infix type constructors and therefore, an implementation example is also given.
  40
  41 \begin{lstlisting}[language=Clean,%
  42         label={lst:sdsclass},caption={\glspl{SDS} in \gls{mTask}}]
  43 :: In a b = In infix 0 a b
  44 :: Main a = {main :: a}
  45
  46 class sds v where
  47         sds :: ((v t Upd) -> In t (Main (v c s))) -> (Main (v c s)) | ...
  48
  49 sdsExample :: Main (v Int Stmt)
  50 sdsExample = sds \x.0 In
  51         {main= x =. x +. lit 42 }
  52 \end{lstlisting}