From: Mart Lubbers <mart@martlubbers.net>
Date: Sat, 24 Jun 2017 18:22:26 +0000 (+0200)
Subject: add return
X-Git-Tag: hand-in~58
X-Git-Url: https://git.martlubbers.net/?a=commitdiff_plain;h=fa4a40715e0b78ee616b98a1c1d889406a31435a;p=msc-thesis1617.git

add return
---

diff --git a/results.mtask.tex b/results.mtask.tex
index 92e0782..50cd1d6 100644
--- a/results.mtask.tex
+++ b/results.mtask.tex
@@ -224,11 +224,29 @@ BCIfStmt (BC b) (BC t) (BC e) = BC (
 	t >>| tell [BCJmp endif, BCLab else] >>|
 	e >>| tell [BCLab endif]
 	)
+
 instance noOp ByteCode where
 	noOp = tell` [BCNop]
 \end{lstlisting}
 
-\todo{Add return instruction}
+The semantics for the \glspl{mTask} bytecode view are different than the
+semantics for the \gls{C} view. \glspl{Task} in the \gls{C} view can start new
+\gls{Task} or themselves to continue, while in the bytecode view, \gls{Task}
+run idefinitly, one-shot or on interrupt. To allow interval and interrupt
+\glspl{Task} to terminate, a return instruction is added. This class was not
+available in the original system and is thus added. It just writes a single
+instruction so that the interpreter knows to stop execution.
+Listing~\ref{lst:return} shows the classes and implementation for the return
+expression.
+
+\begin{lstlisting}[label={lst:return},%
+	caption={Bytecode view for the return instruction}]
+class retrn v where
+  retrn :: v () Expr
+
+instance retrn ByteCode where
+	retrn = tell` [BCReturn]
+\end{lstlisting}
 
 \subsection{Shared Data Sources \& Assignment}
 Shared data sources must be acquired from the state and constructing one