Changeset 187

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• docs/trunk/hacking-guide/tock-intro.tex

  r186	r187
  184	184	I have used `rep' as a short-hand for the replicator (which is not the focus here). Hopefully it is
  185	185	now clear how Structured is used as a body for things. There is only one more aspect to explain,
  186	which is definitions.
  187
  188	%TODO explain definitions
  186	which is definitions, or rather specifications.
  187
  188	\occamsettings\begin{lstlisting}
  189	SEQ
  190	proc1
  191	INT x:
  192	proc2
  193	\end{lstlisting}
  194
  195	According to occam scoping rules, `\lstinline|x|' is in scope for proc2. This is represented in the
  196	AST as follows:
  197
  198	\haskellsettings\begin{lstlisting}
  199	A.Seq m
  200	(A.Several m
  201	[A.OnlyP m proc1
  202	,A.Specification m spec (A.OnlyP m proc2)
  203	]
  204	)
  205	\end{lstlisting}
  206
  207	Where `spec' is shorthand for the full specification of `x'. The specification (third argument)
  208	is in scope for the whole of the body (the fourth argument). Multiple specifications lead to
  209	nested Specifications:
  210
  211	\occamsettings\begin{lstlisting}
  212	SEQ
  213	proc1
  214	INT x:
  215	INT16 y:
  216	proc2
  217	\end{lstlisting}
  218
  219	\haskellsettings\begin{lstlisting}
  220	A.Seq m
  221	(A.Several m
  222	[A.OnlyP m proc1
  223	,A.Specification m specX
  224	(A.Specification m specY (A.OnlyP m proc2))
  225	]
  226	)
  227	\end{lstlisting}
  228
  229	Note that each of the actual items in a Structured is named OnlyP (Process), OnlyA (ALT guard), etc.
  230	To be valid, any SEQ must contain no Only* items except OnlyP. Similarly, an ALT must contain
  231	no Only* items except OnlyA, and so on.
  189	232
  190	233	\subsection{Monadic Code}

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