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| -rw-r--r-- | doc/refman/RefMan-ltac.tex | 54 |
1 files changed, 52 insertions, 2 deletions
diff --git a/doc/refman/RefMan-ltac.tex b/doc/refman/RefMan-ltac.tex index ce2cb277c..7e6c0bd12 100644 --- a/doc/refman/RefMan-ltac.tex +++ b/doc/refman/RefMan-ltac.tex @@ -503,7 +503,7 @@ $v_2$ and so on. It fails if there is no solving tactic. \ErrMsg \errindex{Cannot solve the goal} -\subsubsection[Identity]{Identity\tacindex{idtac} +\subsubsection[Identity]{Identity\label{ltac:idtac}\tacindex{idtac} \index{Tacticals!idtac@{\tt idtac}}} The constant {\tt idtac} is the identity tactic: it leaves any goal @@ -1028,7 +1028,57 @@ Defined {\ltac} functions can be displayed using the command {\tt Print Ltac {\qualid}.} \end{quote} -\section[Debugging {\ltac} tactics]{Debugging {\ltac} tactics\comindex{Set Ltac Debug} +\section{Debugging {\ltac} tactics} + +\subsection[Info trace]{Info trace\comindex{Info}\comindex{Set Info Level} +\comindex{Unset Info Level} +\comindex{Test Info Level}} + +It is possible to print the trace of the path eventually taken by an {\ltac} script. That is, the list of executed tactics, discarding all the branches which have failed. To that end the {\tt Info} command can be used with the following syntax. + +\begin{quote} +{\tt Info} {\num} {\tacexpr}. +\end{quote} + +The number {\num} is the unfolding level of tactics in the trace. At level $0$, the trace contains a sequence of tactics in the actual script, at level $1$, the trace will be the concatenation of the traces of these tactics, etc\ldots + +\begin{coq_eval} +Reset Initial. +\end{coq_eval} +\begin{coq_example*} +Ltac t x := exists x; reflexivity. + +Goal exists n, n=0. +\end{coq_example*} +\begin{coq_example} +Info 0 t 1||t 0. +\end{coq_example} +\begin{coq_example*} +Undo. +\end{coq_example*} +\begin{coq_example} +Info 1 t 1||t 0. +\end{coq_example} + +The trace produced by {\tt Info} tries its best to be a reparsable {\ltac} script, but this goal is not achievable in all generality. So some of the output traces will contain oddities. + +As an additional help for debugging, the trace produced by {\tt Info} contains (in comments) the messages produced by the {\tt idtac} tacticals~\ref{ltac:idtac} at the right possition in the script. In particular, the calls to {\tt idtac} in branches which failed are not printed. + +An alternative to the {\tt Info} command is to use the {\tt Info Level} option as follows: + +\begin{quote} +{\tt Set Info Level} \num. +\end{quote} + +This will automatically print the same trace as {\tt Info \num} at each tactic call. The unfolding level can be overridden by a call to the {\tt Info} command. And this option can be turned off with: + +\begin{quote} +{\tt Unset Info Level} \num. +\end{quote} + +The current value for the {\tt Info Level} option can be checked using the {\tt Test Info Level} command. + +\subsection[Interactive debugger]{Interactive debugger\comindex{Set Ltac Debug} \comindex{Unset Ltac Debug} \comindex{Test Ltac Debug}} |