diff options
Diffstat (limited to 'doc/refman/RefMan-ltac.tex')
| -rw-r--r-- | doc/refman/RefMan-ltac.tex | 104 |
1 files changed, 74 insertions, 30 deletions
diff --git a/doc/refman/RefMan-ltac.tex b/doc/refman/RefMan-ltac.tex index 3ce1d4ecd8..ef0f4af8f6 100644 --- a/doc/refman/RefMan-ltac.tex +++ b/doc/refman/RefMan-ltac.tex @@ -1,4 +1,5 @@ \chapter[The tactic language]{The tactic language\label{TacticLanguage}} +%HEVEA\cutname{ltac.html} %\geometry{a4paper,body={5in,8in}} @@ -197,8 +198,6 @@ is understood as {\cpattern} {\tt =>} {\tacexpr}\\ & $|$ & {\tt context} {\zeroone{\ident}} {\tt [} {\cpattern} {\tt ]} {\tt =>} {\tacexpr}\\ -& $|$ & {\tt appcontext} {\zeroone{\ident}} {\tt [} {\cpattern} {\tt ]} - {\tt =>} {\tacexpr}\\ & $|$ & {\tt \_ =>} {\tacexpr}\\ \\ {\it test} & ::= & @@ -310,10 +309,11 @@ A sequence is an expression of the following form: \begin{quote} {\tacexpr}$_1$ {\tt ;} {\tacexpr}$_2$ \end{quote} -The expressions {\tacexpr}$_1$ and {\tacexpr}$_2$ are evaluated -to $v_1$ and $v_2$ which have to be tactic values. The tactic $v_1$ is -then applied and $v_2$ is applied to the goals generated by the -application of $v_1$. Sequence is left-associative. +The expression {\tacexpr}$_1$ is evaluated to $v_1$, which must be +a tactic value. The tactic $v_1$ is applied to the current goal, +possibly producing more goals. Then {\tacexpr}$_2$ is evaluated to +produce $v_2$, which must be a tactic value. The tactic $v_2$ is applied to +all the goals produced by the prior application. Sequence is associative. \subsubsection[Local application of tactics]{Local application of tactics\tacindex{[>\ldots$\mid$\ldots$\mid$\ldots]}\tacindex{;[\ldots$\mid$\ldots$\mid$\ldots]}\index{Tacticals![> \mid ]@{\tt {\tac$_0$};[{\tac$_1$}$\mid$\ldots$\mid$\tac$_n$]}}\index{Tacticals!; [ \mid ]@{\tt {\tac$_0$};[{\tac$_1$}$\mid$\ldots$\mid$\tac$_n$]}}} %\tacindex{; [ | ]} @@ -546,7 +546,7 @@ Yet another way of branching without backtracking is the following structure: $v_2$ which must be tactic values. The tactic value $v_1$ is applied in each subgoal independently and if it fails \emph{to progress} then $v_2$ is applied. {\tacexpr}$_1$ {\tt ||} {\tacexpr}$_2$ is equivalent to {\tt - first [} {\tt progress} {\tacexpr}$_1$ {\tt |} {\tt progress} + first [} {\tt progress} {\tacexpr}$_1$ {\tt |} {\tacexpr}$_2$ {\tt ]} (except that if it fails, it fails like $v_2$). Branching is left-associative. @@ -560,7 +560,7 @@ The tactic is a generalization of the biased-branching tactics above. The expression {\tacexpr}$_1$ is evaluated to $v_1$, which is then applied to each subgoal independently. For each goal where $v_1$ succeeds at -least once, {tacexpr}$_2$ is evaluated to $v_2$ which is then applied +least once, {\tacexpr}$_2$ is evaluated to $v_2$ which is then applied collectively to the generated subgoals. The $v_2$ tactic can trigger backtracking points in $v_1$: where $v_1$ succeeds at least once, {\tt tryif {\tacexpr}$_1$ then {\tacexpr}$_2$ else {\tacexpr}$_3$} is @@ -709,6 +709,55 @@ runs is displayed. Time is in seconds and is machine-dependent. The {\qstring} argument is optional. When provided, it is used to identify this particular occurrence of {\tt time}. +\subsubsection{Timing a tactic that evaluates to a term\tacindex{time\_constr}\tacindex{restart\_timer}\tacindex{finish\_timing} +\index{Tacticals!time\_constr@{\tt time\_constr}}} +\index{Tacticals!restart\_timer@{\tt restart\_timer}} +\index{Tacticals!finish\_timing@{\tt finish\_timing}} + +Tactic expressions that produce terms can be timed with the experimental tactic +\begin{quote} + {\tt time\_constr} {\tacexpr} +\end{quote} +which evaluates {\tacexpr\tt{ ()}} +and displays the time the tactic expression evaluated, assuming successful evaluation. +Time is in seconds and is machine-dependent. + +This tactic currently does not support nesting, and will report times based on the innermost execution. +This is due to the fact that it is implemented using the tactics +\begin{quote} + {\tt restart\_timer} {\qstring} +\end{quote} +and +\begin{quote} + {\tt finish\_timing} ({\qstring}) {\qstring} +\end{quote} +which (re)set and display an optionally named timer, respectively. +The parenthesized {\qstring} argument to {\tt finish\_timing} is also +optional, and determines the label associated with the timer for +printing. + +By copying the definition of {\tt time\_constr} from the standard +library, users can achive support for a fixed pattern of nesting by +passing different {\qstring} parameters to {\tt restart\_timer} and +{\tt finish\_timing} at each level of nesting. For example: + +\begin{coq_example} +Ltac time_constr1 tac := + let eval_early := match goal with _ => restart_timer "(depth 1)" end in + let ret := tac () in + let eval_early := match goal with _ => finish_timing ( "Tactic evaluation" ) "(depth 1)" end in + ret. + +Goal True. + let v := time_constr + ltac:(fun _ => + let x := time_constr1 ltac:(fun _ => constr:(10 * 10)) in + let y := time_constr1 ltac:(fun _ => eval compute in x) in + y) in + pose v. +Abort. +\end{coq_example} + \subsubsection[Local definitions]{Local definitions\index{Ltac!let@\texttt{let}} \index{Ltac!let rec@\texttt{let rec}} \index{let@\texttt{let}!in Ltac} @@ -874,21 +923,6 @@ Goal True. f (3+4). \end{coq_example} -\item \index{appcontext@\texttt{appcontext}!in pattern} - \optindex{Tactic Compat Context} -For historical reasons, {\tt context} used to consider $n$-ary applications -such as {\tt (f 1 2)} as a whole, and not as a sequence of unary -applications {\tt ((f 1) 2)}. Hence {\tt context [f ?x]} would fail -to find a matching subterm in {\tt (f 1 2)}: if the pattern was a partial -application, the matched subterms would have necessarily been -applications with exactly the same number of arguments. -As a workaround, one could use the following variant of {\tt context}: -\begin{quote} -{\tt appcontext} {\ident} {\tt [} {\cpattern} {\tt ]} -\end{quote} -This syntax is now deprecated, as {\tt context} behaves as intended. The former -behavior can be retrieved with the {\tt Tactic Compat Context} flag. - \end{Variants} \subsubsection[Pattern matching on goals]{Pattern matching on goals\index{Ltac!match goal@\texttt{match goal}}\label{ltac-match-goal} @@ -1105,19 +1139,14 @@ Fail all:let n:= numgoals in guard n=2. Reset Initial. \end{coq_eval} -\subsubsection[Proving a subgoal as a separate lemma]{Proving a subgoal as a separate lemma\tacindex{abstract}\tacindex{transparent\_abstract}\comindex{Qed exporting} +\subsubsection[Proving a subgoal as a separate lemma]{Proving a subgoal as a separate lemma\tacindex{abstract}\tacindex{transparent\_abstract} \index{Tacticals!abstract@{\tt abstract}}\index{Tacticals!transparent\_abstract@{\tt transparent\_abstract}}} From the outside ``\texttt{abstract \tacexpr}'' is the same as {\tt solve \tacexpr}. Internally it saves an auxiliary lemma called {\ident}\texttt{\_subproof}\textit{n} where {\ident} is the name of the current goal and \textit{n} is chosen so that this is a fresh name. -Such auxiliary lemma is inlined in the final proof term -unless the proof is ended with ``\texttt{Qed exporting}''. In such -case the lemma is preserved. The syntax -``\texttt{Qed exporting }\ident$_1$\texttt{, ..., }\ident$_n$'' -is also supported. In such case the system checks that the names given by the -user actually exist when the proof is ended. +Such an auxiliary lemma is inlined in the final proof term. This tactical is useful with tactics such as \texttt{omega} or \texttt{discriminate} that generate huge proof terms. With that tool @@ -1378,6 +1407,21 @@ The following two tactics behave like {\tt idtac} but enable and disable the pro {\tt stop ltac profiling}. \end{quote} +\tacindex{reset ltac profile}\tacindex{show ltac profile} +The following tactics behave like the corresponding vernacular commands and allow displaying and resetting the profile from tactic scripts for benchmarking purposes. + +\begin{quote} +{\tt reset ltac profile}. +\end{quote} + +\begin{quote} +{\tt show ltac profile}. +\end{quote} + +\begin{quote} +{\tt show ltac profile} {\qstring}. +\end{quote} + You can also pass the {\tt -profile-ltac} command line option to {\tt coqc}, which performs a {\tt Set Ltac Profiling} at the beginning of each document, and a {\tt Show Ltac Profile} at the end. Note that the profiler currently does not handle backtracking into multi-success tactics, and issues a warning to this effect in many cases when such backtracking occurs. |