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[Jason Gross <jasongross9 AT gmail.com>]

What about making a tactic notation that takes an ident_list and a tactic, creates evars for all of the identifiers in the list, runs the tactic, and cleans them up afterwards?  You could also make a functional variant that returned the result of the tactic afterwards.  This would be analogous to needing a list of variable declarations in the code to use variables.  It's a bit suboptimal, perhaps, but I think it should work.  (You may need to play some games to actually make use of the ident_list, or might need to do something else that's morally equivalent to an ident_list.)

On 8:52pm, Sat, Jan 24, 2015 Emile Lunardon <emile.lunardon AT gmail.com> wrote:

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2015-01-24 16:33 GMT+01:00 Jonathan Leivent <jonikelee AT gmail.com>:

On 01/24/2015 03:11 AM, Jason Gross wrote:

Hi,

In case others may find this discovery interesting (if you have not already
made it yourselves):
It is possible to mostly eliminate the verbose [match goal with ... end]
construct in trunk/8.5 by using the following tactic:

   Ltac hyp := multimatch goal with H : _ |- _ => constr:H end.

Note that [let H := hyp in ... ] will automatically backtrack across
failures of subsequent tactics, due to [multimatch]:

   Goal False -> True -> False -> True.
     intros.
     let H := hyp in exact H.

Using open_constr and uconstr tactic notations, I presume the other
features of match (pattern matching on the body and the type) can be
duplicated with shorter syntax, too.

-Jason

I wasn't able to duplicate the match feature of named pattern variables with any combo of open_constr and uconstr, at least not without using evars in their place (which is not as good as one can easily leave unsolved evars as a result).

Which is one reason why I was asking you about those other Tactic arg notations that are undocumented.

-- Jonathan