Now tactics supporting locations can also specify the goal among the locations by using the name `⊢` or `|-`. Also `rw at *` is implemented so that it will rewrite any hypotheses or the goal for which the whole sequence of rewrites succeeds. (This is different from `rw at h1 h2 ... hn |-`, which requires that all rewrites run to completion on each specified target.)
`rewrite` tactic improvements
- Add support for `auto_param` and `opt_param`
- Order new goals using the same strategies available for `apply`
- Allow user to set configuration object in interactive mode.
@Armael This commit should address the issue you raised about the order
of new goals in the `rewrite` tactic.
See new test tests/lean/run/rw1.lean for examples.
I kept a few core methods (e.g., exact_core and apply_core). Reason:
if we use default parameters
meta constant exact (e : expr) (md := semireducible) : tactic unit
then, we will not be able to write
to_expr p >>= exact
The workaround is
do t <- to_expr p, exact t
or
to_expr p >>= (fun x, exact x)
One alternative is to change how we handle default parameters, and
eta-expand applications that involve default parameters.
We may also have an attribute [eta_expand]. Then
attribute [eta_expand] foo
instructs the elaborator to automatically eta-expand foo-applications.
The attribute would give users more control, and avoid potential
performance problems. Without the attribute, then for every function
application the elaborator has to check the type and decide whether it
must be eta-expanded or not.
@gebner @kha What do you think?
The idea is to make sure lean doesn't timeout (at reflexivity) when we apply simp or
rewrite in goals such as
(x y : nat) |- x + y + 10000000000 = x + y + 200000000000000
This commit also addresses an issue raised at #1218
