Keyed unification option, compiling the whole standard library

(but deactivated still).

Set Keyed Unification to activate the option, which changes
subterm selection to _always_ use full conversion _after_ finding a
subterm whose head/key matches the key of the term we're looking for.
This applies to rewrite and higher-order unification in
apply/elim/destruct.

Most proof scripts already abide by these semantics. For those that
don't, it's usually only a matter of using:

Declare Equivalent Keys f g.

This make keyed unification consider f and g to match as keys.
This takes care of most cases of abbreviations: typically Def foo :=
bar and rewriting with a bar-headed lhs in a goal mentioning foo works
once they're set equivalent.
For canonical structures, these hints should be automatically declared.

For non-global-reference headed terms, the key is the constructor name
(Sort, Prod...). Evars and metas are no keys.

INCOMPATIBILITIES:
In FMapFullAVL, a Function definition doesn't go through with keyed
unification on.

1 files changed, 1 insertions, 3 deletions

diff --git a/theories/Numbers/Cyclic/Abstract/NZCyclic.v b/theories/Numbers/Cyclic/Abstract/NZCyclic.v
index 1d5b78ec4..c9f3a774d 100644
--- a/theories/Numbers/Cyclic/Abstract/NZCyclic.v
+++ b/theories/Numbers/Cyclic/Abstract/NZCyclic.v
@@ -126,9 +126,7 @@ Let B (n : Z) := A (ZnZ.of_Z n).
 
 Lemma B0 : B 0.
 Proof.
-unfold B.
-setoid_replace (ZnZ.of_Z 0) with zero. assumption.
-red; zify. apply ZnZ.of_Z_correct. auto using gt_wB_0 with zarith.
+unfold B. apply A0.
 Qed.
 
 Lemma BS : forall n : Z, 0 <= n -> n < wB - 1 -> B n -> B (n + 1).