5cef84709f
See Section "Other goodies" at https://github.com/leanprover/lean/wiki/Refactoring-structures This commit also improves the support for projections in the unifier/matcher. Now, we consider the extra case-split for projections. Given a projection `proj`, and the constraint `proj s =?= proj t`, we need to try first `s =?= t` and if it fails, then try to reduce. This is needed in the standard library because we now have constraints such as: ``` @has_le.le ?A ?s ?a ?b =?= @has_le.le nat nat.has_add x y ``` If we reduce the right hand side, we get the unsolvable constraint ``` @has_le.le ?A ?s ?a ?b =?= nat.le x y ``` Before this change, the constraint was `@le ?A ?s ?a ?b =?= @le nat nat.has_add x y`, and we already perform a case-split in this case. Moreover, projections were eagerly reduced whenever possible. The extra case-split generates a performance problem in several tests. For example `fib 8 = 34` was timing out. I worked around this issue by performing the case-split only when the constraint contains meta-variables. There are also minor issues. Example. `<` is notation for `has_lt.lt`, but `>` is for `gt`.
15 lines
351 B
Text
15 lines
351 B
Text
open tactic
|
|
|
|
add_key_equivalence has_add.add nat.succ
|
|
|
|
set_option pp.binder_types true
|
|
|
|
example (a b c : nat) : a + 1 = b + 1 → b + 1 = a + 1 :=
|
|
by do
|
|
a ← get_local `a, b ← get_local `b,
|
|
e₁ ← mk_app `nat.succ [a],
|
|
e₂ ← mk_app `nat.succ [b],
|
|
generalize e₁ `x,
|
|
generalize e₂ `y,
|
|
trace_state,
|
|
intros, symmetry, assumption
|