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`.
16 lines
492 B
Text
16 lines
492 B
Text
attribute [reducible]
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definition nat_has_add2 : has_add nat :=
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has_add.mk (λ x y : nat, x + y)
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attribute [reducible]
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definition nat_has_add3 : nat → has_add nat :=
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λ n, has_add.mk (λ x y : nat, x + y)
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open tactic
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set_option pp.all true
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example (a b : nat) (H : (λ x : nat, @has_add.add nat nat_has_add2 a x) = (λ x : nat, @has_add.add nat (nat_has_add3 x) a b)) : true :=
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by do
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s ← simp_lemmas.mk_default,
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get_local `H >>= infer_type >>= s^.dsimplify >>= trace,
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constructor
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