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`.
10 lines
733 B
Text
10 lines
733 B
Text
λ (A : Type u_1) [_inst_1 : has_add A] [_inst_2 : has_zero A] (a : A)
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(H : @eq A (@has_add.add A _inst_1 a (@has_zero.zero A _inst_2)) a) [_inst_3 : has_add A]
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(H : @eq A a (@has_add.add A _inst_3 (@has_zero.zero A _inst_2) (@has_zero.zero A _inst_2))),
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@has_add.add A _inst_3 a a :
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Π (A : Type u_1) [_inst_1 : has_add A] [_inst_2 : has_zero A] (a : A),
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@eq A (@has_add.add A _inst_1 a (@has_zero.zero A _inst_2)) a →
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Π [_inst_3 : has_add A],
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@eq A a (@has_add.add A _inst_3 (@has_zero.zero A _inst_2) (@has_zero.zero A _inst_2)) → A
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λ (a b : nat) (H : @gt nat nat.has_lt a b) [_inst_1 : has_lt nat], @has_lt.lt nat _inst_1 a b :
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Π (a b : nat), @gt nat nat.has_lt a b → Π [_inst_1 : has_lt nat], Prop
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