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`.
27 lines
406 B
Text
27 lines
406 B
Text
namespace test
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open tactic
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meta def my_tac : tactic unit := abstract (intros >> simp)
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structure monoid (α : Type) :=
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(op : α → α → α)
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(assoc : ∀ a b c, op (op a b) c = op a (op b c) . my_tac)
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def m1 : monoid nat :=
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monoid.mk (+)
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def m2 : monoid nat :=
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monoid.mk (*)
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#print m1
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#print m2
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def m3 : monoid nat :=
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{op := (+)}
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def m4 : monoid nat :=
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{op := (*)}
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#print m3
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#print m4
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end test
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