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`.
17 lines
575 B
Text
17 lines
575 B
Text
g x y =?= f z
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unification failed
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g x y =?= f z
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g x y =?= f z
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unification successful
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unification hints:
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(has_add.add, nat.succ) #2 + succ #1 =?= succ #0 {#0 =?= #2 + #1}
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(toy.f, toy.g) f z =?= g #1 #0 {}
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Canonical.carrier A_canonical =?= A
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unification failed
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Canonical.carrier A_canonical =?= A
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Canonical.carrier A_canonical =?= A
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unification successful
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unification hints:
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(has_add.add, nat.succ) #2 + succ #1 =?= succ #0 {#0 =?= #2 + #1}
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(toy.f, toy.g) toy.f toy.z =?= toy.g #1 #0 {}
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(canonical.A, canonical.Canonical.carrier) A =?= Canonical.carrier #0 {#0 =?= A_canonical}
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