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`.
36 lines
723 B
Text
36 lines
723 B
Text
universe variables u v
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structure Func :=
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(A : Type u) (B : A → Type v) (fn : Π a, B a → B a)
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instance F_to_fn : has_coe_to_fun Func :=
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{ F := λ f, Π a, f^.B a → f^.B a,
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coe := λ f a b, f^.fn a (f^.fn a b) }
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variables (f : Func) (a : f^.A) (b : f^.B a)
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#check (f a b)
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def f1 : Func :=
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{ A := nat,
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B := λ a, nat,
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fn := (+) }
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-- set_option trace.type_context.is_def_eq_detail true
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/- We need to mark 10 as a nat.
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Reason: f1 is not reducible, then type class resolution
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cannot find an instance for `has_one (Func.A f1)` -/
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example : f1 (10:nat) (30:nat) = (50:nat) :=
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rfl
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/-
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#exit
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attribute [reducible] f1
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example : f1 10 30 = 50 :=
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rfl
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example (n m : nat) : f1 n m = n + (n + m) :=
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rfl
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-/
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