lean4-htt/tests/elab/wfWithSidecondition.lean
Garmelon 08eb78a5b2
chore: switch to new test/bench suite (#12590)
This PR sets up the new integrated test/bench suite. It then migrates
all benchmarks and some related tests to the new suite. There's also
some documentation and some linting.

For now, a lot of the old tests are left alone so this PR doesn't become
even larger than it already is. Eventually, all tests should be migrated
to the new suite though so there isn't a confusing mix of two systems.
2026-02-25 13:51:53 +00:00

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section setup
variable {α : Sort u}
variable {β : α → Sort v}
variable {γ : Sort w}
def callsOn (P : α → Prop) (F : (∀ y, β y) → γ) :=
∃ (F': (∀ y, P y → β y) → γ), ∀ f, F' (fun y _ => f y) = F f
variable (R : αα → Prop)
variable (F : (∀ y, β y) → (∀ x, β x))
local infix:50 " ≺ " => R
def recursesVia : Prop := ∀ x, callsOn (· ≺ x) (fun f => F f x)
noncomputable def fix (wf : WellFounded R) (h : recursesVia R F) : (∀ x, β x) :=
wf.fix (fun x => (h x).choose)
def fix_eq (wf : WellFounded R) h x : fix R F wf h x = F (fix R F wf h) x := by
unfold fix
rw [wf.fix_eq]
apply (h x).choose_spec
theorem callsOn_base (y : α) (hy : P y) : callsOn P (fun (f : ∀ x, β x) => f y) := by
exists fun f => f y hy
intros; rfl
@[simp]
theorem callsOn_const (x : γ) : callsOn P (fun (_ : ∀ x, β x) => x) :=
⟨fun _ => x, fun _ => rfl⟩
theorem callsOn_app
{γ₁ : Sort uu} {γ₂ : Sort ww}
(F₁ : (∀ y, β y) → γ₂ → γ₁) -- can this also support dependent types?
(F₂ : (∀ y, β y) → γ₂)
(h₁ : callsOn P F₁)
(h₂ : callsOn P F₂) :
callsOn P (fun f => F₁ f (F₂ f)) := by
obtain ⟨F₁', h₁⟩ := h₁
obtain ⟨F₂', h₂⟩ := h₂
exists (fun f => F₁' f (F₂' f))
intros; simp_all
theorem callsOn_lam
{γ₁ : Sort uu}
(F : γ₁ → (∀ y, β y) → γ) -- can this also support dependent types?
(h : ∀ x, callsOn P (F x)) :
callsOn P (fun f x => F x f) := by
exists (fun f x => (h x).choose f)
intro f
ext x
apply (h x).choose_spec
theorem callsOn_app2
{γ₁ : Sort uu} {γ₂ : Sort ww}
(g : γ₁ → γ₂ → γ)
(F₁ : (∀ y, β y) → γ₁) -- can this also support dependent types?
(F₂ : (∀ y, β y) → γ₂)
(h₁ : callsOn P F₁)
(h₂ : callsOn P F₂) :
callsOn P (fun f => g (F₁ f) (F₂ f)) := by
apply_rules [callsOn_app, callsOn_const]
theorem callsOn_map (δ : Type uu) (γ : Type ww)
(P : α → Prop) (F : (∀ y, β y) → δ → γ) (xs : List δ)
(h : ∀ x, x ∈ xs → callsOn P (fun f => F f x)) :
callsOn P (fun f => xs.map (fun x => F f x)) := by
suffices callsOn P (fun f => xs.attach.map (fun ⟨x, h⟩ => F f x)) by
simpa
apply callsOn_app
· apply callsOn_app
· apply callsOn_const
· apply callsOn_lam
intro ⟨x', hx'⟩
dsimp
exact (h x' hx')
· apply callsOn_const
end setup
section examples
structure Tree (α : Type u) where
val : α
cs : List (Tree α)
noncomputable def List.map' (f : α → β) : List α → List β :=
fix (sizeOf · < sizeOf ·) (fun map l => match l with | [] => [] | x::xs => f x :: map xs)
(InvImage.wf (sizeOf ·) WellFoundedRelation.wf) <| by
intro l
dsimp only
cases l -- check that the predicate of `callsOn` is appropriately refined
· simp
· simp only [cons.sizeOf_spec, sizeOf_default, Nat.add_zero]
apply callsOn_app2
· apply callsOn_const
· apply callsOn_base
simp
noncomputable def Tree.map (f : α → β) : Tree α → Tree β :=
fix (sizeOf · < sizeOf ·) (fun map t => ⟨f t.val, t.cs.map map⟩)
(InvImage.wf (sizeOf ·) WellFoundedRelation.wf) <| by
intro ⟨v, cs⟩
dsimp only
apply callsOn_app2
· apply callsOn_const
· apply callsOn_map
intro t' ht'
apply callsOn_base
decreasing_trivial
end examples