68c006a95b
This PR enables transforming nondependent `let`s into `have`s in a number of contexts: the bodies of nonrecursive definitions, equation lemmas, smart unfolding definitions, and types of theorems. A motivation for this change is that when zeta reduction is disabled, `simp` can only effectively rewrite `have` expressions (e.g. `split` uses `simp` with zeta reduction disabled), and so we cache the nondependence calculations by transforming `let`s to `have`s. The transformation can be disabled using `set_option cleanup.letToHave false`. Uses `Meta.letToHave`, introduced in #8954.
41 lines
1.4 KiB
Text
41 lines
1.4 KiB
Text
/-! Equational theorem generation regression test.-/
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structure PrefixTable (α : Type _) extends Array (α × Nat) where
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/-- Validity condition to help with termination proofs -/
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valid : (h : i < toArray.size) → toArray[i].2 ≤ i
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def PrefixTable.step [BEq α] (t : PrefixTable α) (x : α) (kf : Fin (t.size+1)) : Fin (t.size+1) :=
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match kf with
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| ⟨k, hk⟩ =>
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let cont := fun () =>
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match k with
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| 0 => ⟨0, Nat.zero_lt_succ _⟩
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| k + 1 =>
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have h2 : k < t.size := Nat.lt_of_succ_lt_succ hk
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let k' := t.toArray[k].2
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have hk' : k' < k + 1 := Nat.lt_succ_of_le (t.valid h2)
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step t x ⟨k', Nat.lt_trans hk' hk⟩
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if hsz : k < t.size then
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if x == t.toArray[k].1 then
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⟨k+1, Nat.succ_lt_succ hsz⟩
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else cont ()
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else cont ()
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termination_by kf.val
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/--
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info: PrefixTable.step.eq_def.{u_1} {α : Type u_1} [BEq α] (t : PrefixTable α) (x : α) (kf : Fin (t.size + 1)) :
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t.step x kf =
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match kf with
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| ⟨k, hk⟩ =>
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have cont := fun x_1 =>
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match k, hk with
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| 0, hk => ⟨0, ⋯⟩
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| k.succ, hk =>
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have h2 := ⋯;
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let k' := t.toArray[k].snd;
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have hk' := ⋯;
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t.step x ⟨k', ⋯⟩;
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if hsz : k < t.size then if (x == t.toArray[k].fst) = true then ⟨k + 1, ⋯⟩ else cont () else cont ()
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-/
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#guard_msgs in
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#check PrefixTable.step.eq_def
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