41a2e9af19
This PR makes functions defined by well-founded recursion use an `opaque` well-founded proof by default. This reliably prevents kernel reduction of such definitions and proofs, which tends to be prohibitively slow (fixes #2171), and which regularly causes hard-to-debug kernel type-checking failures. This changes renders `unseal` ineffective for such definitions. To avoid the opaque proof, annotate the function definition with `@[semireducible]`.
21 lines
478 B
Text
21 lines
478 B
Text
import Lean
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@[semireducible]
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def ack : Nat → Nat → Nat
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| 0, y => y+1
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| x+1, 0 => ack x 1
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| x+1, y+1 => ack x (ack (x+1) y)
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set_option maxHeartbeats 500
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open Lean Meta
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/-- error: (kernel) deterministic timeout -/
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#guard_msgs in
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run_meta do
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let type ← mkEq (← mkAppM ``ack #[mkNatLit 4, mkNatLit 4]) (mkNatLit 100000)
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let value ← mkEqRefl (mkNatLit 100000)
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addDecl <| .thmDecl {
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name := `ack_4_4
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levelParams := []
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type, value
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}
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