3a408e0e54
This PR changes the signature of `Array.get` to take a Nat and a proof, rather than a `Fin`, for consistency with the rest of the (planned) Array API. Note that because of bootstrapping issues we can't provide `get_elem_tactic` as an autoparameter for the proof. As users will mostly use the `xs[i]` notation provided by `GetElem`, this hopefully isn't a problem. We may restore `Fin` based versions, either here or downstream, as needed, but they won't be the "main" functions. --------- Co-authored-by: David Thrane Christiansen <david@davidchristiansen.dk>
33 lines
1 KiB
Text
33 lines
1 KiB
Text
opaque fin_max {n: Nat} (f: Fin n → Nat) : Nat
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set_option maxRecDepth 30 in
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-- NB: Important to not specify the implicit argument of fin_max here
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def test (a: Array Nat) : Nat := @fin_max _ fun i =>
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let h : i < a.size := by
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-- this may apply once
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with_reducible apply Fin.val_lt_of_le
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fail_if_success with_reducible apply Fin.val_lt_of_le;
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exact Nat.le_refl _
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a[i]
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set_option pp.mvars false
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-- This used to cause
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-- error: maximum recursion depth has been reached in #5061
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/--
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error: failed to prove index is valid, possible solutions:
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- Use `have`-expressions to prove the index is valid
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- Use `a[i]!` notation instead, runtime check is performed, and 'Panic' error message is produced if index is not valid
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- Use `a[i]?` notation instead, result is an `Option` type
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- Use `a[i]'h` notation instead, where `h` is a proof that index is valid
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a : Array Nat
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i : Fin ?_
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⊢ ↑i < a.size
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-/
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#guard_msgs in
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set_option maxRecDepth 40 in
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def test2 (a: Array Nat) : Nat := @fin_max _ fun i =>
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let h : i < a.size := by
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get_elem_tactic
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a[i]
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