18 lines
758 B
Text
18 lines
758 B
Text
getElem.lean:2:2-2:6: 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 perfomed, 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 : Nat
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⊢ i < Array.size a
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def f2 : (a : Array Nat) → Fin (Array.size a) → Nat :=
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fun a i => a[i]
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def f3 : {n : Nat} → (a : Array Nat) → n ≤ Array.size a → Fin n → Nat :=
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fun {n} a h i => a[i]
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def f5 : (i : Nat) → i < n → Nat :=
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fun i h => a[i]
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def f6 : Nat → Nat :=
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fun i => a[i]!
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def f7 : Nat → Option Nat :=
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fun i => a[i]?
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