9cce0ce8d9
This PR fixes the behavior of the indexed-access notation `xs[i]` in cases where the proof of `i`'s validity is filled in during unification. Closes #6999.
19 lines
559 B
Text
19 lines
559 B
Text
/-!
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# List index validity proofs synthesized by unification
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https://github.com/leanprover/lean4/issues/6999
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The tactic `get_elem_tactic` should not fail if invoked in a situation in which the necessary proof
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of index validity has already been filled in during unification.
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-/
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set_option linter.unusedVariables false
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axiom A : Type
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axiom B : A → Type
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axiom as : List A
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axiom fn : (l : Nat) → (_ : l < as.length) → Option (B as[l])
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#guard_msgs in
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example {l : Nat} {llen : l < as.length} {b : B as[l]}
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(b_mem : b ∈ fn l llen) : True := trivial
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