10 lines
436 B
Text
10 lines
436 B
Text
open List
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reset_grind_attrs%
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attribute [grind →] Array.eq_empty_of_append_eq_empty eq_nil_of_length_eq_zero
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attribute [grind] Vector.getElem?_append getElem?_dropLast
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#guard_msgs (trace) in -- should not report any issues
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set_option trace.grind.issues true
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theorem dropLast_concat : dropLast (l₁ ++ [b]) = l₁ := by
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fail_if_success grind
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grind -ext only [List.dropLast_append_cons, List.dropLast_singleton, List.append_nil]
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