9 lines
369 B
Text
9 lines
369 B
Text
namespace Array
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@[simp] theorem getElem_pop (a : Array α) (i : Nat) (hi : i < a.pop.size) :
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a.pop[i] = a[i]'(Nat.lt_of_lt_of_le (a.size_pop ▸ hi) (Nat.sub_le _ _)) :=
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sorry
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theorem ex {as : Array α} (h : i < size as) (hlt: i < size (pop as)) :
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as[i] = (pop as)[i] := by
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rw [getElem_pop] -- should close the goal, proof should be found by unification
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