258d3725e7
This PR changes the signature of `Array.set` to take a `Nat`, and a tactic-provided bound, rather than a `Fin`. Corresponding changes (but without the auto-param) for `Array.get` will arrive shortly, after which I'll go more pervasively through the Array API.
17 lines
517 B
Text
17 lines
517 B
Text
def zero_out (arr : Array Nat) (i : Nat) : Array Nat :=
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if h : i < arr.size then
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zero_out (arr.set i 0) (i + 1)
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else
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arr
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termination_by arr.size - i
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decreasing_by simp; apply Nat.sub_succ_lt_self _ _ h
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-- set_option trace.Elab.definition true
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theorem size_zero_out (arr : Array Nat) (i : Nat) : (zero_out arr i).size = arr.size := by
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unfold zero_out
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split
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· rw [size_zero_out]
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rw [Array.size_set]
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· rfl
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termination_by arr.size - i
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decreasing_by simp; apply Nat.sub_succ_lt_self; assumption
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