186a81627b
This PR a bug in the optimized and unsafe implementation of `Array.foldlM`. Issue was reported here: https://leanprover.zulipchat.com/#narrow/channel/113488-general/topic/Array.2Efoldl.20bug.20.28can.20prove.20False.29/near/565077432
23 lines
633 B
Text
23 lines
633 B
Text
/--
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error: Tactic `native_decide` evaluated that the proposition
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foldl (fun x1 x2 => x1 + x2) 0 #[1, 2, 3] 0 5 = 0
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is false
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-/
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#guard_msgs in
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theorem Array.foldl_broken : False := by
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let x := #[1,2,3].foldl (. + .) 0 (stop := 5)
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have : x = 6 := by rfl
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have : x = 0 := by native_decide -- must fail
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contradiction
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/--
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error: Tactic `native_decide` evaluated that the proposition
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Array.foldl (fun x1 x2 => x1 + x2) 0 #[1, 2, 3] 0 5 = 0
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is false
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-/
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#guard_msgs in
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example : #[1,2,3].foldl (. + .) 0 (stop := 5) = 0 := by
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native_decide -- must fail
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example : #[1,2,3].foldl (. + .) 0 (stop := 5) = 6 := by
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native_decide
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