14 lines
511 B
Text
14 lines
511 B
Text
module
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reset_grind_attrs%
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example {l : List α} {f : β → α → β} {b : β} :
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l.foldl f b = l.reverse.foldr (fun x y => f y x) b := by
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grind [List.foldr_reverse]
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/-
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The following example doesn't work yet. `grind` doesn't have a mechanism
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for inferring that `fun x y => g y x` is equal to `f` given
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the equality `g = (f x y => f y x)`
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-/
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-- example {l : List α} {f : β → α → β} {b : β} :
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-- g = (fun x y => f y x) → l.foldl f b = l.reverse.foldr g b := by
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-- grind [List.foldr_reverse]
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