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lab04b: WIP

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Yura
2026-02-14 18:30:31 -08:00
parent 931bda5ffb
commit 14dc6dee28
1 changed files with 5 additions and 1 deletions
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6
lab04/lab.lhs
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@@ -7,18 +7,22 @@ defined as myFoldl
> myFoldl :: (a -> b -> a) -> a -> [b] -> a > myFoldl :: (a -> b -> a) -> a -> [b] -> a
> myFoldl _ _ _ = error "TBD" > myFoldl _ _ _ = error "TBD"
> myFoldl f acc [] = acc
> myFoldl f acc (x:xs) = f acc $ myFoldl f x xs
Next, define a function to reverse a list using foldl. Next, define a function to reverse a list using foldl.
> myReverse :: [a] -> [a] > myReverse :: [a] -> [a]
> myReverse _ = error "TBD" > myReverse = foldl (\acc x -> x : acc) []
Now define your own version of foldr, named myFoldr Now define your own version of foldr, named myFoldr
> myFoldr :: (a -> b -> b) -> b -> [a] -> b > myFoldr :: (a -> b -> b) -> b -> [a] -> b
> myFoldr _ _ _ = error "TBD" > myFoldr _ _ _ = error "TBD"
> myFoldr f acc [] = acc
> myFoldr f acc (x:xs) = f x $ myFoldr f acc xs
Now try using foldl (the library version, not yours) to sum up the numbers of a large list. Now try using foldl (the library version, not yours) to sum up the numbers of a large list.