module CSE230.List where
import Prelude hiding (maximum)
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— | clone
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— >>> clone 5 ‘a’
— “aaaaa”
— >>> clone 3 “cat”
— [“cat”,”cat”,”cat”]
clone :: Int -> a -> [a]
| n <= 0 = error "fill this in"
| otherwise = error "fill this in"
-------------------------------------------------------------------------------
-- | Padding a List
-------------------------------------------------------------------------------
data Dir = DirL | DirR
deriving (Eq, Show)
-- >>> pad DirL 10 0 [1,2,3,4,5]
— [0,0,0,0,0,1,2,3,4,5]
— >>> pad DirR 10 0 [1,2,3,4,5]
— [1,2,3,4,5,0,0,0,0,0]
— >>> pad DirL 3 0 [1,2,3,4,5]
— [1,2,3,4,5]
— >>> pad DirR 3 0 [1,2,3,4,5]
— [1,2,3,4,5]
pad :: Dir -> Int -> a -> [a] -> [a]
pad dir n x ys = error “fill this in”
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— | ‘isSubSequence s1 s2’ returns True if `s1` is a sub-sequence of `s2` i.e.
— if `s1` can be obtained by deleting some elements of `s2`
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— >>> isSubSequence “cat” “dog”
— >>> isSubSequence “cat” “craptasticdog”
isSubSequence :: (Eq a) => [a] -> [a] -> Bool
isSubSequence [] _ = error “fill this in”
isSubSequence _ [] = error “fill this in”
isSubSequence (y:ys) = error “fill this in”
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— | maximum
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— >>> maximum 99 []
— >>> maximum 99 [90, 100, 200, 52]
maximum :: (Ord a) => a -> [a] -> a
maximum d xs = foldr f base xs
base = error “fill this in”
f = error “fill this in”
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— | intersperse
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— >>> intersp ‘|’ “chewbacca”
— “|c|h|e|w|b|a|c|c|a|”
— >>> intersp “yo!” [“which”, “way”, “is”, “the”, “park”]
— [“yo!”,”which”,”yo!”,”way”,”yo!”,”is”,”yo!”,”the”,”yo!”,”park”,”yo!”]
intersp :: a -> [a] -> [a]
intersp s xs = foldr f base xs
base = error “fill this in”
f x r = error “fill this in”
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— Higher Order: iter
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— >>> iter 10 (\x -> 2 * x) 1
iter :: Int -> (a -> a) -> a -> a
iter 0 _ x = error “fill this in”
iter n f x = error “fill this in”
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