How to get every Nth element of an infinite list in Haskell?

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再見小時候
再見小時候 2020-12-04 23:58

More specifically, how do I generate a new list of every Nth element from an existing infinite list?

E.g. if the list is [5, 3, 0, 1, 8, 0, 3, 4, 0, 93, 211, 0

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  •  北海茫月
    2020-12-05 00:43

    My version using drop:

    every n xs = case drop (n-1) xs of
                  (y:ys) -> y : every n ys
                  [] -> []
    

    Edit: this also works for finite lists. For infinite lists only, Charles Stewart's solution is slightly shorter.

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