[Haskell-cafe] Ultra-newbie Question

Ivan Lazar Miljenovic ivan.miljenovic at gmail.com
Sat Sep 18 03:55:46 EDT 2010

On 18 September 2010 17:51, Christopher Tauss <ctauss1 at gmail.com> wrote:
> Hello Haskell Community -
> I am a professional programmer with 11 years experience, yet I just do not
> seem to be able to get the hang of even simple things in Haskell.  I am
> trying to write a function that takes a list and returns the last n
> elements.
> There may be a function which I can just call that does that, but I am
> trying to roll my own just to understand the concept.
> Let's call the function n_lastn and, given a list  [1,2,3,4,5], I would like
> n_lastn 3 = [3,4,5]
> Seems like it would be something like:
> n_lastn:: [a]->Int->[a]
> n_lastn 1 (xs) = last(xs)
> n_lastn n (x:xs) = ????
> The issue is I do not see how you can store the last elements of the list.

Easiest way I can think of:

n_lastn n = reverse . take n . reverse


n_lastn n xs = drop (len - n) xs
        len = length xs

Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com

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