[Haskell-cafe] beginner's problem about lists

[Neil Mitchell]

Hi,

The trick is not call "length", since length demands the whole of a
list, and won't terminate on an infinite list. You will want to
recurse down the lists.

Is this a homework problem? It's best to declare if it is, and show
what you've managed to do so far.

Thanks

Neil

On 10/10/06, falseep at gmail.com <falseep at gmail.com> wrote:
> Hi all,
>
> I'm trying to implement a function that returns the shorter one of two given
> lists,
> something like
> shorter :: [a] -> [a] -> [a]
> such that shorter [1..10] [1..5] returns [1..5],
> and it's okay for shorter [1..5] [2..6] to return either.
>
> Simple, right?
>
> However, it becomes difficult when dealing with infinite lists, for example,
> shorter [1..5] (shorter [2..] [3..])
> Could this evaluate to [1..5]? I haven't found a proper implementation.
>
> Again it's ok for shorter [2..] [3..] to return whatever that can solve the
> above problem correctly.
> An infinite list could work, I guess, but I don't know how.
>
> Thanks for any help.
>
>
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