[Haskell-cafe] Non Empty List?
tom at lokhorst.eu
Thu Jun 4 19:21:55 EDT 2009
Are you looking for something like Streams ?
They're infinite sequences, defined like this:
data Stream a = Cons a (Stream a)
They can obviously never be empty (unless you see bottom (undefined) as empty).
On Thu, Jun 4, 2009 at 11:53 PM, GüŸnther Schmidt <gue.schmidt at web.de> wrote:
> I need to design a container data structure that by design cannot be empty
> and can hold n elements. Something like a non-empty list.
> I started with:
> data Container a = Single a | Many a [a]
> but the problem above is that the data structure would allow to construct a
> Many 5  :: Container Int.
> I can't figure out how to get this right. :(
> Please help.
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