[Haskell-cafe] Re: Non Empty List?
gue.schmidt at web.de
Thu Jun 4 19:40:47 EDT 2009
thanks for replying, no, I'm not looking for streams.
I hope I made myself a bit more clear in my response to Jake.
Tom Lokhorst schrieb:
> 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).
> - Tom
>  http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Stream
> 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.
>> Haskell-Cafe mailing list
>> Haskell-Cafe at haskell.org
More information about the Haskell-Cafe