[Haskell-beginners] ignature for a list of a set length

Ozgur Akgun ozgurakgun at gmail.com
Tue Sep 28 10:41:38 EDT 2010


On 28 September 2010 15:07, Martin Tomko <martin.tomko at geo.uzh.ch> wrote:

> I want to have a function that acts only on lists of length 3 (I have a
> function that filters a list of lists and returns only those of that
> length). I guess I could change them into tuples (is there a way?)

Well if both the producer and the consumer of this value are your own
functions, you can use something other than a list. You can also implement a
length indexed list, or use such an implementation but it will be overkill
for this task, I think.

The two options are either implementing a wrapper type with three fields, or
using a 3-tuple.
I would use a 3-tuple in both the producer and consumer functions.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.haskell.org/pipermail/beginners/attachments/20100928/26166427/attachment.html

More information about the Beginners mailing list