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

And if that isn't a possibility, you can use pattern matching: bla (x:y:z:[]) = do something bla _ = do nothing On Tue, Sep 28, 2010 at 4:41 PM, Ozgur Akgun wrote:

Hi,

On 28 September 2010 15:07, Martin Tomko 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.

Best, Ozgur

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