[Haskell-beginners] Abstracting Data.List

[Giacomo Tesio]

Do you see any issue with using ListLike? In my particular domain, the
concept of position, is actually relevant.

Giacomo



On Fri, May 31, 2013 at 4:31 PM, Brandon Allbery <allbery.b at gmail.com>wrote:

> On Fri, May 31, 2013 at 6:16 AM, mukesh tiwari <
> mukeshtiwari.iiitm at gmail.com> wrote:
>
>> Data.List can be abstracted using Foldable and Traversable but
>> unfortunately I could not find the functions corresponding to head, take.
>>
>
> Those are, again, more general than you want. What is the `head` of a
> HashMap? (Consider that an implementation may choose to randomize the hash
> function to avoid hash collision attacks.) Foldable and Traversable express
> the concept of a collection which has no meaningful concept of an element's
> relative position within the collection. ListLike adds the concept of
> position, thereby admitting an indexing operation (and, by extension,
> `head` which is index 0).
>
> --
> brandon s allbery kf8nh                               sine nomine
> associates
> allbery.b at gmail.com
> ballbery at sinenomine.net
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