Talk:Purely functional

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Contents 1 Name convention breaking 2 Red Black Tree 3 lazyness 4 Better example than thesaurus?

[edit] Name convention breaking

Since the title of this page is an adjective rather than a noun, it violates Wikipedia: Naming conventions. Of course, this may be justified in this case, but if it is I think we should be explicit about it here before someone decides to proactively move it. Deco 21:13, 15 July 2005 (UTC)

The article actually spends most of its time discussing purely functional data structures. I vote we rename the page accordingly. Neilc 09:05, 2 December 2005 (UTC)

I agree, if the unrelated material is moved out to somewhere suitable. Deco 23:20, 3 December 2005 (UTC)

[edit] Red Black Tree

Okasaki doesn't give the routine for deletion of Red-Black Trees. Since this encyclopedia article is basically a selection from his book and you mention that one specifically I think we should do the deletion case. Anyone else agree?

[edit] lazyness

I think lazyness and data structures deserves more explanation. Its one of the areas where functional languages differ and thus efficiency computations give different results.

[edit] Better example than thesaurus?

It's artificial, the simpler solution is to keep one common thesaurus and one private for each user and search in both than to impose additional requirements on the data structure.

--78.0.85.5 02:55, 12 September 2007 (UTC)

User:Brianski added XML comments to the article body. They should be discussed here on talk. LotLE×talk 23:36, 31 December 2007 (UTC)

(context) For example, a thesaurus service on a website uses a red-black tree to store its list of which words are synonyms for which other words; because the thesaurus is comprehensive, this tree has a large number of nodes. Consider adding a feature that allows each user to add their own custom words to their personal thesaurus. One way to do this is to make a copy of the tree for each user, and then add their custom words to it; however, this is wasteful duplication. Moreover, it would cause a significant processing delay to make the complete copy of the tree.

(Brianski) this is a bad example - the same problem could be solved by checking one thesaurus, then the other, and returning their union. no programmer, sane or not, would make a copy for each user presented this problem

The thesaurus/dictionary problem isn't very good. Some ideas for better examples: (1) A 3D game world where users can make their own private customisations. Because 3D scenes are very complex and large, and you can't solve this with the "two worlds" (private + shared) as you can in the dictionary case, a purely functional data structure would make more sense. (2) A filesystem like this: http://okmij.org/ftp/papers/zfs-talk.pdf (3) A way to implement an XML document editor where you allow infinite undo steps. Each undo step is essentially a shared copy of the document tree with private changes. Richard W.M. Jones (talk) 11:50, 1 January 2008 (UTC)