[cltl3-devel] Some questions

[Jochen Schmidt]

Am 22.12.2009 um 14:08 schrieb Edward Tate:

> Hello,
> 
> I have a few questions about some issues:
> 
> Are user extensible streams ala: http://www.doc.gold.ac.uk/~mas01cr/papers/ilc2007/sequences-20070301.pdf going to be catered for in cltl3?

Short: yes
See the thread about "RFC: CLtL3 Charter" in august/september '09. Drew Crampsie has posted a CLtL3-Charter and started a discussion about it. I've put a copy on here:

http://pmeta.net/projects/cltl3/charter/cltl3-charter-draft-2.txt

> There is no functional converse to SORT & STABLE-SORT. All the other operations that I can think of have functional / destructive operations, why the non uniformity?

Actually I don't know why - but it is important to understand that SORT is "potentially destructive". You cannot rely on an old reference of the sorted sequence. So SORT being destructive is specified to _allow_ efficient implementation of sorting sequences - not to enable users to safe some characters by "in-place-modification". Not that you meant that :-) just because it is a quite common error not to use the return value of SORT "because it is destructive".

Regarding CLtL3: To me this never was a real problem since COPY-SEQ isn't actually very difficult to add and I think of it more as a library issue (its easy to add portably using some utility-library). I 
personally would have nothing against adding a "non-destructive SORT"; though I fear the name debate would come up again with people demanding SORT to be called NSORT or even SORT! ;-) . Naming issues are explicitely NOT part of the CLtL3-Charter.

> 
> Are Generators & Series being thought of? :)

Similar to the non-destructive SORT: Those facilities should be easy to do using libraries in a portable way and only an ASDF:OOS away. It would only make the mudball bigger without making anything easier. So yes - Generators and Series make a cool (library-)extension to CL but they need not necessarily be a part of CLtL3. I understand the idea behind it and the symbolic/political value though. There already was the idea to make a CLtL3-Core without any library-add-ons and some CLtL3-Extensions which would be documented extensions. This could be an alternative.

ciao,
Jochen Schmidt

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Jochen Schmidt 
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