On 23 Nov 2006, at 21:53, Christophe Rhodes wrote:
Hi,
I have plans to modify CDR 3 slightly, adding a non-portable test case to the Test Case section and improving the references. I appreciate that the issue that CDR 3 describes is largely theoretical, but are there any comments from anyone out there? Getting any feedback before the finalization date would obviously be useful; it may be a theoretical issue at the moment but I hope that it will become a practical issue in the not-distant future.
[I am posting this as a regular Common Lisper, not as a CDR editor.] I have just read your proposal and the respective original CONCATENATE-SEQUENCE issue in the HyperSpec. Apart from the fact that I have a hard time imagining what other interesting implementations one could have for sequences with fixed length apart from lists and vectors, I also have a hard time to imagine how sequences with non-fixed lengths could be integrated, for example with concatenate-sequence. To be more concrete: You could regard lazy lists and streams as kinds of sequences, and they could indeed be made subtypes of 'sequence. In those cases, though, it doesn't make a lot of sense that concatenate- sequence supports them, for example, especially when they model infinite sequences (like "all prime numbers", or so). I think a different way to say this is as the following question: What guarantees do the existing sequence functions give us? For example, do they have to terminate? What other kinds of subtypes of sequence do you have in mind? Pascal -- Pascal Costanza, mailto:pc@p-cos.net, http://p-cos.net Vrije Universiteit Brussel, Programming Technology Lab Pleinlaan 2, B-1050 Brussel, Belgium