[armedbear-devel] User-extensible sequences?

Axel Rauschmayer axel at rauschma.de
Wed Jan 6 14:42:49 UTC 2010

I was looking for something similar to lazy lists or iterators in CL and asked a friend who told me about the following paper (abstract see below):

Is this something worthy of inclusion into ABCL?

Axel.Rauschmayer at ifi.lmu.de

User-extensible sequences in Common Lisp
Christophe Rhodes

Common Lisp is often touted as the programmable programming language, yet it sometimes places large barriers in the way, with the best of intentions. One of those barriers is a limit to the extensibility by the user of certain core language constructs, such as the ability to define subclasses of builtin classes usable with standard functions: even where this could be achievable with minimal penalties. We introduce the notion of user-extensible sequences, describing a protocol which implementations of such classes should follow. We show examples of their use, and discuss the issues observed in providing support for this protocol in a Common Lisp, including ensuring that there is no performance impact from its inclusion.

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