[Jtsummers]

And it remains in a state of almost getting to the point of generic collections (like C++, Clojure, many others) using the standard functions, but not quite getting there. There are functions (not generic functions) which operate on sequences, but no standard way to extend what types are considered sequences (as one example). It makes sense that the 1995 version of the spec would be incremental, but without a further development (or consensus amongst the implementations if no official standard) it's difficult to continue moving forward to make better use of the language's generic function capabilities.

That's where Clojure, Julia, and many others have advanced beyond what CL (by the standard) provides. The language needed at least one or two more standards to drive those features forward, but never got them.

[Pay08]

I don't quite understand what you mean by generic collections in this case. Do you want to restrict a list to only contain one specific type?

[Jtsummers]

I wrote that quickly and should have edited it for clarity. What I meant was a new collection type that could be treated as a sequence.

https://www.lispworks.com/documentation/HyperSpec/Body/17_a....

None of the functions operating on sequences are generic, so you cannot create your own type and do a `defmethod` and have them automatically adapt to it. And unlike `print-object` which gets used by format and print and others, there's also no "protocol" (or whatever term you like) generic function you can implement which will make your collection acceptable as a sequence.

You could build something like this, and maybe shadow the standard functions so that it's not a new set of functions from a user perspective, but it's a notable absence in a language with a rich OO system through CLOS. It makes sense that it wasn't in the original spec, but I still think it would have been something that would have been added if the development of CL (as a standard) had continued.

[Pay08]

Oh, I understand. For what it's worth, some implementations do have that as an extension, although I've personally never used it. See http://www.sbcl.org/manual/#Extensible-Sequences.