List of extensions beyond CL available in lisp implementations, and the status of its spread. The progress can be seen in the "Github Projects" page. This is a leaderboard for tracking the progress across implementations, not a place to post your new ideas. Unimplemented features will be closed immediately. But you can fork an existing Lisp implementation to implement your idea and make a proposal here.
If you know any extentions that are not included in the learderboard, please make a new issue thread.
"Extensions" refers to the additional features implemented in the functions and macros in the :common-lisp package,
not the libraries based on the implementation-specific functions. For example, CAPI in Lispworks does not count as the
language extensions of CL.
Syntactic constructs implemented with macros on top of CL do not count as the "Extensions" either. Therefore, most public libraries that provide macros are not considered "extensions" in this repository's term.
Similarly, simple reader macros (such as hash-table literals) are not considered "Extensions". However, features that require significant changes in the reader algorithm, such as package prefixed sexp and local package nickname, are considered extensions.
Compiler features are considered as "extensions". For example, sb-ext:*inline-expansion-limit* is an example of compiler extensions.