[whitten]

Is there a set of code written in a subset of Common Lisp which implements the parts of Common Lisp not currently part of this Lua+CL ?

Since there were many Lisp variants when Common Lisp first came out, there ought to be a lot code created when trying to first get compatibility working. How much of that historic code is available now ?

[emarsden]

That's pretty much the objective of SICL, which is "intentionally divided into many implementation-independent modules that are written in a totally or near-totally portable way, so as to allow other implementations to incorporate these modules from SICL, rather than having to maintain their own, perhaps implementation-specific versions".

   https://github.com/robert-strandh/SICL

[lispm]

CMUCL was developed as "open source" (Publich Domain). It was a reworked Spice Lisp. Several other implementations used code from there. Additionally there was an open source LOOP, an open source CLOS implementation, etc.

[postdoc74]

As former maintainer of ECL, another open software Common-Lisp, I can attest that both CMUCL's and SBCL's are extremely useful as reference implementation for much of ANSI CL. I learned a lot regarding LOOP, or how to implement the floating point printer, which has a lot of complexity (and reproducibility) as compared to ANSI C and other standards.

[Guthur]

I thought that was pretty much what the standard was. Being together as much of each of the other Lisps as possible.