If I had to guess:

1. lack of native GC, you had to roll your own by providing a runtime.

2. lack of tail-call elimination in V1 of the spec. This essentially forces you to trampoline everything.

> lack of tail-call elimination

But lisp doesn't need TCO.

Common Lisp doesn't technically require TCO but Scheme does.

IMHO a Common Lisp without TCO is not a serious tool because I cannot write tail-recursive code with it.

Typical programming style in Common Lisp is procedural, not functional.

The CL spec doesn't guarantee tail-call elimination, and most CL implementations don't guarantee it either (it could be on or off depending on the current optimization level). So most people don't bother relying on it.

True. My CL code is atypical because I prefer functional style to iterative style. I know how to use declarations to turn on TCO for implementations that support it, which is most of the big ones. ABCL being a notable exception.

Whoa, what a surprising fact! I had not considered TCO in LISP was "nice to have." That's a good example where it's easy to hack but hard to make production ready.

It sorta has been. As a language design it is already native via the WAT[0] which compiles to web assembly.

[0]: https://webassemblyman.com/wat_webassembly_text_format.html

Do you know why only sorta? My understanding is that only toy implementations exist right now but nothing production ready. I'm poking around Google and GitHub and not finding any new information.

> Implementing Lisp onto WebAssembly is so obvious that you may wonder why somebody did not have this idea long ago.

I did find this on the Femto GitHub and got a chuckle. Yes, dear author, that is exactly the piece of information I want explained. Too funny.

It doesn’t have to very last trapping of a proper LISP if I recall correctly is why I say kinda.

It’s an S expression language though with some similarities to LISP

Thanks for clarifying. I've been speculating on this for a while but haven't had the chops to know what to research. The details folks are providing are yielding much better search results.