ribbit VS STklos

Marc Feeley's lab develops Ribbit Scheme, which is a tiny Scheme implementation. It is an AOT compile which produces a string of bytecode that is interpreted by a VM, of which there are various implementations. The one in C could be compiled to your target microcontroller and thus give you a Scheme REPL.

I have a question regarding Ribbit Scheme. (https://github.com/udem-dlteam/ribbit).

You might want to look at this 400 LOC implementation of Scheme in Haskell: https://github.com/udem-dlteam/ribbit/blob/main/src/host/hs/rvm.hs

Ribbit is a very interesting minimal Scheme driven by Marc Feeley. I spent a bit of time to benchmark some of the target runtimes and the results might be of interest to some.

A small and portable Scheme implementation that supports closures, tail calls, first-class continuations, a REPL and AOT and incremental compilers. All that for a run time footprint around 4 KB! https://github.com/udem-dlteam/ribbit

> No dynamic memory allocation = no garbage collector, no non-deterministic allocation/deallocation, no write barriers, no out-of-memory possibilities, no fragmentation. For a surprisingly large class of programs, this is a great situation!

I know you know this already, but your statement is a little too broad. Those problems all still exist, but are greatly reduced. Data structures still need to be compacted, caches evicted, scratch space cleared, etc. It is just that one class of intractable issues gets removed when dynamic memory allocation goes away.

On a side note, have you seen this? https://github.com/udem-dlteam/ribbit

You should also mention the JS version of Ribbit Scheme which supports tail-calls, continuations, a REPL, an AOT and incremental compilers, and a 4K run time footprint. There are also C, Python and Scheme versions of the Ribbit VM (more to come!). Demo: https://udem-dlteam.github.io/ribbit/repl-max-tc.html Repo: https://github.com/udem-dlteam/ribbit Paper: http://www.iro.umontreal.ca/\~feeley/papers/YvonFeeleyVMIL21.pdf Clearly Ribbit has fewer features than Gambit to achieve a 4K footprint. Gambit (700K footprint) offers a better development environment, in particular precise error messages and live debugging with a REPL in the browser. Gambit also has: - R7RS conformance including R7RS modules - a JavaScript FFI that supports asynchronous calls between JS and Scheme - a thread system build on top of first-class continuations - serializable closures and continuations allowing task migration - access to files on the server using Scheme file I/O - Scheme to JS compilation for fast execution

STklos was indeed born in 2001, but it was the successor of Stk, which is much older. Its first release was in 1993. As far as I know, STkos did use code from STk, so I'm not sure one couldn't say it was born in 1993, as "STk".

That said, I'd just like to mention that I have made an effort to write internals documentation ( general: "hacking", bytecode: "vm") to STklos. It's an interesting implementation because it's easy to add primitives and change the compiler. The internals of the VM is actually a bit more complex... But it's really interesting code.

I've been working on enhancing STklos' macro system. The idea is to implement `syntax-case` properly and use it to obtain a better implementation of `syntax-rules` (the one in STklos is quite old and has some issues).

SRFI 143 has already been accepted, and there are recent pull requests for 170, 215, 217! :)