patty VS Carp

This comment is misleading &| misinformed.

Sum types are built-in [1] for formal parameters. `nil` is only for `ref|ptr` types. In much code you can just use stack allocated value types and there is neither GC concern nor nil concern, but there is also a mode to help: https://nim-lang.github.io/Nim/manual_experimental_strictnot...

Nim has an easy-ish to use Lisp-like syntax macro system where you just receive & process an AST. So, to do the rest you can make libraries adding the feature without relying upon upstream compiler: such as https://github.com/beef331/sumtypes for variables with sum types or pattern matching libs like https://andreaferretti.github.io/patty/ | https://github.com/alehander92/gara.

...except that macros don't change the syntax of the language! They just offer convenience on top of it, most common example is the `=>` lambda operator from the `sugar` module. I do agree, that the pattern matching macro presented in the article is a bit hard to get used to, but you don't have to, if you don't like pattern matching. And of course there are plenty of alternatives available as well, the simplest one imo is https://github.com/andreaferretti/patty

Carp - https://github.com/carp-lang/Carp - "A statically typed lisp, without a GC, for real-time applications." where it's "Ownership tracking enables a functional programming style while still using mutation of cache-friendly data structures under the hood".

Looking for a personal project so open-source would be great, but maturity/production readiness is not really a factor.

The only significant thing i can find so far is https://github.com/carp-lang/Carp.

Anything notable that i might have missed ?

Not CL, but there is ulisp (http://www.ulisp.com/) for microcontrollers, supposed to be really tiny, and there is Carp (https://github.com/carp-lang/Carp) which is without a GC so seems suitable for real-time stuff.

by their powers combined

Everybody is trying to make a more user-friendly Rust. The problem is that it is not clear yet whether that's possible, and if it is, how it may look. I know Vale and have tried it, though it's extremely early to judge anything so far. It does have a much stronger theoretical background than V, but even the theory is not completely clear at this point.

There is also Carp by the way: https://github.com/carp-lang/Carp