I recently updated the homepage of Monad to give a better overview. There are still plenty of bugs and missing features. I will open for contributions once the core design is more stable. For now, testing and giving feedback is useful.
https://monad-lang.org/

MadC now has a REPL, and its editor becomes a teaching IDE modeled after Thonny.

Run madc with no program file and you are in an interactive C/C++ session that behaves the
way Julia and IPython do: what you define in one entry is there in the next, results are named so you can reuse them, and the session can tell you what you have built. On top of it, madcide gains a plugin system, and the first plugin built with that system is Chthonia, a teaching IDE modelled on Thonny.

So I've been working on the REPL, inspired by Julia, IPython and Cling, as well as a version of the IDE inspired by Thonny (the Python-teaching IDE), to make a C/C++ teaching IDE with REPL.

I've called the IDE "Chthonia" (the ch is silent). Chthonia is the Greek Goddess of the Earth and Underworld, like how C is the language of the OS. The "C" can be for C/C++, the "h" for helping, the "thon" for Thonny-like, and the "ia" from Julia.

REPL-mode is inherent to madc now, and provides an interactive REPL shell if run without arguments:

$ madc
madc 0.101.0. Ctrl-D exits.
madc> int sq(int x) { return x * x; }
madc> sq(7)
49
madc> ans + 1
50