It's very much not thinking outside the box, using lambdas and all, but I threw together an idea.
The colors were just some I thought looked nice together; they could easily be swapped for others or some which might be more meaningful.
The second attachment is a variation on the first one.
And, then, the last could be a shorter (and, obviously, more compact) version that could be used in specific cases where called for.
For example, the longer, spelled out, version wouldn't make sense in a situation like the fourth attachment but the shorter, more symbolic version would.
I'd, originally, tried to come up with, like, a wireframe globe icon but using parentheses with a lowercase lambda in the middle of it and, maybe, a mouse arrow hovering over it, to evoke those logos of the World Wide Web that're pretty common but the parens just kept looking awkward and it felt really busy, for a logo (very last attachment is one saved attempt, for amusement).
In any case, the parentheses are Fira Code, the lambda is Hack, and the rest of the letters ("rtanis") are Gidole. I'm pretty certain all are free and open-source.
ArtanisLogo1.svg
web-development-frameworks2.png
ArtanisLogo.png